Treatment of coal gasification wastewater by anaerobic SBR–aerobic SBR process for elimination of toxic organic matters-a lab scale study

Abstract

As a typical refractory industrial wastewater, coal gasification wastewater has a high toxicity and poor biodegradability. In this paper, an anaerobic SBR–aerobic SBR process was used to treat coal gasification wastewater. Average removal efficiency of COD, total phenols, volatile phenols, NH₄⁺–N were 65.1%, 79.6%, 99.5% and 99.39%, with final concentration in the effluent were 380 mg L⁻¹, 45.2 mg L⁻¹, 0.52 mg L⁻¹ and 0.32 mg L⁻¹, respectively. There are 72 kinds of organic matters in the influent, a total of 10 categories. After biological treatment, the types and concentration of organic matters in the effluent of A (anaerobic 48 h effluent), B (anaerobic 48 h–aerobic 48 h effluent), C (anaerobic 24 h effluent), D (anaerobic 24 h–aerobic 48 h effluent) has dropped significantly and the types of organic compounds were reduced to simpler 42, 45, 46 and 61 kinds, respectively. The process showed ascendancy in the treatment of toxic matters. Organics degradation and transformation were analysed by GC-MS. Additionally, microbial community analysis in anaerobic sludge was investigated by means of polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) along with SEM, revealed that it had a great variety of bacterial dominant species. The study demonstrated that hydrolytic acidification at SBR anaerobic 24 h + aerobic 48 h could be a technically feasible method to enhance NH₄⁺–N, COD, TP removal and degradation of complex organic compounds in coal gasification wastewater.