A novel system for zero-discharge treatment of high-salinity acetonitrile-containing wastewater: Combination of pervaporation with a membrane-aerated bioreactor

Abstract

High-salinity acetonitrile (ACN)-containing wastewater is a typical chemical wastewater with high salinity, high volatility, high toxicity and nitrogen-rich organic matter. To efficiently treat high-salinity ACN wastewater without generating secondary pollution, a novel zero-discharge treatment system was developed based on the combination of pervaporation (PV) with a membrane-aerated bioreactor (MAB). Integrated (IMABS) and separate (SMABS) MAB systems were constructed and compared. In these two systems, the ACN was separated from the high-salinity ACN wastewater by PV. The separated ACN entered the MAB for biodegradation, and the high-salinity water remaining after separating ACN was reused for industrial production. The effects of the hydraulic retention time (HRT), salt content of the feed liquid, initial ACN concentration of the feed liquid, and aeration pressure on the process performance were investigated. The ACN separation and removal by SMABS were superior to those by IMABS. With an initial feed liquid ACN concentration of 2000 mg/L and salt content (as NaCl) of 5 wt%, ACN was not detected in the feed liquid of SMABS over an 8-day operation, and the high-salinity water remaining after ACN separation satisfied the requirements for reuse. The corresponding ACN permeation flux and ACN removal rate at 8 days were 0.131 g/(m2·h) and 98.75%, respectively. This research shows that the zero-discharge treatment of high-salinity ACN wastewater can be realized by the combination of PV with an MAB.