生活垃圾持续回灌纳滤浓缩液的产气与水质变化

膜处理技术已成为大多数填埋场处理渗滤液的常用方法，过滤后产生的浓缩液通常采用回灌法进行处置。虽然回灌法投资少、操作方便、运行费用低，但浓缩液高盐低生化性的特点可能导致在回灌后对垃圾的产气和渗滤液水质产生负面影响。通过模拟生化反应器，将纳滤浓缩液周期性回灌至由实际填埋场采集的高、低有机质垃圾样本中，监测甲烷产量、臭气浓度以及渗滤液水质。结果表明：相比清水对照组，回灌浓缩液对产甲烷过程具有抑制效果，且对低有机质含量垃圾的抑制比高有机质垃圾更强；回灌浓缩液后NH₃和H₂S的释放量变大，主要在快速产甲烷阶段和产甲烷衰减阶段释放；随着浓缩液回灌次数的增加，COD、BOD₅、NH₃-N、TN、动植物油呈现较好的去除效果，但出水盐浓度将持续上升并超过浓缩液本身。

GAS PRODUCTION AND LEACHATE PROPERTIES OF MUNICIPAL SOLID WASTE WITH CONTINUOUS INJECTION OF CONCENTRATED NF LEACHATE

For most landfills, membrane filtration has become a common method for leachate treatment. The filtered concentrated leachate is usually recirculated back to the landfill for such operation is convenient, of low investment and running cost. However, concentrated leachate has characteristics of high salt and poor degradability, which might affect landfill gas production and the effluent quality of leachate after injection. In this study, the nanofiltration concentrate was periodically reinjected into simulating bioreactors filled with waste samples of high/low organic content collected from the landfill site. And then the methanogenesis, odor gas and leachate quality were monitored. The experimental results showed that compared with the injection of water (blank and control), the reinjection of concentrated liquid had an inhibitory effect on methanogenesis process, and the inhibition for low organic waste was stronger. After the injection of the concentrated leachate, the release of ammonia and hydrogen sulfide became stronger. The odor gases were mainly released in rapid methanogenesis phase and the methanogenic attenuation phase. With the increase of the reinjection cycles, the reinjection of concentrated leachate showed good removal effect on COD, BOD₅, ammonia nitrogen, total nitrogen and oil in the effluent, but it also led to the rise of salt concentration in the effluent, even higher than the original concentrated leachate.