Performance of Anaerobic Co-digestion of Pig Slurry with Pineapple (Ananas comosus) Bio-waste Residues

Agro-food industries produce large amounts of bio-waste, challenging innovative valorisation strategies in the framework of circular economy principles. Anaerobic digestion technology is an interesting route to stabilise organic matter and produce biogas as a renewable energy source. This paper aimed to study the optimal performance conditions for anaerobic co-digestion (AcoD) of pig slurry with pineapple (Ananas comosus) peel bio-waste. The anaerobic digestion (AD) trials were performed at lab scale, in a continuous stirred reactor, for 16 days' hydraulic retention time in mesophilic conditions (37 +/- 1 degrees C). Three hydraulic retention time were performed, one for the reference scenario (T-0) and two for AcoD trials (T-1, T-2). Feeding mixtures (20:80; v:v) of pineapple peel liquor and pig slurry, with an OLR of 1.46 +/- 0.04 g TVS L-reactor(-1) day(-1) were used during AD/AcoD trials, presenting high values for soluble chemical oxygen demand and C/N ratio. This operational conditions highlight bioenergy recovery up to 0.58 L CH4 g TVSadded-1, in comparison with that obtained with pig slurry substrate (0.31 L CH4 g VSadded-1). The AD performance showed a total volatile solids and chemical oxygen demand removal efficiency of 23% to 47% and 26% to 48%, comparing T-0 with the average of T-1 and T-2, respectively. The digester stability, evaluated by specific energetic loading rate, was below the limit (0.4 day(-1)) throughout the trials. Pig slurry co-digestion with pineapple peel liquor seems to be a promising approach for potential bioenergy recovery. [GRAPHICS] .

Automated summary

Agro-food industries generate large amounts of bio-waste, leading to the need for innovative valorization strategies within the framework of circular economy principles. Anaerobic digestion technology offers a promising route for stabilizing organic matter and producing biogas as a renewable energy source. This study focused on optimizing the conditions for anaerobic co-digestion of pig slurry with pineapple peel bio-waste, showing potential for increased bioenergy recovery compared to traditional substrates.