Hydrolytic enzymes as coadjuvants in the anaerobic treatment of dairy wastewaters

Abstract

Abstract. -An enzymatic extract produced by Penicillium restrictum having a high level of lipase activity (17.2 U.g -1 ) was obtained by solid-state fermentation using babassu cake as substrate. The enzymatic extract was used in the hydrolysis of a dairy wastewater with high fat contents (180, 450, 900 and 1,200 mg.L -1 ). Different hydrolysis conditions were tested, and it was determined that it should be carried out at a temperature of 35ºC, without agitation, with 10% v/v enzymatic extract and a hydrolysis time of 12 hours. Both crude and hydrolysed effluents were then submitted to an anaerobic biological treatment. It was observed that for the enzymatically pretreated effluent there was a significant improvement in the efficiency of the anaerobic treatment. For the highest fat content tested (1,200 mg.L -1 ), removal efficiencies of 19 and 80% were attained for crude and hydrolysed effluents, respectively. In addition, a tenfold increase in the removal rate of COD from the hydrolysed effluent (1.87 kg COD.m -3 .d -1 ) was observed in relation to the crude effluent (0.18 kg COD.m -3 .d -1 ). The results obtained in this study illustrate the viability of using a hybrid treatment (enzymatic-biological) for wastewaters having high fat contents.

An insight into microbial lipases and their environmental facet

“…There are several such instances where hydrolytic enzymes have been successfully used as adjuvants in the anaerobic treatment of dairy wastewaters (Leal et al 2002). Enzymatic pre-hydrolysis has also been helpful in remediating slaughter house wastewater.…”

Lipase Pre-Hydrolysis Enhance Anaerobic Biodigestion of Soap Stock from an Oil Refining Industry

“…To overcome such limitations, several strategies have been proposed, including lipids removal prior to the biodigestion by physical methods or pretreatment steps chemical or biochemical for increasing lipids liquefaction and bioavailability for anaerobic microorganisms 6,7 . Among these, the alternative of using the biochemical route specific enzymes, lipases has, recently, potentially gained more attention because of stringent environmental regulations and clean and friendly application of enzymes 6,8 .…”

Seed lipases: sources, applications and properties - a review

“…The participation of lipases in the worldwide enzyme industry market has grown significantly and it is believed that, in the future, they will acquire importance comparable to that of the peptidases, which currently represent 25 to 40% of industrial enzyme sales (Hasan et al 2006). Lipases act, by definition, at the organic-aqueous interface, catalyzing the hydrolysis of estercarboxylate bonds and releasing fatty acids and organic alcohols (Pereira et al, 2003;Leal et al 2002;Kamimura et al, 1999;Merçon et al 1997). However, as Pottevin showed for the first time in 1906, in water-restricted environments, the reverse reaction (esterification) or even various transesterification reactions can occur Castilho 2008, Castro et al 2000).…”