Ramaswami Sreenivasan, Behrendt Joachim, Otterpohl Ralf
Institute of Wastewater Management and Water Protection, Hamburg University of Technology (TUHH), Eissendorfer Str. 42, 21073 Hamburg, Germany.
Membranes (Basel). 2018 Mar 21;8(2):17. doi: 10.3390/membranes8020017.
Reverse osmosis (RO) and nanofiltration (NF) are among the state-of-the-art technologies for treating landfill leachates. Due to the complexity and variance in the composition of leachates, numerous combinations of multiple technologies are used for their treatment. One process chain for the treatment of raw leachate is RO followed by further concentration of RO-retentate using NF (RO-NF scheme). The aptness of this process train used by some landfill sites around the world (usually with the aim of volume reduction so as to re-inject the concentrate into the landfill) is questionable. This study investigated two schemes RO-NF and NF-RO (nanofiltration of raw leachate followed by reverse osmosis of NF permeate) to identify their merits/demerits. Experiments were conducted in bench scale using commercial membranes: DOW Filmtec NF270 and SW30HR. Filtration trials were performed at different pressures to compare the water and solute transports in the individual stages of the two schemes. Based on the water fluxes and compositions of retentates and permeates; osmotic pressures, energy demands, and other possible operational advantages were discussed. NF-RO offers some advantages and flexibility for leachate treatment besides being energy efficient compared to RO-NF, wherein osmotic pressure steadily increases during operation in turn increasing operation and maintenance costs.
反渗透（RO）和纳滤（NF）是处理垃圾渗滤液的先进技术。由于渗滤液成分的复杂性和变异性，多种技术的众多组合被用于其处理。一种处理原生渗滤液的工艺链是先进行反渗透，然后使用纳滤对反渗透截留物进行进一步浓缩（RO-NF方案）。世界各地一些垃圾填埋场使用的这种工艺序列（通常旨在减少体积以便将浓缩液重新注入垃圾填埋场）的适用性值得怀疑。本研究调查了RO-NF和NF-RO两种方案（对原生渗滤液进行纳滤，然后对纳滤渗透物进行反渗透），以确定它们的优缺点。使用商业膜DOW Filmtec NF270和SW30HR在实验室规模进行了实验。在不同压力下进行过滤试验，以比较两种方案各个阶段的水和溶质传输情况。基于水通量以及截留物和渗透物的组成，讨论了渗透压、能量需求和其他可能的操作优势。与RO-NF相比，NF-RO除了具有能源效率外，在渗滤液处理方面还具有一些优势和灵活性；在RO-NF中，运行期间渗透压会稳步增加，进而增加运营和维护成本。
