effluent standard

Effluent standards are regulations that directly address the quality of treated wastewater discharged from a sewage treatment plant. These standards typically control parameters such as biochemical oxygen demand (BOD), suspended solids, acidity, and coliform bacteria.123

Wastewater treatment involves several levels:
* Primary treatment removes about 60% of suspended solids and 35% of BOD.123
* Secondary treatment removes over 85% of suspended solids and BOD.123
* Tertiary treatment is used when higher levels of purification are needed, such as reducing nitrates and phosphates, or achieving near-drinking-water quality. This can include processes like effluent polishing with filters or land treatment methods.123

Disinfection, often with chlorine or UV radiation, is the final step to destroy remaining pathogens before discharge.123