Overview
CEN ISO/TR 20736:2023 - "Sludge recovery, recycling, treatment and disposal - Guidance on thermal treatment of sludge" is a Technical Report providing good practice for the thermal treatment of wastewater sludges. It consolidates guidance on processes such as incineration, pyrolysis, gasification, drying and related thermal technologies. The report applies to sludges from storm water handling, night soil, urban wastewater collection and treatment systems, and industrial wastewaters comparable to urban wastewater. Thermal conditioning is excluded. Hazardous industrial sludge and dredged sludge are also excluded.
Key Topics
The document presents practical, non‑normative guidance across technical subjects including:
- Sludge properties: physico‑chemical, calorific value, dry matter, loss on ignition, trace elements, pathogens and organic micropollutants.
- Thermal process fundamentals: drying, hydrolysis, incineration, pyrolysis, gasification, thermolysis, carbonization, wet oxidation, melting and pasteurization.
- Technologies: direct/indirect/solar dryers, fluidized bed, multiple‑hearth and hybrid furnaces, advanced/emerging technologies (plasma gasification, microwave, ultrasound, enzymatic hydrolysis).
- Design and auxiliary equipment: receiving, storage, feeding systems, heat recovery, gas cleaning, ash and residue handling, wastewater treatment and safety systems.
- Operational aspects: process monitoring, emissions control, residue management and occupational health/safety considerations.
The report focuses on best practices rather than prescriptive limits, helping stakeholders evaluate suitability, environmental impacts and operational requirements for thermal sludge treatment.
Applications
CEN ISO/TR 20736:2023 is intended for practical use in:
- Feasibility studies and technology selection for thermal treatment of sludge and sludge incineration projects.
- Design and engineering of treatment plants incorporating drying, combustion, gasification or thermal conversion systems.
- Environmental assessment and operational planning for sludge management including emissions control, ash handling and resource recovery (energy, phosphorus).
- Training and operational manuals for plant operators and environmental managers.
Who should use this standard
- Municipal wastewater utilities and plant operators
- Environmental and process engineers designing sludge treatment systems
- Technology vendors and equipment manufacturers (dryers, furnaces, gasifiers)
- Regulators and consultants performing environmental compliance assessments
- Researchers evaluating emerging thermal technologies for sludge valorization
Related standards
- Developed under ISO/TC 275 and adopted by CEN/TC 308.
- Should be used alongside relevant national and EU regulations on air emissions, waste management and sludge reuse.
Keywords: CEN ISO/TR 20736:2023, thermal treatment of sludge, sludge incineration, sludge recycling, wastewater sludge, pyrolysis, gasification, sludge management.