Improvement of biomass aggregation in sludge bulking by magnetic field application

Abstract

High biomass aggregation is commonly associated with good solid–liquid separation that can inhibit the occurrence of sludge bulking. The application of magnetic fields in the removal of pollutants has been studied previously but the relation between a magnetic field with biomass aggregation and its effect on pollutant removal efficiency receives very little attention. This present study was conducted to analyze the effect of the magnetic field toward biomass aggregation that can eventually contribute to the good removal performance of the pollutants. Two continuous laboratory-scale sequencing batch reactors known as Reactor A and Reactor B were set up. Reactor A was equipped with an 88 mT magnetic field while Reactor B acted as the control. Reactor A recorded higher biomass aggregation with the range of 75.0–95.2% compared to Reactor B which possessed mostly medium aggregation with an average of 65.5%. As a result, lower sludge volume index (SVI) was recorded in Reactor A (25.8 ml/g) compared to Reactor B (73.1 ml/g). Likewise, Reactor A showed significantly higher chemical oxygen demand (COD) and ammonia-nitrogen removal compared to Reactor B. These findings imply that the magnetic field successfully improves biomass aggregation, therefore improving the removal performance under the sludge bulking occurrence.