Recovery of Effluent Heat for Beneficial Use in Biosolids Stabilization

Tetra Tech, teamed with Active Energies, performed an energy audit for the Rifle Regional Wastewater Reclamation Facility (RRWWRF). As part of the audit, numerous energy conservation opportunities (ECOs) were identified. One of the proposed ECOs involved extraction of heat from the treated plant effluent to comply with new discharge temperature standards that will be enforced upon renewal of the facility's discharge permit. The team proposed using the recovered heat to provide some, or all, of the energy required for energy-intensive biosolids stabilization processes. Since the RRWWRF is currently in negotiations with a third-party contractor to operate a compost facility on a site adjacent to the existing treatment facility, Tetra Tech recommends using heat recovered from the effluent stream for a thermal drying step to evaporate some water from the waste activated sludge (WAS) produced by the RRWWRF and increase the solids content prior to composting. This would result in an optimized composting process requiring less amendment.