Biosolids are nutrient rich organic materials from the treatment of sewage at a wastewater treatment facility. Biosolids can be recycled and applied as fertilizer when treated and processed to improve and maintain productive soils and stimulate plant growth. The Hall Street Wastewater Treatment Plant produces Class A biosolids. Class A biosolids (PDF) are suitable for agricultural and horticultural land application.
The solids that enter the wastewater treatment plant are treated in the wastewater treatment process. Microbial pathogens are destroyed with time, temperature, lime, and a high pH level. The temperature of the solids is raised to a minimum of 158 degrees Fahrenheit. The treated solids are discharged into another vessel where the temperature is maintained for an additional 30 minutes to complete the stabilization process. Once the treatment process is complete, the biosolids are conveyed to trucks to be shipped off-site for utilization in agricultural land application and land reclamation projects. All biosolids produced at the Hall Street Wastewater Treatment Plant are managed in full compliance with the EPA and NHDES requirements. The City of Concord also conducts monthly sampling and testing to ensure the quality of the biosolids.
Biosolids have valuable nutrients and organic matter that can effectively improve the condition of soil when applied to gardens, grass, and crops and yield better results than commercial fertilizers. Biosolids are safe to use and they can reduce erosion and decrease surface run-off. Returning biosolids to land recycles useful resources and helps continue the cycle of natural biological processes. Applying biosolids to our land returns over 150,000 pounds of nitrogen annually to the environment.