Mofrad Mohammad Mehdi Golbini, Pourzamani Hamidreza, Amin Mohammad Mehdi, Parseh Iman, Alipour Mohammadreza
Environmental Research Center, Department of Environmental Health, School of Health, Isfahan University of Medical Sciences, Iran.
Department of Environmental Health Engineering, Behbahan Faculty of Medical Sciences, Behbahan, Iran.
Heliyon. 2019 Dec 26;6(1):e03091. doi: 10.1016/j.heliyon.2019.e03091. eCollection 2020 Jan.
The hybrid treatment techniques have been proven that could be a proper solution to the metalworking fluid (MWF) wastewaters disposal challenge. Hence, this investigation was conducted aim to the assessment of chemical addition-dissolved air floatation (CA-DAF) unit followed with a heterogeneous photocatalytic (PC) process as UV/HO/ZnO to treat MWF wastewater produced in one of the central industrial estates in the Middle East. The CA-DAF unit was implemented as trial and errors and had an appropriate efficiency. However, the environmental discharge standards were not achieved only by this unit, so that, a PC process considered for this purpose in a pilot-scale reactor. And also, Chemical oxygen demand (COD), total petroleum hydrocarbons (TPHs) were considered as physicochemical parameters to analyze the applied photochemical reaction throughout the concentrations of ZnO and HO, and pH value as variables of the study. The ideal and optimized conditions were observed at pH 10, 600 mg l of ZnO, and 13.11 g l of HO via 99.87% and 97.9% reduction rates in total COD and TPH, respectively. These removal rates were obtained for this integrated strategy under the optimized reaction. By evaluating the synergistic effect, it was found that UV/ZnO could be a predominant reaction in this process. The organic and intermediates analysis appeared 78.46% reduction for all detected organic matters. Besides, PC generation of bis phthalate, mono phthalate, benzene, and benzoic acid to 2,6-bis (1,1-dimethylethyl)-4-mthyl phenol was the reason of the residual phenolic compound concentration in the reaction solution with low removal rate. The kinetic study showed that this reaction could be well fitted with the pseudo-first-order kinetic model by equal with 0.973 and 0.988 in turn for COD and TPH. The expenditures to treat 1 m of the CA-DAF was estimated at 5.335 us$ via cost analysis. Finally, the collected findings indicate that CA-DAF integrated with UV/HO/ZnO can be an efficient approach in the MWF wastes disposal or treatment for reuse.
混合处理技术已被证明是解决金属加工液（MWF）废水处理难题的合适方案。因此，本研究旨在评估化学添加 - 溶解空气浮选（CA - DAF）单元，随后采用非均相光催化（PC）工艺，即UV/HO/ZnO，来处理中东某中央工业区产生的MWF废水。CA - DAF单元通过反复试验实施，具有适当的效率。然而，仅靠该单元无法达到环境排放标准，因此，为此在中试规模反应器中考虑采用PC工艺。此外，化学需氧量（COD）、总石油烃（TPH）被视为物理化学参数，以分析在不同浓度的ZnO和HO以及pH值（作为研究变量）下所应用的光化学反应。在pH值为10、ZnO浓度为600 mg/L和HO浓度为13.11 g/L时，观察到理想和优化的条件，此时总COD和TPH的去除率分别为99.87%和97.9%。这些去除率是在优化反应下通过这种综合策略获得的。通过评估协同效应，发现UV/ZnO可能是该过程中的主要反应。有机物和中间体分析表明，所有检测到的有机物减少了78.46%。此外，PC过程中双邻苯二甲酸酯、单邻苯二甲酸酯、苯和苯甲酸生成2,6 - 双（1,1 - 二甲基乙基）- 4 - 甲基苯酚，这是反应溶液中残留酚类化合物浓度去除率低的原因。动力学研究表明，该反应能很好地拟合伪一级动力学模型，COD和TPH的拟合度依次为0.973和0.988。通过成本分析，处理1立方米CA - DAF的费用估计为5.335美元。最后，收集到的结果表明，CA - DAF与UV/HO/ZnO相结合可以成为MWF废物处理或处理后再利用的有效方法。
