Experimental investigation of high saline wastewater treatment using aerobic granules

Abstract

Complete aerobic granulation could be achieved in shaking sequencing batch reactors (SSBR) with saline wastewater respectively inoculated conventional activated sludge and anaerobic granules. Pretty good specific TOC removal rates could be achieved without inoculating the halo-bacteria at the start-up time. When the salinity was less than 10 g/L NaCl with the synthetic glucose-rich wastewater as substitute, the TOC removal efficiency was in the range of 70.3%-97.6%. After the salinity was 35 g/L NaCl and the influent was completely changed to Vc wastewater as substrate, similar TOC removal efficiency about 70% could be achieved compared with the performance of fresh Vc wastewater treatment under the same condition. The granules in saline wastewater had a diameter of 0.5-3 mm, and saline aerobic granules had much higher settling velocity, higher oxygen utilization rate (OUR), lower sludge production and better structural integrity than those of the granules from fresh wastewater. Saline aerobic granules showed perfect protecting-ability against the saline shock and could quickly recover from long term sharp saline change. Due to the different sludge inoculation, the aerobic granules from aerobic floes had superior TOC removal performance and inferior saline shock protecting-ability compared with the aerobic granules from anaerobic granules.