2024 Vol. 14, No. 1

Display Method:
Carbon-oxygen balance analysis of the terrestrial ecosystem of Beijing-Tianjin-Hebei region in 2025
JIA Gang, LI Darui, KONG Cuixia, ZHOU Zhifeng, GUO Junguang
2024, 14(1): 1-7. doi: 10.12153/j.issn.1674-991X.20230243
Abstract(232) HTML (114) PDF(1032KB)(67)

According to the data of Beijing-Tianjin-Hebei region in 2020, the carbon release and oxygen consumption, and carbon fixation and oxygen release in 2020 were calculated, and the carbon release and oxygen consumption, carbon fixation and oxygen release, as well as the demand area of ecological land in 2025 were calculated. The results showed that the carbon release and oxygen consumption in Beijing-Tianjin-Hebei region in 2020 were 125.5761 million tons and 143.5337 million tons, respectively, and in 2025, they would be 135.957 0 million tons and 163.392 0 million tons. In 2025, the required standard ecological land area to maintain carbon balance in Beijing-Tianjin-Hebei region was smaller than the existing standard ecological land area, indicating that there was no need to increase the area. However, from the perspective of different provinces, the ecological land area of Beijing and Hebei could meet the needs of carbon and oxygen balance, but Tianjin should increase the standard ecological land to meet the needs of maintaining carbon and oxygen balance in the city. In the process of actual social and economic development, the area of ecological land would be slightly adjusted, and the structure and quality of ecological land would also change. Therefore, in actual production and scientific research, it should be gradually corrected according to the actual annual change of ecological land.

Inventory and spatiotemporal distribution characteristics of greenhouse gas emissions from vehicles on expressways in Kunming City
CHEN Zhenyu, HE Chao, LI Jiaqiang, FU Mingliang, XU Jiachen, LI Ju
2024, 14(1): 8-16. doi: 10.12153/j.issn.1674-991X.20230226
Abstract(184) HTML (56) PDF(3270KB)(43)

In order to study the emission inventory of greenhouse gases (GHGs) such as CO, CO2, N2O and CH4 from motor vehicles on expressways in Kunming City, the expressway passenger traffic flow data and vehicle GPS information data in Kunming City in 2021 were used to obtain the basic data such as vehicle type composition and vehicle flow on the expressway network. The localized modified MOVES model was applied to calculate the emission factors of CO, CO2, N2O and CH4 of vehicles on the expressways. Based on the actual traffic flow data, GHG emission factors and the actual road information of expressways, the GHG emission inventory of the expressways in Kunming City was constructed, and its emission characteristics and spatial distribution characteristics were analyzed. The results showed that the emissions of CO, CO2, N2O and CH4 from expressway vehicles in Kunming City in 2021 were 20 337.1, 2 575 677.1, 33.8 and 72.9 t, respectively, with a total CO2 equivalent of 2 626 212.5 t. According to emission standards, the vehicles with national stage Ⅳ emission standards were the main contributors to the four types of GHG emissions. According to vehicle types, passenger cars were the main contribution models to CO, CO2 and N2O emissions, while large buses were the main contribution models to CH4 emissions. Divided by fuel type, gasoline vehicles were the main contribution models of CO, CO2 and N2O, while diesel vehicles were the main contribution models of CH4 emission. The temporal distribution characteristics showed that the emission intensity had a positive correlation with the traffic flow in different time periods, and the GHG emission intensity of motor vehicles on expressways in Kunming City showed a "bimodal" change within 24 h. The spatial distribution of emission intensity was closely related to road network density and regional traffic flow. The region with higher road network density and higher traffic flow had higher emission intensity.

Study on carbon capture technology and development trend of exhaust gas from ocean-going ships
QU Ziyi, KONG Cunjin, YIN Honghao, ZHANG Derong, DU Min
2024, 14(1): 17-24. doi: 10.12153/j.issn.1674-991X.20230303
Abstract(329) HTML (138) PDF(1367KB)(140)

The urgency of reducing carbon dioxide as the main greenhouse gas is becoming increasingly prominent, and a series of international shipping carbon reduction measures have entered the stage of compulsory enforcement. Carbon capture technology is the most direct and effective technology for reducing carbon dioxide emissions. However, the research and application of carbon capture technology for ship exhaust is still in its infancy, and there is an urgent need for a large amount of in-depth targeted research. Therefore, the carbon capture technology and its development trend for the exhaust gas of ocean-going ships were discussed. Firstly, the background and current status of carbon capture technology for ship exhaust were introduced, and the current industrial source exhaust treatment schemes and mainstream carbon capture technologies were analyzed and studied. Then, the carbon emission requirements of the International Maritime Organization for the shipping industry were quantified, and the feasibility and applicability of various carbon reduction technologies in the field of shipping were compared. A detailed study was conducted on the challenges and influencing factors encountered by ocean-going vessels using carbon capture technology, including technical requirements, technical costs, equipment reliability, energy consumption, secondary pollution, etc. Finally, based on the combination of historical data and future trend prediction, prospects were made for the future development of carbon capture technology for ocean-going ship exhaust, and improvement methods were proposed to help reduce the carbon footprint of ship emissions.

Evaluation on greenhouse gas emission reduction of the whole county's promotion project of livestock and poultry manure resource utilization
ZHU Zhicheng, ZHONG Minzheng, HOU Lei, TIAN Yucong, FU Jintao, YANG Yang
2024, 14(1): 25-32. doi: 10.12153/j.issn.1674-991X.20230486
Abstract(259) HTML (121) PDF(776KB)(65)

In order to explore the change of greenhouse gas (GHG) emissions of manure disposal before and after the implementation of the whole county's promotion project of livestock and poultry manure resource utilization, referring to IPCC Guidelines for National Greenhouse Gas Inventories,, the accounting and assessment of the new manure disposal engineerings in X City was carried out. The results showed that the net carbon emission was 479.31 t (in terms of carbon dioxide equivalent, the same below) after project implementation according to the executed solution, and compared to that before project implementation, it was reduced by 21172.81 t. The carbon emission per unit of livestock waste disposal was reduced by 513.48 kg, a decrease of 97.79% after project implementation according to the executed solution. In terms of carbon emission from livestock manure disposal by different processing units, the carbon emission of aerobic composting was reduced by 50% compared with that of open-air manure storge, and the carbon emission of closed anaerobic fermentation was reduced by 83.04% compared with that of anaerobic oxidation pond. Based on the above evaluation results, it was recommended to apply the model of solid manure mulching aerobic compost, liquid manure closed storage fermentation and manure full return to the field, to further reduce the GHG emissions of manure disposal.

Evaluation method of synergistic benefits enhancement technologies for pollution abatement and carbon reduction in the ironmaking process
YIN Zhou, KUANG Yue, LIU Dandan, ZHAO Yazhou, ZHANG Xin, LI Yanping
2024, 14(1): 33-42. doi: 10.12153/j.issn.1674-991X.20230560
Abstract(173) HTML (78) PDF(6481KB)(44)

To promote the synergetic reduction technologies of pollution and carbon, the ironmaking process technology was taken as the research object, and the synergistic benefits of source and process-control technologies, end treatment technologies, and low-carbon technologies were evaluated from three perspectives of synergy level, cost-benefit, and environmental impact. In terms of synergy between pollution abatement and carbon reduction, the source and process-control energy-saving technologies could effectively promote the synergistic reduction of pollutants and carbon emissions of the ironmaking process, while end treatment technologies could not synergistically reduce pollutants and carbon emissions. Specifically, the green hydrogen smelting technology and flux-based pellet preparation technology had a high degree of synergy in reducing pollution and carbon emissions. The injection coke oven gas technology, blast-furnace gas recovery technology, and dual preheating of the hot blast furnace could synergistically reduce VOCs and carbon emissions. Under China's current carbon trading prices, energy-saving technologies and pollutant treatment technologies could be popularized according to the cost-benefit analysis. The cost of green hydrogen smelting and CCS technologies was declining with the rise of carbon trading prices. Green hydrogen smelting and pollutant treatment technologies were the most effective ways to reduce environmental impact, while other energy-saving technologies could also correspondingly reduce environmental impact. Under existing conditions, the implementation of CCS technologies would increase environmental impact. Based on the assessment of synergy between pollution abatement and carbon reduction, economic benefits and environmental benefits, the source prevention and energy-saving technologies in the ironmaking process could be promoted as China's current pollution reduction and carbon reduction synergy technologies. With the increase in carbon emission trading prices and green transformation in the future, green hydrogen smelting and CCS technologies would have great application prospects.

