Advanced treatment of bio-treated coal chemical wastewater by a novel combination of microbubble catalytic ozonation and biological process

摘要

The advanced treatment performance of real bio-treated coal chemical wastewater (BCCW) by a novel combination of microbubble catalytic ozonation and biological process was investigated. The refractory compounds in BCCW could be degraded effectively by microbubble catalytic ozonation treatment, which resulted in efficient COD removal, inorganic nitrogen release and significant improvement of biodegradability. The dissolved oxygen (DO) supplied by microbubble catalytic ozonation was also enough for aerobic digestion in the following biological treatment even without aeration. The biodegradable COD and ammonia nitrogen released in microbubble catalytic ozonation treatment could be removed further in the following biological treatment efficiently. There was no off-gas ozone required to be treated due to high ozone utilization efficiency of close to 100%. The ratio of ozone dosage to influent COD amount showed a marked impact on the performance of the combination treatment system and its optimal value obtained in this study was 0.44 mg/mg. In this case, for microbubble catalytic ozonation, the COD removal efficiency was 32.16%, the ratio of ozone dosage to COD removed was 1.38 mg/mg and the ozone utilization efficiency was 98.0%. For biological treatment, the COD removal efficiency was 41.93%. For the combination system, the total COD removal efficiency was 60.82%, the average final effluent COD concentration was 91.5 mg/L and the estimated total ratio of ozone dosage to COD removed was 0.68 mg/mg. Therefore, the combination of microbubble catalytic ozonation and biological process is an effective and economical solution for advanced treatment of BCCW.