Waste into green energy

Primary producer uses wastewater technology

Clean water and green energy technology from Global Water Engineering (GWE) has been used by Chokyuenyong Industrial in Thailand to cut effluent COD pollution levels at its cassava production plant by more than 95%. The gas from its wastewater has also been extracted to power its boilers and generate electricity for its own use and to sell back to the provincial grid.

Processing 1200 tonnes of cassava roots a day, Chokyuenyong Industrial uses GWE anaerobic technology with a capacity of 3200 m³ effluent a day. Commissioned and refined over the past three years, the Chokyuenyong installation:

Chokyuenyong’s process involves an equalisation basin (total volume 1600 m³) with submerged agitators, degasifying basin with agitator (24 m³) inline pH adjustment, NaOH storage tank (25 m³) UASB methane reactor (active volume 4800 m³) and biogas flare (standby, for use if required). The technology is all above ground for simplicity and ease of maintenance.

GWE’s anaerobic treatment significantly reduces the plant’s carbon footprint by avoiding the release of methane gas into the atmosphere. The wastewater passes through several pre-treatment steps before entering a GWE methane reactor in which the wastewater’s organic content (COD) is digested by bacteria in a closed reactor, degrading the compounds and converting them into valuable biogas and cleaned effluent. Biogas from the process is collected and re-used as renewable fuel in the plant’s thermal oil boiler, saving money that would otherwise be spent on bunker oil. Chokyuenyong’s excess biogas is used in electrical power generation.

Results achieved at Chokyuenyong can be even further improved by also converting its solid wastes (residual pulp from the roots, after starch extraction) into biogas as well, using GWE’s Raptor treatment system for solid organic residues, says GWE.