LAUSR

Coal gasification wastewater (CGW) contains very high concentrations of phenols and ammonia. However, the potential impact of ammonia on the anaerobic digestion of phenols remained unclear. Firstly, the methanogens and phenols degraders had a good tolerance up to 1gL-1 of total ammonia nitrogen (TAN), but the substrate utilization rate for phenol, and specific methanogenic activity of sludge were decreased by 89% and 67% at 5g TAN L-1, and 94% and 100% at 10g TAN L-1, respectively. Secondly, the optimum struvite crystallization conditions (pH=8.5, 10g TAN L-1, n(Mg2+):n(TAN):n(PO43-)=1:1:1) were obtained by the orthogonal tests. Thirdly, the removal efficiencies of chemical oxygen demand (COD) and phenols were recovered to around 82% and 66%, respectively in the upflow anaerobic sludge blanket reactor using the pretreatment of struvite precipitation at 10g TAN L-1 and 1g phenols L-1. Therefore, anaerobic digestion coupled with struvite precipitation was considered as an alternative way for CGW treatment.