Comparison of Class A and Class B Private Biosolids Stabilization Technologies

oncerns over the long-term reliability of land application of Class B biosolids are causing many utilities to examine alternatives for effectively disposing of biosolids. Most wastewater treatment plants in Florida rely upon private contractors to dispose of residual biosolids in either a liquid or cake form. Currently, the predominant disposal method is application of digested biosolids on agricultural land. However, many utilities are reevaluating this method because of two major concerns: (1) the ability of existing digestion systems to consistently meet Class B pathogen reduction requirements under 40 CFR 503; and (2) the uncertain long-term availability of suitable agricultural land within reasonable haul distances. In this study, the costs of three Class A and two Class B pathogen reduction technologies were compared at various system capacities. The results described were derived from recent biosolids management planning efforts conducted for wastewater utilities in Broward County and Fort Pierce. The purpose of the study is to compare the costs of various sludge management alternatives and provide general guidance to utility managers who are examining options to their current means of biosolids management.