Methanogenic toxicity and anaerobic biodegradation of chemical products in use in a brewery

Brewery industry effluents, as any other industrial effluent, contain a number of chemical products that could be toxic in biological wastewater treatment plants. Most of these products come from clean in place (CIP) systems, i.e. detergents and disinfectant, and from lubrication systems. To evaluate the toxicity effect of these compounds on an anaerobic effluent treatment pilot plant, studies of methanogenic activity were carried out. The results showed that the synthetic lubricant evaluated had a high toxicity level, compared to the organic lubricant; the disinfectant showed inhibition to some extent. To decrease the toxicity effect, the recovery and reutilization of these chemicals are suggested. Experiments to study the feasibility of adapting anaerobic sludge to these compounds were carried out. Working with UASB reactors, the adaptation of the sludge takes place in the presence of the most toxic chemical products; certain inhibition was observed on methanogenic bacteria in the reactor where a disinfectant was added, even though there was sludge wash out. In general a decrease in the operational behaviour was observed after adding the compound, a new steady state was reached in absence of the toxic compounds, in terms of alkalinity ratio, removal of COD, methane production. The reactors were able to be recovered and to be adapted again.