A biological wastewater treatment is being implemented on a large hog farm in west central Minnesota. If successful in reducing odor and cleaning wastewater, the system could be replicated all across Minesota.

By Andrea Frazeur

Raymond, Minn. -- Jerome and Marcia Taatjes never expected to live next door to 700 sows. Not that they mind it. In fact, they've found keeping a sow herd and rearing 15,000 young pigs a year to processing weight is a good way to make a living. The only major drawback -- handling the hog sewage.

The Kandiyohi pork producers are doing everything they can to run an up-to-date, money-making and environmentally-sound operation. For that reason, they recently agreed to participate in the first scale-up test of a new hog waste treatment, conducted by West Central Environmental Consultants (WCEC) of Morris, Minn. Denoted by the acronym SBEACR™, the treatment is similar to the way cities handle sewage.

Through the floors
Slatted floors in the Taatjes' two sow buildings allow manure to fall through into an 18-inch-deep gutter. Once a week, the Taatjes flush manure from the gutters with a 300-gallon-per-minute water pressure system. The effluent flows into a lagoon where solids are allowed to sink to the bottom. Water left on top drains into a second lagoon and is recycled for the next week's barn-flushing.

For about a month each spring, when the ice in the lagoon melts and "turns over," the smell is pretty strong. Though the Taatjes haven't had complaints from the neighbors yet, Jerome decided to do something about the odor. In 1997, he talked with Jeff Lopez, University of Minnesota Extension manure resource coordinator for west central Minnesota. Lopez told the Taatjes about WCEC.

Established in 1990, WCEC was purchased in 1996 by Prince Wallace, Bloomington; John Malinka, Sartell; and James Van Alstine, Morris. Initially cleaning soil contaminated by underground storage tanks, WCEC grew rapidly and became a major industrial employer in Morris.

"As time went on, more and more people came on board," says Bruce Droegemueller, WCEC general manager. "We started to spread out to other things."

Fishing for hog waste treatments
In the summer of 1996, WCEC bought AquaCare International, a product line developed by an engineering company based in the state of Washington. AquaCare systems were initially designed for wastewater treatment on fish farms. When WCEC purchased the line, they modified it for use with hog waste.

"The hog farmers are all saying, 'We need help,'" Droegemueller says. "They want to be responsible citizens without it having to cost an arm and a leg. They can't afford to be put out of business ... This came along, and we wondered how we could modify it to solve their problem."

The result is WCEC's modified AquaCare Single Basin Extended Aeration Cyclic Reactor, or SBEACR. It combines a low-cost solid separation technique with a biological process for cleaning wastewater.

Droegemueller learned that AURI provided technical and financial support for waste utilization and odor control projects, so he asked for assistance. Knowing WCEC's successful track record in solving environmental waste issues, AURI provided funds to help construct two SBEACR systems.

"The odor problem is consuming the poultry, swine and cattle industries," says Michael Sparby, manager of AURI's Morris office, "and it affects the small, medium and large producer. This project is one that deals with odor on a natural level. It also adds value back to the solid waste, as far as the creation of fertilizer from the solid separation process."

"This is a paradigm shift," says Jack Johnson, who has provided technical assistance as AURI's waste utilization manager. "Producers, until this time, have stored and land-applied manure. A few have done some manure treatment, but this is an opportunity for a solid separation treatment system. This is taking the next step."

Cleaning up with biology
In the SBEACR system, when the barn gutters are flushed, the effluent enters a liftstation. Solids are separated out of the stream and collected, and the resulting wastewater is pumped to the reactor tank.

In the tank, aerators inject air into the wastewater to provide aerobic microbes with the necessary oxygen to break down contaminants in the wastewater. Following the aeration cycle, the biomass is allowed to settle. That creates an environment for anaerobic bacteria to break down more contaminants and cause denitrification.

When sufficient time for settling has elapsed, the water is decanted. It is now clean enough to be used for barn flushing, irrigation systems, or direct discharge into the environment.

At the Taatjes farm, the SBEACR system, including a 32-foot diameter reactor tank, takes up 1,200 square feet just to the west of the two hog barns. They plan for the clean water to enter the lagoons and be reused for flushing the barn. Every 10 to 20 days, WCEC will haul away the stabilized solids, which have a fertilizer smell and a soil-like consistency.

WCEC plans to develop a system for processing the solids into custom-made fertilizer. Eventually, neighboring farmers using SBEACR systems may want to put up a fertilizer plant in a central location. They could make fertilizer for their own fields as well as for sale.

Project engineer Pat Kinney also expects SBEACR to lessen odor considerably. "Animal odor will still be there," he says, "but it's not bothering someone a half mile away. The only way they'll know the facility exists is because they'll see the buildings."

Proven in Mexico and Europe
SBEACR is a proven wastewater management system. Eight SBEACR systems are operating in Mexican municipalities. In the state of Washington, a packing plant uses SBEACR to reduce waste concentrations to levels that can be discharged into a municipal system. Farmers in Europe have successfully used similar processes, Droegemueller says.

If the system unexpectedly fails, WCEC has constructed precautionary measures. The Taatjes can simply turn some piping and the effluent will flow directly into the lagoon. However, if things work well at the Taatjes' farm, several other farmers have expressed an interest in installing SBEACR systems.

WCEC's hog SBEACR system costs from $80,000 to $120,000, depending on size, and Droegemueller says the system is probably not economical for operations with less than 300 sows.