Faculty of Civil and Environmental Engineering, Technion, Haifa, Israel.
Water Sci Technol. 2010;61(4):911-7. doi: 10.2166/wst.2010.613.
This paper investigates denitrification of brines originating from membrane treatment of groundwater in an upflow sludge blanket (USB) reactor, a biofilm reactor without carrier. A simulated brine wastewater was prepared from tap water and contained a nitrate concentration of 125 mg/l as N and a total salt concentration of about 1%. In order to select for a suitable energy source for denitrification, two electron donors were compared: one promoting precipitation of calcium compounds (ethanol), while the other (acetic acid), no precipitation was expected. After extended operation to reach steady state, the sludge from the two reactors showed very different mineral contents. The VSS/TSS ratio in the ethanol fed reactor was 0.2, i.e., 80% mineral content, while the VSS/TSS ratio in the acetic acid fed reactor was 0.9, i.e., 10% mineral content. In spite of the low mineral content, the sludge from the acetic acid fed reactor showed remarkably excellent granulation and settling characteristics. Although the denitrification performance of the acetic acid fed reactor was similar to that of the ethanol fed reactor, there was a huge difference in the sludge production due to mineral precipitation, with the corresponding negative aspects including increased costs of sludge treatment and disposal and moreover, instability and difficulties in reactor operation (channeling). These arguments make acetic acid a much more suitable candidate for brine denitrification, despite previous findings observed in groundwater denitrification regarding the essential role of a relatively high sludge mineral fraction for stable and effective USB reactor operation. Based on a comparison between two denitrification reactors with and without salt addition and using acetic acid as the electron donor, it was concluded that the reason for the excellent sludge settling characteristics found in the acetic acid fed reactor is the positive effects of higher salinity on granular sludge formation.
本文研究了在上流式污泥床（USB）反应器中用膜处理地下水产生的卤水的反硝化作用，该生物膜反应器中没有载体。模拟的卤水废水是由自来水制成的，含有 125mg/l 的硝酸盐浓度（以 N 计）和约 1%的总盐浓度。为了选择适合反硝化的合适能源，比较了两种电子供体：一种促进钙化合物沉淀（乙醇），而另一种（乙酸），预计不会发生沉淀。在延长运行时间以达到稳定状态后，两个反应器中的污泥表现出非常不同的矿物质含量。在乙醇进料的反应器中，VSS/TSS 比为 0.2，即 80%的矿物质含量，而在乙酸进料的反应器中，VSS/TSS 比为 0.9，即 10%的矿物质含量。尽管矿物质含量低，但乙酸进料的反应器中的污泥表现出非常出色的颗粒化和沉淀特性。尽管乙酸进料的反应器的反硝化性能与乙醇进料的反应器相似，但由于矿物质沉淀，污泥产量存在巨大差异，这带来了增加污泥处理和处置成本的负面影响，而且还会导致反应器操作不稳定和困难（沟流）。尽管先前在地下水反硝化中观察到了相对较高的污泥矿物质分数对稳定和有效 USB 反应器运行的重要作用，但这些论点使得乙酸成为卤水反硝化的更合适的候选物。基于两个有盐和无盐添加的反硝化反应器以及使用乙酸作为电子供体的比较，得出结论，在乙酸进料的反应器中发现的出色污泥沉淀特性的原因是较高盐度对颗粒污泥形成的积极影响。
