气田产出水生物可处理性评价

Biodegradability evaluation of produced water in gasfield

采用三台平行的小型MBR进行了实验研究,评价了其对化学需氧量(COD)去除的影响。污泥浓度较低(挥发性悬浮固体的浓度为0.3~1.5 g/L),瞬时通量值为3~15 L/(m^(2)·h)。结果表明,COD去除率平均为60%(54%~63%),其中约三分之一的去除率归因于物理去除,操作参数值对去除率无显著影响。尽管趋势与以前报告的一些炼油厂废水研究结果一致,但总体清除量低于预期。生物反应器污泥的pH值在4.9到6.0,平均为5.2,而给水的pH值为4.3,这可能有助于低碳去除。将进料pH值调整到6.5以上会形成沉淀,从而导致膜污染。然而,MBR处理去除了所有给水醋酸盐和90%以上的油和油脂。处理似乎是有限的,既考虑到没有硝化作用(所有去除的有机氮明显被吸收到污泥中),也考虑到污泥固体浓度较低。有证据表明,给水中含有相当一部分(约40%)的高抗药性有机化合物,这些化合物被认为是含氮油田化学品。

Three parallel small-scale MBR were used to carry out the experimental study,and their effects on the removal of chemical oxygen demand(COD)were evaluated.The sludge concentration is low(the concentration of volatile suspended solids is 0.3~1.5 g/L),and the instantaneous flux value is 3~15 L/(m^(2)·h).The results show that the average COD removal rate is 60%(54%~63%),about one third of which is attributed to physical removal,and the operation parameters have no significant effect on the removal rate.Although the trend is consistent with some previously reported refinery wastewater studies,the overall removal is lower than expected.The pH value of bioreactor sludge is between 4.9 and 6.0,with an average of 5.2,while the pH value of feed water is 4.3,which may contribute to low carbon removal.When the feed pH value is adjusted above 6.5,precipitation will be formed,resulting in membrane fouling.However,MBR treatment removed all feed water acetate and more than 90%of oil and grease.The treatment appears to be carbon limited,taking into account both the absence of nitrification(all removed organic nitrogen is obviously absorbed into the sludge)and the low solids concentration of the sludge.There is evidence that the feed water contains a significant proportion(about 40%)of highly resistant organic compounds,which are considered to be nitrogenous oilfield chemicals.