The organic matter in the wastewater is consumed by the microbial decomposition of oxygen, the impact of the life of aquatic life, dissolved oxygen in the water, the organic matter for the anaerobic decomposition, produce hydrogen sulfide, and other unpleasant gases, so that the water quality further deterioration.
Exists acid alkali,, oxidant, copper and, cadmium, mercury, and other compounds arsenic, benzene, ethane and dichloro ethylene glycol organic poison poison, stagnant water biota There