Effect of transient organic load and aeration changes to pollutant removal and extracellular polymeric substances

Transient organic load shocks have an important influence on the removal of pollutants and the content and composition of extracellular polymeric substances (EPS). This study was based on a micro-pressure reactor (MPR) with the influent COD concentration as the variable, while different operating conditions were controlled by adjusting the aeration rate. The effect of single-cycle transient organic loading shocks on EPS and pollutant removal and the correlation between their changes were investigated. The results showed that COD removal was unaffected under the shock, and the effect of nitrogen and phosphorus removal decreased. As the incoming carbon source increased, the EPS content at shock increased, with the polysaccharide (PS) content being the most affected. As aeration increased, the effect of organic load shock on EPS and pollutant removal decreased. Under different aeration conditions, PS contributed to denitrification and anaerobic phosphorus release during transient organic load shocks, and protein (PN) contributed to aerobic phosphorus uptake. The reduction in PS and PN relative to the pre-shock caused by the shock resulted in the EPS exhibiting a favourable effect on COD removal and an inhibitory effect on the effectiveness of nitrogen and phosphorus removal.