Spatio-temporal distribution of phosphorus pollution in the upper reaches of Beijing-Hangzhou Canal and its source analysis
JIN Meng, LAN Yaqiong, DING Miao, JI Chunhong, LIU Rui
2024, 14(1): 43-51. doi: 10.12153/j.issn.1674-991X.20230546
Abstract(143) HTML (49) PDF(3414KB)(44)

To reveal the reason why total phosphorus failed to consistently meet the Class Ⅲ standard of Environmental Quality Standards for Surface Water (GB 3838-2002) in Tongxiang segment of Beijing-Hangzhou Canal, 24 sampling sites were set up in Tongxiang section of the mainstream and 18 sampling sites were set up in the tributaries to carry out water quality monitoring and study the spatio-temporal changes of phosphorus pollution. The main sources of phosphorus pollution in key river segments were analyzed by the principal component analysis based on routine water quality indexes, and the correlation analysis of strong load index in each principal component factor and three-dimensional fluorescence component. The quantitative evaluation of the contribution of major pollution sources was conducted using the absolute principal component-multiple linear regression model. The research results revealed that the total phosphorus concentration originating from Tongxiang segment of Beijing-Hangzhou Canal's upper reaches was 0.14-0.20 mg/L, while the water quality along the monitoring sites 5-7, 9 and 21-24 tended to deteriorate significantly, with the highest concentration reaching 0.40 mg/L. Certain tributaries into the mainstream exhibited poor water quality, and the total phosphorus concentration reached 0.44 mg/L. Three main factors were obtained by the principal component analysis. Factor 1 was mainly loaded with ammonia nitrogen and dissolved phosphorus, and was significantly correlated with protein-like component, representing production and domestic pollution. Factor 2, with permanganate index, dissolved phosphorus and particulate nitrogen as the main loads, was significantly correlated with humic-like component, representing agricultural sources. Factor 3, with particulate phosphorus and nitrogen as the main loads, was significantly correlated with turbidity, representing the dock and sediment source. The phosphorus pollution in the upper reaches of the canal mainly occurred at the monitoring sites 5-7 and 9, mainly from the dock and sediment sources, with contribution rates of 65.9% and 31.8% during the high and flat water periods, respectively. At monitoring sites 21-24, agriculture was the primary source of phosphorus pollution, contributing at rates of 34.0% and 32.1% during the high and flat water periods, respectively. Furthermore, the production and domestic pollution exhibited a significant influence during the high water periods. The contribution rates of the prodution and domestic to the monitoring sites 5-7, 9 and 21-24 were 42.6% and 31.8%.

Community structure and dominant species niche characteristics of periphytic algae in the Beijing section of the Chaobai River
SHENG Xiangrui, LUO Zunlan, SUN Guang, XIAO Nengwen, KANG Lingling, LI Huiqing, HAN Jing
2024, 14(1): 52-59. doi: 10.12153/j.issn.1674-991X.20230588
Abstract(230) HTML (50) PDF(4515KB)(40)

To clarify the changes in phytoplankton communities in Chaobai River basin of Beijing, 17 sampling sites of periphytic algae were selected and two surveys were conducted in May 2021 and September 2021. Community structure was analyzed by applying the number of periphytic algae species and cell density, and the dominance index of the dominant species(Y) and dominant species turnover rate (R) were calculated. The niche width (Bi), niche overlap (Oik) and overall relevance were used to analyze the niche characteristics of the dominant species. The results showed that a total of 109 species of periphytic algae belonging to 4 phylums and 41 genera were found and recorded in two phases. There were 8 dominant species (Y>0.2) of periphytic algae in all sampling periods. The niche width values of dominant species ranged from 0.140 6 to 0.420 9. The niche overlap values of the dominant species ranged from 0.055 1 to 0.897 1, and the overall correlation measurement results were significantly positive correlations. The dominant species were greatly affected by seasonal alternation, and the commonality of resource utilization among dominant species was relatively small. The structure of the periphytic algae tended to stabilize, and the overall development was toward positive succession. The research shows that periphytic algae, as a biological indicator, can respond sensitively to changes in environmental conditions. Based on the niche characteristics of the dominant species of periphytic algae, the community structure and succession characteristics of periphytic algae can be described.

Distribution characteristics and cause of fluoride in Dalinuoer Lake in Inner Mongolia
CHEN Ru, TANG Yufeng, YANG Jun, LI Tao, WANG Shuhang, CHE Feifei, GUO Yunyan, BAI Kai
2024, 14(1): 60-70. doi: 10.12153/j.issn.1674-991X.20230149
Abstract(89) HTML (60) PDF(3834KB)(29)

Dalinuoer Lake is located in Inner Mongolia of Plateau in Northern China, which is a typical primary high fluorine area. In order to reveal the distribution characteristics and causes of fluoride in the lake, the overlying water and surface sediments of Dalinuoer Lake were collected, and the spatial distribution and occurrence of fluoride were investigated in detail. The source of fluoride in Dalinuoer Lake and the influence of environmental factors on fluoride in water were discussed. The results indicated that the fluoride content in Dalinuoer Lake ranged from 3.91 to 4.61 mg/L, with an average value of 4.41 mg/L, significantly exceeding Grade Ⅴ threshold (1.5 mg/L) for Environmental Quality Standards for Surface Water (GB 3838-2002). The fluoride content in surface sediments varied from 252.69 to 940.14 mg/kg, with an average value of 643.07 mg/kg. Spatially, the area with high fluoride content was mainly distributed in the southwest and middle areas of Dalinuoer Lake. Regarding forms, the fluoride concentration in various forms generally showed a pattern of residual > organic bound > water soluble > iron-manganese bound > exchangeable, and the water-soluble fluoride was easy to release to the water body under certain environmental conditions, which became the main endogenous source of fluoride in Dalinuoer Lake. The stability risk assessment indicated that the fluoride in the sediment of Dalinuoer Lake was generally at a moderate risk level. The high fluorine water in Dalinuoer Lake was affected by environmental factors such as cold and dry climate, special hydrochemical conditions, the evaporation and concentration characteristics of inflow rivers and internal lakes under high natural background value caused by stratigraphic lithology. The results could provide theoretical support and scientific basis for the ecological environment security evaluation of Dalinuoer Lake and other lakes with high fluoride.

Distribution characteristics of Chinese sturgeon in the Yangtze River based on environmental DNA
ZHOU Quan, DU Hao, WANG Jie, SHAO Yun, YAN Zhenguang
2024, 14(1): 71-78. doi: 10.12153/j.issn.1674-991X.20230203
Abstract(130) HTML (49) PDF(7877KB)(32)

Chinese sturgeon (Acipenser sinensis) is a flagship species in the Yangtze River basin. Under the background of the 10-year fishing ban in the Yangtze River, it is of great significance to study the nondestructive testing technology of Chinese sturgeon. Environmental DNA (eDNA) technology is an environmentally friendly biological monitoring technology, which can detect species without direct observation or capture of the organism. It was tried to screen out the specific primers that could be used to detect the eDNA of Chinese sturgeon from the literature. In September 2020, four areas where Chinese sturgeon often appeared were selected in the middle and lower reaches of the Yangtze River, and three-dimensional sampling was performed on each section. eDNA of 16 sites was extracted, and the screened primers were used to detect the eDNA of Chinese sturgeon, in order to try to explore the distribution characteristics of Chinese sturgeon. A group of primers that could detect the eDNA of Chinese sturgeon was successfully screened. By using this primer, the eDNA of 4 species of sturgeon in the Yangtze River including the Chinese sturgeon was successfully detected, and about 3 million sequences of sturgeon were measured. Based on the sequencing results, the differences in the eDNA of Chinese sturgeon detected in different sections were analyzed. It was found that the eDNA in Yichang River section was the most, and the eDNA in Dongting Lake mouth section was the least, and there were significant differences in the eDNA detection between the surface and bottom waters. The study found that the screened primers could be used for the detection of eDNA of Chinese sturgeon, and the detection results of eDNA were consistent with the historical investigation and migration characteristics of Chinese sturgeon. There were significant differences in the amount of Chinese sturgeon eDNA detected under different water depths, which indicated that mixed or three-dimensional sampling may be more comprehensive for the detection of Chinese sturgeon eDNA in the future investigation.

Pilot process of arsenic-containing groundwater purification by iron-based granular adsorbent fixed bed column
WU Xiaolong, HUANG Zhengyu, LI Angzhen, DUAN Changhui, LI Rongle, WU Kun
2024, 14(1): 79-88. doi: 10.12153/j.issn.1674-991X.20230286
Abstract(88) HTML (37) PDF(4900KB)(23)

Arsenic (As) pollution in groundwater has become an important environmental issue in China. In order to purify the arsenic-contaminated groundwater in rural areas, an iron-based granular adsorbent (FMGA) capable of synchronously removing As(Ⅲ) and As(Ⅴ) from water was developed and packed into an adsorption fixed bed. A pilot-scale water treatment system was designed and established with a fixed bed as the core unit, which had a good capability for the treatment of As-contaminated groundwater. The results showed that during the continuous operation of 33 days, the residual As concentration in the effluent of the pilot-scale system was continuously below the limit of Standards for Drinking Water Quality (GB 5749-2022 ) (10 μg/L). The breakthrough time of the fixed bed reached 786 h in the first cycle. After the in-situ regeneration using 0.2 mol/L NaOH solution, the breakthrough time of the fixed bed for reuse could still reach 750 h, and the recovery rate of its arsenic adsorption capacity was close to 91%. The turbidity of the effluent for the pilot-scale system was close to zero, and the concentrations of iron and manganese ions were both lower than the limits of the sanitary standard (Fe<0.3 mg/L, Mn<0.1 mg/L). FMGA could be efficiently regenerated and reused without secondary pollution. The adsorption kinetics indicated that the adsorption process of As by FMGA was consistent with the quasi-second-order kinetic model, and As could be removed by chemisorption. The adsorption isotherm showed that the theoretical maximum adsorption capacity of FMGA for As was 74.94 mg/g (pH=7.0). According to the surface characterization results, the maximum load of FMGA was 89.39 N, indicating an excellent mechanical strength.

