Comparison of electrocoagulation and chemical coagulation processes in the treatment of an effluent of a textile factory

Abstract

ABSTRACT:In this work, electrocoagulation and chemical coagulation were applied to the exit effluent of a textile factory located at Douala (Cameroon).The investigations were focused on the operational (pH, conductivity) and pollution parameters (COD, total phosphorus, turbidity). The electrolytic treatment was carried out with 0.4 A current intensity, and chemical coagulation was conducted in adding initially to the effluent the same quantities of aluminium than that electrogenerated.the elimination of pollution contents depended on the quantity of Al 3+ ions produced by the electrodissolution of the aluminium anode and that of the aluminium salt dissolved in solution. In fact, 58.86, 94.44 and 97.81% of COD, total phosphorous and turbidity were respectively removed by electrocoagulation, while hemical coagulation, the turbidity was also reduced roughly at the same level as by electrolytic treatment. Also, 56.08 and 63.64% COD and total phosphorus were respectively removed by chemical route. During electrocoagulation, highest removals were reached after 2.49x10 -3 mol of aluminum was released in solution (after 30 minutes of treatment). Thus, the final pH obtained by this process was around 9 and the conductivity varying slightly, compared to the initial value. By contrast, chemical coagulation rendered the effluent more acidic and more conducting (γ> 4 mS.cm -1 ). Electrocoagulation is the best process, by the fact that the textile effluent treated by this technique can be re-used or rejected without risk in the environment. Chemical coagulation: indeed, the corrosive nature of effluent treated by this method and the significant content of the residual phosphorus can seriously inhibit the perspective of recycling.

Physicochemical, Microbial and Ecotoxicological Characteristics of Textile Effluent Collected in the Southeast Region of Brazil

“…Alkalinity refers to the water capacity of neutralizing a weak acid (Wurts and Durborow 1992;Sudhanya and Chinnamma 2018). The high amount of 4200 mg L -1 of CaCO3 detected in our analyzes is mainly due to the use of large amounts of sodium hydroxide, sodium carbonate and sodium bicarbonate in several stages of textile processing (Beltrame 2000;Rodrigues et al 2013;Khatri et al 2015;Tchamango et al 2017). High alkalinity effluent values, which were seen to have a great variation among others authors (Table 3), were seen to cause significantly changes in the physiological mechanism of plants roots and increase the ecotoxicity degree of samples due the formation of the ammonia through influences in the solution pH (Clément and Merlin 1995;de la Torre-González et al 2018).…”

Mechanism of the electrocoagulation process and its application for treatment of wastewater: A review

“…When chloride anions are present in the solution, chemical reactions given by equations ( 7), ( 8) and ( 9 This shows that the increase of pH caused by the reduction of H + ions is mostly compensated by the formation of H+ ions as shown in equations ( 7), ( 8) and (9). The increase in the pH of acidic effluents is a consequence of the formation of Al 3+ precipitates due to the presence of other anions, as well as the precipitation of aluminum hydroxide [8].…”

“…Electrocoagulation process EC is a process in which coagulants and metal hydroxides are electrochemically generated, in situ, which causes the destabilization and aggregation of contaminants (which are either suspended, dissolved, or dis-persed). Compared to the conventional coagulation process, the EC process is more effective in removing contaminants without the use of additional chemical reagents [8]. Furthermore, in this process, a smaller amount of sludge is generated, so the cost of the sludge removal process is reduced.…”

Microbial Population Inhibition Method Through Spectrophotometry Absorption of Visible Light Applied to Ecotoxicological Analyses

“…The high pH value of 10.31 and the quantity of 4200 mg L -1 of CaCO3 in the effluent were due to the use of caustic reagents in several stages of the textile processing, such as sodium hydroxide, sodium carbonate and sodium bicarbonate (Beltrame, 2000;Rodrigues et al, 2013;Khatri et al, 2015;Tchamango et al, 2017). The pH value, which is known to influence chemical and biochemical reactions, was seen to strongly affect the metabolism of living organisms and cause great influence in aquatics and terrestrial ecosystems (Goodwin et al, 1988;ŠImek & Cooper, 2002;Lacoul & Freedman, 2006;Hartman et al, 2008;Wootton and Forester, 2008).…”