Treatment of beauty salon effluents using advanced oxidative electrochemical processes with boron-doped diamond anode

Abstract

Beauty salons constitute a growing economic sector that is responsible for the release of effluents containing a diversity of pollutant compounds. This work proposes the local treatment of beauty salon effluent (BSE), with the aim of decentralizing the treatment process and avoiding increasing the organic load at municipal effluent treatment stations. The processes of electrochemical oxidation (EO) and simultaneous EO with electrogenerated H2O2 (EO/H2O2) were applied using different anode/cathode electrode pairs: BDD/stainless steel and BDD/GDE. Investigation was made of the influence of salts on the generation of oxidants in different support electrolytes, using the N,N-dimethyl-4-nitrosoaniline (pNDA) decoloration technique. The presence of active chlorine species was shown to influence the global oxidizing power. The BSE was characterized and the conversion rate of the organic load was monitored during 180 min of the processes. For the EO/H2O2 process, without adjustment of the initial pH, the COD conversions in 120 min were 43%, 63% and 69%; with the initial pH adjusted to 3.0 were 53%, 73%, and 78%, for the three different current densities evaluated. Regarding EO/H2O2 process, without pH adjustment, DOC have also a greater reduction reaching in 120 min 33%, 48%, and 73%, for 15, 38 and 62 mA cm−2, respectively. The lowest energy consumptions were 0.002, 0.005 and 0.006 kWh g COD−1, applying 15, 38, and 62 mA cm−2, respectively, with pH adjustment in the EO/H2O2 process. The results showed that the lowest energy consumption and the greatest reduction of the BSE organic load were achieved using the EO/H2O2 process.