The main causes of black odor are: external pollution, sewage direct discharge, non-point source pollution, endogenous pollution, sediment release, poor self-purification capacity, lack of long-term mechanism.
Exogenous pollution mainly includes direct discharge of municipal sewage, stolen discharge of industrial wastewater, Overflow Pollution of combined pipe network, rainwater in the early period of city, agricultural non-point source and litter littering along the coast.
For sewage treatment measures: sewage interception pipe: end or source of sewage interception, sewage treatment in situ, bypass integrated equipment treatment.
Control measures for non-point source: sponge city measures: vegetation buffer zone, rainwater garden, initial mixed water storage tank, constructed wetland
The internal pollution mainly includes sediment release from the bottom of the river and decay of aquatic plants.
The measures to control the internal pollution include dredging and dredging, biological bottom alteration and aquatic plant residue cleaning.
Poor self purification capacity mainly includes inadequate hydrodynamic, poor mobility, anoxia, fragile aquatic ecosystems, etc.
In view of the poor self-purification measures: artificial oxygen, coagulation and sedimentation, microbial enhanced purification, ecological floating island, aquatic ecosystem construction, algae control, aquatic biological restoration, clean water or recharge of reclaimed water.
The lack of long-term mechanism is mainly due to the conflict of departments'functions and the inadequate management, etc. As a result of one or more of the above reasons, resulting in the black and stinky water.
In view of the lack of long-term mechanisms and measures: to strengthen water management, the implementation of the "long River system", the implementation of the "one river one policy", water quality assessment and payment, increase law enforcement efforts, stop the illegal discharge of sewage, improve the monitoring system.