Evaluating role of biosolids derived biochar in addressing nutrients and diffuse pollution from arable land

Biosolids have been well documented to be used as renewable sources of fertilisers in the form of organo-mineral fertiliser (OMF). OMF involves combining organic waste with mineral sources of fertilisers. There has also been decision support tool developed such as the Phosphate Acceptance Map to determine landbank suitability to receive biosolids. Whilst efforts are made to valorise biosolids due to ongoing pressure on landbank availability due to more stringent policies to protect the wider environment, new approaches must also be developed and adopted to address it.

This research project is therefore timely as it seeks to evaluate new approaches to convert biosolids into biochar, being far easier to store as a solid carbonaceous material whilst also potentially tackling nutrients and emerging contaminant mobility in the environment. Biochar has been demonstrated to sequester carbon in soil and increase water holding capacity, a feature very pertinent for potential flood mitigation. Biochar has high pH which further reduces heavy metal mobility. Whilst these are encouraging impacts of using biochar, a robust evaluation is needed if we were to fully exploit it as a potential avenue to utilise biosolids as a feedstock.

The aim of this project is to evaluate role of biosolids-derived biochar as suitable material for land applications to mitigate nutrients and heavy metal transport to watercourses. The specific objectives include:
1. To identify optimum reactor conditions to produce suitable biochar for OMFs. This will generate a product that will be analysed and evaluate the pyrolysis process contributing to the viability of the product.
2. To formulate a suitable OMF from the biochar utilising data from experimental trials and the literature to inform the appropriate composition.
3. To characterise the OMF and char to optimise its role for agricultural applications. This evaluates the product's use and effectiveness as a fertiliser.
4. To explore the mechanisms of heavy metal and nutrient distribution in the soil arising from OMF application.
5. To provide a critical evaluation as to the implications of the potential landbank usage, with particular reference to the area of the Welsh Water and Severn Trent Water regions