Pervov Alexei, Aung Htet Zaw, Spitsov Dmitry
Moscow State University of Civil Engineering, 26, Yaroslaskoye Highway, 129337 Moscow, Russia.
Membranes (Basel). 2023 Jan 25;13(2):153. doi: 10.3390/membranes13020153.
Mine water usually contains heavy metals and other inorganic and organic pollutants that contaminate water bodies. Reverse osmosis (RO) techniques are capable of producing purified water that meets discharge regulations. However, the problem of RO concentrate disposal and utilization is still not solved. The well-known zero liquid discharge (ZLD) process provides total concentrate utilization at the power industries but seems unreasonably expensive for the treatment of large amounts of mine water due to required chemical softening and the evaporation of concentrate. In the present article, a new approach to increase the recovery of reverse osmosis and to avoid high operational costs is demonstrated and discussed. The new technique involves radical RO concentrate flow reduction and withdrawal, together with dewatered sludge. The idea to "hide" concentrate in dewatered sludge is proposed and demonstrated during experiments. The article demonstrates results of the conducted experimental program aimed at reduction of volumes of all liquid wastes produced during mine water treatment using a new approach to concentrate it with a cascade of nanofiltration membranes and to reach a TDS value of 110-120 g per liter. The obtained concentrate is mixed with the wet sludge, which is further dewatered and withdrawn together with the dewatered sludge. Experiments are conducted that demonstrate a reduction in calcium in the concentrate due to deposition of calcium carbonate on the "seed crystals" in the circulation mode. Another distinguishing feature of the new technique is the separation of concentrate into two streams containing high concentrations of monovalent ions (sodium and ammonium chlorides) and divalent ions (calcium, magnesium and copper sulphates). Flow diagrams of the processes are presented to demonstrate the water treatment technique used to produce deionized water and two types of sludges: sludge after clarification and sludge after calcium carbonate deposition.
矿井水通常含有重金属以及其他无机和有机污染物，会污染水体。反渗透（RO）技术能够生产出符合排放标准的净化水。然而，反渗透浓缩液的处置和利用问题仍未得到解决。著名的零液体排放（ZLD）工艺在电力行业实现了浓缩液的完全利用，但由于需要化学软化和浓缩液蒸发，对于处理大量矿井水而言成本似乎过高。在本文中，展示并讨论了一种提高反渗透回收率并避免高运营成本的新方法。这项新技术包括大幅减少反渗透浓缩液流量并将其与脱水污泥一起排出。提出了将浓缩液“隐藏”在脱水污泥中的想法，并在实验中得到了验证。本文展示了所开展的实验项目的结果，该项目旨在通过使用一系列纳滤膜对矿井水处理过程中产生的所有液体废物进行浓缩，使其达到每升110 - 120克的总溶解固体（TDS）值，从而减少其体积。将得到的浓缩液与湿污泥混合，进一步脱水后与脱水污泥一起排出。实验表明，在循环模式下，由于碳酸钙在“晶种”上的沉积，浓缩液中的钙含量有所降低。这项新技术的另一个显著特点是将浓缩液分离成两股流，一股含有高浓度的单价离子（氯化钠和氯化铵），另一股含有二价离子（硫酸钙、硫酸镁和硫酸铜）。文中给出了工艺流程示意图，以展示用于生产去离子水和两种类型污泥（澄清后污泥和碳酸钙沉积后污泥）的水处理技术。