Study on the composition and risk of chlorinated organic compounds in landfills and surrounding groundwater
ZHENG Jing, PAN Qi, WANG Yuxin, SHA Haoqun, WANG Xiange, LIU Hongbao, HE Xiaosong
2024, 14(1): 89-97. doi: 10.12153/j.issn.1674-991X.20230351
Abstract(242) HTML (106) PDF(2075KB)(46)

Chlorinated organic compounds are difficult to degrade and highly toxic, and landfills are important gathering places for chlorinated organic compounds. To evaluate the uncertain risk of landfill leachate contaminating groundwater with chlorinated organic compounds, a groundwater sample was collected from an informal landfill site. Combined with the collected data on the composition and concentration of chlorinated organic compounds in groundwater near 13 landfills in 6 countries including China, Germany, the United States, Spain, Poland, and Norway, a risk assessment model was used to assess their health risks. A total of 41 different types of chlorinated organic compounds, categorized into 10 classes, were identified in the groundwater near the landfills studied. The chlorinated cycloalkanes pose the highest carcinogenic risk, with all measurements surpassing 10−4, far exceeding the tolerable limits for human exposure, and presenting significant health hazards. The F-53B of chloropolyfluoroalkyl ether sulfonate has the lowest carcinogenic risk, between 10−6 and 10−4, and has a possible carcinogenic risk. The non-carcinogenic risk of chlorinated alkanes is the highest, among which the non-carcinogenic risk value of α-hexachlorocyclohexane (HCH) exceeds 1, more than the acceptable level for human beings. However, chlorinated organic pesticides such as propiconazole and permethrin have the lowest non-carcinogenic risk, and their non-carcinogenic risk value does not exceed the acceptable level for human body. Greater emphasis should be placed on risk management strategies for specific chlorinated organic compounds, namely γ-HCH, chlorobenzene, and 1,2-dichlorobenzene. Various methods, including oxidative dechlorination, reductive dechlorination, and co-metabolism dechlorination, can be employed to expedite the dechlorination and degradation processes, ultimately eliminating associated risks.

Distribution characteristics of chlorinated hydrocarbons in contaminated plots of typical organic chemical plants and risk assessment based on Monte Carlo simulation
ZHOU Liyang
2024, 14(1): 98-111. doi: 10.12153/j.issn.1674-991X.20230197
Abstract(268) HTML (69) PDF(13264KB)(60)

A typical organic chemical plot in the Yangtze River Delta was selected as the research object. A total of 651 soil samples and 30 groundwater samples were collected for analysis and determination. The pollution level and spatial distribution characteristics of chlorinated hydrocarbons (CAHs) in the environment were studied. The health risk probability of CAHs in soil and groundwater was analyzed using Monte Carlo simulation method. The results showed that the concentration of most CAHs was in normal distribution, and gradually decreased with the increase of depth. Trichloroethylene pollution in soil and groundwater was the most serious. The contaminant plumes were mainly concentrated in the southwest and northwest of the plot. Trichloroethylene and chloroform were the main pollutants causing health risks. The probability of a carcinogenic risk greater than 10−6 for trichloroethylene in soil was 87.2%, the probability of hazard quotient exceeding 1 was 71.76%, and the probability of chloroform hazard quotient exceeding 1 was 81.28%. The daily soil intake had the highest sensitivity to soil cancer risk (31.9%). The skin surface viscosity coefficient had the highest sensitivity to groundwater cancer risk and hazard quotient, being 16.9% and 23%, respectively. Inhaling gaseous pollutants from the underlying soil in indoor air was the main exposure pathway that caused both carcinogenic and non-carcinogenic risks in soil. Inhaling gaseous pollutants from underground was the main exposure pathway that caused both carcinogenic and non-carcinogenic risks in groundwater.

Assessment and amendment methods of heavy metal non-carcinogenic health risks in agricultural land around smelters
WU Jianfang, WANG Hongmei
2024, 14(1): 112-120. doi: 10.12153/j.issn.1674-991X.20230517
Abstract(161) HTML (75) PDF(8376KB)(41)

To scientifically quantify the non-carcinogenic health risks of soil combined polluted by heavy metals, the Target Organ Toxicity Dose (TTD) model and Weight of Evidence (WOE) analysis model were introduced to modify the non-carcinogenic health risks assessed by traditional human risk assessment (HRA) model. Adults health risks of heavy metals in agricultural soils surrounding a smelting plant in Central China by using the three methods were compared as a field case. The results showed that the average concentrations of heavy metals cadmium (Cd), lead (Pb), chromium (Cr), and arsenic (As) in the soil were 0.37, 36.65, 69.06, and 7.66 mg/kg, respectively. Among them, Cd, Pb, and Cr exceeded the soil background values to varying degrees. Non-carcinogenic health risk values assessed by HRA (HIHRA) for these four heavy metals ranged from 2.27×10−3 to 3.35×10−1. Amended by TTD and WOE model, HITTD and HIWOE values for the four heavy metals ranged from 1.64×10−2 to 5.50×10−1 and from 1.08×10−2 to 6.09×10−1, respectively. The average values of HITTD and HIWOE were 1.88 and 1.17 times higher than that of HIHRA, respectively. The study emphasized the importance to consider the multi-target organs effect of a specific heavy metals and the interactions among the heavy metals for assessing the non-carcinogenic health risks on agricultural land contaminated with multiple heavy metals. This approach helps to prevent the limitations of traditional risk assessment methods, which may not accurately reflect the real health hazards posed by polluted soil to the population exposed to it.

Effects of thermal desorption on the complex contaminated soils of polycyclic aromatic hydrocarbons and heavy metals
WU Bingze, ZHANG Wenwen, LIU Zhaoyue, MA Fujun, LI Haibo, GU Qingbao
2024, 14(1): 121-129. doi: 10.12153/j.issn.1674-991X.20230320
Abstract(113) HTML (41) PDF(6172KB)(29)

Thermal desorption technology is widely used for the remediation of contaminated sites. However, the combined effects of thermal desorption on the complex contaminated soils of polycyclic aromatic hydrocarbons (PAHs) and heavy metals were still unclear. The complex contaminated simulated soils of PAHs and heavy metals were selected to investigate the effects of thermal desorption temperature (220-400 ℃) and residence time (5-60 min) on PAHs in the soil and to analyze the effects of thermal desorption temperature (310, 340, and 370 ℃) on the morphological distribution of heavy metals (Cu, Pb, As, and Cd) in soil under air and nitrogen atmosphere. The results showed that the removal of PAHs from contaminated soil increased significantly with the increase in thermal desorption temperature and residence time. The proportion of low-ring PAHs gradually decreased while that of high-ring PAHs gradually increased. After thermal desorption treatment in both atmospheres, the proportion of Cu, Pb, and As weakly acid-extracted states increased slightly, while the proportion of Cd weakly acid-extracted states decreased significantly. The conversion trends of the reducible and oxidizable states were different. The proportion of residue states of four heavy metals, Cu, Pb, As, and Cd, increased gradually with the increase of thermal desorption temperature, which indicated that thermal desorption was beneficial to the immobilization of the four heavy metals. Compared with air, the proportions of oxidizable and residual states of four heavy metals increased under nitrogen conditions. The proportions of Cu and Pb reducible states decreased significantly, while the proportions of As reducible states decreased and the proportions of Cd reducible states did not change significantly. These results showed that nitrogen was more favorable for the stabilization of Cu, Pb, and Cd. On the contrary, the air was more beneficial to the stabilization of As.

