Novel insights into the evaluation of submerged membrane bioreactors under different aeration intensities by carbon emission

In this work, the impact of aeration intensity on the performance of the submerged membrane bioreactor (SMBR) treating synthetic municipal wastewater was investigated, and subsequently its carbon footprint was primarily calculated. The results showed that the aeration intensity had significant impacts on the removals of ammonium nitrogen (NH3-N), total nitrogen (TN) and total phosphorus (TP) except for the chemical oxygen demand (COD) removal. The growth rate of trans-membrane pressure (TMP) decreased from 4 to 0.5 kPa/day as the aeration intensity increased from 300 to 500 L/(m2 h− 1), suggesting that the membrane fouling was markedly alleviated by higher aeration intensity. With regard to the carbon footprint of the SMBR, it was 10.05, 11.35 and 12.22 kgCO2/kgCOD,removed at aeration intensities of 300, 400 and 500 L/(m2 h− 1), respectively. The higher carbon footprint due to the aeration intensity was mainly attributed to the increase of CO2 emission from energy demand.