Response Surface Methodology (RSM)-Based Prediction and Optimization of the Fenton Process in Landfill Leachate Decolorization

As an advanced oxidative processes, the Fenton process is receiving popularity as a wastewater treatment technique that can be used for hazardous landfill leachate. The treatment is simple, yet involves complex interactions between the affecting parameters including reaction time, H2O2/Fe2+ ratio, pH, and iron (II) ion concentration. Hence, the purpose of this present study was to analyze the factors affecting landfill leachate treatment as well as their interaction by means of response surface methodology (RSM) with central composite design. The independent variables were reaction time, H2O2/Fe2+ ratio, iron (II) ion concentration, and pH, and the dependent variable (response) was color-removal percentage. The optimum treatment conditions for pH, H2O2/Fe2+ ratio, Fe2+ concentration, and reaction time were 8.36, 3.32, 964.95 mg/L, and 50.15 min, respectively. The model predicted 100% color removal in optimum conditions, which was close to that obtained from the experiment (97.68%). In conclusion, the optimized Fenton process using the RSM approach promotes efficient landfill leachate treatment that is even higher than that already reported.

INVESTIGATION of COLOR REMOVAL in REAL TEXTILE INDUSTRY WASTEWATER with MEMBRANE BIOREACTOR-ACTIVE CARBON SYSTEM

The textile industry is an industry that consumes large amounts of water during production, contains various chemicals in its wastewater, conventional treatment methods are insufficient to reduce the wastewater pollution level, and has colloidal substances and color problems. Membrane bioreactor systems provide high efficiency in the treatment of textile wastewater and dyestuff removal. Removal of dyestuffs and turbidity in real textile wastewater by using a laboratory-scale membrane bioreactor system was studied. Chemical precipitation was not applied before the biological treatment for the removal of color and other pollutant parameters. A hollow fiber microfiltration membrane module was used in the system. Then a combination with an active carbon filter was created to take the color removal to a higher level. The development of the microorganism composition adapted to the textile industry was observed in the biological reactor. The system was operated with an endless sludge age and a hydraulic retention time of 24 hours. Color measurement transparency index parameter DFZ (DurchsichtsFarbZahl) was measured in a spectrophotometer at wavelengths of 436, 525, and 620 nm (nanometers) according to EN ISO 7887 standards. In the microfiltration permeate water, the color removal were found in 436 nm: 91-95%, 525 nm: 94-98%, 620 nm: 96-99%, and in activated carbon permeate water, the color removal in 436 nm: 96-99% at 525 nm: 95-99%, 620 nm: 96-99%, respectively. Due to the physical separation of the membrane, which is the simplest definition, high efficiencies in color removal have been achieved in the system. The activated carbon system combined with the membrane was found higher efficiency in color removal than the microfiltration output.

Influence of Leachate Matrix on Oxidation Performance of Ozonation and AOPs

Landfill leachate is a critical environmental issue that should be adequately treated to prevent it from spreading to the environment. This study explored the influence of raw leachate matrix and treated leachate matrix on O3, O3/H2O2, and O3/PS performance. O3 and AOPs were conducted in a laboratory-scale batch reactor. The findings showed the degradation of p-cresol, COD, and humic substances was much slower in treated leachate matrix than in raw leachate matrix. However, color was found easier to remove in treated leachate. The results revealed a synergic effect between molecular O3 and dissolved organic matter in the raw leachate as the O3 performance was enhanced in the presence of raw leachate matrix, except for color removal. The highest degradation of more than 90% was achieved in O3/H2O2 to remove COD, p-cresol, and humic substances, although it is the most affected by the leachate matrix. This study provides vital insight into the notable performance of O3/PS in color removal regardless of the influence of leachate matrix, suggesting that the sulfate radical-induced oxidation outperformed O3 and O3/H2O2 in reducing nitrogen-containing compounds.

The effect of different types of AOPs supported by hydrogen peroxide on the decolorization of methylene blue and viscose fibers dyeing wastewater

Wastewater from the textile industry containing a high concentration of organic and inorganic chemicals have strong color and residual chemical oxygen demand (COD). Therefore, advanced oxidation processes (AOPs) are very good candidates to treat textile industry wastewater. In this study, we investigated the effect of different types of AOPs supported with hydrogen peroxide (H2O2) on the treatment of viscose fibers dyeing wastewater. Fenton, photo-Fenton, and Fenton supported subcritical water oxidation (FSWO) processes were chosen as AOPs to compare the treatment efficiency of viscose fibers dyeing wastewater. The effects of solution pH, Fe2+ concentration, and H2O2 concentration on the treatment of viscose fibers dyeing wastewater were tested. The maximum color and COD removal efficiency was obtained corresponding to pH 2.5 for all oxidation methods when MB dye solution was used. However, the maximum efficiencies were obtained at pH 3.0 for real textile wastewater decolorization. The MB dye removal efficiency was increased to 97.22, 100, and 100% for Fenton, photo-Fenton, and FSWO processes, respectively, when the addition of H2O2 concentration was adjusted to 125 mg/L. However, the maximum color removal efficiencies of viscose fibers dyeing wastewater were obtained 56.94, 61.26, 64.11% for Fenton, photo-Fenton, FSWO processes, respectively. As a result, the FSWO showed maximum color removal efficiencies.

Treatment of textile industry wastewater by electrocoagulation technology

Experiments were carried out by treating the waste samples with electrocoagulation technology. This is done to determine the effectiveness of the removal of the electrocoagulation device against textile waste. The sample used is a synthetic sample with a concentration of 1091 mg/L Pt-Co units. The research was conducted twice with the first experiment being conducted to determine the most effective electrical voltage to remove the existing COD and color pollutants while the second experiment was conducted to determine the type of anode and cathode that was most effective in removing COD, Color, and heavy metal pollutants. In the first experiment, it was found that the electric voltage that could produce the best removal was 4 amperes and in the second experiment, the anode-cathode type with the highest % removal was Fe-Fe with % COD removal of 64.09639% and % color removal of 60.00619%. It was concluded that electrocoagulation method could effectively remove color and COD in waste water.

COD removal, decolorization, and energy consumption of electrocoagulation as a wastewater treatment process

The efficiency of color and COD removal in wastewater treatment is one of the essential factors. High color removal can encourage the reuse of wastewater as raw material in the recycled paper industry. Electrocoagulation (EC) process is effective pollutant removal in wastewater due to the adsorption, coagulation, and flotation. In this study, recycled paper industrial wastewater was used; this type of waste has a high content of disturbing pollutants, and treatment with electrocoagulation has not been widely carried out for this type of waste. EC treatment has a relatively high level of effectiveness to remove these pollutants; the influential factors studied include initial pH, applied current, supporting electrolyte, and processing time on a laboratory scale. The degradation of color, COD, and energy used was also evaluated. The best color removal was obtained as 100% at 80 minutes of process, and a COD concentration is 147 mg/L, and the energy used is 13.56 kWh/L.