Biological and electrochemical oxidation of naphthalenesulfonates

Abstract

A biofilm airlift suspension (BAS) reactor and an undivided flow cell equipped with a boron-doped diamond (BDD) anode and a stainless-steel cathode were used to investigate the effects of varying operating conditions on process performance in the biological and electrochemical oxidation of a mixture of naphthalenesulfonates contained in the infiltration water of a contaminated industrial site. The experiments were aimed at evaluating the feasibility of process integration and the criteria for optimization (i.e. how to maximize degradation efficiency with minimum energy consumption) in combined biological and electrochemical oxidation of scarcely biodegradable compounds. Because of high reactor biomass concentration and long biomass retention time, the BAS reactor achieved a high degradation capacity (up to 6.8 kg COD m(-3) d(-1)). On the other hand, owing to the recalcitrant character of some of the aromatic sulfonates in the leachate, the overall degradation efficiency did not exceed 70% based on COD measurements. All naphthalene-mono- and -disulfonates (except naphthalene-1,5-disulfonate) were completely degraded in the BAS reactor, whereas more complex molecules (e.g. naphthalenetrisulfonates) were more recalcitrant to biological oxidation. These compounds were completely mineralized by electrochemical oxidation using a boron-doped diamond anode. The energy consumption and the time required for the complete mineralization of the infiltration water decreased from 80 kWh m(-3) and 4 h to 61 kWh m(-3) and 3 h for the oxidation of raw and biologically pretreated leachate, respectively. (c) 2005 Society of Chemical Industry

Contributions of electrochemical oxidation to waste‐water treatment: fundamentals and review of applications

“…28 In contrast, application of electrochemical oxidation as a polishing step has the object of completely mineralizing the refractory organic matter remaining in the effluent after biological treatment. Panizza et al 29 demonstrated that integration of a biofilm airlift suspension (BAS) reactor with electro-oxidation by BDD anodes as a polishing step was an effective means of treating a mixture of naphtalenesulfonates contained in the infiltration water of a contaminated industrial site. A reduction in energy consumption from 80 to 61 kWh m −3 was obtained after coupling the two processes.…”

Is the naphthalene sulfonate H-acid biodegradable in mixed microbial cultures under aerobic conditions?

“…In the absence of a readily biodegradable carbon source, the performance of the trickling filter was significantly inhibited for at least one week; thereafter, an adaptation phase was required for rapid and extensive 3-NBS degradation. In another study, complete degradation was obtained for most of the available naphthalene sulfonates having a single sulfonate functional grouping, whereas relatively low and even no biodegradation efficiencies were observed for those bearing two-or three sulfonated functional groupings ranging between 9% and 42% (Panizza et al, 2006).…”

Decontamination of Wastewaters Containing Organics by Electrochemical Methods

“…In contrast, application of electrochemical oxidation as a finishing step envisaging completely mineralizing the refractory organic matter after biological treatment. A reduction of 25% of the energy consumption was reported by Panizza after coupling the electrooxidation and the biological processes [58].…”