Improving Energy Efficiency of Small Water-Resource Recovery Facilities: Opportunities and Barriers

Approximately 80% of US centralized Small Water Resource Recovery Facilities (WRRFs) serve populations less than 10,000 and can be significantly less energy efficient (E2) relative to larger systems. This study's purpose was to provide case studies of E2 in small WRRFs through documentation of unit process energy use (within four small WRRFs), E2 changes reported by operators following a project that provided E2 recommendations to 83 WRRFs, and investigate barriers to E2 through surveying of operators (including comparisons between systems of different size and E2 implementation). Aeration was the largest energy component (66%-73%) of total energy use and space heating can be significant (4%-35%). E2 changes were reported by 19 operators, and facilities with available bills exhibited energy reductions of 4%-35%. Variable frequency drive (VFD) installation and improved operations exhibited the largest savings. Application of an E2 benchmarking model for small WRRFs was effective for measuring E2 improvements in systems with varying flowrates. Responses from 66 operators expressed financial barriers and lack of time or other priorities as the largest barriers in making E2 improvements.