Electrochemical advanced oxidation processes (EAOPs) as alternative treatment techniques for carwash wastewater reclamation

Abstract

Electrochemical advanced oxidation processes such as electrooxidation (EO), electrooxidation with hydrogen peroxide generation (EO-HO) and electro-Fenton process (EF) have been investigated as alternative treatment techniques for complete removal of anionic surfactants and organic matters from real carwash wastewater. The electrochemical processes were performed with acidified real carwash wastewater using boron doped anode and carbon felt cathode. In all cases, the chemical oxygen demand (COD) removal efficiency was always increased with rise in applied current and complete organic matter decay was achieved at applied current of 500 mA or above after 6 h of electrolysis. Faster and higher COD decay was observed with EF compared to either EO or EO-HO treatment, at all currents and electrolysis time. Besides, complete degradation of anionic surfactants - the major organic content of the wastewater could be achieved at all applied currents studied irrespective of the process used, indicating the efficacy of processes for total remediation of real carwash wastewater. The short-chain carboxylic acids formed as the final organic byproducts were identified and quantified by ion-exclusion chromatography. More so, lower energy consumption and higher current efficiency were achieved with EF compared to EO-HO. Electrochemical treatment was found to be a powerful technology for the complete abatement of organic matter in carwash wastewater for possible reuse.

Nature, Mechanisms and Reactivity of Electrogenerated Reactive Species at Thin‐Film Boron‐Doped Diamond (BDD) Electrodes During Electrochemical Wastewater Treatment

“…[92] The scavenging effect of the Cl À ions prevails at high concentration where it is oxidized to ClO À by the electrogenerated hydroxyl radical [Eq. (9)(10)(11)(12). Subsequently, the produced ClO À can further reacts with hydroxyl radical in several steps to form different RCS according to Eq.…”

“…Brito et al (2015) [53] showed that during anodic polarization at low Cl À concentrations, there was a shift in current/potential curves towards the negative direction, which was more pronounced with higher sp 3 /sp 2 ratio (sp 3 /sp 2 = 329)) BDD compared to low sp 3 /sp 2 ratio BDD (sp 3 /sp 2 ratio = 175), which suggested that Cl 2 gas could be predominantly favored at higher current with high sp 3 /sp 2 ratio BDD. (8)(9)(10)(11) or faster direct Cl À oxidation at the anode to form Cl 2 , which is a precursor for the production of RCS. The formation of these species via the electrochemical reactions are assumed to be responsible for the peak observed in the voltammogram.…”

“…[1][2][3][4][5][6][7][8][9] This process is very exciting and requires limited or not the use of chemicals for the production of oxidants, thus, being highly safe and ecofriendly. [8,[10][11][12][13][14] M þ H 2 (1)].…”

Application of a multiple criteria analysis for the selection of appropriate radical based processes in treatment of car wash wastewater

“…[2]. Many European coun-tries have legislation for water recycling in car washing stations to reduce the volume of water consumed as well as reduce the pollutant release to the municipal treatment systems [7]. According to the Turkey Statistical Institute [8], the number of total cars is 23 million, but there is no statistical information about water consumption for car washes.…”

“…Most of these systems are not sufficient for the quality of reuse water [10]. Some treatment methods used for the treatment of car wash wastewater include physicochemical processes [10][11][12][13], electro/chemical coagulation [2,14,15], chemical oxidation [4], electrochemical AOPs [7] and electrooxidation [16]. Although high efficiency is obtained with membrane processes, such processes require large areas and high costs.…”