Photo-Fenton-Like Treatment of Municipal Wastewater

Abstract

In this work, the photochemical treatment of a real municipal wastewater using a persulfate-driven photo-Fenton-like process was studied. The wastewater treatment efficiency was evaluated in terms of total carbon (TC), total organic carbon (TOC) and total nitrogen (TN) removal. Response surface methodology (RSM) in conjunction Box-Behnken design (BBD) and multilayer artificial neural network (ANN) have been utilized for the optimization of the treatment process. The effects of four independent factors such as reaction time, pH, K2S2O8 concentration and K2S2O8/Fe2+ molar ratio on the TC, TOC and TN removal have been investigated. The process significant factors have been determined implementing Analysis of Variance (ANOVA). Both RSM and ANN accurately found the optimum conditions for the maximum removal of TOC (100% and 98.7%, theoretically), which resulted in complete mineralization of TOC at the reaction time of 106.06 min, pH of 7.7, persulfate concentration of 30 mM and K2S2O8/Fe2+ molar ratio of 7.5 for RSM and at the reaction time of 104.93 min, pH of 7.7, persulfate concentration of 30 mM and K2S2O8/Fe2+ molar ratio of 9.57 for ANN. On the contrary, the attempts to find the optimal conditions for the maximum TC and TN removal using statistical, and neural network models were not successful.

UV and Zero-Valent Iron (ZVI) Activated Continuous Flow Persulfate Oxidation of Municipal Wastewater

“…F-and p-values were 20.60 and 0.0019, respectively. While a p-value less than 0.05 indicates the relevance of the model and model terms, the F-value shows the distribution of the actual values around the RSM model [12]. A, B, and AC, namely, space time, PS concentration, and the interaction between space time and PS/ZVI molar ratio, were the most significant parameters in the process as they had a p-value of less than 0.05.…”

“…In addition to sulfate radicals, the UV/PS system can generate hydroxyl and persulfate radicals by the following chemical equations [12,32]:…”

“…The hazardous components of MWW released to nature as a result of poor treatment include organic matter, phosphates, nitrates, and microorganisms [12,13]. Pharmaceuticals, not completely metabolized by humans and animals, also enter the environment as a part of organic matter.…”

“…Apart from oxidizing agents, the activating catalysts vary quite widely, too [23,29]. For example, photolysis [12], sonolysis [31], thermolysis [32], transition metals [33], carbon materials [34], and heterogeneous catalysts [35] may act as an activator. Some papers use activators in combination for synergetic effect [36,37].…”

Degradation of 4-Tert-Butylphenol in Water Using Mono-Doped (M1: Mo, W) and Co-Doped (M2-M1: Cu, Co, Zn) Titania Catalysts

“…Several approaches have been investigated for the removal of 4-t-BP, including biological processes and advanced oxidation processes (AOPs) [11,13,14]. In contrast with the inefficiency of and relatively long time required by biological degradation, AOPs have received a lot of interest for their ability to remove such persistent pollutants by turning them into carbon dioxide and water [15][16][17]. AOPs are based on the generation of highly reactive radicals, such as hydroxyl radicals (•OH), that can easily react with organic compounds [18][19][20].…”