Reducing the Consumption of Water in Ethanol Plants - A Case Study

Abstract

Kishore Rajagopalan - Associate Director, Illinois Sustainable Technology Center, Univ. of Illinois at Urbana-Champaign.

The conversion of biomass to energy, under the current state-of-the-art processes, requires the use of copious amounts of water. Recently constructed dry grind ethanol plants utilize 3 to 4 gallons water per gallon EtOH. Even this level of water usage for bioethanol production can place an undue burden on local water supplies. In some instances, the competition for water among various end-uses, including biofuel production, is sparking debate on the merits of large-scale bioenergy production. This talk presented preliminary results from an ongoing investigation at an operating ethanol facility to identify opportunities for water reduction. Opportunities identified included improving the efficiency of RO operations, recycling of filter backwash, reuse of cooling tower blow down as well as feasibility of using treated municipal effluent. The talk also addressed other considerations that may impact feasibility and extent of water reuse.