secondary treatment
... secondary circuit二次电路,次级电路 secondary treatment二级处理;次级处理 secondary voltage二次电压 ...
secondary treatment process
secondary treatrtaent of sewage
二级处理(secondary treatment),是指污水经一级处理后,用生物处理方法继续除去污水中胶体和溶解性有机物的净化过程。