UTB Envirotec

Zero liquid discharge (ZLD) recovers all of the water from a wastewater stream and leaves only solid salts, so no liquid effluent leaves the site. A typical ZLD plant combines pre-treatment, reverse osmosis, brine concentration by evaporation and a final crystalliser. At Apollo Tyres in Hungary, our 720 m³/day reverse osmosis and LTDis plant recycles almost all of the site's wastewater.

Choose ZLD when regulations demand true zero discharge or water is scarce enough that every cubic metre counts; otherwise MLD often delivers most of the benefit for far less. MLD typically recovers 85–95% of the water and sends a small concentrated stream to disposal, avoiding the most energy-intensive evaporation and crystallisation step. A feasibility study or pilot trial shows which your stream and permit call for.

It depends on whether you have waste heat: if you do, LTDis usually wins on operating cost; if you do not, MVR does. MVR evaporators run on electricity at 8–14 kWh/m³ of evaporated water by recompressing their own vapour, while LTDis runs at 50–80 °C on low-grade heat and handles concentrations through to crystallisation. Many plants combine the two.

Recovered water is often cleaner than the plant's raw water supply, so it can go straight back into production. Depending on polishing, it is reused as process water, cooling-tower or boiler make-up, or ultrapure water for semiconductor and battery production. Reuse cuts both water purchase and discharge costs, and makes energy and power and other industrial sites less dependent on an increasingly scarce supply.

Yes: crystallisation separates salts that can be reused or sold, and the same concentration steps recover valuable metals. That ranges from copper and chrome in surface treatment to lithium and other metals in battery and battery-materials production. At Volta Energy in Tatabánya, separate copper and chrome lines feed LTDis evaporation and crystallisation at 1,024 m³/day.

Yes: we design ZLD and MLD systems for both markets, sized to the local permit and to the value of the water recovered. In India, regulators require zero liquid discharge for a growing range of industries, including textiles, tanneries, distilleries and pharmaceuticals in many states. Across the Gulf, water scarcity makes reuse the cheapest new source of supply, as our chemicals and pharmaceuticals clients know well.

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.