Study on methods for determining the remediation target value of soil arsenic in contaminated sites
LIU Hupeng, DU Ping, YUAN Bei, ZHANG Yunhui, CHEN Juan, ZHANG Hao
2024, 14(1): 130-138. doi: 10.12153/j.issn.1674-991X.20230267
Abstract(138) HTML (81) PDF(9901KB)(51)

The determination of remediation target value is an important part of the process of environmental regulation for contaminated sites, and is usually obtained based on risk assessment to calculate risk control values. However, when it comes to arsenic-contaminated sites, the remediation target values obtained by using the recommended model and parameter derived from Technical Guidelines for Risk Assessment of Soil Contamination of Land for Construction (HJ 25.3-2019) are often lower than the soil arsenic environmental background values, making it difficult to meet regulatory requirements. The methods for determining the target values of soil arsenic remediation in contaminated sites were systematically reviewed, and the implementation paths and practical applications based on soil environmental criteria values, traditional risk assessment, tiered risk assessment, equivalent risk assessment and soil arsenic environmental background values correction were discussed. Combining with China's regulatory strategy for contaminated sites and the current situation of arsenic-contaminated sites development and reuse, a method for determining soil arsenic remediation target values based on soil environmental background values, tiered risk assessment, and bioaccessibility-related parameter correction was proposed, aiming to provide more scientific and reasonable solutions for the remediation and safe reuse of arsenic contaminated sites in China.

A review of heavy metal and polycyclic aromatic hydrocarbon pollution treatment and remediation technologies in coal mine soils
HUA Jie, WANG Jianyuan, CHEN Yunwei, WANG Jian, CHEN Zheng, LIU Yangyang
2024, 14(1): 139-147. doi: 10.12153/j.issn.1674-991X.20230524
Abstract(106) HTML (61) PDF(3117KB)(43)

Soil heavy metal and organic matter pollution is a serious problem currently facing many coal mine sites and surrounding areas, threatening the health of residents, and effective measures should be taken to solve it. Based on the analysis of the sources and hazards of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in soil around coal mining areas, it is found that heavy metal elements are difficult to be degraded under natural conditions, leading to their accumulation in living organisms, and that PAHs are carcinogenic, teratogenic and mutagenic. By comparing the advantages and disadvantages of physicochemical remediation, phytoremediation and bioremediation in the treatment of heavy metals and PAHs-contaminated soils, it was found that phytoremediation and bioremediation are highly dependent on climate and environment, and that physical remediation is more costly and energy-consuming, so it is put forward that remediation technologies for soil pollution around mining areas need to be further innovated to realize the viewpoints of collaborative development in multiple fields and multiple disciplines. Through continuous technological innovation and the joint application of multiple remediation methods, we can achieve the purpose of effectively treating heavy metal and PAHs pollution in and around coal mine areas, realize the reuse of soil, and then realize the benign interaction between environmental protection and sustainable economic development.

Effects of activated sludge extraction on rhizosphere soil microbial community structure of rice
TONG Tong, JI Rongting, XU Qiujin, WANG Jianguo, LI Xiao’ou, ZHANG Yue
2024, 14(1): 148-157. doi: 10.12153/j.issn.1674-991X.20230271
Abstract(97) HTML (34) PDF(1802KB)(30)

A root box experiment was conducted to reveal the mechanisms by activated sludge extracts regulating rice growth and improving soil physicochemical properties from the perspective of soil rhizosphere microorganisms. The experiment was designed to investigate the effects of the extracts application with nitrogen reduction on rice soil physicochemical properties and rhizosphere microorganisms by conducting different treatments (T1, blank control; T2, conventional fertilizer control; T3, 30% nitrogen reduction with 0.2 g/kg extract solution; T4, 30% nitrogen reduction with 0.4 g/kg extract solution; T5, full replacement of fertilizer nitrogen with 8 g/kg extract solution equivalent to 75% nitrogen reduction). The results showed that the application of extracts significantly increased the leaf area, biomass and chlorophyll content of rice seedlings. Compared with conventional fertilizer applications, the application of extracts could significantly increase soil pH, reduce soil conductivity, increase soil soluble organic carbon and reduce soil nitrate and ammonium nitrogen content. β-diversity results showed that the effect of extracts application on soil microbial properties was more prominent in rhizosphere and near-rhizosphere soils, with significant differences in bacterial community structure and diversity between the different extracts treated groups, blank group and the control group (P<0.05). Application of extracts significantly increased the relative abundance of microorganisms associated with organic pollutant degradation and carbohydrate metabolism, such as Flavisolibacter, Candidatus_Udaeobacter, and Sphingomonas, which increased by 151% to 541%, 26% to 320% and 55% to 364%, respectively. By FAPROTAX soil function prediction analysis, it was found that the main soil microbial communities enhanced after the application of the extracts were chemoheterotrophy, aerobic chemoheterotrophy, nitrate reduction, nitrogen fixation, nitrification and aromatic compound degradation, which were related to the behaviours of soil carbon cycling, nitrogen cycling and organic pollutant degradation. The results of the study indicated that the application of extracts could improve the structure of soil rhizosphere and near-rhizosphere microbial communities, increase the abundance of related bacteria communities, and regulate carbon and nitrogen cycles of rhizosphere and near-rhizosphere soil, thereby promoting the growth of rice seedlings and improving soil characteristics. Therefore, the results of this study can provide a new pathway for the resource utilization of activated sludge.

A review of geomagnetic noise sources and denoising methods for landfill sites
NAI Changxin, JIA Zhaozhi, LIU Kuan, SUN Xinyu, QIAN Can, LIU Yuqiang, YAO Guangyuan, XU Ya
2024, 14(1): 158-163. doi: 10.12153/j.issn.1674-991X.20230276
Abstract(74) HTML (31) PDF(676KB)(25)

Landfills are the primary means of centralized solid waste disposal, and it is also the place where the environmental impact of solid wastes on groundwater is concentrated. The leakage of HDPE membrane of the impermeable layer is the main way to lead to groundwater pollution. It is of great significance to carry out the rapid detection and accurate positioning of the leakage of the impermeable layer. The traditional electrical leakage method is difficult to detect the damage of the lower liner of the double-layer or multilayer liner system. The improved electromagnetic method based on the traditional electrical method shows the potential of detecting the lower liner. However, it is urgent to solve the problem of electromagnetic noise interference in the complex service and human environment of the landfill site and the earth's magnetic field environment. The in-depth analysis of the magnetic detection principle and signal characteristics, as well as the overview of the background magnetic noise types, sources, characteristics and electromagnetic noise denoising methods, was thus performed. It is concluded that under specific conditions, the closer the loophole is, the stronger its magnetic field signal is; the landfill noise is mainly derived from the geomagnetic and humanities magnetic fields, and different noises have different characteristics and require different processing; the denoising process is first pre-processed to exclude interference, followed by the selection of appropriate filtering or measurement method to remove noise in the detection.

Characterization of heavy metals solidification during hydrothermal synthesis of tobermorite from incineration fly ash
LI Xiaoding, TIAN Shulei, WU Zongru, WU Qian, WANG Cuo, ZHOU Jieya, ZHOU Xiuyan, WU Hao
2024, 14(1): 164-173. doi: 10.12153/j.issn.1674-991X.20230312
Abstract(116) HTML (41) PDF(9806KB)(30)

The environmentally safe utilization and disposal of municipal solid waste incineration fly ash is an urgent problem that needs to be addressed by environmental management and industry departments. To mitigate the potential risk of heavy metals in incineration fly ash to the environment, the effects of Ca/(Si+Al) (molar ratio) on the crystalline phase composition, microscopic morphology, and surface functional groups of hydrothermally synthesized tobermorite using washed fly ash were investigated. Additionally, the changes in leaching concentration, leaching rate, liquid-phase mobility, morphological distribution, and environmental risk of heavy metals (Hg, Ni, Pb, Zn, and Cr) during the hydrothermal process were examined. The results demonstrated that Ca/(Si+Al) had a significant impact on the type of hydrothermal products, higher Ca/(Si+Al) molar ratio was favorable for inhibiting the formation of zeolite-like structures and promoting the formation of tobermorite. As tobermorite formed, the toxic leaching concentrations and leaching rates of the five heavy metals in the hydrothermal products gradually decreased. Compared to washed fly ash, the leaching concentrations of heavy metals in the hydrothermal products under the optimal ratio (1.1) condition decreased by 99.5%, 99.0%, 99.4%, 88.9%, and 63.7%, respectively, while the leaching rates reached as low as 0.25%, 0.08%, 0.01%, 0.01%, and 2.73%. Moreover, the migration of heavy metals to the liquid phase was limited to 1.41%, 4.28%, 0.29%, 0.05%, and 0%, indicating that most heavy metals were stably present in solid-phase products rather than migrating to the hydrothermal liquid. This was attributed to the formation of tobermorite, which increased the proportion of the five heavy metal residue states and decreased heavy metal mobility. The risk assessment code (RAC) results revealed that RAC of the five heavy metals in the hydrothermal products under the optimal ratio conditions was less than 10%, reaching an environmentally low-risk level. In summary, hydrothermal synthesis of tobermorite was a promising method for stabilizing heavy metals in incineration fly ash, providing a viable alternative for the safe disposal and recycling of hazardous wastes rich in heavy metals.

