Under anaerobic conditions, organic waste and wastewater are converted into biogas, a mixture of methane, carbon dioxide, other trace gases, vapor, and minimal excess sludge. This biogas can be safely captured and utilized, offering both environmental and economic benefits.
Valorizing biogas allows companies to reduce their carbon footprint and lower dependence on fossil fuels. In industries with high concentrations of organic contaminants, the biogas generated can often cover a significant portion, or even all, of a facility’s energy needs.
With over 30 years of practical experience, Global Water & Energy, through its subsidiary DWS, provides proven solutions for biogas utilization. This includes burners and boiler modifications that enable companies to use biogas in single or multi-fuel setups, creating a reliable, sustainable energy source while maximizing the value of organic waste.
See below for our biogas valorization solutions and how they turn waste into sustainable energy.
Biogas is produced through anaerobic digestion. After pre-treatment removes solids and fats, wastewater enters an oxygen-free reactor where microorganisms break down the organic load in four steps: hydrolysis, acidogenesis, acetogenesis and methanogenesis. The resulting biogas, a mix of methane and CO₂, is collected, cleaned and used for heat, electricity or biomethane. The treated water then goes on to polishing or reuse.
Once cleaned, biogas becomes a valuable on-site energy source. It can fuel boilers for process heat, a CHP unit for electricity and heat, or be upgraded to biomethane. This lowers energy costs, reduces dependence on fossil fuels and cuts the carbon footprint. For high-strength effluents, it can cover most or even all of a site’s energy needs.
Each kilogram of COD removed theoretically yields 0.35 m³ of methane (at 0°C, 1 atm). Biogas is about 60–65% methane, so that equals roughly 0.55 m³ of biogas per kg COD. Example: 10,000 kg COD removed per day × 0.35 = 3,500 m³ methane, or about 5,500 m³ biogas (≈35 MWh/day). Actual yields depend on wastewater composition and the final plant design.
Biogas contains hydrogen sulfide (H₂S), which corrodes engines and pipes. The main removal technologies are biological desulfurization (bacteria and air), iron salt dosing in the digester, chemical scrubbers, and adsorption on activated carbon or iron oxide. Many plants combine bulk removal with a final activated carbon polish. The best choice depends on H₂S load, gas flow, end use and operating cost.
