Laboratory-scale trials of electrolytic treatment on industrial wastewaters: microbiological aspects

Animal, civil and industrial waste matter is a source of potential chemical, microbiological and air pollutants. In populated areas the presence of faecal bacteria and the production of malodorous compounds during waste storage and in the tanks of wastewater treatment plants, can cause concern. The general aim of the work was to study electrolytic waste treatment (recently applied on animal slurry) using low electric current across graphite and copper electrodes, determining its effect on the microflora of sludge, collected from the equalisation basin of an industrial aerobic wastewater treatment plant, and on odour emission abatement. Biochemical and enzymatic indicators like ATP content and a pool of 19 enzymatic activities were tested, comparing them with viable cell counts by traditional microbiological methods, to verify the validity of such indicators in monitoring the electrolytic treatment and to assess their correlation with odour reduction. The preliminary results of our laboratory-scale trials showed that in the presence of inert electrodes, such as graphite, metabolic activity is stimulated, whereas with copper electrodes the ATP content and some enzymatic activities are inhibited quite considerably after only four days, this being accompanied by a marked reduction in odour. Consideration was also given to the total copper released from the electrodes and its recovery using iron electrodes.