Co-digestion of organic rich wastewater sludge and brewery spent yeast is a prospectively viable bioenergy substrate, which can enhance future green energy and boost the emerging circular economy. Multi-objective optimization of wastewater treatment plant (WWTP) cost and its environmental footprint are considered significant and vital in modern WWTP. Despite the lauded benefits of co-digestion, current techniques developed to upgrade biogas quantity and quality in the water treatment sector have focussed on mono-substrates. This development has been associated to shortage of suitable substrates and uncertainty on the impact on biogas quality and biosolid production. Therefore, this study presents an analytic evaluation of the mono substrates and co-digestion of wastewater biosolids (WWS), and brewery spent yeast (BSY) to determine their methanogenic potential as biomass for potential energy resource recovery. Here, quantification, characterisation, and waste to energy conversion through anaerobic digestion were investigated and the results obtained were appropriately reported. The test bench was firstly calibrated, and the accuracy determined. The organic samples went through a chemical process producing biogas using the biomethane potential test technique with AMPTS 11 set-up. It was observed that the optimum biomethane yield was obtained at 304,75Nml mono digestion of brewery spent yeast. It was established that the WWS and BSY offers a high prospect for future energy mix and their contribution to circular economy cannot be underestimated. Large-scale exploration of their prospects offers significant benefits in mitigating climate change through alternative energy yield obtainable from them.