Enzymatic pre-treatment of red meat abattoir effluent to reduce fat, oil and grease while enhancing biogas generation

The discharge of untreated abattoir effluent has been identified as posing a significant environmental risk due to its high organic content and fats, oils, and grease (FOG). This study investigated the effect of enzymatic pre-treatment of abattoir effluent using a commercial biological product (Eco-flush™), to improve the quality of abattoir effluent and enhancing bio-energy recovery in anaerobic digestion. The raw abattoir effluent characterisation results revealed a soluble chemical oxygen demand of 1818 mg/L, FOG of 2593 mg/L, turbidity of 592 FAU, ammonia content of 155 mg/L, and dissolved oxygen content of 1.78 mg/L. The optimal FOG hydrolysis occurred at an enzyme concentration of 0.5% v/v, yielding a maximum FOG concentration of 17,174 mg/L. An increase in enzyme concentration above this optimal level resulted in reduced process performance. Moreover, an increase in total suspended solids (TSS), turbidity, and ammonia was noted. However, such an increase should be viewed with caution since it may not always translate to a positive response in terms of improved quality. Nevertheless, despite such an increase, there was an enhancement in bioenergy recovery from the pre-treated effluent. This was based on an increase in biogas production by as much as 134% and a methane composition of 70%.