Alcohol and ethanol distilleries operate on grain, molasses, sugar cane juice, beet jiuce or cactus juice. At grain distilleries, stillage is disposed of in one of the three ways: discharge onto filtration fields, dry distillery grain production (DDGS), and biogas production.
Discharge onto filtration fields according to environmental standards is becoming an increasing problem for the local community and the enterprise itself. This method of disposal is discarded in favor of the other two.
Equipment for the production of DDGS is cheaper than biogas equipment. However, after decanting and stillage drying filtrate remains. Filtrate is discharged onto the filtration fields or sent to treatment facilities.
DDGS production with filtrate does not completely solve the waste problem. In the case of evaporation of the filtrate, the distillery incurs additional energy costs for evaporation. The final product – DDGS competes in the market with grain and is often sold at a loss.
Processing of distillery stillage into biogas allows a company to eliminate 100% of its natural gas or bunker oil use. Thus, it is possible to reduce the cost of alcohol.
Stillage is processed into biogas using classical technology or vertical reactor technology.
NGE Biogas has experience at the ethanol distillery in Hincesti, Moldova, since 2013.
The plant produces ethanol from grain and molasses. The biogas plant was originally designed to work with grain stillage. But in fact, it works on grain one season and on the molasses the next.
The distillery in Hincesti changed burners in the DKVR-10 boilers. The new burners allow the boilers to work on gas with different methane numbers. The distillery completely eliminated its natural gas usage.
When designing a biogas plant, it is necessary to take into account the differences between molasses vinasse and grain stillage. Molasses vinasse has insufficient content of micronutrients to support bacterial growth. Therefore, the addition chemical additives is required.
Unlike grain stillage, molasses vinasse is not suitable for production of DDGS. Therefore, biogas plants for molasses distilleries are generally the only possible solution. The same is applied to the vinasse from sugar cane, vinasse from nopal, cactus, agave, beet juice, effluent from ethanol plants with straw as a substrate.