Competing belief about biosolids and their transformation technologies have restricted their application and acceptance. This includes resistance to their adoption among farmers, who may identify important limitations with proposed biosolids products that researchers need to take account of in order to develop improved, appropriate products.

Resistance to biosolids use may be also rooted in farmers’ and others’ lack of understanding of biosolids products, and their perceived (versus actual) risks of biosolids and related products.

The PhD student will focus on identifying the social and industrial knowledge basis of biosolids and related products, the perceived risks of process technologies and materials application, and the practical challenges and opportunities they pose for farmers. By procuring this information, the project can design appropriate strategies for improving the products and reducing their actual and perceived risks.

The ICPD will subsequently investigate existing tools to improve communication and transparency between utilities and the community about the production and distribution of biosolids products. From here the project will identify specific community and industry barriers to biosolids acceptance and application at scale, and enhance existing tools to address these barriers and promote biosolids benefits.

These tools, as well as improving biosolids awareness, will be measured in their ability to improve biosolids feasibility and acceptability. In this way, the project will ensure a sustainable biosolids market via the development of industry-appropriate tools.

Biosolids transformation includes managing a range of chemical, stability and pathogenic risks to protect public health, reduce nuisances and maximise the benefits of the use of this resource. In Australia, biosolids are regulated at the state level, using outdated guidelines, still largely based on risk management concepts originally published in the 70’s by the USEPA.

While some states have attempted to update the guidelines, many challenges remain. One of these challenges relates to the exposure pathways for persistent emerging contaminants such as hydrochlorocarbon pesticides, brominated flame retardants, per fluorinated alkyl substances (PFAS) and endocrine disrupters.

The PhD student and ICPD will work together to develop a comprehensive validation framework for biosolids recycling schemes, with an emphasis on emerging contaminants for existing processing technologies, enabling the development of new, robust Australian Guidelines for Biosolids Management. Such guidelines will place emphasis on developing biosolids safety plans and process barrier monitoring, rather than an over-reliance on conventional end-point quality monitoring.

In Australia most biosolids are applied on agricultural land, providing a range of benefits including carbon sequestration, increasing water holding capacity and providing nitrogen, phosphorus and micronutrients to the soil. However, the economic benefits in terms of renewable energy generation, chemical fertiliser offsetting and increased drought resistence, while acknowledged, have not been comprehensively investigated.

This project aims to develop a generic and flexible framework for the solids processing train of existing and new biosolids treatment technologies. It will also develop pathways to enable the comparison of alternatives.

An existing innovative, economy-wide hybrid life cycle assessment tool will be adapted to enable Triple Top Line assessments for advanced transformation of biosolids and its management.

The major task of the PhD student will be to develop the hybrid life cycle assessment tool and its application in biosolids transformation and management.

The ICPD will work closely with water and agriculture industries and EPAs and will develop formal recommendations for these industries to consider.

There has been significant progress made in the last decade in converting biomass waste into value-added advance carbon materials using thermochemical methods.  Biosolids, however have not been investigated properly for value-added product formation and their future applications.

This project will identify and test new indirect agriculture applications of high value biosolids-based advanced carbon materials such as biochar, hydrochar and activated char produced by various advanced thermochemical methods (e.g. pyrolysis, gasification and hydrothermal liquefaction).

The PhD student will mainly develop and test new applications of these carbon materials in water and soil remediation as well as odour reduction.

The ICPD will examine the techno-commercial viability of the advanced thermochemical processes and their different applications and will prepare recommendations for the water industry.

Attempts to increase organic carbon in Australian cropping soils by means such as retaining crop stubble, adding compost, and growing green manure crops or perennial pastures have achieved very little; soil carbon is still decreasing in many soils. Maintaining organic carbon in cropping soils will aid amelioration of rising atmospheric carbon dioxide and improve soil physical and chemical characters, thereby aiding crop yields.

Recent Australian research shows functionalisation of carbon by keeping correct ratios of key nutrients (C: N: P: S) can help carbon transformed into persistent forms. However, research on functionalising carbon in biosolids or biosolids-related products such as biochar or hydrochar remains limited in this area.

The PhD student will investigate if blended biosolids can be used to produce a safe and cheap (transportable) product with optimal ratios of key nutrients, to aid the formation through the actions of soil microbes of stable organic carbon in the soils of the broadacre cropping systems in southern Australia.

The 0.4 ICPD will investigate how biochar and hydrochar, produced from pyrolysis or hydrothermal processing of biosolids, can help restore soil carbon and compare them with biosolids blended with nutrients and other forms of carbon produced from a PhD project.

In this project, advanced microbial technologies will be employed together with pioneering approaches that combine bioanalytical tools and advanced mass spectrometry techniques to investigate which microbiological processes directly impact the properties of the biosolids during anaerobic digestion or products from the advanced transformation of biosolids, studied in Theme 2.

This will lead to an understanding of the risk associated with biosolids processing and transformation, informing projects in Theme 3.

One key foci of the research undertaken will be on assessing poor performance of anaerobic digestion during stabilisation of sewage sludge. Arguably the top issues with anaerobic digestion which can influence the activity and diversity of the microbial community is foaming, and this will be a particular focus for this project.

Other factors which will also be examined are acidification, increasing viscosity, increasing volatile fatty acid and alkalinity and low methane yield (volatile solids destruction).

This project investigates the influence of these factors on microbial populations and performance.

Currently, there is no broadly applicable, non-agricultural beneficial use option for biosolids. Incineration dissipates the nitrogen, fixes the phosphorus, is generally energy negative, and has nil community support. Landfill is unsustainable and extremely expensive.

This project will investigate new thermal and chemical technologies such as pyrolysis, gasification and hydrothermal liquefaction (through an ICPD) to effectively capture chemical and energy resources, leading to development of a zero-waste processing route.  The aim will be to develop a comprehensive technology assessment tool that can assist water industries in selecting thermal/hydrothermal technology for regional and urban settings.

The HDR projects will specifically investigate hydrothermal liquefaction, pyrolysis and gasification as key future technology options.  The HDR projects will focus on:

1. Identification of optimum process conditions for producing high-value products for hydrothermal processing, and
2. Investigation of the fate of nutrients mainly in the solids and aqueous streams in thermochemical processing such as pyrolysis, gasification and hydrothermal liquefaction.