Optimizing microplastic treatment in the effluent of biological nutrient removal processes using electrocoagulation: Taguchi experimental design.

Microplastics (MPs) have become one of the most critical environmental pollution problems in recent years. Due to the growing abundance of MPs in aquatic environments, extensive research has been conducted and continues to be ongoing to develop effective treatment methods. In this study, the removal of MPs in the effluent of biological wastewater treatment plant (WWTP) was investigated by electrocoagulation (EC) process with aluminum electrodes. Using Taguchi design, the importance of process variables such as pH, current density, and reaction time were evaluated by Analysis of Variance (ANOVA). Statistically, according to F and p values, the most effective parameter for microplastic (MP) removal was current density, followed by pH and reaction time. The R2 value of the created model was found to be above 98%. According to Taguchi results, the optimum process conditions were determined as pH 9, current density 1.905 mA/cm2, and reaction time 15 min and 99% MP removal efficiency was obtained. Under these optimum conditions, the process cost was calculated as 0.049 $/m3 wastewater, considering energy and electrode consumption. As a result of visual analyses, fiber, film, pellet, amorphous, and undefined forms were dominant in WWTP effluent, while only fiber structures were observed after treatment with EC. In this study, it was concluded that the EC process is an alternative treatment method that can be integrated into wastewater treatment plant effluent to achieve MP removal at very low cost and high efficiency. In addition, as a result of this study, it was observed that the EC process can also be used in MP removal by applying it to real wastewater.

Investigation of microplastics in advanced biological wastewater treatment plant effluent.

In recent years, plastic pollution in the environment has also increased due to the increasing production and consumption of plastics worldwide. The presence of microplastics (MPs) in the environment from different sources is observed almost everywhere, especially in aquatic environments. A standard method for sampling, identification, and quantification of MPs in wastewater has not yet been established. In this study, it was aimed to determine the MPs and their characteristics in the effluent of an advanced biological domestic wastewater treatment plant. The seasonal changes of MPs in a year were revealed. Pre-treatments suitable for the studied wastewater were developed for visual determination of MPs. Fibers are the dominant type of MPs, with numbers ranging between 32.0 and 95.5 particle/L. MPs in five different polymer structures were determined by FTIR analysis. These are Polyethylene, Polypropylene, Polyester, Polyurethane and Polyethylene terephthalate. The results were evaluated according to QA/QC and determined to meet the standards.

Optimizing electrocoagulation for poultry slaughterhouse wastewater treatment: a fuzzy axiomatic design approach.

White meat consumption is increasing day by day, and accordingly, there is an increase in the amount of wastewater resulting from the processes. Today, the reuse of wastewater has become a goal within the scope of the Green Deal. For this reason, wastewater treatment with high pollution and volume has gained importance. In this study, the fuzzy axiomatic design (FAD) method, one of the multi-criteria decision-making methods, has been used. With this method, coagulation, electrocoagulation (EC), dissolved air flotation (DAF), and anaerobic treatment alternatives preferred in poultry slaughterhouse wastewater (PSW) treatment were compared with each other and their information contents were calculated. The information content from the smallest to the largest is EC, DAF, coagulation, and anaerobic treatment, respectively. This treatment method was chosen because the smallest information content is in electrocoagulation. EC was applied to bloody PSW containing 1% blood by volume. The effectiveness of Fe and Al electrodes for PSW treatment in the batch EC reactor has been compared. The effective surface areas of 2 anodes and 2 cathodes connected bipolarly in the processes are 288 cm2. The electrolyte, pH, time, and current density effects on energy consumption were also investigated. The optimum conditions for Al and Fe electrodes were found to be 0.5 g·L-1 NaCl concentration, pH 5, 0.639 mA·cm-2 current density, and 5 min time. Under optimum conditions for the Fe electrode, COD, TOC, TN, and oil-grease removal efficiencies were determined as 76.3%, 71.8%, 70%, and 74%, respectively. Moreover, the highest COD, TOC, TN, and oil-grease removal efficiencies were achieved with an Al electrode (82.2%, 82.3%, 82.7%, and 78.9%, respectively). The experimental data were fit to a variety of isotherms and kinetic models to determine the characteristics of the EC. The results indicated that the pseudo-second-order equation provided the best fit for COD removal. Under optimum conditions, the operating cost was calculated as $3.39 and $3.09 for Al and Fe electrodes, respectively. In this study, the fuzzy axiomatic design method was used for the first time to select the most appropriate treatment method for PSW. In addition, blood, a major problem for the poultry slaughterhouse industry, was mixed with PSW at a ratio of 1% (v/v) and treated with EC for the first time with high removal efficiency. By treating PSW, which has a high pollution load, with electrocoagulation, the pollution load of the water to be given to secondary treatment has been greatly reduced.

Removal of microplastics in food packaging industry wastewaters with electrocoagulation process: Optimization by Box-Behnken design.

Currently, the vast majority of studies on microplastics (MPs) focus on determining the quantity and presence of these particles in various receiving environments and their treatment in domestic wastewater treatment plants. However, little research has been conducted on the treatment of microplastics in industrial effluent. Therefore, in this study, effluent samples from the cooling water tank of a local food packaging manufacturing company were analyzed to determine the presence and quantity of MPs for the first time. MPs removal from industrial wastewater using the electrocoagulation (EC) method was optimized using the Box Behnken Design (BBD). A second-order model was developed to estimate the microplastic removal efficiency, and the R2, adjusted R2, and predicted R2 of the model were 0.9994, 0.9985, and 0.9962, respectively. The optimal reaction parameters resulting in the maximum removal rate of microplastics (99 %) were determined to be pH 6.74, current density of 3.16 mA cm-2, and duration of 13.58 min. The cost of microplastic treatment per m3 of wastewater in the EC system, operated under optimal conditions, was calculated as 0.125 $. In this study, it was concluded that the EC process is a highly efficient technique for the removal of MPs from industrial wastewater at a low cost. Determining the most favorable conditions with BBD for the EC process at the feasibility stage of treatment plants will provide economic benefits and increase treatment efficiency during the installation of large-scale plants.

Interaction of TiO2 nanoparticles with the C. vulgaris: oxidative stress, lipid peroxidation and lipid amount.

Nanoparticles are widely used in many industries such as food and cosmetics. With increasing use, its spread to environmental environments is also increasing. Microalgae have an important place in the uptake of nanoparticles into the food chain. In this study, the effect of TiO2 nanoparticle on antioxidant enzyme activity, malondialdehyde, hydrogen peroxide, chlorophyll-a and total lipid amount in C. vulgaris microalgae has been investigated. As a result of the dose study, while the superoxide dismutase and ascorbate peroxidase enzyme activities decreased, the amount of MDA, H2O2 and chlorophyll-a increased. Depending on the times at different light:dark ratios, both an increase and a decrease occurred in the SOD, APX enzyme activity and the amount of MDA, H2O2. There was an increase in the amount of chlorophyll-a. In the time study, while the SOD and APX enzyme activities increased, the amount of MDA and H2O2 decreased. The amount of chlorophyll-a increased. In the total lipid study, the total lipid amount in the group with nano TiO2 increased compared to the control group. At the same time, C18:2 T (linoleic acid) has been found as fatty acid methyl ester in both groups.