Mechanism of release of heavy metals in solidified/stabilized bodies of fly ash piperazine chelating agents
MU Zongyu, YANG Yufei, WANG Fei, GUO Mingkun, HUANG Qifei, YANG Yanmei, LUO Zhongli
2024, 14(1): 174-183. doi: 10.12153/j.issn.1674-991X.20230106
Abstract(140) HTML (45) PDF(18658KB)(27)

Heavy metals in fly ash from municipal solid waste incineration are major environmental hazard, and their solidification/stabilization have become the primary problem in fly ash treatment and disposal. Portland cement is commonly used to treat waste incineration fly ash. In order to reduce energy consumption and improve product efficiency, the ability of a new macromolecular organic chelator, sodium piperazine-N,N'-bis-dithiocarboxylate (TS300), to solidify heavy metals in fly ash in concert with different amounts of cement (30%, 40%) was investigated. The effects of TS300 on the leaching concentration, chemical morphological changes, and microstructure of the target heavy metals Zn, Cd, Cr, Pb, and Ni were investigated. The results showed that TS300 co-cement could effectively immobilize the heavy metals in fly ash and reduce the leaching concentration by more than 60%. The chemical morphology of heavy metals Cr, Cd, Pb and Ni moved to a more stable direction overall after solidification. With the rise of TS300 and cement addition, curing block crystal composition, acid resistance strength, and pore density increased. The curing block with 40% addition of ordinary silicate cement and 8% addition of TS300 had the lowest heavy metal leaching concentration and the best curing effect. In summary, investigating the effect and mechanism of TS300 co-cement solidification/stabilization of heavy metals could analyze the effect of cement synergistic agents in curing and stabilizing fly ash heavy metals, reduce the environmental risk of landfill leachate, and provide new ideas for the subsequent research and development of fly ash heavy metal chelating agents.

Whole process simulation of MSW gasification and melting system based on Aspen Plus
WU Song, DANG Wenbo, SHI Xiaojun, LI Wenjian, YUAN Shuxia, FAN Yuguang
2024, 14(1): 184-193. doi: 10.12153/j.issn.1674-991X.20230349
Abstract(126) HTML (39) PDF(5198KB)(26)

The gasification and melting process of municipal solid waste (MSW) can reduce the formation of dioxins and melt heavy metals, which is a clean and efficient solid waste treatment method. At present, most of the research is on the pyrolysis characteristics of MSW and the generation and emission of pollutants, while the research on the influence between the modules of the gasification and melting process system and the linkage change process of material flow and energy flow between each reactor is insufficient. The whole process simulation of MSW gasification and melting process was carried out by using Aspen Plus simulation platform based on Gibbs free energy minimization principle. The effects of waste drying temperature, waste moisture content, gasification temperature, gasification medium and ash melting point on the process node parameters, material flow and energy flow were analyzed, and the optimized process flow and operation parameters were proposed. The results showed that when the moisture content of garbage was 9%, the simulation of garbage pyrolysis could achieve energy self-sufficiency through flue gas circulation. Under the same conditions, different gasification agent media had the highest gasification efficiency using water vapor as the gasification medium, and the optimal process was achieved at a gasification temperature of 850 ℃ and a water vapor equivalence ratio of 50%. When the char produced after gasification was burned in the melting furnace to meet the ash melting point temperature, the increase of ash melting point made the proportion of gasification agent, the effective gas molar flow of gasification gas and the carbon conversion rate decreased continuously. The changes of material flow and energy flow under different working conditions has guiding significance for practical engineering.

Analysis of fixation effect and mechanism of phosphorus in phosphogypsum by multiple substances combination
ZHANG Chenyan, FU Fugang, TAN Wenchao, YANG Yilin, LIU Tingyi
2024, 14(1): 194-203. doi: 10.12153/j.issn.1674-991X.20230135
Abstract(103) HTML (43) PDF(2095KB)(23)

Two phospho-accumulating bacteria were enriched and screened in the soil of the slag field by the harmless treatment method of phosphogypsum by microbial-plant combination, and the bacteria were identified as Pseudomonas sp. and Pseudomonas putida, respectively. The phosphogypsum modified by quicklime was mixed with a small amount of soil according to the mass ratio, and was evenly mixed with the already allocated organic fertilizer and microbial liquid bacteria agent. The mixture was put into the infiltration soil column device according to different mixing ratios, tall fescue was planted on the surface, and the leachate was collected at the bottom. The change of total phosphorus concentration in the liquid was measured by ammonium molybdate spectrophotometry. With phosphogypsum: soil: organic fertilizer: microorganism: grass seeds mass ratio of 7∶3∶0.2∶0.2∶0.03∶0.03, the phosphorus leaching concentration in the liquid was below 1 mg/L. The concentration of total phosphorus in the leaching solution of group 8∶2∶0.2∶0.2∶0.03∶0.03 was no more than 4 mg/L, and the concentration of total phosphorus in the leaching solution of fresh phosphogypsum was 633.9 mg/L. The fixation rate of phosphorus in the combined multi-substance treatment of phosphogypsum was more than 99%. The survival rate of the selected strains in the mixed soil was up to 6.4×106 cfu/mL, and the number of viable strains maintained stable or slow growth trend over time. This experiment successfully solved the problem of excessive phosphorus leaching concentration in the phosphogypsum accumulation area, and provided effective support for harmless treatment of phosphogypsum.

Recycling of non-metallic components in PCB based on 298/77 K cycle treatment
LI Pengbo, ZHANG Linnan, ZHANG Xiao, LI Xuanyan, LI He, GAO Tong
2024, 14(1): 204-209. doi: 10.12153/j.issn.1674-991X.20230156
Abstract(143) HTML (72) PDF(5056KB)(22)

In order to solve the problems of difficult recovery of non-metallic components and high secondary pollution rate in waste printed circuit board (PCB), 298/77 K cycling treatment technology was introduced. First, the effect of temperature change on the internal structure of PCB and the change of mechanical properties in PCB were analyzed, and the actual effect of static and centrifugal separation on the recovery rate of non-metallic components in PCB was tested. Then, CaF2 was introduced as strong oxidant in the refining process. The recovery of silicon components after the change of internal structure of PCB was tested and the actual purity of silicon elements after recovery was determined. The results showed that after 298/77 K cycle treatment, the internal structure of PCB changed significantly under the influence of temperature cycle. The mechanical properties were significantly reduced. The actual output of PCB non-metallic components and the recovery of silicon components had been significantly improved compared with the traditional treatment, and the impurities in the original PCB had been well removed. The mass fraction of silicon element accounted for more than 97%.

Research on the key influencing factors and operating parameters for the weight reduction of kitchen waste achieved by hydrothermal reaction
LIU Guanhong, ZANG Yufei, LIU Bing, CHEN Feiyong, WANG Jing, SHI Shuihe, SUN Xiuqin, ZHANG Ruina
2024, 14(1): 210-215. doi: 10.12153/j.issn.1674-991X.20230188
Abstract(239) HTML (95) PDF(1297KB)(30)

Using the hydrothermal carbonization process, the effect of varying temperatures (170 to 270 ℃), residence time (0 to 100 min), and solid-water ratios (1∶1, 1∶3, and 1∶9) on the weight reduction of hydrothermal reaction of kitchen waste was researched, and the operating parameters were optimized. The findings of this test revealed that as the temperature rose, the weight loss rate of kitchen waste increased, reaching a value of over 91%. The weight loss rate increased slightly as the residence time extended from 20 to 40 minutes and from 80 to 100 minutes. During the residence times of 0 to 100 minutes, the weight loss rate increased from 83.90% to 86.80%. A higher solid-water ratio would have a negative impact on the weight loss rate. The corresponding weight loss rates were 91.60% to 91.87%, 86.20% to 87.00% and 83.90% to 88.10% at solid-water ratios of 1∶9, 1∶3 and 1∶1, respectively. The solid-water ratio and the reaction temperature were the main factors affecting COD of the liquid products, which initially gradually decreased and leveled off as the reaction progressed before slightly increasing. This was demonstrated by the results of COD measurement of the liquid products. The higher heating value of hydrochar obtained in the test was 30.50 to 31.90 MJ/kg, which was greater than the national standard coal calorific value of 29.30 MJ/kg.

Effect analysis on hydraulic pulping coupled with anaerobic digestion of food wastes
ZHU Hao, LIU Xiaoji, ZHONG Jisheng, WU Yixiang, LIU Zhao, ZHANG Yingying, SUN Yansong, WANG Yongqun
2024, 14(1): 216-223. doi: 10.12153/j.issn.1674-991X.20230246
Abstract(105) HTML (48) PDF(14053KB)(33)

Considering the characteristics of the high water content of food wastes, the hydraulic pulping pretreatment technology was comprehensively evaluated from the aspects of hydraulic simulation, characteristics of pulp, key equipment operation indicators and project operation effect. The CFD (computational fluid dynamics) hydraulic simulation results showed that during the pulping process, the fluid particles spirally converged to the rotor blades to form three internal swirling eddies, which produced obvious velocity and pressure differences in the fluid interior. Under the hydraulic action, the pulping of food wastes could be performed quickly. The analysis of pulp and impurity characteristics showed that the pulping product was of fine particles, with low organic matter loss and high impurity removal, which could be highly integrated with different back-end resource utilization technologies (anaerobic digestion, aerobic fermentation, etc.). Taking the resource utilization project of food waste as an example, which adopted hydraulic pulping and anaerobic fermentation technologies, the relevant operation data showed that after the pretreatment of food wastes by hydraulic pulping, the loss rate of organic matter was about 8.5%, the separation rate of non-biodegradable impurities was about 94%, and the extraction rate of crude oil was about 91%. Moreover, the average oil production rate per ton of food waste was 3.76%, and the gas production rate per ton of food waste was 85.57 m3. The treatment method had a higher resource utilization rate compared to mechanical pre-treatment, which could greatly improve the economic benefits of the project.

