Wastewater reuse is now becoming more accepted in areas where agricultural demand for water is increasing yet it is in the production of fuel where it could have greatest potential, according to new research.
A study by the University of Illinois Urbana-Champaign believes that potable freshwater used for cellulosic ethanol production could be replaced instead by treated wastewater effluent.
Cellulosic ethanol plants are estimated to consume around six to 10 gallons of water per gallon of ethanol produced.
At present, the average water requirement for a 50 million gallon ethanol plant is 150 to 250 million gallons per year, according to the University.
The report stated: “One of the major concerns in ethanol plants is the amount of water consumed in the process of ethanol production. Use of fresh water in ethanol plants results in depletion of a precious natural resource, which cannot be sustained in the long term.”
Titled “Use of Treated Ethanol Water in Cellulosic Ethanol Production”, the findings highlighted the advantages of using non-food cellulosic feedstock for fuel production as “lowering greenhouse gas emissions, reducing cost pressure on food and feed markets and use of land”.
Wastewater discharge from fuel production facilities was also highlighted by the report. “Another major concern is the quality of discharge of wastewater streams from these ethanol plants and its impact on the environment due to a distinct chemical profile. Therefore monitoring and control of both quantity and quality of water in ethanol plants assumes significance.”
Water used in a dry grind ethanol plant is categorized into two types: process water and non-process water.
The report concluded: “This study shows that with proper characterization studies, the use of treated effluent water is feasible in cellulosic ethanol production. However, due to the limited effluent water samples used in this study, more extensive research is required in this field.”
A copy of the report can be found here.