Influence of biosolid treatment on the presence and mobility of emerging organic contaminants in agricultural soils after land application

Land application of biosolids introduces Emerging Organic Contaminants (EOCs) into the soil. While biosolids have benefits to soil fertility, EOC content is affected by sewage treatment processes. The mechanisms for how biosolids treatment affects EOC degradation and mobility are not fully understood. We have previously shown that intensive management of an alkaline (lime) stabilized biosolid in agro-ecosystems leads to significant EOC accumulation and potential transport into water. Understanding how biosolid treatment drives EOC interactions in soil is the key short-term objective for this 5-year program in order to address the broader long-term objective of what the risks are for soil health. The questions driving the short-term objectives are:

How does sewage sludge treatment impact the presence of EOCs in the final biosolid product?

Does the process of generating biosolids affect the rate at which EOCs will biodegrade after adding to soil?

Are the mechanisms driving EOC degradation or mobility related to the properties of soil or the properties of the biosolid?

Laboratory and field-based studies will be used to test the hypotheses that biosolid treatment has a significant impact on EOC-soil interactions. First, we will examine how EOC concentrations in a single source raw sewage sludge respond to three stabilization techniques: composting, anaerobic digestion, and lime stabilization. These biosolids will be used in controlled environment soil incubation and soil column transport studies to examine EOC biodegradation and mobility. These results will be linked to two contaminant transport models that we have previously worked on. A field study will be established to evaluate how EOCs from the different biosolid treatments respond in soils under conditions of variable temperature and moisture, as well as with plants. The mechanistic studies will develop an understanding of underlying processes driving the EOC responses from biosolid treatments amended to soils. The empirical field study will contextualize these dynamics in soils under the rapidly changing conditions of managed agricultural landscapes.

The proposed work is original and has the capacity to have significant immediate impact nationally and internationally. Concentration of wastewater solids in urban environments is rapidly growing issue in Canada and globally. The dispersal of biosolids in agricultural systems has the capacity to introduce hundreds of tons annually of anthropogenic chemicals that we have limited understanding of the full scope of their impact. I have built significant field and laboratory infrastructure in support of studying EOCs from land applied biosolids and I not aware of many similar experimental systems established in Canada or internationally. These studies will focus our understanding of how municipal sewage treatment affects EOC dynamics in soils receiving biosolid amendments.