Rain couldn’t stop a parade of local and state leaders, as well as nutrient recovery experts, from pouring into Madison, Wisconsin on Wednesday, June 4th for the launch of a revolutionary project: the $40 million 11th Addition to the Nine Springs Wastewater Treatment Plant (NSWWTP) for the Madison Metropolitan Sewerage District (MMSD).
The high-profile ceremony marked the official opening of the nutrient recovery facility constructed during the 11th Addition, which was designed by Applied Technologies, Inc. As part of the District’s continuous improvement program, the facility will help protect area freshwater lakes and rivers by recovering phosphorus from wastewater streams at the plant and transforming it into an environmentally responsible fertilizer named Crystal Green®.
About the Project
The NSWWTP is a 40 million gallon per day advanced wastewater treatment plant (WWTP). Wastewater generated within the District’s 180-square mile service area is collected and treated at the NSWWTP and then discharged to Badfish and Badger Mill Creeks.Treated biosolids from the NSWWTP are recycled to agricultural land through MMSD’s successful Metrogro program. Under current waste loadings, the NSWWTP solids handling system processes approximately 100,000 lbs/day of solids, yielding the liquid Class B biosolids product for the Metrogro program. Before the 11th Addition Project, the District transported and applied about 40 million gallons of Metrogro on area farmland annually. Plant loading projections predicted that the solids handling system loadings would increase to more than 150,000 lbs/day by the year 2030.
All decisions made by the MMSD regarding its plant support the District’s focus on sustainability: That decisions today are made so that life will be even better for future generations. The District has a long standing commitment to sustainability from protecting public health and the environment to managing community resources responsibly and cost effectively.
The 11th Addition focused on this belief as well. It was undertaken to support the District’s goal of producing Class A biosolids. In order to achieve this designation, the existing anaerobic sludge digestion system was converted to a multi-stage acid phase digestion (mesophilic acid phase, thermophilic gas phase). A second goal of the Project was to recover phosphorus from the treatment process in a useable form, thus turning a potential nuisance into an asset.
Uncontrolled struvite formation has long been a nuisance to wastewater treatment plants due to the maintenance headaches associated with its coating of piping, valves, and equipment. Struvite is a crystalline mineral composed of magnesium, ammonium and phosphate. MMSD, however, turned its struvite issue at Nine Springs into an asset with the 11th Addition Project, and has created an additional revenue stream. The struvite is harvested in the form of pellets, known as Crystal Green®, that can be sold on a commercial basis, since struvite is a desirable slow release fertilizer for agriculture. With worldwide natural deposits of phosphate dwindling, struvite is becoming a valuable source of fertilizer grade phosphorus.
Struvite harvesting at Nine Springs begins with the collection of filtrates produced during the thickening of waste activated and digested sludges. Filtrate is delivered to the Struvite Harvesting Building, where two upflow reactors (Ostara Pearl® 2000) extract the phosphorus in the form of struvite pellets. Magnesium chloride and sodium hydroxide are added to promote pellet formation. Struvite pellets are harvested from the reactors, dried, sorted, and bagged prior to shipping to commercial fertilizer blenders. At full future loadings, phosphorus recoveries up to 1,400 lbs per day (as P) are expected, which would translate to over 2,000 tons of struvite pellets per year, with a nutrient makeup of 5% N – 28% P – 0% K – 10% Mg.
Crystal Green® from MMSD’s facility will soon be available to gardeners and homeowners in an all-purpose garden blend created by fertilizer blender Spring Valley, located in Jackson, Wisconsin, and sold through local retailers. The Wisconsin fertilizer company has already committed to include the environmentally responsible fertilizer in a new garden blend product to be sold throughout wholesale and retail outlets. In the agriculture sector, Wisconsin farms are among a number of sites throughout the north and Pacific Northwest where Crystal Green® has been successfully used in grower trials on various crops including potatoes and fruit trees.
The June 4th ceremony marked the unveiling of this groundbreaking project, and further cemented MMSD’s commitment to sustainability. The day began with facility tours lead by MMSD staff and the Applied Technologies project team. Attendees viewed firsthand the new processes at the treatment plant, including WAS Pretreatment for P-release, WAS thickening via gravity belt thickening, acid digestion, and struvite harvesting. After the tour, attendees listened intently to remarks from Ostara CEO Phillip Abrary, MMSD Commission President Caryl Terrel, MMSD Chief Engineer and Director Michael Mucha, and Dane County Executive Joe Parisi. Also in attendance was Robert F Kennedy Jr., an Ostara Board Member and Keynote Speaker for the event.
“Our lakes and waterways contribute to our high quality of life – they are one of the main reasons people want to live, work, and play in Dane County,” said Mr. Parisi. “It is imperative that we do all we can to keep our waterways clean. Today’s event demonstrates the importance of adopting innovative technologies to make it happen.” As resources continue to dwindle, prices rise, and regulations tighten, the MMSD 11th Addition Project will no doubt remain the gold standard in an increasingly sustainable world!