Technische Universität Berlin, Centre for Water in Urban Areas, Berlin, Germany.
Water Sci Technol. 2010;61(2):301-6. doi: 10.2166/wst.2010.800.
The widespread application of nanofiltration (NF) and reverse osmosis (RO) membranes in wastewater reuse inevitably generates a concentrate stream. Due to high concentrations of phosphate and salts, disposal of membrane concentrates is a problem which seriously constrains the application of this technology, especially in inland applications. There is a need for technologies which facilitate an affordable and environmentally-safe disposal of membrane concentrates. The objectives of this study are to investigate appropriate treatment techniques to (1) increase the recovery of the membrane filtration thus minimising the volume of the concentrate stream, and (2) increase the concentrate quality to enable discharge into surface water bodies. The results show that both adsorption onto granular ferric hydroxide (GFH) and chemical precipitation are generally effective for phosphate removal from NF concentrates. Chemical precipitation by dosing of sodium hydroxide solution is rapid and removes more than 90% of phosphate and calcium ions. By the removal of calcium ions, chemical precipitation can significantly reduce the scaling potential of NF and RO concentrates. This may allow higher recoveries in the NF/RO process.
纳滤 (NF) 和反渗透 (RO) 膜在废水再利用中的广泛应用不可避免地会产生浓缩液。由于磷酸盐和盐分浓度高，膜浓缩液的处理是一个问题，这严重限制了这项技术的应用，特别是在内陆应用中。需要有技术来实现膜浓缩液的经济实惠且环境安全的处理。本研究的目的是探索合适的处理技术，（1）提高膜过滤的回收率，从而最大限度地减少浓缩液的体积，和（2）提高浓缩液的质量，使其能够排入地表水。研究结果表明，颗粒状氢氧化铁 (GFH) 吸附和化学沉淀通常可有效去除 NF 浓缩液中的磷酸盐。通过投加氢氧化钠溶液进行化学沉淀，反应迅速，可去除超过 90%的磷酸盐和钙离子。通过去除钙离子，化学沉淀可以显著降低 NF 和 RO 浓缩液的结垢潜力。这可能允许在 NF/RO 工艺中实现更高的回收率。
