Treatment Of Petrochemical Wastewater By Micro-aerobic Hydrolysis Acidification-A/O Processes And Analysis Of Microbial Community

In this dissertation, the micro-aerobic hydrolysis acidification-A/O processes were developed to treat real petrochemical wastewater and microbial community of sludge in each tank was analyzed. The lab-scale system was composed of hydrolysis acidification reactors and A/O process. The micro-aerobic and anaerobic hydrolysis acidification reactors were operated in parallel for comporison. The results showed that1. The removal efficiency of chemical oxygen demand(COD) and ammoniummaintained stable despite their great fluctuation in influent. At a HRT of 20 h,the COD removal efficiency kept at 72-29%, with 31-42% in the micro-aerobicreactor and 29-31% in the anaerobic reactor, respectively. This indicates thatorganic removal efficiency of micro-aerobic reactor was higher than that ofanaerobic hydrolysis acidification reactor. The ammonium removal of 95.4%was much higher than COD removal.2. To verify the feasibility of treatment of petrochemical wastewater using micro-aerobic hydrolysis acidification-A/O technique, a pilot-scale micro-aerobichydrolysis acidification-A/O reactor(1.0 m3/h) was established. Resultsshowed that, the removal efficiency of COD maintained stable despite theirgreat fluctuation in influent. With the influent COD of 389 ± 92 mg/L, theeffluent COD remained at 73 ± 33 mg/L. The COD removal efficiency was 15-37% in the micro-aerobic reactor, and reached 70-85% in the total system. Thammonium concentration removal efficiency was 88%. The removalefficiency of UV254, TN and TP were 72%, 54% and 69%, respectively. Micro-aeration intensity in 5.5~13.8L/m3 h did not affect the activity of theacidification bacteria. The VFA/COD ratio increased from 0.26 to 0.40,indicating the good hydrolysis acidification performance. The sulfideconcentration was very low, indicating that micro-aerobic hydrolysisacidification could inhibit the production of harmful gas H2 S effectively. Theresults of GC-MS analysis revealed that the organic pollutants in the influentinvolved benzenes, ketones, alcohols, amines, nitriles, phonels compounds. 3. Results of Ilumina Miseq pyrosequencing analysis of the sludge showed that at the phylum levels, Proteobacteria, Chloroflexi were highly enriched inmicro-aerobic hydrolysis and anaerobic hydrolysis and A/O reactor. Inaddition, Chloroflexi was highly enriched in micro-aerobic and anaerobichydrolysis acidification and A tanks. Nitrifiers were highly enriched in A/Oreactor, and a higher proportion of denitrifying bacteria was observed in A tank.The bacteria belonging to genera Xanthomonadales and Novosphingobiumwhich were reported to degrade petroleum and PAHs and glycogenaccumulating bacteria Defluviicoccus were highly enriched in the total system,which is benefit for the degradation of petrochemical wastewater. The aboveresults demonstrated that micro-aerobic hydrolysis acidification is a promisingtechnique for treating prtrochemical wastewater.