Smouldering combustion of biosolids from wastewater treatment plants (WWTPs)

The management of biosolids, the major by-product from wastewater treatment plants (WWTPs), exists as a main global challenge which takes up most of WWTP operating costs. Self-sustaining smouldering is a new method for organic waste treatment, where the waste (i.e., biosolids) is destroyed in an energy efficient way after mixing it with porous medium (i.e., sand). Column experiments, utilising biosolids generated from a WWTP, were used to detect whether smouldering combustion was able to be utilized for biosolids treatment or not. According to the peak tempertures of thermocouples obtained from the experiments, it can be identified whether the smouldering reactions are self-sustaining (SS) or non-self-sustaining (NSS). In addition, the average front velocity (AFV) can be calculated then. In this study, Self-sustaining Treatment for Active Remediation applied ex-situ (STARx) refers to the commercial technology which utilizes smouldering combustion to destroy organic wastes (i.e., biosolids). An economic consideration would be completed to estimate the expected payback period and cost savings for considering STARx as a biosolids treatment retrofit in a large WWTP in Australia. The cost savings and payback period concerning replacing either landfill or incineration were considered as these are the most popular disposals for biosolids treatment. Finally, it is obtained that STARx is a good option to be employed in the WWTPs which have employed typical disposal methods (e.g., landfill and incineration) for recent decades