Comprehensive treatment for black and odorous water body: a case study of Meishe River in Haikou City

The main causes of the black and odorous of the Meishe River, the mother river of Haikou City, and the remediation engineering measures were described, and the treatment effectiveness of the black and odorous water body was summarized. Due to the weak municipal infrastructure, there were many problems such as direct discharge of the sewage along the Meishe River, wrong or mixed connection of rain and sewage pipes, and overflow pollution in combined drainage system, which resulted in the black and odorous water body all year around. Since 2015, Haikou City had carried out black and odorous water bodies treatment for Meishe River, which had taken the watershed as a unit, following the advanced concepts of “Sponge city” and “Ecological river”, and three-steps principle of source control and pollution interception, internal source control, and ecological restoration. In terms of source control and interception of pollution, combined discharge pipes and sewage interception pipelines were installed for a total of 7.2 km long, and three integrated sewage treatment facilities were newly constructed, increasing sewage treatment capacity by 7 500 m³/d. In terms of pollution control of internal source, the dredging by the excavator combined with cutter suction dredging boat was performed to remove the contaminated sediments. For ecological restoration, the environmental restoration agent was used to improve the sediment matrix, 360 000 m²of submerged vegetation was planted, two rubber dams with 1.0 m×22 m were built and water environmental restoration agent was dosed in the whole water area. In addition, the cascade subsurface flow wetlands were constructed in the Meishe River for enhancing the treatment effect and creating a good landscape. By taking the above comprehensive measures, the black odor of Meishe River was eliminated in 2017.