Resource Recovery

Because thickening, dewatering, transport and disposal all grow with the volume of sludge that leaves the site. The less sludge there is, and the drier and cleaner it is, the lower that cost. Our sludge line reduces volume at source, stabilises and hygienises what remains with AEROTHERM, and turns its organic content into energy before dewatering, cutting disposal cost by 15–25%.

It does the same job with far less energy: conventional thermal hydrolysis (THP) uses steam at 150–170 °C under pressure, while AEROTHERM is a thermophilic process with no pressure vessels or high-grade steam. It hydrolyses and hygienises sludge, gives up to 50% more biogas in the digester, and produces a Class A end product and a saleable liquid fertiliser. AEROTHERM has been installed at 123 plants since 1982, including Zielona Góra in Poland.

Anaerobic digestion converts the organic load in sludge, biomass and industrial waste into methane-rich biogas. METHANATOR runs mesophilic or thermophilic, in CSTR, UASB or AnMBR configurations, and has been delivered to 21 plants since 1988. Co-digestion, adding food waste, agricultural residues or high-strength industrial streams to sewage sludge, uses spare digester capacity and raises gas production. Industrial streams are especially productive: the anaerobic stage at Kall Ingredients produces 9,936 Nm³/day of biogas.

Yes: desulphurisation and upgrading remove carbon dioxide, hydrogen sulphide and moisture, bringing raw biogas to biomethane quality for the gas grid or to bioCNG for vehicle fuel. At Zalaegerszeg, 3,159 Nm³/day of biogas feeds gas engines, upgrading and a bioCNG filling station. Where upgrading is not viable, the gas runs a combined heat and power (CHP) unit for the plant's own electricity and heat, as at Eger with 1,800 Nm³/day.

Yes: sludge and digestate are rich in nitrogen and phosphorus, and our processes return them to agriculture as fertiliser instead of sending them to landfill. AEROTHERM also enables struvite recovery, and our reNEW research extracts volatile fatty acids (VFA) and nutrients (NPK) from biosolids as feedstocks for new products. Nutrient recovery is also becoming a regulatory requirement for larger plants in Europe.

By using less energy on the water side and recovering more on the sludge side, with both designed together as one plant. That means efficient aeration and biological nutrient removal in the wastewater treatment stage, and hydrolysis, digestion and CHP or biomethane in the sludge line. It matters now because the revised EU Urban Wastewater Treatment Directive requires larger plants to reach energy neutrality by 2045.