Enhancing combined biological nitrogen and phosphorus removal from wastewater by applying mechanically disintegrated excess sludge

The goal of the study was to evaluate the possibility of applying disintegrated excess sludge as a source of organic carbon to enhance biological nitrogen and phosphorus removal. The experiment, performed in a sequencing batch reactor, consisted of two two-month series, without and with applying mechanically disintegrated excess sludge, respectively. The effects on carbon, nitrogen and phosphorus removal were observed. It was shown that the method allows enhancement of combined nitrogen and phosphorus removal. After using disintegrated sludge, denitrification effectiveness increased from 49.2 +/- 6.8% to 76.2 +/- 2.3%, which resulted in a decline in the NOx-N concentration in the effluent from the SBR by an average of 21.4 mg NOx-N/L. Effectiveness of biological phosphorus removal increased from 28.1 +/- 11.3% to 96.2 +/- 2.5%, thus resulting in a drop in the PO43 - P concentration in the effluent by, on average, 6.05 mg PO43 - P/L. The application of disintegrated sludge did not deteriorate effluent quality in terms of COD and NH4+ - N. The concentration of NH4+ - N in both series averaged 0.16 +/- 0.11 mg NH4+ - N/L, and the concentration of COD was 15.36 +/- 3.54 mg O-2/L. (C) 2015 Elsevier Ltd. All rights reserved.