any treatment method or process employed following biological treatment (1) to reduce pollution load (2) to remove substances that may be harmful to receiving waters or the environment (3) to produce [..]

Any process of water renovation that upgrades treated wastewater to meet specific reuse requirements. May include general cleanup of water or removal of specific parts of wastes insufficiently removed [..]

The removal of noncarbonaceous materials such as excess phosphorus and nitrogen. The term implies treatment beyond secondary treatment, and advanced treatment is most effective after the organic matte [..]