Solid waste generation and characterization are some of the most important parameters which affect environmental sustainability. Municipal solid waste (MSW) characterization depends on social structure and income levels. This study aims to determine the variations in waste components within MSW mass by income levels and seasonal conditions following the analysis conducted on the characterization of solid wastes produced in the Kartal district of the province of Istanbul, which is the research area of this study. To this end, 1.9 tons of solid waste samples were collected to represent four different lifestyles (high, medium, and low income levels, and downtown) in the winter and summer periods, and characterization was made on these samples. In order to support waste characterization, humidity content and calorific value analyses were also conducted and various suggestions were brought towards waste management in line with the obtained findings. According to the results obtained in the study, organic waste had the highest rate of waste mass by 57.69%. Additionally, significant differences were found in municipal solid waste components (MSWC) based on income level. Average moisture content (MC) of solid waste samples was 71.1% in moisture analyses. The average of calorific (heating) value (HHV) was calculated as 2518.5 kcal·kg⁻¹.

This study deals with chemical oxygen demand (COD), phenol and Ca⁺² removal from paper mill industry wastewater by electrocoagulation (EC) and electro-Fenton (EF) processes. A response surface methodology (RSM) approach was employed to evaluate the effects and interactions of the process variables and to optimize the performance of both processes. Significant quadratic polynomial models were obtained (R² = 0.959, R² = 0.993 and R² = 0.969 for COD, phenol and Ca⁺² removal, respectively for EC and R² = 0.936, R² = 0.934 and R² = 0.890 for COD, phenol and Ca⁺² removal, respectively). Numerical optimization based on desirability function was employed; in a 27.55 min trial 34.7% of COD removal was achieved at pH 9 and current density 96 mA/cm² for EC whereas in a 30 min trial 74.31% of COD removal was achieved at pH 2 and current density 96 mA/cm² and H₂O₂/COD molar ratio 2.0 for EF. The operating costs were calculated to be 6.44 €/m³ for EC and 7.02 €/m³ for EF depending on energy and electrode consumption at optimum conditions. The results indicate that the RSM is suitable for the design and optimization of both of the processes. However EF process was more effective technology for paper mill industry wastewater treatment as compared with EC.

In this paper, the response surface methodology (RSM) approach using central composite design (CCD) was applied to develop mathematical model and to optimize process parameters for COD and TSS removal from tannery wastewater by electrocoagulation and electro-Fenton processes using iron electrodes. Analysis of variance (ANOVA) was used to analyze the data and to obtain the interaction between the process variables and the responses. ANOVA showed the relative significance of process parameters in the removal process. The second-order regression model was developed to predict the removal efficiency using Statgraphics Centurion XVI.I software program. The optimal conditions were determined as reaction time 5.0 min, pH 3.31, current density 53.72 mA/cm², and H₂O₂ dose 0.14 g/L for electro-Fenton process, and reaction time 40.4 min, pH 7.0, and current density 50.9 mA/cm² for electrocoagulation process. At optimum conditions 54.8 and 87.3% COD removal efficiencies, 86 and 88% TSS removal efficiencies were achieved in electrocoagulation and electro-Fenton processes, respectively. The operating costs for elecrocoagulation and electro-Fenton processes at optimized conditions were calculated to be 6.4 and 6.8 €/m³. Electro-Fenton process was found to be more effective for tannery wastewater treatment.

In this study, response surface methodology was applied for food wastewater by electrocoagulation (EC) and electro-Fenton (EF) processes. The optimum conditions for the chemical oxygen demand (COD) removal were found to be 21.36 min, pH 10 and 86 mA/cm² in EC, whereas 27.11 min, pH 2.38, 86 mA/cm² and H₂O₂/COD:2 in EF process. COD removal efficiencies were determined to be 29.4% for EC and 59.1% for EF processes and higher than 99% total suspended solids removal efficiencies were achieved. It can be concluded that high COD removal was obtained (4998 mg/L COD removal by EC and 10,047 mg/L COD removal by EF).