Electrochemical versus photochemical pretreatment of industrial wastewaters

Electrochemical and photochemical treatments have been applied on industrial non-biodegradable effluents originated from a flavour manufacturing facility. The efficiency has been measured in each case. Such an approach has been used before successfully on model substances and is confirmed in the present study as a valid approach for industrial waste water. During electrochemical treatment, the values for the temperature, pH, electrode characteristics, initial concentration of effluents and NaCl used have been optimized through preliminary experiments. After a charge of 5 Ah/l the TOC observed decreased by 52% and the ratio TOC/COD decreased from 3.3 to 1.7. After electrochemical treatment and chlorine neutralization the effluents become easily biodegradable and no toxicity was observed. Photo-Fenton system under solar lamp have shown to be efficient in the photochemical degradation of industrial effluent when Fe3+-ion (4.3 mg in 40ml) and H2O2 (30μl/h in 40 ml) is added to the solution. After 10 hours a degradation of 56% of TOC was observed. The toxicity and biodegradability of pretreated wastewater were evaluated after having decomposed the residual H2O2 with catalase. Toxicity did not increase during photochemical treatment but the biodegradability strongly increased.