Study on the comprehensive utilization of nutrients in the anaerobic digestion process of kitchen waste
ZHOU Haiyun, ZHANG Tong, BIAN Bo, YUAN Sijia, LIU Bo, YANG Zhenzhen, GU Huanglin
2024, 14(1): 224-230. doi: 10.12153/j.issn.1674-991X.20221283
Abstract(118) HTML (48) PDF(7973KB)(33)

The output of kitchen waste is large, the recycling value is high, the harm is great, and it is urgent to rationally utilize the value of its phosphorus resources to avoid its pollution risk. Scenario analysis and material flow analysis methods were comprehensively used and, based on the scenario analysis concept model and nutrient flow concept model, the material flow analysis of total phosphorus (TP) was conducted for three by-product treatment scenarios of anaerobic digestion of kitchen waste in southern Jiangsu Province. Among the scenarios, Scenario 1 (S1) was water treatment of biogas slurry and biogas residue incineration, Scenario 2 (S2) was biogas slurry returned to the field and biogas residue to organic fertilizer, and Scenario 3 (S3) was water treatment of biogas slurry and biogas residue to organic fertilizer. Taking the 100 t scale of kitchen waste treatment as a reference, the results showed that for S1, 0.99 kg of TP in the kitchen waste was returned to the field, and finally 0.96 kg TP entered the rice. For S2, 64.05 kg of TP was returned to the field in the kitchen waste, and 62.10 kg TP eventually entered the rice. For S3, 8.67 kg of TP was returned to the field in the kitchen waste, and eventually 8.49 kg TP entered the rice. Combined with the economic performance, the three scenarios were comprehensively evaluated, and it was found that S2 was the optimal mode of kitchen waste resource utilization, and the resource utilization rate of TP was 91.53%, which was much higher than that of S1 and S3.

Preparation technology and application of solid recovered fuels from municipal solid wastes
JIA Ting, LUO Liqun
2024, 14(1): 231-238. doi: 10.12153/j.issn.1674-991X.20230141
Abstract(126) HTML (50) PDF(6449KB)(34)

Solid wastes such as municipal solid wastes (MSWs) are increasingly produced with complex components, and greenhouse gases are generated in the process of disposal, so the effective management of such solid wastes and the carbon emission reduction have become a hot topic of current concern.The current status of MSWs treatment and the standards of solid recovered fuels at home and abroad were introduced, the processes of biological drying and mechanical sorting technology included in the mechanical biological treatment technologies were described, and the potential problems in the combustion process of solid recovered fuels were analyzed. Combining the effects of conventional treatment and mechanical biological treatment of MSWs, the calorific value of solid recovered fuels after mechanical biological treatment was obtained to reach 10 536 kJ/kg, which was three times higher than the calorific value of virgin waste and did not require the addition of auxiliary fuel for combustion. The application of solid recovered fuels in cement and electric power industries could improve the effective reuse of resources and reduce the use of fossil fuels, which was important for cost saving, environmental protection and promoting the process of waste separation and carbon neutrality in China.

Study of atmospheric visibility and its influence factors in six typical cities in China
ZHANG Xia, WANG Taiming, MENG Xiaoyan, YOU Yang, HOU Yujing, HUANG Weiming, ZHANG Xiaoxu
2024, 14(1): 239-247. doi: 10.12153/j.issn.1674-991X.20230553
Abstract(101) HTML (37) PDF(12842KB)(32)

The statistical methods such as linear correlation analysis and categorical variable analysis were employed to analyze the data of particulate matter and meteorological observations in six cities (Bayannaoer, Shijiazhuang, Langfang, Zhengzhou, Wuhan, Guangzhou) from 2019 to 2020. The influences of particulate matter concentration and atmospheric relative humidity on atmospheric visibility were investigated. The results indicated that there were significant differences in the annual variation of atmospheric visibility among the six cities, but the lowest values consistently occurred from December to February of the following year, and the annual variation pattern was generally consistent. The influences of meteorological conditions, relative humidity, and particulate matter concentration on visibility were apparent, with relative humidity indirectly affecting visibility through changes in the physicochemical properties of particulate matter, but with a relatively weak correlation. There was a good linear correlation between PM2.5 concentration and visibility, mainly following a power function. Overall, relative humidity and particulate matter had a synergistic effect on visibility, and cities with higher relative humidity required stricter control of particulate matter. Additionally, the study found that when PM2.5 concentration was higher than the threshold value, visibility did not continue to decrease with increasing particulate matter, but significantly improved only when PM2.5 concentration was below the threshold value. There was a significant difference in PM2.5 concentration between the turning point and the platform period point associated with visibility in each city.

Research on the preparation and application of collaborative turbidity and fluorine removal agents for typical coal mine water in the Yellow River basin
LI Qiang, ZHANG Liping, YAO Ruihan, ZHAO Xiaoxi, CUI Xingjian, CHEN Jiale, HE Xuwen, MA Zeyu
2024, 14(1): 248-257. doi: 10.12153/j.issn.1674-991X.20230484

The Yellow River basin is the region with the greatest coal potential in China. Although the amount of coal mine water inflow is large, the resource utilization rate is not high and, especially in arid and semi-arid areas with high fluorine content, the excessive fluoride ions in coal mine water have become one of the main factors restricting the improvement of mine water resource utilization rate. Orthogonal experiments were used to screen out five components of efficient defluorination agents, including polyaluminium chloride (PAC), poly-aluminum silicate, magnesium nitrate, poly-ferric chloride (PFC), and carboxyl methyl starch sodium. The single factor experimental method was used to explore the effects of different preparation and reaction conditions on the defluorination effect, and the defluorination mechanism was preliminarily explored through X-ray energy spectrum analysis (EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) characterization. The experimental results showed that the fluoride removal agent developed under the conditions of the total amount of metal to Si molar ratio of 43, Al/Mg molar ratio of 40, and Al/Fe molar ratio of 40 could reduce the concentration of fluoride ions in wastewater from 20 mg/L to below 1.0 mg/L, meeting the Class Ⅲ water fluoride limit requirements (1.0 mg/L) of Environmental Quality Standards for Surface Water (GB 3838-2002). When the dosage of the fluoride removal agent was 1.25 g/L, the initial pH was 2-12, the suspended solids concentration was 100-2 000 mg/L, and the polyacrylamide (PAM) dosage was 0.4 mg/L, the residual fluoride ion concentration in the supernatant after treatment could be controlled below 1.0 mg/L, and the fluoride removal rate could reach over 95%. Al and Si elements of the defluorination agent played an important role in defluorination, and their mechanism was mainly through the formation of metal complexes such as Al-F-Al for precipitation and removal. Applying defluorination agents to the treatment of fluorinated mine water in a certain coal mine in the Yellow River Basin, the concentration of fluoride ions decreased from 5.6 mg/L to 0.85 mg/L when the dosage of defluorination agents was 400 mg/L and PAM was 0.2 mg/L. Simultaneously, the turbidity of mine water could be reduced from 500 NTU to 4.59 NTU. The cost of water treatment agents per ton was 1.602 yuan. The defluorination agent has good application potential in the treatment of mine water containing fluorine in the Yellow River basin.

Isolation of Exiguobacterium sp. H-1 from the sulfamethazine wastewater treatment system and its environmental adaptation characteristics
CHEN Tian, WANG Zhuang, LU Mengyao, CHEN Yan, ZHOU Jia, QU Jianhang, PAN Jingshi, LUO Yu
2024, 14(1): 258-267. doi: 10.12153/j.issn.1674-991X.20230281
Abstract(155) HTML (56) PDF(7646KB)(26)

Sulfamethazine (SMZ) is a broad-spectrum antibiotic that is difficult to degrade, and its widespread presence poses a serious threat to the aquatic environment. Microorganisms are the main drivers of antibiotic degradation and transformation in the environment, but microbial resources for efficient degradation of SMZ are limited. Therefore, a strain of SMZ-degrading bacteria H-1 was isolated and screened from the activated sludge of SMZ wastewater treatment system by the pure culture technique. The strain H-1 was classified as the genus of Exiguobacterium sp. based on its morphological observation, physiological and biochemical characteristics, and 16S rRNA gene sequence analysis. The effects of initial SMZ concentration, inoculum, pH and temperature on the degradation of SMZ by strain H-1 were investigated by a single-factor test, and it indicated that the inoculum, pH and temperature affected greater on the degradation of SMZ by strain H-1. The optimal conditions for the degradation of SMZ by strain Exiguobacterium sp. H-1 were further optimized by response surface methodology: pH 7.21, temperature 28.86 ℃, inoculum level 4.40%, and its removal efficiency of 5 mg/L SMZ was 10.54%. It is found for the first time that Exiguobacterium sp. H-1 has the ability to degrade SMZ, and it is able to remove SMZ from SO2 first to produce pyrimidine and aniline rings, which are coupled to generate N-4,6-dimethylpyrimidin-2-yl)-1,4-diphenylamine, and then the deamination reaction proceeds to produce 2-phenyl-4,6-dimethylpyrimidine, which is subsequently demethylated to produce product 6 (m/z=159.97). In addition, strain H-1 also shows a strong salt tolerance within a wide range of 0-10% NaCl, providing a resource of salt-tolerant microbial strains for the bioremediation of SMZ-polluted waters.

