OXIDATION-REDUCTION POTENTIAL (ORP) REGULATION OF NUTRIENT REMOVAL IN ACTIVATED SLUDGE WASTEWATER TREATMENT PLANTS

Redox potential(ORP) regulation of nutrient removal in aera-tion tanks was tested for one year in three activated sludge wastewater treament plants. The experiment results show a good relationship between ORP values and nutrient removal. Macro-biodegradation and sorption of substrate by activated sludge can significantly increase wastewater ORP, indicating the improvement of redox status of the bulk liquor. High DO concentrations(6-8mg/l) does not help im-prove the redox status because in fully-aerated wastewater endogenous metabolism predominates.