FEW: Speakers zero in on reducing water use

By Holly Jessen | June 10, 2010
Posted June 16, 2010

Cutting back on water consumption or going to zero liquid discharge at an ethanol plant doesn't exactly translate into increased income. However, as several speakers pointed out June 16 at the 2010 International Fuel Ethanol Workshop & Expo (FEW), the yield in positive public opinion just might make it very worthwhile. "We've all heard the negative propaganda about ethanol," said Trevor Cassel, vice president and director of operations for Biodynamics Inc. "Just do a Google search and you'll find headline after headline."

Although there has been a 40 percent reduction in water use in the ethanol production process in the past 12 years, the typical ethanol plant still uses about three gallons of water to produce one gallon of ethanol, he said. That's more than is used to produce gasoline: two gallons of water for one gallon of gas.

Besides lending a helping hand in swaying public opinion, reducing water use or discharge can help the industry in other ways, said Mike Mowbray, marketing manager for U.S. Water Services, who spoke about zero liquid discharge. For one thing, environmental compliance is getting stricter every year. In some cases, zero liquid discharge is the only way to meet the restrictions. In addition, while zero liquid discharge is mainly about discharge, it can result in a 20 to 30 percent decrease in water needs.

Cassel and Mowbray spoke during a panel titled "Wringing Water out of the Production Equation" as did Nandakishore Rajagopalan, associate director of the Illinois Sustainable Technology Center, and Phil Bonneau from Ortman Ethanol Water Resources. Jon Cohen, vice president and technical director of H-O-H Water Technology, served as moderator.

Rajagopalan agreed that, to grow the industry, water usage at ethanol plants must be reduced. There are many possible methods that can be used to reduce water consumption. "It depends how much you want to do and how aggressive you want to be," he said.

One way an ethanol plant could reduce water use is by focusing on boiler water, which makes up 12 percent of water use. Water savings can be achieved by reusing filter water backwash, a move that could save about 4 million gallons of water a year. Or, an ethanol plant could increase RO recovery, with yearly potential savings of 17.6 million gallons of water at maximum. Another avenue is to minimize cooling tower waste, which could save about 11 million gallons a year of water. In all, he said, there's a potential to save approximately 40 million gallons of water a year.

To achieve zero liquid discharge, Mowbray said, ethanol plants need to work with a company familiar with the fuel alcohol industry, not a company that does a bolt-on system previously designed for another industry. It's also absolutely vital, he said, to have real time monitoring of the system on and off site. This monitoring helps head off any potential problems before they happen. "After all, that's what you guys do, create ethanol and DDGs that are sellable on the market," he said.

There is no single design that works for every ethanol plant, he said. U.S. Water Services has had success with one or more of four approaches: recycling water using cold lime softening, evaporation or crystallization of the discharge stream, discharging water to the ethanol process and/or evaporator ponds, which only work in the southwest U.S.

Cassel talked about reducing water usage through recycling thin stillage, resulting in valuable coproducts and energy savings. The Biodynamics process uses traditional wastewater treatment processes to remove waste solids, corn oil and other fermentation inhibitors. Testing shows that the process results in greater or equal ethanol yields and the company is awaiting the results of an independent third party review to confirm that, he said.

Bonneau's topic was water, not the reduction of water use or discharge, but what he called a catastrophic event at an ethanol plant: no water. Basic failures include electrical (a power surge, lightening or electrical shorts) and mechanical (plugged pump or well, metal fatigue or piping failure), he said. Overall, the hydrologist's message was about what to do to avoid these failures. "You don't have to wait until it's an emergency."

Encouraging attendees to work with a qualified well contractor to have periodic maintenance inspections, Bonneau said, "It's great if an ethanol plant has two good, functioning wells," however, if one well suddenly has to be shut down for a while, the plant is suddenly in the position of relying on one well. Some well failures are slow to arise and can be identified ahead of time, by proactive action. Besides periodic maintenance inspections, Bonneau suggested that ethanol plants do testing to gather data.