Aerobic treatment of wastewater: Removal of nitrogen and phosphorus in the presence of humic substances

Abstract

This paper describes results of studies on the removal of ammonia (NH3‐N) and phosphorus (T–P) during biological treatment of wastewater in the presence of humic substances (humate). Initial respirometric tests indicated that the investigated system complied with the Haldane model for inhibitory wastes. Addition of humate mitigated the inhibitory effect of the wastewater on the returned activated sludge (RAS), resulting in an increased biological oxygen uptake and in better removal of NH3‐N and T–P. In the presence of 2000 mg l−1 of humate, the system complied with the Monod model for non‐inhibitory wastes and both NH3‐N and T–P were almost completely removed. It is suggested that an application of humic substances has great potential as a simple and inexpensive method to reduce the nutrient levels in water, and also allow the recycling of phosphorus, incorporated into an organic fertilizer.