污水二级处理：污水经一级处理后，再经过具有活性污泥的曝气池及沉淀池的处理，使污水进一步净化的工艺过程。常用生物法和絮凝法。生物法是利用微生物处理污水，主要除去一级处理后污水中的有机物；絮凝法是通过加絮凝剂破坏胶体的稳定性，使胶体粒子发生凝絮，产生絮凝物而发生吸附作用，主要是去除一级处理后污水中无机的悬浮物和胶体颗粒物或低浓度的有机物。
Secondary treatment of sewage: The process of further purification of sewage by primary treatment of sewage followed by treatment of aeration tank and sedimentation tank with activated sludge. Biological and flocculation methods are commonly used. Biological method is to treat sewage by microorganisms, mainly removing the organic matter in the first-stage treated sewage; flocculation method is to destroy the stability of colloidal particles by adding flocculants, so that colloidal particles flocculate and produce flocculants, which can adsorb, mainly removing inorganic suspended matter and colloidal particles or particles in the first-stage treated sewage. Low concentration of organic matter.
经过二级处理后的污水一般可以达到农灌水的要求和废水排放标准。但在一定条件下仍可能造成天然水体的污染。
The wastewater after secondary treatment can generally meet the requirements of agricultural irrigation water and wastewater discharge standards. However, under certain conditions, it may still cause pollution of natural water body.