Biological nutrient removal in a sequencing batch reactor treating domestic wastewater

Abstract

This investigation aims to monitor a strategy for biological nutrient removal (nitrogen and phosphorus) in a Sequencing Batch Reactor (SBR) treating domestic wastewater. For this, the performance of an SBR with nitrification, denitrification, carbon oxidation and phosphorus removal is evaluated. During this study the influent used was pre-settled domestic wastewater from Bennekom-Municipal Treatment Plant (The Netherlands). The average influent COD, TKN and phosphate were 443 mg COD/1, 71 mg N/1 and 7 mg P/1, respectively. Acetic acid was added to this influent from a feed solution, to increase the COD by an extra 100 mg COD/1. In this study, a pilot plant SBR was operated during 5 months in order to have: i) a mixed culture able to perform carbon oxidation, nitrification, denitrification and biological phosphorus removal and ii) long term assessment of the biological nitrogen and phosphorus removal processes. Pilot plant SBR consists of two cylindric polystyrene vessels, the first with total volume of 0.35 m3 (Reactor 1) and the second with total volume of 1.3 m3 (Reactor 2). The effluent had, in average, phosphate concentration lower than 1 mg P/1 and nitrogen concentration lower than 12 mg N/1.