Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, South Korea.
Future Environmental Research Center, Korea Institute of Toxicology, 17 Jeigok-gil, Munsan, Jinju, Gyeongsangnam-do, 660-844, South Korea.
J Environ Manage. 2016 Oct 1;181:425-434. doi: 10.1016/j.jenvman.2016.06.041. Epub 2016 Aug 5.
While drinking water treatment residuals (DWTRs) inevitably lead to serious problems due to their huge amount of generation and limitation of landfill sites, their unique properties of containing Al or Fe contents make it possible to reuse them as a beneficial material for coagulant recovery and adsorbent. Hence, in the present study, to comprehensively handle and recycle DWTRs, coagulant recovery from DWTRs and reuse of coagulant recovered residuals (CRs) were investigated. In the first step, coagulant recovery from DWTRs was conducted using response surface methodology (RSM) for statistical optimization of independent variables (pH, solid content, and reaction time) on response variable (Al recovery). As a result, a highly acceptable Al recovery of 97.5 ± 0.4% was recorded, which corresponds to 99.5% of the predicted Al recovery. Comparison study of recovered and commercial coagulant from textile wastewater treatment indicated that recovered coagulant has reasonable potential for use in wastewater treatment, in which the performance efficiencies were 68.5 ± 2.1% COD, 97.2 ± 1.9% turbidity, and 64.3 ± 1.0% color removals at 50 mg Al/L. Subsequently, in a similar manner, RSM was also applied to optimize coagulation conditions (Al dosage, initial pH, and reaction time) for the maximization of real cotton textile wastewater treatment in terms of COD, turbidity, and color removal. Overall performance revealed that the initial pH had a remarkable effect on the removal performance compared to the effects of other independent variables. This is mainly due to the transformation of metal species form with increasing or decreasing pH conditions. Finally, a feasibility test of CRs as adsorbent for phosphate adsorption from aqueous solution was conducted. Adsorption equilibrium of phosphate at different temperatures (10-30 °C) and initial levels of pH (3-11) indicated that the main mechanisms of phosphate adsorption onto CRs are endothermic and chemical precipitation; the surfaces are energetically heterogeneous for adsorbing phosphate.
尽管饮用水处理厂污泥（DWTRs）由于产生量巨大且受限于垃圾填埋场而不可避免地导致严重问题，但由于其含有 Al 或 Fe 等独特特性，使其有可能被重新用作回收混凝剂和吸附剂的有益材料。因此，在本研究中，为了全面处理和回收 DWTRs，研究了从 DWTRs 中回收混凝剂以及回收后的混凝剂残渣（CRs）的再利用。在第一步中，使用响应面法（RSM）对影响变量（pH、固体含量和反应时间）进行统计优化，以确定响应变量（Al 回收率）。结果表明，Al 回收率高达 97.5±0.4%，与预测的 Al 回收率 99.5%非常接近。从纺织废水处理中回收的混凝剂与商业混凝剂的比较研究表明，回收的混凝剂在废水处理中具有合理的应用潜力，在 50mg Al/L 时，其对 COD、浊度和色度的去除效率分别为 68.5±2.1%、97.2±1.9%和 64.3±1.0%。随后，以类似的方式，也应用 RSM 优化了最大程度去除 COD、浊度和色度的实际棉纺织废水的混凝条件（Al 剂量、初始 pH 和反应时间）。整体性能表明，与其他独立变量相比，初始 pH 对去除性能有显著影响。这主要是由于金属物种形态随 pH 值的升高或降低而发生变化。最后，还对 CRs 作为吸附剂从水溶液中吸附磷酸盐的可行性进行了测试。在不同温度（10-30°C）和初始 pH 值（3-11）下的磷酸盐吸附平衡表明，磷酸盐吸附到 CRs 上的主要机制是吸热和化学沉淀；表面对于吸附磷酸盐是能量不均匀的。
