Removal of microplastics from wastewater through electrocoagulation-electroflotation and membrane filtration processes

Wastewater treatment plants (WWTPs) are one of the major vectors of microplastics (MPs) pollution for the recipient water bodies. Therefore, the recovery of MPs from WWTPs is extremely important for decreasing their accumulation and impact in aquatic systems. In this present study, the electrocoagulation-electroflotation (EC/EF) and membrane filtration processes were investigated in removing MPs from wastewaters. The effectiveness of different electrode combinations (Fe-Al and Al-Fe), current density (10–20 A/m2), pH (4.0–10.0) and operating times (0–120 min) on the removal of two different polymer particles in water were investigated to obtain maximum treatment efficiency. The effect of pressure (1–3 bar) on membrane filtration removal efficiency was also investigated. The maximum removal efficiencies were obtained as 100% for both polymer types with electrode combination of Al-Fe, initial pH of 7, current density of 20 A/m2 and reaction time of 10 min. The membrane filtration method also displayed a 100% removal efficiency. In addition, these laboratory-scale results were compared with the one-year average data of a plant treating with real-scale membranes. The results indicated that the proposed processes supplied maximum removal efficiency (100%) compared to conventional secondary and tertiary treatment methods (2–81.6%) in the removal of microplastics.

Analysis of EDM Performance, through a Thermal–Electrical Model with a Trunk-Conical Discharge Channel, Using a Steel Tool and an Aluminium Workpiece

In this article, a finite element (FE) thermal–electrical model with a trunk-conical discharge channel is employed to simulate individual EDM discharges with a time-on of 18 μs up to 320 μs, which are subsequently compared with the experimental results to validate the model. The discharge channel is a trunk-conical electrical conductor which dissipates heat by the Joule heating effect, being the correspondent factor equal to 1. Instead of the usual copper–iron electrode combination, steel (DIN CK45) and aluminium alloys (DIN 3.4365) are the implemented materials on both the tool and the workpiece, respectively. The numerical results were measured using the melting temperature of the materials as the boundary of material removal. The results obtained with the thermal–electrical model, namely the tool wear ratio, the tool wear rate, the material removal rate, and the surface roughness, are in good agreement with experimental results, showing that the new FE model is capable of predicting accurately with different materials for the electrodes.

The effect of electrodes on the voltage generation of microbial fuel cell

Microbial fuel cell (MFC) is a device that coverts the chemical energy contents of organic matter to electrical energy by the catalytic action of microorganisms. Cow dungs as organic substrates were used in three sets of dual chambered MFCs to study the effects ofelectrodes on the open circuit voltage (OCV) generation of MFC. The anode and cathode compartments were connected using a protonexchange membrane, 1 kg of the cow dung diluted with 500 ml of water was introduced in the anode compartment of each of the setups. The electrode configurations for set-up 1, 2 and 3 respectively were Carbon-Carbon(C-C), carbon-copper(C-Cu) and carbon- zinc(C-Zn). Samples for microbial load count were collected every two days from the anode compartment of the MFC and analyzed using standard microbiological methods. The OCV of the three setups were measured daily for two weeks using a digital multimeter. The microbial load ranged from 4.2 × 104 to 8.5 × 104 CFU/ml for bacteria and 2.1 × 102 to 2.3 × 103 CFU/ml for fungi. The range (average) of the OCV obtained from the set-ups were 0.06 to 0.72 V (0.42 V) for the C–C; 0.02 to 0.67 V (0.26 V) for C-Cu and 0.11 to 0.78 V (0.39 V) for the C-Zn. The OCV for the C-C electrode combination showed an increasing trend while the OCV of C-Cu and C-Zn showed decreasing trends with increasing number of days. The C-C electrode combination gave the best OCV. Keywords: microbial fuel cell, open circuit voltage, electrodes, organic substrate

Thickness Optimization of Thin-Film Tandem Organic Solar Cell

The organic solar cells (OSCs) have drawn attention in the past decade due to its cynosure in industrial manufacturing because of its promising properties such as low weight, highly flexible and low cost production. However, low η restricts the utilization of OSCs for potential application such as low cost energy harvesting devices. In this paper, OSCs structure based on triple junction tandem scheme is reported with three different absorber materials with the objective to enhance the absorption of photons which in turn improves the η, as well as its correlating performance parameters. The investigated structure gives the higher value of η = 14.33% with Jsc=16.87 (mA/m2), Voc=1.0 (V), and FF=84.97% by utilizing a stack of three different absorber layers with different band energies. The proposed structure is tested under 1.5 (AM) with 1 sun (W/m2). The impact of top, middle and bottom sub cells thickness on η is analyzed with a terse to find the optimum thickness for three sub cells to extract high η. The optimized structure is then tested with different electrode combination and the highest η is recorded with FTO/Ag. Moreover, the influence of upsurge temperature is also demonstrated on the proposed structure and observed that the upsurge temperature has greatly affected the electrical parameters of the device and η decreases from 14.33% to 11.40% when the temperature of the device rises from 300-400 K.

