Lipids-rich wastewater was partial hydrolyzed with porcine pancreas lipase and the efficiency of the enzymatic pretreatment was verified by the comparative biodegradability tests (crude and treated wastewater). Alternatively, simultaneous run was carried out in which hydrolysis and digestion was performed in the same reactor. Wastewater from dairy industries and low cost lipase preparation at two concentrations (0.05 and 0.5% w.v-1) were used. All the samples pretreated with enzyme showed a positive effect on organic matter removal (Chemical Oxygen Demand-COD) and formation of methane. The best results were obtained when hydrolysis and biodegradation were performed simultaneously, attaining high COD and color removal independent of the lipase concentration. The enzymatic treatment considerably improved the anaerobic operational conditions and the effluent quality (lower content of suspended solids and less turbidity). Thus, the use of enzymes such as lipase seemed to be a very promising alternative for treating the wastewaters having high fat and grease contents, such as those from the dairy industry.
O presente trabalho teve como objetivo o pré-tratamento de efluente da indústria de laticínios na hidrólise de lipídeos, empregando lipase de fonte de células animais de baixo custo disponível comercialmente (pâncreas de porco) na formação de gás metano por biodegradabilidade anaeróbia empregando diferentes concentrações de lipase (0,05 e 0,5 % w.v-1). A utilização de lipase no pré-tratamento do efluente acelerou a hidrólise de lipídeos e, conseqüentemente, auxiliou o tratamento biológico resultando na redução da matéria orgânica em termos de Demanda Química de Oxigênio (DQO), cor e sólidos em suspensão como lipídeos. Os melhores resultados em termos de remoção de DQO e cor foram obtidos quando a hidrólise e biodigestão foram realizadas simultaneamente, independente da concentração de lipase empregada. Estes resultados mostram que a hidrólise e biodigestão podem ser realizadas simultaneamente empregando baixa concentração de lipase (0,05% w.v-1), contribuindo para a redução de custo e tempo no processo de biodegradação aneróbia.
The process of anaerobic digestion has been greatly developed during the last decades for the treatment of wastewater from food industries as for example, wastewaters from sugar and starch manufacturing and from breweries. However, for wastewaters which contain high amounts of fats and proteins, such as those from slaughterhouses and dairies, anaerobic digestion was found to be troublesome, due to the potential of sludge flotation, the formation of scum layers of lipids at the surface of the reactor, which are not digested and the toxicity of the intermediate compounds (long chain fatty acids) generated during the anaerobic digestion of the wastewater. The addition of hydrolytic enzymes, such as lipases prior to the anaerobic digestion can minimize these problems. In this work, this strategy is reviewed and the technical issues that must be considered in determining its feasibility are discussed.