Investigating the Advantages and Limitations of Modeling Physical Mass Transfer of CO2 on Flat Plate by One Fluid Formulation in OpenFOAM

One fluid formulation is an approach used for modeling and analysis of mass transfer between two immiscible phases. In this study we implement and analyze the advantages and limitations of this approach for CO2 physical mass transfer into MEA. The domain is a flat plate and gas liquid flow is counter current. The analysis was carried for operating parameters like liquid phase Reynolds number, MEA mass fraction and the angle of inclination of flat plate. The results clearly show that the model effectively captures the deviation in liquid side mass transfer coefficient due to the surface instabilities and liquid properties which are generally neglected by standard correlations. Also the model shows that the standard Higbie correlation is preferable at low Reynolds number at any angle of inclination. The grid independent studies show that a size of 6.25 µm is required in the interface region for effectively using this approach. The computational resource time at this resolution was found as the only limitation for using this approach and we suggest a procedure to overcome this limitation. The present simulation results can help CFD researchers investigating immiscible gas-liquid mass transfer using OpenFOAM

Slaughterhouse Wastewater Treatment by Combined Chemical Coagulation and Electrocoagulation Process

Slaughterhouse wastewater contains various and high amounts of organic matter (e.g., proteins, blood, fat and lard). In order to produce an effluent suitable for stream discharge, chemical coagulation and electrocoagulation techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from slaughterhouse effluent. The purpose of this work was to investigate the feasibility of treating cattle-slaughterhouse wastewater by combined chemical coagulation and electrocoagulation process to achieve the required standards. The influence of the operating variables such as coagulant dose, electrical potential and reaction time on the removal efficiencies of major pollutants was determined. The rate of removal of pollutants linearly increased with increasing doses of PACl and applied voltage. COD and BOD5 removal of more than 99% was obtained by adding 100 mg/L PACl and applied voltage 40 V. The experiments demonstrated the effectiveness of chemical and electrochemical techniques for the treatment of slaughterhouse wastewaters. Consequently, combined processes are inferred to be superior to electrocoagulation alone for the removal of both organic and inorganic compounds from cattle-slaughterhouse wastewater

Electrochemical treatment of wastewaters from poultry slaughtering and processing by using iron electrodes

Poultry slaughterhouse wastewater (PSWW) originating from slaughterhouse and meat processing contains high concentrations of organic substances. Discharging this kind of wastewater to a river, sewer system or soil causes a severe pollution problem for receiving body. The aim of this study was to investigate the treatability of poultry slaughterhouse wastewater using electrocoagulation method. The reactor had a cylindrical iron shell with three separate iron rods mounted vertically inside that to work as cathode and anode respectively. The effects of the current density, supporting electrolyte (Na2SO4) dosage, wastewater flow rate, initial pH and the polyelectrolyte material were evaluated in a continuous flow mode. The peroxy-electrocoagulation was also investigated by addition of H2O2 with different concentrations to reach higher removal efficiencies. When the poultry slaughter wastewater was subjected to the peroxy-electrocoagulation, chemical oxygen demand (COD) decreased to 425 mg L-1 from 8800 mg L-1 which corresponds to 95.48% of removal efficiency with an operation cost of $9 per m(3) of wastewater treated. (C) 2017 Elsevier Ltd. All rights reserved

Electrocoagulation of food waste digestate and the suitability of recovered solids for application to agricultural land

Digestates from anaerobic digestion (AD) of food waste contain fertiliser nutrients (such as P and N) which are valuable for agricultural purposes and can be environmentally hazardous if disposal is uncontrolled. Here, we applied electrocoagulation (EC) for treatment of digestates, to separate liquids and nutrient-rich solids. Coagulant-dosing electrocoagulation (CDEC) was used to compare Al and steel anodes for treatment of digestate from AD fermenters fed a controlled diet representative of food waste. When applying metal dosing concentrations of 0–4.66 mM, Fe was found to be up to 29.8 % superior to Al in terms of aiding removal of chemical oxygen demand (COD). To mitigate plate fouling, the digestate was diluted to 0.25 and 0.1 concentrations to enable successful treatment by continuous-flow electrocoagulation (CFEC). The highest recovery of soluble P per Fe added by CFEC was 22.4 mg-P g-Fe−1. This was achieved when using 2.33 mM Fe to treat a 0.25 dilution of digestate. In comparison to a control, these optimal conditions also caused a reduction of 4.5 mg L−1 (or 87.7 %) of soluble P and the removal of 254 mg L−1 (33.2 %) of COD in the filtrate. The NH4+ concentration in filtrate was not influenced by EC treatment. Analyses of a range of known toxic elements (Cu, Ni, Zn, As, Cd, Cr, Mo and Pb) indicates that the solids recovered by CFEC could be suitable for application to land