Thermochemical Treatment of Sludge and Organic Residues
Thermochemical conversion of sludge-based feedstocks with material characterisation and ongoing controlled agronomic validation.
The research route links thermochemical material production with laboratory characterisation, soil incubation and controlled greenhouse cultivation. Lettuce treatments compare the recovered material alone and in combination with different mineral-fertiliser rates. Material handling and experimental conditions are managed within the agronomic research programme.
Agronomic validation is ongoing. Interpretation of analytical results depends on consistent reporting units and methods. Use of sewage-sludge-derived material remains subject to the applicable research, national or product-market requirements and contaminant limits.
The Marche nutrient-recovery pathway investigates the thermochemical conversion of sewage sludge into a carbonaceous material for controlled agronomic research. The work connects material production with detailed physicochemical characterisation, soil incubation and greenhouse cultivation, allowing the properties of the recovered material to be studied before wider agricultural application is considered.
Characterisation combines carbon, hydrogen and nitrogen analysis with proximate analysis, elemental analysis by ICP, FTIR spectroscopy, zeta-potential measurements and scanning electron microscopy with elemental analysis. Together, these methods describe composition, mineral phases, surface properties and the heterogeneous carbon-mineral structure. Phosphorus-, calcium-, potassium- and iron-containing phases are among the features examined.
Agronomic testing includes soil incubation and a six-treatment lettuce experiment. The treatments comprise an untreated control, full mineral fertilisation, the recovered material alone, and the material combined with 100%, 75% or 50% of the mineral fertiliser rate. Monitoring includes plant growth, chlorophyll-related SPAD readings, biomass, nutrient content and soil properties. Soil incubation follows carbon dioxide evolution over an extended period to investigate carbon mineralisation.
The programme is designed to examine both immediate crop response and residual effects in subsequent cultivation. Material characterisation and experimental preparation have progressed, while crop and soil evaluation continue. Agricultural use also depends on the applicable feedstock and product requirements, separately from the material's experimental performance.
The research explores the recovery of carbon and nutrient-bearing mineral material from sewage sludge. Its environmental and agronomic value is being investigated through complementary measurements of material composition, soil behaviour and crop response.
The incubation experiment examines carbon mineralisation, while the lettuce treatments compare the material with a mineral-fertiliser reference and with reduced fertiliser combinations. This allows potential fertiliser substitution and soil effects to be studied experimentally. Long-term carbon storage, crop-yield improvement and fertiliser savings cannot be inferred from composition alone; they depend on the results and duration of the corresponding assessments.
