Helping Canneries Make Better Use of Leftover Water

With the help of a well-stocked kitchen cupboard, a can opener, and a microwave oven, a steaming-hot bowl of your favorite tomato soup can be ready to savor in just minutes. For decades America's canneries have helped make soups—as well as vegetables, fruits, juices and other familiar foods—more convenient for us to enjoy.

Now, Agricultural Research Service (ARS) scientists are helping canneries tackle the tough problem of what to do with the millions of gallons of water left over after processing field, orchard and vineyard harvests.

Strict environmental regulations make some of yesterday's disposal choices no longer an option, according to Donald Suarez, director of the agency's U.S. Salinity Laboratory in Riverside, Calif.

Suarez, laboratory soil scientist Pete Shouse, and University of California-Riverside colleague Scott Lesch have teamed up with the Sacramento-based California League of Food Processors to use scientifically sound water-management practices to solve processors' water reuse problems.

Right now, the researchers are determining how a major California cannery might get more value from wastewater that's left after processing plump, field-fresh tomatoes. The salinity lab scientists are an apt choice for the work, given that some salt—in the form of either sodium hydroxide or potassium hydroxide—that's used at the cannery to loosen tomatoes' tightly attached skins ends up in the wastewater.

The factory uses wastewater to irrigate fields of a forage crop. The researchers have already employed the ARS lab's own technology, known as "electromagnetic salinity profiling," and its accompanying software package to map the salinity levels of the wastewater-irrigated fields. And, they're looking at how often, and how uniformly, the wastewater is applied.

For example, irrigating more often—without overwatering—and more uniformly can help prevent soil from drying and cracking and can improve use of the water. Cracks can serve as direct channels to the underground water supply, and can exacerbate leaching of salts and other pollutants.

Read more about this research in the January 2009 issue of Agricultural Research magazine.

ARS is a scientific research agency of the U.S. Department of Agriculture.