Biosolids, the nutrient-rich organic materials resulting from the treatment of domestic and industrial sewage, have steadily becoming more accepted in the city of Sioux Falls in South Dakota. Since 1995, the city has been turning a sludge into a valuable resource that is beneficial to farmers. These are given at no cost to farmers who receive enough materials to fertilize 2,500 acres of land a year.
Phil Greenwood, the Residue Coordinator of the City of Sioux Falls and southeast South Dakota believes that sludge fertilizer is a win-win for farmers and the environment. Phil holds an animal science degree from Missouri State University and worked on a South Dakota farm before working with the City of Sioux Falls in 2009. His interest in the process started in his family. His grandparents farmed in Minnesota and used fertilizers while his father was in wastewater treatment.
The Sioux Falls facility, a regional wastewater treatment takes in 18-20 million gallons of wastewater daily. Ninety-nine percent (99%) of that is water that comes from things like dishwasher, sinks and laundry. About four percent (4%) is solid material – suspended or dissolved solids and only part of that is human waste. The wastewater goes to the plant through pipes and the city segregates the plastic, paper and other materials.
Bacteria digests the waste in aeration basins. Each basin is provided with blowers to add oxygen and mix the sludge and bacteria. In the process, the bacteria die and end up in the city’s sludge holding lagoons. The material then settles into the bottom where it further decomposes. The ponds are cleaned up about twice a year after and then waste material, which has the look and texture of dark chocolate milk, is taken to the farm fields. The liquid portion is measured in gallons, while the solids are measured as 3,200 “dry-tonne” equivalent.
The City of Sioux Falls adheres to the strict regulations set by the Environment Protection Agency (EPA). The amount applied on the field is calculated according to the active ingredients, based on agronomic rates and yield goals depending on the type of crop. The city offers soil testing to help farmers maintain the optimum amount of fertilizer. A set proportion of the percentage concentrations of nitrogen, phosphorus and potassium needs to be observed. The city closely monitors heavy metal levels and if the biosolids exceed the maximum level, then they are disposed in a landfill or undergo further processing. Usually, around 75 percent of the sludge is spread on the field beginning late September to ground freeze-up around Veteran’s Day. They utilize a Challenger tractor, pulling a Balzer Magnum plow system that runs mostly from 6 to 10 inches deep.
Tom Brown and his son Joey Brown, both farmers of Brandon, South Dakota are satisfied customers. They have been using the biosolids for about five years. Their farm is about six miles from the facility, on about 400 acres, mostly in demonstration plots that consist of corn and soybeans. They prefer biosolids because they are organic and natural, and come from recycled materials. It provides them with the nutrients needed to grow their crops.
Besides providing vital nutrients in the soil, biosolids also affords the farmers big savings that can add up. These savings help them better manage their operations and they can invest their money on other areas of their business. The City of Sioux Falls is also happy since diverting sludge to the agricultural lands saves them $36 per ton that the city would have paid if they had to take it to the landfill. That’s a savings of about $400,000 a year.
If you are a farmer in the Niagara Region and are interested in considering biosolids as a potential application to your fields, please call us on 1 (877) 479-1388. There is no cost for us to apply to the MOE or to spread biosolids on your field. These costs are covered by the Region of Niagara.