Treatment of Pulp Mill D-Stage Bleaching Effluent Using a Pilot-Scale Electrocoagulation System

Performance of an electrocoagulation-flotation system in the treatment of domestic wastewater for urban reuse

Domestic wastewater is an important alternative source of water in the face of a growing discrepancy between water availability and demand. The use of techniques that enable the urban reuse of treated sewage is essential to make cities more sustainable and resilient to water scarcity. The main goal of this study was to evaluate the performance of an electrocoagulation-flotation system in the treatment of domestic wastewater for urban reuse. The study was performed using raw domestic wastewater samples. The electrocoagulation-flotation system was a cylindrical reactor with aluminum electrodes. The treatment conditions involved agitation at 262.5 rpm, electrical current of 1.65 A, electrolysis time of 25 min, an initial pH of 6, and inter-electrode distance of 1 cm. Overall, the electrocoagulation-flotation system was highly efficient for removal of apparent color (97.9%), chemical oxygen demand (82.9%), turbidity (95.8%), and orthophosphate phosphorous (> 98.2%). The electrocoagulation-flotation system had a consumption of electrical energy ranging from 9.5 to 13.3 kWh m^-3, electrode mass from 294.7 to 557.0 g m^-3, and hydrochloric acid from 4.3 to 6.6 L m^-3. Sludge production in the system ranged from 1,125.7 to 1,835.7 g m^-3. Treated wastewater had a satisfactory quality for several urban reuse activities. The electrocoagulation-flotation system showed potential to be used for domestic wastewater treatment for urban reuse purposes.

Electrocoagulation technology for water purification: An update review on reactor design and some newly concerned pollutants removal

Water shortage and quality deterioration are plaguing people all over the world. Providing sustainable and affordable treatment solutions to these problems is a need of the hour. Electrocoagulation (EC) technology is a burgeoning alternative for effective water treatment, which offers the virtues such as compact equipment, easy operation, and low sludge production. Compared to other water purification technologies, EC shows excellent removal efficacy for a wide range of contaminants in water and has great potential for addressing limitations of conventional water purification technologies. This review summarizes the latest development of principle, characteristics, and reactor design of EC. The design of key parameters including reactor shape, power supply type, current density, as well as electrode configuration is further elaborated. In particular, typical water treatment systems powered by renewable energy (solar photovoltaic and wind turbine systems) are proposed. Further, this review provides an overview on expanded application of EC in the removal of some newly concerned pollutants in recent years, including arsenite, perfluorinated compounds, pharmaceuticals, oil, bacteria, and viruses. The removal efficiency and mechanisms of these pollutants are also discussed. Finally, future research trend and focus are further recommended. This review can bridge the large knowledge gap for the EC application that is beneficial for environmental researchers and engineers.

Heterogeneous photo-Fenton oxidation of lignin of rice husk alkaline hydrolysates using Fe-impregnated silica catalysts

Present work shows results of a study on heterogeneous Fenton-like degradation of lignin alkaline hydrolysates formed in the process of obtaining a fibrous mass from rice husk. Fe-impregnate biogenic amorphous silica Fe/RH-SiO₂ obtained from rice husk was used as a catalyst. Using IR spectroscopy, X-ray diffraction and EDX analysis it was shown that iron(III) oxide in the form of hematite is present on the catalyst surface. Phenol was used for preliminary assessment of catalytic activity of the catalyst Fe/RH-SiO₂. The degree of degradation of phenol by the UV/visible radiation/Fe/RH-SiO₂/H₂O₂ system reaches 90%. The catalytic activity of Fe/RH-SiO₂ was studied in the reaction of lignin degradation of rice husk alkaline hydrolysates under ultraviolet and visible irradiation in the presence of hydrogen peroxide. The lignin solutions with COD: Н₂О₂ ratios from 1:2 to 1:16 were exposure under UV irradiation for 15-minute and the subsequent lightening on sunny days between 9 am and 8 pm in April for 7 days in the presence of a catalyst and without it. The catalyst concentration was 1.0 g L^-1. After that, it was found the content of phenolic compounds in the presence of a catalyst is 2-20 times lower than without it. The COD with the COD: Н₂О₂ = 1:16 ratio in the presence of a catalyst decreases 1.5 times as compared with the initial solution, whereas without a catalyst it increases 13 times.