Hydraulic Performance of the Denitrification Bioreactor

Denitrification bioreactors, also known as woodchip bioreactors, are a new strategy for improving drainage water quality before these flows arrive at local streams, rivers, and lakes. A bioreactor is an excavated, woodchip-filled pit that is capable of supporting native microbes that convert nitrate in the drainage water to nitrogen gas. The idea of these edgeof-field treatment systems is still relatively new, meaning it is important for investigations to be made into how to design these “pits” and to determine how drainage water moves through the woodchips. Because the bioreactor at the ISU Northeast Research Farm (NERF) is one of the best monitored bioreactor sites in the state, it provided an ideal location to not only monitor bioreactor nitrate-reduction performance, but also to investigate design hydraulics.

The University Compost Facility after Three Years

The University Compost Facility, 52274 260th St., Ames, Iowa has completed three full years of operation. The facility is managed by the ISU Research Farms and has a separate revolving account that receives fees and sales, and pays expenses. The facility is designed to be self-supporting, i.e. not receive allocations for its operations. The facility consists of seven, 80 × 140 ft hoop barns and a new 55 × 120 ft hoop barn, all with paved floors. The facility also has a Mettler-Toledo electronic scale with a 10 ft × 70 ft platform to weigh all materials. Key machinery is 1) compost turner, a used pull-type Aeromaster PT-170, 14 ft wide made by Midwest Biosystems, Tampico, IL; 2) a converted dump truck trailer used to construct windrows and haul material; 3) telehandler, Caterpillar TH407 with cab and 2.75 cubic yard bucket; and 4) tractor, John Deere 7520 (125 hp) with IVT (Infinite Variable Transmission) and front-wheel assist used to pull the turner and dump trailer.