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Forward osmosis coupled with lime-soda ash softening for volume minimization of reverse osmosis concentrate and CaCO 3 recovery: A case study on the coal chemical industry
Frontiers of Environmental Science & Engineering ( IF 6.4 ) Pub Date : 2020-07-30 , DOI: 10.1007/s11783-020-1301-6
Jiandong Lu , Shijie You , Xiuheng Wang

Reverse osmosis (RO) is frequently used forwaterreclamation fromtreated wastewaterordesalination plants. The RO concentrate (ROC) produced from the coal chemical industry (CCI) generally contains refractory organic pollutants and extremely high-concentration inorganic salts with a dissolved solids content of more than 20 g/L contributed by inorganic ions, such as Na+,Ca2+,Mg2+,Cl, and SO42−. To address this issue, in this study, we focused on coupling forward osmosis (FO) with chemical softening (FO-CS) for the volume minimization of CCI ROC and the recovery of valuable resources in the form of CaCO3. In the case of the real raw CCI ROC, softenin2g trea2tment by lime-soda ash was shown to effectively remove Ca2+/Ba2+ (>98.5%) and Mg2+/Sr2+/Si (>80%), as well as significantly mitigate membrane scaling during FO. The softened ROC and raw ROC corresponded to a maximum water recovery of 86% and 54%, respectively. During cyclic FO tests (4 × 10 h), a 27% decline in the water flux was observed for raw ROC, whereas only 4% was observed for softened ROC. The cleaning efficiency using EDTA was also found to be considerably higher for softened ROC (88.5%) than that for raw ROC (49.0%). In additio3 CaCO3 (92.2% purity) was recovered from the softening sludge with an average yield of 5.6 kg/m3 treated ROC. This study provides a proof-of-concept demonstration of the FO-CS coupling process for ROC volume minimization and valuable resources recovery, which makes the treatment of CCI ROC more efficient and more economical.



中文翻译:

正向渗透与石灰-苏打灰软化相结合,可最大程度地减少反渗透浓缩液的体积和CaCO 3的回收:以煤化工为例

反渗透(RO)通常用于处理过的废水或淡化厂的水回收。煤炭化学工业(CCI)生产的RO精矿(ROC)通常包含难熔的有机污染物和极高浓度的无机盐,其溶解固体含量超过20 g / L,是由无机离子(例如Na +,Ca 2+,镁2+,氯-和SO 4 2-。为了解决这个问题,在本研究中,我们专注于将正向渗透(FO)与化学软化(FO-CS)结合使用,以实现CCI ROC的体积最小化和以CaCO 3形式回收有价值的资源。对于真正的原始CCI ROC,softenin 2石灰-苏打灰处理的g trea 2处理可有效去除Ca 2+ / Ba 2 +(> 98.5%)和Mg 2+ / Sr 2+ / Si(> 80%),并在使用过程中显着减轻膜结垢FO。软化的ROC和原始ROC分别对应于最大水回收率86%和54%。在循环FO试验(4×10小时)中,未处理的ROC的水通量下降了27%,而软化的ROC仅观察到了4%。还发现使用EDTA的软化ROC的清洁效率(88.5%)明显高于未处理的ROC(49.0%)。在additio 3的CaCO 3(92.2%纯度)从软化污泥回收5.6千克/米的平均产率3处理过的ROC。这项研究为FO-CS偶联过程实现ROC体积最小化和有价值的资源回收提供了概念验证,这使CCI ROC的治疗更加有效和经济。

更新日期:2020-07-31
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