Bioenergy Recovery in Full-Scale Anaerobic Co-digestion of Swine Wastewater and Pig Bedding Material

Pig farming represents a rapidly expanding segment of Brazil’s agricultural sector, concomitant with the generation of substantial volumes of wastewater, the effective management of which demands strategic solutions. Anaerobic digestion has been identified as a promising solution for the preliminary treatment of these effluents, concurrently yielding methane-rich biogas, which possesses the capability to generate thermal or electrical energy. This study evaluates a new anaerobic treatment method, through the co-digestion of swine wastewater (SWW) and bedding material (BM) on a real scale, changing the production of bioenergy. The experiment was divided into four phases: Phase 1, monitoring the biodigester operating solely with swine wastewater (SWW); Phase 2, application of SWW + 2 tonnes of BM (SWW+2 T); Phase 3, SWW + 6 tonnes of BM (SWW + 6 T); and Phase 4, SWW + 10 tonnes of BM (SWW+10 T). Loads of 320 ( ± 2.3) to 805 ( ± 18) kg COD d?¹ in the summer and from 310 ( ± 1.5) to 780 ( ± 13) kg COD d?¹ in the winter were applied. The concentrations of methane and CO? were measured by gas chromatography. Biogas productions three times higher were recorded when 12 tons of BM were applied, which, when converted into bioenergy potential, resulted in the generation of 635 kWh per day of bioenergy in the summer and 270 kWh per day in the winter. Methane yield was highest in the summer with the application of 12 tons of BM (0.34 m3 KgCODRem?1). Volatile solids and COD removals ranged between 60-70% and 61-84%, respectively. The findings highlight that the use of deep bedding alongside SWW contributes significantly to biogas production, and co-digestion is recommended to enhance electricity generation on farms, with the added benefit of treating two waste types in a single reactor.