Application of Electrocoagulation for the Removal of Color from Institutional Wastewater: Analysis with Response Surface Methodology

The removal percentage of color from institutional wastewater was studied using an electrocoagulation process with different electrode combination at the anode and cathode. This was done by considering operational parameters such as pH at (3, 6 and 9), current at (0.03A, 0.06A and 0.09A) and reaction time at (20, 40 and 60 minutes). When electrode combined in the form of Al-Al (anode-Cathode/Cathode-Anode) and Fe-Fe (anode-Cathode/Cathode-Anode) the percentage removal of color was up to 95.50% and 97.24% respectively. On the other hand around 98.03% and 91.95% of color was removed when Al-Fe (Anode-Cathode) and Fe-Al (Anode-Cathode) combined at pH 9 and 60 minutes of reaction time respectively. Central composite design from response surface methodology was used up to analysis the statistical and mathematical data based on experimental results such as the model was significant for all electrode combinations. Similarly a quadratic model was used for further study of operational effects on the removal (%) of color from institutional wastewater. The value of coefficient of the determination (R2) also indicated the model was a good fit as well as optimization was done by Response Surface Methodology.

Performance of Graphite and Titanium as Cathode Electrode Materials on Poultry Slaughterhouse Wastewater Treatment

Despite the potential applicability of the combination between aluminium (anode) and graphite or titanium (cathode) for poultry slaughterhouse wastewater treatment, their technical and economic feasibilities have not been comprehensively captured. In this study, aluminium (anode) and graphite and titanium as cathode electrode materials were investigated and compared in terms of their performance on poultry slaughterhouse wastewater treatment. The wastewater samples collected from the Izhevsk Production Corporative (PC) poultry farm in Kazakhstan were treated using a lab-based electrochemical treatment plant and then analyzed after every 20 and 40 min of the treatment processes. Cost analysis for both electrode combinations was also performed. From the analysis results, the aluminium–graphite electrode combination achieved high removal efficiency from turbidity, color, nitrite, phosphates, and chemical oxygen demand, with removal efficiency ranging from 72% to 98% after 20 min, as well as 88% to 100% after 40 min. A similar phenomenon was also observed from the aluminium–titanium electrode combination, with high removal efficiency achieved from turbidity, color, total suspended solids, nitrite, phosphates, and chemical oxygen demand, ranging from 81% to 100% after 20 min as well as from 91% to 100% after 40 min. This means the treatment performances for both aluminium–graphite and aluminium–titanium electrode combinations were highly affected by the contact time. The general performance in terms of removal efficiency indicates that the aluminium–titanium electrode combination outperformed the aluminium–graphite electrode combination. However, the inert character of the graphite electrode led to a positive impact on the total operating cost. Therefore, the aluminium–graphite electrode combination was observed to be cheaper than the aluminium–titanium electrode combination in terms of the operating cost.

Evaluation of Electrochemical Methods for Poultry Slaughterhouse Wastewater Treatment

Understanding the efficiency of different wastewater treatment technologies tested under real conditions is essential for successful decision making by engineers and managers. In this study, real poultry slaughterhouse wastewater coming from defeathering, cooling, and evisceration processes was treated using a lab-scale electrochemical process by use of iron-iron (Fe-Fe), iron-graphite (Fe-Gr) and aluminum-graphite (Al-Gr) electrode combinations. A water quality index (WQI) was developed and used as a tool for evaluating and classifying the effectiveness of different electrode combinations. The Al-Gr electrode combination showed an impressive performance achieving an “excellent” status for all of the three studied sources of wastewater with a WQI ranging from 13 to 34. The Fe-Gr electrode combination showed an “excellent” status performance for the wastewater from the cooling process as classified by the WQI and “good water” class for the defeathering and evisceration processes. The lower performance, which was highly affected by the increase in turbidity, was observed for the Fe-Fe electrode combination with a “poor water” status for the wastewater coming from defeathering and cooling processes and “good water” status for evisceration process.