Positive Business Cases for Codigestion and Resource Recovery Facilities in Australia without Pre-Existing Anaerobic Digesters

Several successful codigestion projects have been implemented in North America involving small -and large-scale facilities with existing anaerobic digesters. The current perception is that smaller facilities, typically less than 5 mgd in size, are limited in their opportunities for beneficial biogas generation. However, recent experience from two conceptual design projects in Victoria, Australia (Yarra Valley Water and City West Water) has shown that small-scale wastewater treatment facilities can also be associated with positive business cases for the implementation of new anaerobic digestion and resource recovery facilities. This can be achieved with the co-digestion of municipal treatment residual solids with high-strength waste streams for biogas production. The associated high biogas yield can be used for power cogeneration and power export to the power grid. When coupled with the income from tipping fees associated with the high strength wastes, it can in several cases improve the business case for these facilities markedly and allow for the beneficial digestion of waste feedstocks and production of green energy and high-quality reclaimed water and biosolids resources.