In the present study, a pilot-scale process of anaerobic hydrolysis-acidification with pulse water allocation (PHA) and anoxic/oxic (A/O) reactors was developed to treat actual petrochemical wastewater. The effective volume of PHA and A/O reactor was 2.6 m³ and 3.9 m3, respectively. The impulse frequency of the pulse tank was 10 times per hour. The sludge retention time of A/O reactor maintained at 25 d. The sludge from the settling tank was recycled into the anoxic tank with a recirculation ratio of 100%. The temperatures of the system ranged 15~32℃. The results during nearly 7-months operation showed that the removal efficiency of COD and ammonium remained stable although the influent COD and ammonium fluctuated. At the influent COD concentration of (458 ±107) mg·L^-1, the COD removal efficiency reached 80% on average, in which the PHA reactor contributed around 29% COD removal. The average ammonium removal was 86% at the influent ammonium concentration of (35.9 ±11.3) mg·L^-1. The removal efficiency of UV₂₅₄ and TN was around 58%. The TP removal could reach 86%. The PHA reactor exhibited good mixing of wastewater and sludge and a higher efficiency of acidogenic fermentation. The VFA levels in the PHA effluent were higher nearly twice than that in the influent. The ratio of BOD₅/COD of PHA effluent increased by 35% compared to that in influent, indicating that the biodegradability of the petrochemical wastewater was improved by PHA treatment. Results of Ilumina Miseq pyrosequencing demonstrated that Proteobacteria and Bacteroidetes were highly enriched in the system with abundance of more than 50% at the phylum levels. The predominant genera in PHA and A/O tanks were Anaerolineaceae and Clostridiales, Flexibacter, Thiobacillus, Nitrosomonadaceae and Nitrospira, respectively. The complex petrochemical wastewater was degraded efficiently owing to combined contribution of different bacteria in each tank. The above results demonstrate that the PHA-A/O process is a promising technique to treat petrochemical wastewater and could be applied in the treatment of other industrial wastewater.

pulse water allocation  /  hydrolysis acidification  /  Ilumina Miseq sequencing  /  industrial wastewater  /  wastewater treatment