DC9: Understanding the fate of carbon, nutrient and pollutants to propose typology of organic sludge fertilisers

Project title: Understanding the fate of carbon, nutrient and pollutants to propose typology of organic sludge fertilisers (WP3)

Host Institution: INRAE

Country: France

Supervisor: Dominique Patureau (PhD promoter); Co-supervisors: Nadine Boelée (Nijhuis)

Objectives: To characterise the effectiveness of various treatments on the quality of the treated sludges, digestates and the char-based materials (hydrochar, EBM) as a fertiliser.

DC9 will study the impact of the various treatments on the organic contaminant accessibility and mobility. DC9 will adapt and apply recent methodologies to assess the stability of the organic matter, the nutrient availability, and the mobility of the remaining organic contaminants. DC9 will apply statistical analysis to build a methodology to define optimal process conditions to obtain a targeted organic fertiliser, depending on the associated agrosystem needs. DC9 will characterize the impact of the produced organic fertilisers on the C, N and P compounds fate in soil using an in-house developed biochemical sequential extraction technique. DC9 will apply particle-size fractionation to characterize the fraction that could be vertically transferrable in soil thanks to colloidal transport. DC9 will develop a design support tool for sludge treatment and application and assess the environmental impact.

Expected Results: Knowledge and design support tool on fertiliser properties of different INCLUE sludges, digestates and or char-based materials to asses the agronomic value and fate of (residual) pollutants.

Enrolment in Doctoral degree(s): Gaia Doctoral School, University of Montpellier (FR)

Planned secondments:

• Nijhuis (Sup.: N. Boelee): M12-15 (4 months): Understanding the source and handling principles of the samples and investigating the impact of electrochemical treatment on sludge nutrient availability.
• Ingelia (Sup.: M. Hitzl): M29-31 (3 months): Impact of the HTSC process conditions on hydrochar properties; consequences for heavy metal and organic pollutant immobilisation.