Developing a sustainable biosolids program through a comprehensive, collaborative approach for arlington county

Abstract

Arlington County, Virginia has recently completed a wastewater solids master plan addressing the near-and long-term needs of the County’s biosolids program. The planning process included comprehensive evaluation of over 70 technologies. The project team included representatives from engineering, operations, maintenance, and management from the County; a consultant team of national and local experts; a technical expert advisory committee from consultants, utilities, and academia; and community stakeholders. There were multiple project team workshops and regular presentations to stakeholders, feedback from which was incorporated into the planning process. Ultimately, there was a detailed evaluation of four process options-lime-stabilization (the current process), mesophilic anaerobic digestion, thermal hydrolysis pre-treatment leading to anaerobic digestion, and anaerobic digestion with thermal drying. The four options were evaluated against nineteen criteria representing economic, operating, environmental, and social issues of the ‘quadruple bottom line.’ The County has now developed a more sustainable biosolids program plan that includes the development of anaerobic digestion with thermal hydrolysis pre-treatment to produce a commercially viable biosolids product. The process will also produce biogas for use as fuel. The collaborative approach, which included evaluating numerous options and engaging with many stakeholders, contributed to the project’s success and has provided a resilient roadmap towards a more sustainable biosolids program.