The Effect of HLRs on Nitrogen Removal by Using a Pilot-scale Aerated Steel Slag System

Abstract

Abstract. Discharge from domestic wastewater treatment plant amongst the main sources of nitrogen pollution in the environment. However, to remove nitrogen conventionally in domestic wastewater require high cost and complex chemical treatment method. Vertical flow aerated rock filter emerged as one of attractive alternative wastewater treatment method due to simplicity and compactness of the system. However, the application is yet to be developed in warm climate countries in particular Malaysia. Therefore, this study was conducted to investigate the effect of hydraulic loading rate (HLR) to the performance of a pilot-scale Vertical Flow Aerated Rock Filter (VFARF) in removing nitrogen from domestic wastewater using pilot-scale VFARF systems with steel slag as the filter media. Furthermore, this study has been designed to focus on the effects of two HLRs; 2.72 and 1.04 m 3 /m 3 .day. Influent and effluent of the filter systems were monitored biweekly basis for 11 weeks and analyzed for selected parameters. Results from this study shows that the VFARF with HLR 1.04 m 3 /m 3 .day has performed better in terms of removal ammonium-nitrogen and TKN as the system able to remove 90.4 r 6.9%, 86.2 r 10.7%, whilst the VFARF with 2.72 m 3 /m 3 .day remove 87.4 r 9.9%, 80 r 11.7%, respectively. From the observation, it can be concluded that nitrogen removal does affect by HLR as the removal in lower HLR system was higher due to high DO level in the VFARF system with 1.04 m 3 /m 3 .day which range from 4.5 to 5.1 mg/L whilst the DO level was slightly lower in the VFARF system with 2.72 m 3 /m 3 .day in the range of 3.7 to 4.5 mg/L.