Effect of pH on Pollutants Removal of Ship Sewage Treatment in an Innovative Aerobic-Anaerobic Micro-Sludge MBR System

Abstract

The implementation of the latest International Maritime Organization (IMO) emission standard has raised stringent requirements for marine domestic sewage discharge. In this study, a novel aerobic-anaerobic micro-sludge membrane bioreactor (O-AMSMBR) was used to analyze the effect of pH variation on the effluent chemical oxygen demand (COD) and total nitrogen (TN) for marine domestic sewage. Results showed that the novel MBR achieved better COD and TN removal efficiency (Ravg(COD) = 87.77% and Ravg(TN) = 91.01%). In acid environment (pH = 5), anaerobic micro-sludge MBR technology can enhance the pollutants removal efficiency under pH shock. These two findings indicated that anaerobic micro-sludge membrane bioreactor (MBR) technology has great potential in acidity or alkalinity wastewater treatment. The activity of six different enzymes was analyzed in this study. The results showed that nitrate reductase and nitrite reductase can serve as special indicating factors for anaerobic micro-sludge MBR technology on domestic ship sewage. Moreover, wavelet neural network (WNN) and back-propagation neural network (BPNN) were used to simulate the effect of pH on reactor performance. The order of relative importance inculcated that pH is the key factor to consider for biodegradation of organic matter in O-AMSMBR system. The outcomes of this study suggest that post-anaerobic integrated with micro-sludge methods can play a vital role in keeping good pollutant degradation in ship wastewater treatment under pH shift.