Performance evaluation of a modified step-feed anaerobic/anoxic/oxic process for organic and nutrient removal

A pilot scale modified step-feed process was improved to increase nutrient(N and P) and organic removal operations frommunicipal wastewater.It combined the step-feed process and amethod named "University of Cape Town(UCT)".The effect of nutrient ratios and inflow distribution ratios were studied.The highest uptake efficiency of 95% for chemical oxygen demand(COD) has been achieved at the inflow distribution ratio of 40/35/25.However, maximum removal efficiency obtained for total nitrogen(TN) and phosphorus at 93% and 78%, respectively.The average mixed liquor suspended solids(MLSS) was 5500 mg·L^-1.In addition, convenient values for dissolved oxygen(DO) concentration, and pH were obtained throughout different stages.The proposed system was identified to be an appropriate enhanced biological nutrient removal process for wastewater treatment plants owing to relatively high nutrient removal, sturdy sludge settle ability and COD removal.