How to treat wastewater containing sulfur and phosphorus

To achieve the required standards for phosphorus treatment, it is necessary to proceed in stages. The first step is that some phosphorus can be removed using lime. In the second step, there is phosphorus that cannot be removed, such as organic phosphorus, polyphosphorus, hypophosphorus, etc. First, a coagulation reaction is carried out to remove the \"easily removable phosphorus\", and then methods such as intensification are used to convert the phosphorus that is difficult to remove into forms that can be removed more easily (phosphorus release), followed by treatment via chemical precipitation. This is somewhat similar to the biochemical treatment process that makes use of chemical phosphorus removal; generally, chemicals such as ferrous sulfate are used in the anaerobic stage, as the polyphosphate-forming bacteria in the wastewater are suppressed under anaerobic conditions, causing them to release the phosphates stored within them. Phosphates then form precipitates with iron ions, which are removed from the treatment system along with the sludge, thereby achieving phosphorus removal.