Optimizing COD removal from greywater by photoelectro-persulfate process using Box-Behnken design: assessment of effluent quality and electrical energy consumption
Optimizing COD removal from greywater by photoelectro-persulfate process using Box-Behnken design: assessment of effluent quality and electrical energy consumption
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DOI：
10.1007/s11356-016-7139-6
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发表时间：
2016-10-01
影响因子：
5.8
通讯作者：
Ghanbari, Farshid
中科院分区：
文献类型：
--
作者：
Ahmadi, Mehdi;Ghanbari, Farshid
灰水（GW）是各种应用中水回用的潜在来源。然而，在环境标准和对公众健康的风险的情况下，GW处理仍然是水再利用的一个重要问题。本研究旨在探讨一种复合式废水COD去除工艺的优化与建模。研究了电生亚铁离子（EC）和紫外光（UV）同时激活过硫酸根（PS）产生硫酸根自由基.采用Box-Behnken试验设计对光电过硫酸盐（PEPS）进行优化，考察了pH、PS投加量、电流密度和电解时间4个因素对COD去除率的影响。结果表明，该模型可用于预测COD去除率。在pH = 6.9、PS = 8.8mM、电流密度为2.0mA/cm ~ 2、电解时间为49.3min的最佳工艺条件下，COD和BOD_5均能达到排放标准，BOD_5、浊度、TSS、磷酸盐和UV_（254）均得到有效去除。不同配置的工艺进行了评估COD去除。COD去除率的大小顺序为：PS < Fe（II）< UV/PS絮凝剂标记Fe（II）/PS < Fe（II）/PS/UV <电絮凝剂标记电絮凝剂/UV <电-PS < PEPS。在上述过程中，在60 min反应时间内监测PS浓度表明，PEPS可以显着激活PS。溶液的pH值也进行了监测和相关的结果表明，PS的存在下，在10分钟的第一次降低pH值，而在阴极的氢氧离子的产生显着增加pH值。电化学过程对电能消耗的贡献远小于光解过程。
Greywater (GW) is a potential source for water reuse in various applications. However, GW treatment is still a vital issue in water reuse in cases of environmental standards and risk to public health. This study investigates optimization and modeling of a hybrid process for COD removal from GW. Persulfate (PS) was simultaneously activated by electrogenerated ferrous ion (EC) and UV to generate sulfate radical. Photoelectro-persulfate (PEPS) was optimized by Box-Behnken design and the effects of four variables (pH, PS dosage, current density, and electrolysis time) were evaluated on COD removal. The results and several coefficients showed that the obtained model was acceptable for predicting the COD removal. Moreover, under optimum conditions (pH = 6.9, PS = 8.8 mM, current density = 2.0 mA/cm(2), and 49.3 min electrolysis time), BOD5, turbidity, TSS, phosphate, and UV254 were effectively removed and COD and BOD5 values reached to discharge standards. Different configurations of the processes were assessed for COD removal. The order of COD removal efficiency followed: PS < Fe(II) < UV/PS aecurrency sign Fe(II)/PS < Fe(II)/PS/UV < electrocoagulation aecurrency sign electrocoagulation/UV < electro-PS < PEPS. The monitoring PS concentration during 60 min reaction time in the aforesaid processes indicated that PEPS could remarkably activate PS. The solution pH was also monitored and related results revealed that the presence of PS during the 10 min first time decreased pH value while production of hydroxide ion at cathode increased pH significantly. Finally, the contribution of electrochemical process in the electrical energy consumption was far less than that of photolysis process in hybrid PEPS process.