Lystek THP: Land Application and Biosolids Markets

Liquid biosolids land application programs have successfully operated in North America for decades. Land application of biosolids is an economical way for farmers to improve crop production and soil health while reducing greenhouse gas emissions and the landfilling of biosolids. However, with growing populations and increasing wet weather events, some programs have more recently experienced operational challenges surrounding hauling, land application, and inadequate storage. This has encouraged some programs to explore alternatives to their traditional biosolids management practices. Lystek THP is a biosolids management solution that uses thermal hydrolysis to transform biosolids and residuals into a concentrated and pathogen free liquid fertilizer product. It is a cost-effective way to extend liquid storage and reduce management stresses in facilities with existing dilute liquid land application programs. The patented process produces a concentrated (13-16% solids) EPA Class A biosolids fertilizer, LysteGro. This concentrated liquid fertilizer is applied via sub-surface injection, ensuring cleanliness when compared to traditional surface methods. Injection application increases soil contact, ensuring efficient nutrient use, and mitigation of run-off potential. The liquid product also allows for efficient loading and off-loading, as well as odor mitigation at the plant and throughout transportation. Notably, the concentrated liquid biosolids fertilizer contains added potassium (K), a key nutrient that is present in only very low quantities in other biosolids. The addition of potassium ensures the product can be used as a full replacement for conventional mineral fertilizers - providing significant value to the farmer. Benefits of this biosolids fertilizer application are realized over multiple years due to the slow-release nature of the nutrients in the product and improvements in soil health. Micronutrients, including zinc and copper, as well as macronutrients, including calcium and sulfur, important for crop growth are inherent in biosolids. This provides farmers with an accessible and sustainable option for these nutrients that would typically be expensive to purchase in the mineral fertilizer form. The addition of organic matter to soils helps improve overall soil health - including improved water holding capacity, soil structure and tilth, increased microbial activity, as well as increased resilience to severe weather conditions. We will discuss two relevant case studies: St. Cloud, Minnesota, and the South Huron Valley Utility Authority (SHUVA) in Brownstown, Michigan and the operational improvements they have realized as a result of a reducing residual biosolids volumes by implementing a concentrated Class A liquid biosolids fertilizer program. The City of St. Cloud's Nutrient, Energy, and Water Recovery Facility was looking to pursue a Class A treatment technology as part of its Resource Recovery and Energy Efficiency master plan to prepare for possible future regulatory changes. Facing storage capacity issues with their previous dilute liquid Class B program, they were also looking for solutions that could reduce their biosolids volume. St. Cloud's Class B biosolids application program had been successfully managed and operated for many years by City staff, with a receptive farming community for biosolids. Lystek was selected by the City of St. Cloud to supply the Class A biosolids treatment technology. The system became operational in the plant by September 2018 and St. Cloud has continued to operate their successful land application program using their existing infrastructure and equipment, without the addition of any new buildings or biosolids storage. They have seen a dramatic 70% reduction in their biosolids volumes and associated trucking, correspondingly reducing their biosolids program's transport greenhouse gas emissions by 70%. The program itself has also become easier to manage as the City of St. Cloud saw decreases of 85% in their overtime hours associated with land application. The estimated cost savings of producing and managing a concentrated liquid fertilizer at St. Cloud are approximately $12 million over the 20-year life cycle when compared to alternative solutions. The South Huron Valley Utility Authority (SHVUA) was seeking a solution to manage their dilute liquid biosolids program at their wastewater treatment plant serving a population of 90,000. The existing low-solids, lime stabilized Class B biosolids program was severely limited by insufficient winter storage and the WWTP was required to implement a costly contingency option of dewatering and hauling to landfill. Switching to a concentrated liquid fertilizer program has provided the SHVUA WWTP with a solution to reduce biosolids volumes by over 50%, effectively doubling that plant's storage capacity, while also producing a Class A biosolids fertilizer for local agricultural use. This change has ensured operational security and eliminated the need to dispose of 'excess' biosolids in landfills, allowing the Authority's resource recovery program to advance. Additionally, the plant was able to eliminate the use of lime stabilization and the associated chemical costs, as well as necessary storage clean out activities. The Lystek THP module processing footprint was small enough that it could be installed in an existing building with unused space, maximizing the use of existing infrastructure. Concentrated liquid biosolids fertilizer programs allow for efficient biosolids management through integration with conventional wastewater treatment plant equipment and processes. This program can greatly reduce a WWTPs volume of biosolids and required storage infrastructure, remove the need for complex management systems and infrastructure, and decrease trucking costs, all while providing a desirable fertilizer product.