Degree Name

Bachelor of Environmental Science (Honours)


School of Earth & Environmental Sciences


Today’s world is facing a range of environmental challenges. It is becoming clear that along with clean air, the planet also requires enhanced supplies of clean water. Wastewater treatment is a key component of the water supply chain, and the resulting biosolids need to be managed in a more sustainable and focused manner on a global scale. In Australia, hundreds of thousands of tonnes of biosolids are produced each year with a majority of these biosolids being used in land application for agricultural purposes. Benefits of biosolids land application range from improving soil quality for crop production, through the addition on organic matter, vital trace elements for plant growth and increased nutrient levels to reductions in erosion and economic incentives for various stakeholders. Land application of biosolids presents some environmental risks if not managed effectively. Risks range from contamination of surface and groundwater supplies, pathogens, odour, vector borne disease and ingestion by animals. Many of these issues are minimised through the soil incorporation of land applied biosolids which forms a physical barrier between biosolids and potential risk causing agents while also decreasing ingestion by animals. Currently there is a lack of documentation surrounding what is considered adequate levels or specific percentages of incorporation which are required to reduce these potential risks to those acceptable by industry regulators. To develop a process of assessing adequate levels of incorporation a number of techniques were trialled to assess surface coverage of biosolids pre and post-incorporation and relate this to potential risks. Using a technique developed through this study it was found that incorporation of biosolids lead to statistically significant reductions in biosolids surface coverage for two different ploughing techniques used. The biosolids surface coverage post-incorporation was found to have little to no potential for causing environmental risks, when compared with other studies of surface applied biosolids. This study highlights a need for biosolids and industry regulators to develop a technique, such as, those used in this study for assessing adequate levels of biosolids soil incorporation. Making this information readily available to biosolids practioners and regulators will minimise confusion surrounding what represents adequate levels of incorporation.



Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.