Biogas production from the recycling of organic and agricultural waste constitutes a fundamental pillar of the transition toward renewable energy and a circular economy, leveraging Anaerobic Digestion (AD) to convert waste streams into biomethane. The environmental and economic viability of this process multiplies when integrated with Combined Heat and Power (CHP) cogenerational systems. This coupling enables simultaneous electricity generation for grid supply and waste-heat recovery for district heating or thermal reactor parasitic loads, pushing total system efficiency to benchmark levels.The primary technical and engineering challenges stem from the high composition variability and structural recalcitrance of lignocellulosic agricultural residues, which slow hydrolysis rates and depress biomethane yields. Furthermore, anaerobic digesters face biological instability risks driven by volatile fatty acid accumulation (acidification) or inhibition from high ammonia and sulfur concentrations. Regarding CHP engine operations, trace impurities in raw biogas—specifically hydrogen sulfide ($H_2S$), siloxanes, and high moisture content—present severe operational hazards. These contaminants cause rapid internal engine corrosion, abrasive deposit buildup on combustion chambers and turbine blades, and lubrication oil degradation, significantly shortening asset lifespans and elevating maintenance overheads.To mitigate these technical hurdles, researchers and engineers have pioneered advanced solutions, including thermochemical and mechanical feed pre-treatments to disrupt complex polymer matrices and accelerate enzymatic hydrolysis, alongside co-digestion strategies that optimize carbon-to-nitrogen (C:N) ratios across mixed substrates. For CHP reliability, multi-stage biogas upgrading and conditioning trains are deployed—incorporating chillers for moisture knockout, bio-scrubbers, and activated carbon beds to strip $H_2S$ and siloxanes down to sub-ppm levels prior to combustion. This architecture is finalized by automated thermal load management, driving total CHP system energy conversion efficiencies beyond 85% and securing comprehensive economic and environmental sustainability. Al-Mustaqbal University – The First Private University in Iraq