Remediation of domestic wastewater by electrochemical oxidation of dissolved organic species
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ORIGINAL PAPER
Remediation of domestic wastewater by electrochemical oxidation of dissolved organic species Isaac Mwangi1 · Esther Kinyua1 · Ruth Wanjau1 · Sauda Swaleh1 · Jane Catherine Ngila2 Received: 4 September 2019 / Accepted: 17 August 2020 © Iranian Chemical Society 2020
Abstract This study reports on the treatment of wastewater containing dissolved organic matter (DOM). DOM introduces complexing agents, promotes bacterial growth, and affects the color plus taste of water negatively. The normal practice for treatment such pollutants is the use of introduction of oxidizing agents in the water. However, this introduces secondary pollutants to the treated water, and to overcome the challenge, this study has developed an electrochemical method for treating wastewater with no secondary pollutants. A two-chamber electrochemical cell separated by a proton exchange membrane (PEM) was constructed with inert electrodes. The PEM was made from a conducting polymer inert in aqueous media. The anode water was bubbled with air for reduction of oxygen and therefore formation of strong oxidizing agent for the degradation of DOM. The degradation was monitored using Ultraviolet–visible (UV–VIS) spectroscopy as the potential difference across the cell was monitored. There was a significant reduction in the color and the decay followed first-order kinetics, for unimolecular degradation with a constant of 0.0148 min−1. A high potential of 1.25 V was registered within the first 40 min confirming that the degradation was spontaneous making the water safe for consumption. The degradation was confirmed by voltametric method where the concentration of iron within the vegetative matter was observed to increase at a potential of − 0.18 V with time due to the release of the labile metal ions. This shows that the constructed cell has a potential application in the remediation of domestic wastewater at a point of use. Keywords Electrochemical cell · Proton exchange membrane · Oxidation · Pollution · Wastewater
Introduction The supply of water for man is of concern globally due to its diminishing supply and pollution. The molecular structure gives the water molecule polarity, or a lopsided electrical charge [1]. This makes water to be a universal solvent that easily gets polluted due to contamination after it gets incorporated with polar species. This reduces available freshwater and also affects human health and ecosystem. Domestic wastewater is one of the major sources of water pollution. This is because it contains dissolved organic matter (DOM) that can promote bacterial growth or become complexing * Isaac Mwangi [email protected] 1
Department of Chemistry, Kenyatta University, P.O. Box 43844‑00100, Nairobi, Kenya
Department of Chemical Technology, University of Johannesburg, Doornfontein Campus, P.O Box 17011, Doornfontein, Johannesburg 2028, South Africa
2
agents that affects the color and taste of water negatively. Pollutants found in domestic wastewater include nutrients such as detergents and organic matter
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