Comprehensive treatment of urban black and odorous water bodies in southern cities: a case study of Zhupai River e section (Nakao River) in Nanning City

Zhupai River e section (Nakao River Basin) was a typical urban black and odorous water body in Nanning City which was in dire need of governance. The water pollution characteristics of Nakao River were analyzed and the main sources of pollution were recognized. In view of the problems such as the inflow of sewage and initial rainwater into the river, the siltation of river sediment, the lack of ecological base flow and the serious degradation of river water ecosystem, the measures of controlling sources and cutting off pollution, cleaning up internal sources, maintaining the quality of living water and ecological restoration for comprehensive treatment of Nakao River were put forward. The ecological revetment technology of “water purification terraces” suitable for the basin was developed according to the local conditions, so as to carry out multi-stage purification of overflow or runoff rainwater. The construction model of government and social capital cooperation (PPP) + pay-for-performance was adopted. After treatment, the river water quality improved steadily and achieved Grade Ⅳ of Surface Water Environmental Quality Standards(GB 3838-2002), the ecological benefit was remarkable, and the surrounding residential and commercial water environment improved significantly.