Upcycling of biosolids into biochar as a win-win-win for environment, economy and community

Biosolids is recognised as a valuable resource due to the presence of organic carbon and nutrients that can improve agricultural soils. However, the management of biosolids is an increasing concern for the wastewater sector due to large stockpiled volumes, their high management costs, and the potential risks associated with heavy metals, pathogens and contaminants of concern. A solution is to subject biosolids to controlled high temperature processes – gasification or pyrolysis – to reduce the volume to be managed, minimise the risk of contaminants and recover valuable resources like biochar and ash. Even though detailed scientific and industrial studies focussed on these two technologies (pyrolysis and gasification) are available, there are no specific comprehensive studies or guidelines that can aid water industries in Australia to make informed decisions on technology selection. Also, the commercial applications and environmental, social and economic benefits of biosolids-derived biochar and ash are not yet adequately identified, studied, and demonstrated in Australia and hence their potential remains unclear.

This project undertook work to assess the social, environmental and economic benefits of biosolids-derived biochar and ash produced from pyrolysis and gasification. This will help Australian wastewater utilities and the potential end-users of biochar and ash in making decision around the technology, biochar product quality and potential market application of the transformed products.

The project consists of five work packages delivered as individual reports:

1. Establishing a missing link between thermal technologies, transformed products, and market applications for biosolids transformation.
2. Regulatory landscape for thermal treatment of biosolids in Victoria and New South Wales.
3. Selection criteria, standard trial framework and testing protocol for assessing different thermal technologies.
4. Biosolids Transformation and Technology Assessment based on Selection Criteria (BTTAS-SC tool).
5. Opportunities, challenges, and solutions during the co-processing of different feedstocks along with biosolids during thermal treatment.