Phosphorus removal methods for brewing wastewater are generally divided into biological and chemical methods:
1. Biological methods: Biological phosphorus removal refers to the nitrification and decomposition of organic phosphorus or metaphosphate by aerobic bacteria under certain conditions. Some phosphorus is absorbed by the microorganisms, becoming microbial sludge; the remaining phosphorus is decomposed into smaller orthophosphate molecules, which are then further precipitated using chemical methods in subsequent treatment. In terms of phosphorus removal efficiency, biological methods cannot reduce phosphorus concentrations to low levels. Firstly, the ability of microorganisms to decompose organic phosphorus is limited; secondly, residual phosphorus is excreted by the microorganisms through metabolism.
2. Chemical precipitation methods: Chemical phosphorus removal includes chemical precipitation, ion exchange, reverse osmosis, and electrodialysis. Chemical precipitation is the most widely used method, while the latter methods are difficult to use due to high treatment costs. Generally, biological methods can remove most of the total phosphorus, but they may not completely reduce it below the discharge standard. Furthermore, due to process aging or seasonal changes and lower temperatures, total phosphorus concentrations may exceed the standard, and the process may not be able to reduce it further. At this point, a combination of biological and chemical precipitation methods is needed.
