Optimizing TOC and COD removal for the biodiesel wastewater by electrocoagulation

In this study, the chemical oxygen demand (COD) and the total organic carbon content (TOC) in biodiesel wastewater iron and aluminum electrodes arranged in a bipolar position. In the EC of the biodiesel wastewater, the effects of the supporting electrolyte, initial pH, electrolysis time and current density were examined. The results showed that the majority of the pollutants in the biodiesel wastewater were effectively removed when the iron or aluminum electrodes were used as a sacrificial anode. The highest COD and TOC removal efficiencies were successfully obtained with the iron electrode. COD removal efficiencies are 91.74 and 90.94% for iron and aluminum electrode, respectively. In the same way, TOC removal efficiencies were obtained as 91.79 and 91.98% for the iron and aluminum electrodes, respectively, at initial pH of 6, the current density of 0.3226 mA/cm(2), NaCl concentration 1 g/L and 1 min of operating time

Numerical simulation of rarefied gas flows with specified heat flux boundary conditions

Our recently developed lattice Boltzmann model is used to simulate droplet dynamical behaviour governed by thermocapillary force in microchannels. One key research challenge for developing droplet-based microfluidic systems is control of droplet motion and its dynamic behaviour. We numerically demonstrate that the thermocapillary force can be exploited for microdroplet manipulations including synchronisation, sorting, and splitting. This work indicates that the lattice Boltzmann method provides a promising design simulation tool for developing complex droplet-based microfluidic devices

<bold>The efficiency of electrocoagulation using aluminum electrodes</bold>i<bold>n treating wastewater from a dairy industry</bold>

This research deals with the investigation of electrocoagulation (EC) treatment of wastewater from a dairy plant using aluminum electrodes. Electrolysis time, pH, current density and distance between electrodes were considered to assess the removal efficiency of chemical oxygen demand (COD), total solids (TS) and their fractions and turbidity. Samples were collected from the effluent of a dairy plant using a sampling methodology proportional to the flow. The treatments were applied according to design factorial of half fraction with two levels of treatments and 3 repetitions at the central point. The optimization of parameters for treating dairy industry effluent by electrocoagulation using aluminum electrodes showed that electric current application for 21 minutes, an initial sample pH near 5.0 and a current density of 61.6A m-2 resulted in a significant reduction in COD by 57%; removal of turbidity by 99%, removal of total suspended solids by 92% and volatile suspended solids by 97%; and a final treated effluent pH of approximately 10. Optimum operating condition was used for cost calculations show that operating cost is approximately 3.48R$ m-3.</p

Sorption of cadmium (II) ion from aqueous solution onto sweet potato (Ipomoea batatas L.) peel adsorbent:characterisation, kinetic and isotherm studies

Sweet potato peels was used for the removal of Cd (II) from aqueous solutions. The residue was characterised using SEM, EDX, XRF, N2 BET, TGA and ATR-FTIR. Sorption of Cd (II) was carried out by varying pH, contact time and initial ion concentration at 25 °C and the results showed a strong dependence of the ion removal on the adsorbate pH with optimum observed at pH 7. Kinetics of Cd (II) sorption indicates optimum time of 180 min and the removal of Cd (II) occurred via a fast initial uptake. This was modelled using the pseudo first, pseudo-second and intraparticle diffusion models. The pseudo-first order gave a better description of the uptake kinetics than the pseudo-second order model with an r2 value of 0.99. The intraparticle-diffusion model showed that sorption had multi-linear steps indicating that the intraparticle-diffusion is not the only rate controlling step in Cd (II) sorption. FTIR analysis of the PTPS before and after adsorption of Cd (II) indicates that some functional groups such as hydroxyl, carbonyl and carboxylate groups may be involved in metal ion sorption. Isotherm modelling of Cd (II) sorption was carried out using the Langmuir and Freundlich isotherms using a non-linear optimisation. The Langmuir isotherm gave a better fit for Cd (II) sorption and maximum loading capacity (qmax) was 18 mg g−1 with an isotherm constant of 5.21 × 10−3 l mg−1 and r2 value of 0.99 at 25 °C. Hence, the PTPS residue was found to be a promising adsorbent for Cd (II) removal from aqueous streams

Operating Temperatures of the Solar Cells Used in the Concentrator System With Radiating Plates

WOS: 000389624700009A solar cell concentrator system is offered to satisfy the energy requirement of the satellites orbited around the Earth. The solar cells coupled to the system are exposed to sunlight concentrated 124 times with a Cassegrain type reflector system. To dissipate the waste heat to the space, the cells are bonded on a radiating plate. To calculate the temperature distribution on the surface of the radiating plate, a new FAS (Full Approximation Scheme) solver is developed. This new FAS solver is validated with the Newton method. Additionally, the FAS solver is shown to be 92 times more efficient computationally than the Newton method. Afterwards, radiating plate efficiencies are calculated. These efficiency figures change between 0.1 and 0.02 for different cell temperatures. Next, an energy balance equation is constructed in order to calculate the theoretical operating temperatures of the solar cells. Using energy balance equation and the FAS solver iteratively, solar cell operating temperatures are calculated successfully for different radiating plate thicknesses and solar cell conversion efficiencies. Solar cell operating temperatures are found between 500 K and 1000 K. The present study points out that concentrator systems require highly efficient solar cells operating in the very high temperatures. For instance, in order to operate the cell temperature at 750 K for a 3 mm radiating plate thickness, the cell conversion efficiency should be 70%. Ongoing projects which aim to develop solar cells capable of operating in high intensity-high temperature environments are believed to make it possible to embed solar cell concentrator systems on the next generation satellites