Impact of Enzymatic Pretreatment on the Anaerobic Digestion of Coffee Processing Wastewater

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Abstract

Abstract Coffee processing generates large amounts of wastewater, especially during the pulping and fermentation stages. This wastewater has high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) and contains macromolecules such as polyphenols, tannins, polysaccharides, and caffeine, which are challenging to degrade naturally and inhibit biological treatment processes. This study evaluated and optimized the pretreatment of CPWW using a crude enzyme extract of Pleurotus ostreatus produced in the CPWW itself and assessed the anaerobic biodegradability of both pretreated and untreated CPWW. The results showed that pH and agitation were the variables with the most significant impact on pretreatment, with a pH of 4 and agitation at 120 rpm leading to higher phenolic compound removal. For anaerobic biodegradability, enzymatic pretreatment was found to reduce methane production, suggesting that the crude enzyme extract may contain secondary metabolites that inhibit the anaerobic consortium. Additionally, non-inhibitory concentrations of phenolic compounds may play an important role in supporting anaerobic digestion.