Pesticide decontamination using UV/ferrous-activated persulfate with the aid neuro-fuzzy modeling: A case study of Malathion.

In the current study, the Malathion decontamination by the aid of the UV/ferrous-activated persulfate (PS) was investigated and the effects of pH, persulfate (PS) concentration, ferrous concentration, Malathion concentration, and different inorganic ions were evaluated. Also, the Adaptive Neuro-Fuzzy Inference System (ANFIS) was applied to model Malathion degradation data. The maximum degradation efficiency was associated with pH = 3, PS concentration of 1.2 mM, the ferrous concentration of 0.6 mM, Malathion concentration of 20 mg/L for 60 min. The degradation efficiency was decreased in the presence of Cl- (23%), NO3- (13.5%), HCO3- (35.4%) and H2PO4- (48.7%) ions. Results revealed that persulfate radical (52%) plays a more important role in Malathion degradation while compared with hydroxyl radical (15%). The low root mean square error (RMSE = 6.451), mean absolute error (MAE = 3.8306), absolute-average-deviation (AAD = 0.1005) and high coefficient of determination (R2 = 0.972) correlated with the proposed ANFIS models confirmed the model accuracy. Besides, the process optimization was conducted by using ANFIS to predict the best operating circumstances, which resulted in the maximum Malathion degradation (95.54%).

Degradation of dimethyl phthalate using persulfate activated by UV and ferrous ions: optimizing operational parameters mechanism and pathway.

The present study aimed to model and optimize the dimethyl phthalate (DMP) degradation from aqueous solution using UVC/ Na2S2O8/Fe2+ system based on the response surface methodology (RSM). A high removal efficiency (97%) and TOC reduction (64.2%) were obtained under optimum conditions i.e. contact time = 90 min, SPS concentration = 0.601 mM/L, Fe2+ = 0.075 mM/L, pH = 11 and DMP concentration = 5 mg/L. Quenching experiments confirmed that sulfate radicals were predominant radical species for DMP degradation. The effect of CO3 - on DMP degradation was more complicated than other aquatic background anions. The possible pathway for DMP decomposition was proposed according to HPLC and GC-MS analysis. The average oxidation state (AOS) and carbon oxidation state (COS) values as biodegradability indicators demonstrated that the UVC/SPS/Fe2+ system can improve the bioavailability of DMP over the time. Finally, the performance of UVC/SPS/Fe2+ system for DMP treatment in different aquatic solutions: tap water, surface runoff, treated and raw wastewater were found to be 95.7, 88.5, 80.5, and 56.4%, respectively. Graphical abstract.

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater.

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal.