Application of advanced oxidation processes including O3, H2O2 and O3/H2O2 for decolorisation and COD concentration removal of instant coffee wastewater treatment after anaerobic treatment. This wastewater mainly contains inert COD that is hard treated by the biological process. The efficiency of decolorisation and COD removal is investigated by changing of pH, concentrations of O3 and H2O2, O3:H2O2 molar ratio, and concentrations of Cl–, SO4 2–, HCO3 –. The advanced oxidation process applied O3/H2O2 is the highest efficiency of decolorisation and COD removal to compare with that of O3 and H2O2 separately. A pH optimum range is between 7 and 9 of O3, H2O2 và O3/H2O2 and the best molar ratio of O3:H2O2 is 3 for the highest efficiency. In the optimal conditions, decolorisation and COD removal efficiencies of O3, H2O2 and O3/H2O2 are 71 % and 62 %, 70 % and 47 %, 95 % and 73 %, respectively. Additionally, a presence of Cl–, HCO3 –, SO4 2– ions will moderately decrease the decolorisation and COD removal efficiencies. Advanced oxidation process using O3/H2O2 is applied as a possible method for instant coffee wastewater removal after treated by the biological processes.
In this study, electro-Fenton (EF) was employed for the removal of tricyclazole (TC) and total organic carbon (TOC) in real pesticide wastewater (RPW). The central composite design (CCD) with three parameters, that is, current density, Fe2+ concentration, and electrolysis time, has been conducted to predict the TOC and TC removal efficiency. The high correlation of the quadratic models of 0.9842 and 0.9781 for TC and TOC removal, respectively, indicates the significance of the models. The obtained results revealed that the high-efficiency removal of both TC and TOC in RPW. Approximately 99.6% of TC was decomposed under the optimum conditions of a current density of 2.2 mA/cm2 and an Fe2+ concentration of 0.2 mM during 188 min with an operating cost of 121.392 $/kg TC or ∼2.692 $/m3, while 84.2% TOC was eliminated at a current density of 2.2 mA/cm2 and an Fe2+ concentration of 0.2 mM during 217 min with an operating cost of 3.019 $/kg TOC or 3.916 $/m3. Acute toxicity tests at optimal condition revealed moderate exhibition toxicity of treated wastewater against Daphnia magna with LC50 values of 3.12%, 2.05%, 1.84%, and 1.36% at 24 h, 48 h, 72 h, and 96 h, respectively. The removal of TC and TOC followed pseudo-first-order kinetic with an R2 of ∼0.993 and 0.923, respectively.
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