Global population growth creates a severe pressure on wastewater treatment plants, and specifically on sludge management. Meanwhile, the global challenge of achieving food-security requires smart recycling of energy, water and agro-chemicals. The hydrothermal technology, using subcritical water as the conversion media has been intensively studied for a wide range of waste feedstocks including sewage sludge. Most of the research in this area was motivated by energy recovery and therefore focused on the solid and oil phases. However, less attention has been given to the aqueous phase – the process water remained after the hydrothermal reaction. This talk will review several implementation opportunities of the aqueous phase by-product. Those include: (1) fast anaerobic digestion for heat and electricity use; (2) membrane distillation – using the internal heat storage; and (3) recovery of valuable agrochemicals with high potential of pre-emergent herbicidal activity. Those pathways suggest that subcritical water can be applied as a green solvent for the recovery of energy and valuable resources from sewage sludge and improve the circular economy in wastewater treatment plants.
4. Dr. Roy Posmanik
Subcritical Water – A Green Solvent for Resource Recovery and Circular Economy
Volcani Institute, Agricultural Research Organization, Israel