Treatment of Municipal Strength Wastewater Using a Novel Air Suction Flow Biofilm Reactor

The performance of a new technology - the Air Suction Flow Biofilm Reactor (ASF-BR) - in treating municipal strength wastewater

E. Clifford*, 1,2, P. Forde1, S. McNamara1, M. Rodgers1, E. O’Reilly1,2,

1 Civil Engineering, NUI Galway;

2 Ryan Institute, NUI Galway

* Corresponding author: eoghan.clifford@nuigalway.ie

Abstract

The provision of technologies that can meet increasingly stringent wastewater discharge standards while reducing energy, operation and maintenance costs is vital to government, local authorities, industry and the public at large. The air suction flow biofilm reactor (ASF-BR) is a novel batch biofilm technology, suitable for treating wastewaters from municipal, industrial and agricultural sources. This paper presents an investigation into the performance of a laboratory scale ASF-BR in treating municipal strength wastewater over two operational periods (Phase 1 and Phase 2). Phase 1 concentrated on organic carbon removal and nitrification while Phase 2, which followed Phase 1, included an anoxic step to achieve denitrification. The operation of the unit was also investigated by monitoring organic carbon and nitrogen in the reactors during a number of treatment cycles.

In Phases 1 and 2 (29 and 124 days of steady state operation respectively) of this laboratory study, using a municipal strength synthetic wastewater, the average influent total chemical oxygen demand (CODt) was 288 mg/l and 313 mg/l, respectively, while the influent filtered COD (CODf) averaged 127 mg CODf/l and 148 mg CODf/l, respectively. The CODf removal rates averaged 92% during Phase 1 and 79% during Phase 2. Average nitrogen removals during Phases 1 and 2 of greater than 95% ammonium-nitrogen (NH4-N) were achieved. By reducing the number of pumping cycles during the aerobic step, the overall energy consumed was reduced by 37.5% during Phase 2, while achieving similar results.

Based on these positive initial results, a pilot scale reactor has been constructed...