Odour emissions remain one of the major challenges for community acceptance of biosolids. Attempts to incorporate an odour classification into the regulatory framework has not yet been successful in Australia.

The project will develop a new odour classification system for biosolids by investigating the fundamental science on how odours are formed and emitted. There has been work done in this area already; however, there still exist wide gaps in our knowledge about

• how biological and chemical stability impact odour potential,
• how different processing routes result in quantitatively different odours, and
• how different materials should be handled for minimising odour formation.

The PhD student will work on deriving the fundamental science governing biological and chemical stability and identify links between stability and production routes with odour.

The ICPD will focus on developing an odour classification system in an Australian context that can be considered for incorporation into a regulatory framework.

Current uses of biosolids as fertiliser are largely in low-value landscaping applications, where tailored and consistent formation is not required. A shift to using biosolids in high value agricultural and retail products will require tailored formulations, informed by robust testing, resulting in known impact on target plants and easy, cheap delivery (e.g. concentrated, dry, granular products).

Achieving desirable nutrient formulation may be best achieved by blending with other waste streams, such as food and chicken waste.

Challenges to be tackled by the Centre are those that contribute to meeting goals for plant nutrition, growth, yield, and final product quality and safety in terms of pathogens and contaminants. Goals may also be regionally specific; for example, the need for low phosphorus (P) formulations in areas with P-enriched soils and environmentally unacceptable off-farm P movement, such as Peel Harvey in Western Australia.

Target industries could include turf, specific ornamentals, fruit trees and vegetable crops (home or commercial), and broadacre crops.

The Masters student will focus on optimising and integrating unit operations such as composting, drying and granulation, while the PhD student will look at developing and testing different recipes to tailor end product suitable for various applications in horticulture, agriculture and greenhouses.

The ICPD will work with the HDRs and also independently perform horticulture, agriculture and greenhouse trials to develop recommendations for industry.

The agricultural application of biosolids is likely to remain a major beneficial use option. The major risk is the presence of odour, heavy metals, micro-plastics, emerging contaminants, drugs and pesticides that pose a risk to adoption. Also, biosolids are bulky in nature, have very high moisture content and are difficult to dewater.

Research is needed to reduce the (currently) high transportation costs, high diesel consumption, and related carbon dioxide emissions. Industries are actively looking for alternative technologies that can reduce biosolid volume as well minimise/eliminate undesirable characteristics.

The project will focus on:

1. Developing low cost, innovative biological and additive drying, hydrolysis and pyrolysis technologies with/without blending with other organic food or meat industry waste streams, and
2. Characterising and determining transformations that occur during biological and additive drying, hydrolysis and pyrolysis in the inert fractions contributed from both primary and activated sludges, with an aim to produce high quality next generation products for agriculture applications.

The ICPD working on this project will perform experimental investigations and detailed techno-economic comparison of biological and additive drying, hydrolysis and pyrolysis technologies.