Research progress on the characteristics of biochar material and its application in greywater treatment
DAI Chang, HE Zhiqin, LI Yun, WANG Bin, CHEN Xiaodong, FANG Fei, QIN Xiaopeng, LI Zhitao
2024, 14(1): 268-277. doi: 10.12153/j.issn.1674-991X.20230301
Abstract(167) HTML (92) PDF(514KB)(60)

Biochar has the advantages of large specific surface area, high porosity and abundant surface functional groups, and has large potential for application in greywater treatment. The water quality and quantity characteristics of greywater and common treatment technologies were introduced, the properties of biochar, modification methods and the progress of domestic and international applications of biochar substrates in greywater treatment were mainly reviewed, and the regeneration performance of biochar was analyzed. The results showed that most of the biochar currently applied in greywater treatment was wood-derived biochar which has an alkaline range of pH and the advantages of large specific surface area and high porosity, and its specific surface area and porosity were mostly in the range of 0-520 m2/g and 48%-83%. Among numerous modification methods, there were many studies on the modification of metal salt biochar. This method could improve the adsorption capacity of biochar and make it magnetized, making it convenient for later separation and recovery. The biochar matrix was mostly used in constructed wetlands, green walls and other ecological treatment systems for greywater treatment, and the removal rate of organic matter and nutrients in greywater could reach 90% under optimal operating conditions, which had good application prospects. Finally, the problems in the application of biochar in greywater treatment were summarized, and an outlook on three aspects of the research was provided, including strengthening the removal of new pollutants, the regeneration of biochar and the energy saving and consumption reduction.

Review on diagnostic technologies of illicit discharge and groundwater infiltration in the storm drainage network
ZHAO Zhichao, HUANG Xiaomin, YIN Hailong, LI Gang, LI Yingxi, PENG Shouhai, TANG Guangtao, XU Qi
2024, 14(1): 278-288. doi: 10.12153/j.issn.1674-991X.20230359
Abstract(152) HTML (47) PDF(11278KB)(52)

Stormwater network is an important municipal infrastructure to mitigate urban waterlogging and improve water environmental quality. Owing to the aging and corrosion, and improper construction of pipes, and so on, the urban stormwater network after construction in China often confronts the challenges of illicit discharge and groundwater infiltration, which restricts the efficient functioning of stormwater network. Technologies of diagnosing inflow and infiltration into drainage system can provide important support to identify and locate the illicit discharge and groundwater infiltration of stormwater network. The basic principles, research processes and applicable characteristics of the diagnostic technologies for inflow and infiltration into drainage networks (including geophysical detection, flow analysis, tracer parameter analysis, and hydrodynamic inversion model technologies) were reviewed, and then the practicalities, the key points of application, diagnostic levels, and development stages of these technologies were analyzed and compared. According to this, the future development trend of diagnostic technologies was proposed. The results showed that: 1) The tracer parameter analysis technology could identify and quantify the illicit discharge and groundwater infiltration without interfering with the normal operation of stormwater network, and provide retrofit priorities, resulting in significant economic and environmental benefits. 2) The fiber-optic distributed temperature sensing (FDTS) technology and hydrodynamic inversion model technology had outstanding advantages in non-interference locating of the illicit discharge and groundwater infiltration into stormwater network. The former was easy to implement and had high locating accuracy, while the latter had the characteristics of low cost and could be used to evaluate the levels of illicit discharge and groundwater infiltration. These two technologies could be selected according to local conditions. 3) The future development trend of diagnostic technology would be towards low-cost, non-interference, quantifiable, and locatable direction. By evaluating the comprehensive application effects of different technologies in the current and future, it was found that single diagnostic technology was difficult to possess the desired characteristics, while a hierarchical diagnostic system based on tracer parameter analysis technology coupled with FDTS technology or hydrodynamic inversion model technology had the advantage potential of achieving the future development goal. This study could provide references to carry out scientific application and optimization innovation of diagnostic technologies.

Research on the index system and evaluation method for ecological services of river shorelines
ZHANG Dengcheng, WANG Zhongmin, LI Yajun, FAN Hao, LIU Yangyang
2024, 14(1): 289-297. doi: 10.12153/j.issn.1674-991X.20230352
Abstract(157) HTML (210) PDF(2100KB)(67)

River shorelines are important components of the natural ecological space of rivers. In recent years, human activities have affected the ecological service function of river shorelines. In order to accurately carry out the restoration, it is urgent to develop a targeted evaluation index system and evaluation methods for the ecological service function of river shorelines. The type and structure of riverfronts were analyzed. Based on the relevant domestic research results and relevant technical specifications of water conservancy, environmental protection, marine and other industries, the ecological function evaluation indicators of riverfronts were preliminarily sorted out and comprehensively selected according to the principles of scientificity, comprehensiveness, independence and operability. Based on relevant technical specifications and research results, the utility values of each evaluation index were determined, and the evaluation method of riverfront ecological service function was developed. The results indicated that: 1) River shoreline could be divided into ecological protection type and ecological restoration type, the former could be subdivided into good vegetation type, desert type and rock type, and the latter could be subdivided into 7 types, including dike type, farmland type, village type, aquaculture pond type, town type, river mouth type and compound type. The riverfront had five ecological service functions: flood control, erosion control, water quality protection, biological habitat and landscape functions. 2) The constructed evaluation index system of river shoreline ecological service function included target layer, criterion layer and index layer. The target layer was the river shoreline ecological service function, and the criterion layer was the five ecological service functions corresponding to river shorelines. The index layer included flood control compliance rate, dike safety, vegetation coverage, bank slope stability, reasonable degree of sewage outfall layout, ecological buffer zone status, biological diversity index, plant community status, water bird status, landscape ecological value, and landscape comfort. The utility values of each indicator were defined as five grades based on the overall evaluation. 3) AHP was used to determine the weight of each evaluation index, and multi-attribute utility theory was used to calculate the comprehensive index of riverfront ecological service function, and the riverfront ecological service function was divided into five grades, i.e. excellent, good, medium, poor and extremely poor, so as to evaluate the status of riverfront ecological service function. This study could provide basis and reference for identifying ecological issues, evaluating the effectiveness of ecological restoration, and improving long-term mechanisms for river shoreline management.

Coupling and coordination analysis of urban spatial expansion and landscape ecological security in the Pearl River Delta in the past 20 years
WU Dafang, GAN Ziying, NING Fangjie, HE Xiaoli, ZHENG Jiaxin, LAI Huanming
2024, 14(1): 298-307. doi: 10.12153/j.issn.1674-991X.20230279
Abstract(93) HTML (58) PDF(4176KB)(43)

In view of the increasingly severe ecological landscape stress in the Pearl River Delta region caused by the accelerated urbanization process, it is urgent to strengthen regional ecological protection. A coupling and coordination model between new urbanization and landscape ecological security was constructed, and the spatiotemporal pattern and development status of urban spatial expansion and landscape ecological security coupling and coordination in the Pearl River Delta region from 2000 to 2020 were quantitatively measured. The driving mechanism was revealed by using multiple regression analysis and a grey prediction model, and the development trend of urban spatial expansion and landscape ecological security coupling in 2040 was predicted. The results showed that: 1) The coupling coordination degree between urbanization and landscape ecological security in nine cities in the Pearl River Delta had shown a slow fluctuating upward trend over the 20 years, with the range of coupling coordination degree increasing from 0.305-0.436 in 2000 to 0.385-0.545 in 2020. It was currently in the antagonistic coupling stage, and would continue to move towards coordinated, synchronized, and orderly development in the next 20 years. 2) The economic development in the Pearl River Delta was unbalanced, and urban development and ecological environment protection were difficult to develop simultaneously. The landscape ecological situation was not optimistic, the number of cities with a lagging ecological environment was increasing, and a good coordinated development had not yet been fully formed. 3) The degree of openness, level of economic development, and investment in science and education funds had a significant impact on the coupling coordination degree (P<0.05). In the future, it is necessary to strengthen the research on the mechanism of coupling and coordination for regional sustainable development and continue to pay attention to the trend and characteristics of coordinated development between urban spatial expansion and landscape ecological security.

