Agronomic Evaluation of ThermAer ATAD Biosolids; Greenhouse Growth Trials

Greenhouse growth trials of ThermAer ATAD (Autothermal Thermophilic Aerobic Digestion) biosolids were conducted at the University of Guelph, Kemptville campus, Ontario Canada, in order to evaluate the agronomic value of ThermAer ATAD biosolids as compared to a recognized commercial fertilizer. ThermAer ATAD is a process involving the controlled and intense aeration of waste slurries in an enclosed, insulated bioreactor under fully aerobic conditions. The ThermAer system generates a Class A, pathogen reduced, malodor free biosolid. ThermAer ATAD biosolids from 5 different treatment plants were utilized in the growth trials. Feedstock for these plants included primary, secondary and anaerobically digested WWTP sludges, as well as corn processing waste and source separated municipal organic waste. Tests were carried out with lettuce, Kentucky blue grass and fescue; these plants were chosen due to their differential growth patterns and nutrient uptake rates. Results indicate that both yield and biomass quality was enhanced by the ATAD products. There were some differences among these products likely due to the variations in the mineralization kinetics due to the differences in the initial waste feed. ATAD products also left more residual nutrients in soil at the end of the trial indicating their potential for long term soil agronomic quality.