Cutting effluent and pollution at cassava starch plant

Chokyuenyong Industrial in Thailand worked with Global Water Engineering (GWE) to cut effluent COD pollution levels at its cassava production plant by more than 95% while extracting gas from its wastewater to power its boilers and generate electricity for its own use and to sell back to the provincial grid.

Processing 1200 tons of cassava roots a day, Chokyuenyong Industrial, headed by Tawatchai Yuenyong, has installed GWE anaerobic technology supplied by local GWE agent Retech Energy with a capacity of 3200 m³ effluent a day.

Commissioned and refined over the past three years, the Chokyuenyong installation has cut the COD pollution level of influent wastewater from 22,500 mg/L (14,525 mg/L BOD O₂) to less than 1125 mg/L, resulting in substantially cleaner discharges to treatment ponds and ultimately the environment (and in the process reduced odour from the ponds).

The system returns up to 2.7 MW of electricity a year to a provincial power grid, PEA, which serves some areas distant from major generating sources and welcomes fresh input of green power generated locally.

Up to 21,000 L/day of fuel oil is saved by producing bio-gas, which is used to power the boilers and heating equipment used extensively in cassava drying and processing and to generate electricity for the large amounts of rotating equipment used in processing.

The installation generates carbon credits under the United Nations’ Framework Convention on Climate Change, through which it earns internationally tradeable CER certificates, representing the right to emit one tonne of carbon dioxide or carbon dioxide equivalent.