Two-state, mixed plug flow anaerobic digester is designed to recycle phosphorous and reduce the amount of the material that ends up in waterways.
Engineering firm DVO Inc. based in Chilton, Wisconsin, has introduced a system that the company says removes between 75 and 95 percent of phosphorus from anaerobically digested wastes. Following research, the company has commissioned the system for a dairy farm in the Northwest.
DVO also reports that a commercial mixed-waste anaerobic digestion facility in Indiana and a dedicated poultry litter digester in Ohio have installed the system at full-scale.
The company points out that while phosphorus is a valuable nutrient for agriculture, it is a nonrenewable resource with a finite global supply. Furthermore, the company says that farm and commercial/industrial bio-wastes can contribute to excess phosphorus in the environment, leading to algae blooms and possibly damaging aquatic ecosystems.
By treating the wastes in DVO’s Two-Stage Mixed Plug Flow anaerobic digester and then employing the phosphorus recovery system, one can both conserve and recycle the phosphorous, while keeping it out of waterways. As a result, the majority of a waste stream’s phosphorus resides in a condensed solid — a new and useful byproduct from digestion that is stackable, storable, spreadable and profitable, DVO says.
Operating costs for the new phosphorus recovery system average one-eighth of a penny per gallon of liquid processed, according to DVO, a small amount compared with the cost of transporting the material. The phosphorus-rich solids generated by DVO’s phosphorus recovery system can be easily transported from the area and are marketable as a soil amendment, fertilizer or potting soil/peat moss replacement, the company says.
“Not only is DVO’s PR system a low-maintenance, sustainable treatment solution that works for agriculture and industry — it also provides real benefits for the environment,” says Doug VanOrnum, vice president strategy and technology for DVO. “Largely because these ‘plant-ready’ fertilizers and micronutrients are captured in a form that can now be safely transported and utilized in areas that need them. DVO’s mission has always been to provide our customers with groundbreaking nutrient management solutions that work.”
The company says that nearly 100 of the company’s patented Two-Stage Mixed Plug Flow anaerobic digester systems are installed in 18 states, with total electrical generation capacity of more than 75 megawatts. DVO digesters are also operating internationally, the company reports.