The evolution of wastewater treatment has shifted from merely avoiding environmental harm to exploring reuse and energy generation from waste streams. Anaerobic treatment processes, with lower energy requirements and yielding energy as a byproduct, have become a focal point. Anaerobic biological processes involve microorganisms breaking down biodegradable material in the absence of oxygen, producing methane, commonly known as biogas. This combustible biogas can be harnessed for electricity, heat, renewable natural gas, or transportation fuels.

In wastewater treatment, anaerobic digestion optimizes the natural process, providing controlled conditions in anaerobic reactors. Various reactor types, including traditional anaerobic digesters, sludge digesters, Continuously Stirred Tank Reactors (CSTR), or Upflow Anaerobic Sludge Blanket reactors (UASB), are designed to maximize biogas production by fostering ideal conditions for anaerobic bacteria. Biogas, comprised of methane, carbon dioxide, and trace gases, can be used for energy generation, while the digested material, called digestate, is often repurposed for soil enhancement.

The global attention on anaerobic digestion for wastewater, septage, or sludge treatment stems from its environmental and economic benefits. Beyond safeguarding water bodies, this approach enhances economic resilience amid uncertainties in energy production and waste disposal. Anaerobic reactors not only facilitate energy recovery but also reduce wastewater treatment costs. Biogas, with minimal processing, can be utilized on-site for heating or electricity generation, contributing to Combined Heat and Power (CHP) operations. The nutrient-rich residue post-digestion becomes a valuable resource for plant and soil enhancement after dewatering.