Spatial selection and strategy of ecological compensation areas based on ecosystem service value in Altay Prefecture
DONG Jingwen, WANG Chengwu
2024, 14(1): 308-317. doi: 10.12153/j.issn.1674-991X.20230398
Abstract(219) HTML (91) PDF(5408KB)(43)

Ecological compensation can effectively alleviate the contradiction between regional economy and ecology. Based on the land use classification data of Altay Prefecture, Xinjiang Autonomous Region from 2010 to 2020, the ecosystem service value (ESV) of the study area was calculated by using equivalent factor method and the spatial-temporal change analysis was carried out. The revised ecological compensation priority index was used to select the ecological compensation areas in 6 counties and 1 city of Altay Prefecture, and the amount of ecological compensation was calculated. The results showed that the land use change in Altay Prefecture from 2010 to 2020 was "four increases and two decreases". The area of grassland, cultivated land, water area and construction land increased, while the area of forest land and unused land decreased. From 2010 to 2020, the total ESV showed a fluctuating change of decreasing and increasing alternately, and the overall decrease was 0.85%, with the largest decrease in forest ESV. The highest proportion of the value of a single function was the adjustment service. The theoretical total amount of ecological compensation in Altay Prefecture is 6.005 billion yuan, and the proportion of ecological compensation priority and compensation amount in the total amount is as follows: Qinghe County (21.60%) > Burjin County (18.33%) > Jimunai County (10.46%) > Habahe County (11.43%) > Altay City (10.99%) > Fuyun County (14.12%) > Fuhai County (13.07%). Based on the research results, the strategies of improving ecological compensation in Altay Prefecture were put forward from the aspects of giving play to the role of the government, perfecting the legal system, broadening the fund channels, innovating the compensation methods and standardizing the compensators and the indemnators.

Study on water quality criteria, ecological risk and adverse outcome pathway of lindane in freshwater environment
ZHENG Yixin, LI Quanwei, QIAN Yaru, WANG Feifei, QUAN Zhanjun
2024, 14(1): 318-329. doi: 10.12153/j.issn.1674-991X.20230366
Abstract(178) HTML (117) PDF(2205KB)(34)

In order to evaluate the ecological risk of lindane in freshwater bodies of China, the short-term and long-term freshwater quality criteria values were derived according to the method of Technical Guideline for Deriving Water Quality Criteria for Freshwater Organisms (HJ 831-2022). The derived short-term and long-term freshwater quality criteria values were 6.15 and 0.12 μg/L, respectively. According to the water quality criteria, the ecological risk of lindane in major freshwater bodies of China was assessed and the results showed that the ecological risk of lindane was at high risk level in Taihu Lake and the Minjiang River of Yangtze River basin, the Yellow River, the Haihe River and the Daliao River estuary. At present, the toxic effect endpoints of ecological risk assessment are still the general toxic effects (MATC, EC10, EC20, NOEC, LOEC, EC50, LC50, etc.), while the adverse outcome pathway (AOP) can qualitatively and quantitatively analyze the causal relation between the pollutants and their toxic effects from the levels of genes, cells, tissues and organs, which can provide a scientific basis for future refined ecological risk assessment. Thus, based on the results of the bibliometric analysis on the toxicity of lindane to freshwater organisms, three adverse outcome pathways of liver injury, reproductive injury and nerve injury were constructed according to the guidelines of the Organization for Economic Co-operation and Development (OECD).

Application of equilibrium partitioning approach to derive sediment quality guideline (SQG) values for heavy metals in the Dianbu River
XIONG Hongbin, WANG Zhongyi
2024, 14(1): 330-335. doi: 10.12153/j.issn.1674-991X.20230569
Abstract(81) HTML (31) PDF(2567KB)(18)

The Dianbu River was taken as the study object, the normalized equilibrium partitioning approach was used to derive the sediment quality guideline (SQG) values of five heavy metals (Cr, Cu, Zn, Cd, Pb) in the sediments of the river, and the contribution of each metal binding phase to the SQG value for five different heavy metals was analyzed. The results showed that the SQG values of Cr, Cu, Zn, Cd, and Pb in the sediments of the Dianbu River were 318.80, 122.24, 1 326.99, 7.88 and 31.43 mg/kg, respectively. There were differences in the contribution of each metal binding phase to the SQG values of five heavy metals. The contribution rate of fine particulate material (particle size < 63 μm) to the SQG values of five heavy metals in the sediments of the Dianbu River was 24.49%-48.93%, and the contribution rate to the SQG values of Cr, Zn and Cu sediments were the largest. The contribution rate of acid volatile sulfide to the SQG values of Cu, Zn, Cd and Pb was 2.11%, 0.22%, 50.13% and 21.67%, respectively, which mainly determined the SQG value of Cd. Total organic carbon and residual state contributed less than 3% to the SQG values of these five heavy metals.

Feasibility study on roof rainwater utilization in seven geographical areas of China based on the precipitation data in recent 40 years
ZHANG Chen, YU Jianghua, LING Chang, SHENG Shanqiang, SU Wei
2024, 14(1): 336-344. doi: 10.12153/j.issn.1674-991X.20230139
Abstract(151) HTML (57) PDF(2026KB)(39)

Rainwater utilization is an effective way to solve urban water resources crisis and alleviate urban waterlogging. Precipitation characteristics and rainwater utilization reliability are key indicators to measure the feasibility of rainwater utilization projects. Based on the rainfall data (from 1980 to 2020) from various monitoring stations in China, the precipitation characteristics of 7 geographical regions were analyzed. Using the principle of water balance, a daily precipitation-water consumption balance model was established, the influencing factors of roof rainwater utilization was discussed and the rainwater utilization feasibility of 7 typical cities in 7 geographical regions was analyzed. The results showed that: 1) the average annual rainfall depth decreased gradually from southeast to northwest in China due to the impact of terrain and climate differences. The spatial distribution trend of seasonal and annual rainfall depth was consistent. The seasonal rainfall was the highest in summer, followed by spring and autumn. The distribution characteristics of rainfall concentration were different from that of rainfall, and rainfall was more concentrated in areas with less annual rainfall depth. 2) Precipitation characteristics, rainwater harvesting tank volume, rainwater harvesting area, daily water demand, water saving efficiency and overflow rate had significant influence on the reliability of rainwater utilization in different areas. The greater the rainfall depth, the higher the reliability. The reliability order of the seven typical cities was Guangzhou > Wuhan > Nanjing > Kunming > Harbin > Beijing > Xining, but the reliability of each city could not reach 100%. 3) With the increase of the rainwater harvesting tank volume, the reliability of rainwater utilization increased. However, when the volume of rainwater harvesting tank reached 10 m³, the increase in reliability significantly slowed down. The reliability of rainwater utilization was directly proportional to rainwater collection area and inversely proportional to daily water demand. The curve trend change of water saving efficiency was accordant with that of reliability, but the value was higher than that of reliability. Reasonable control of overflow rate can improve the efficiency of rainwater utilization. In practical applications, both reliability and overflow rate should be considered to determine the optimal size of rainwater harvesting tanks. In general, the feasibility of rainwater utilization is higher in South China, East China and Southwest China, followed by Northeast China and North China, and the lowest in Northwest China.

Analysis of temperature characteristics and influencing factors of the stormwater runoff in typical catchment in Beijing
LI Zimu, LI Junqi, LI Jing, LI Xiaojing
2024, 14(1): 345-354. doi: 10.12153/j.issn.1674-991X.20230429
Abstract(86) HTML (27) PDF(9700KB)(19)

With the development of urbanization, the rate of impervious surface area has increased greatly, and a series of problems have attracted more and more attention. The risk of adverse impacts on the water ecology and water environment has become more and more prominent in the summer when the surface of the urban catchment produces high temperature runoff and then sinks into the downstream receiving water bodies caused by the thermal pollution of stormwater runoff. A typical catchment in Beijing was selected to monitor and analyze the runoff temperature of several rainfall events from 2021 to 2022. The data of meteorological factors, underlying surface temperature and pipeline runoff heat were collected simultaneously, and the Pearson correlation coefficient method was applied to analyze the influencing factors. The results showed that the temperature of stormwater runoff often increased in summer rainfall in the study area, and rainfall events with precipitation less than 12.5 mm and durations shorter than 250 min were more prone to warming, with a maximum warming of 4.1 ℃. Runoff temperature increases tended to occur at the beginning of the runoff process, with an average time to peak of 38 min, and there was no obvious relationship between the temperature rise and the peak location of rainfall intensity. The highly significant (P<0.01) influencing factors of stormwater runoff temperature included air temperature, precipitation, rainfall duration, and the impervious surface temperature at the initial moment of rainfall. The four indicators of air temperature during rainfall, rainfall duration, impervious surface temperature, and pipe wall temperature at the initial moment could explain 96.7% of the runoff temperature output in the study area.