Product Overview

Summary: This Anaerobic Digestion Operations SOP sets out clear, step-by-step requirements for running biogas and digestate processes safely, efficiently and in full alignment with Australian WHS obligations. It helps operators control confined space, gas, biological and process hazards while maximising plant uptime and resource recovery outcomes.

Anaerobic digestion plants handle a unique combination of hazards: flammable biogas, toxic gases such as hydrogen sulphide, confined spaces, high-pressure systems, and biologically active feedstocks and digestate. Without a robust, documented procedure, even routine tasks like feedstock loading, gas handling, or mixing and heating adjustments can expose workers to serious risks including explosion, asphyxiation, biological exposure and environmental releases. This Anaerobic Digestion Operations Safe Operating Procedure provides a structured, WHS-led approach to managing day-to-day operations, start-up and shutdown, monitoring, and maintenance within Australian regulatory expectations.

Developed for councils, utilities, agribusinesses and commercial waste-to-energy facilities, this SOP turns complex process engineering requirements into practical, on-the-ground instructions. It clarifies who does what, when, and how, from pre-start inspections and lock-out/tag-out through to gas detection, flare and CHP management, digestate handling and emergency response. By embedding hazard controls, PPE requirements, isolation protocols and environmental safeguards directly into the workflow, businesses can demonstrate due diligence, reduce reliance on informal “tribal knowledge”, and support consistent, defendable operations across shifts and contractors.

Beyond safety, the procedure also supports process stability and asset protection. Standardised monitoring of key parameters (such as pH, temperature, loading rates, gas quality and pressure) helps prevent foaming, sour digesters, odour complaints and unplanned outages. This gives Australian operators a practical tool to align WHS, environmental and performance objectives in a single, easy-to-implement document.

Key Benefits

• Ensure safe, consistent operation of anaerobic digestion and biogas systems in line with Australian WHS legislation.
• Reduce the risk of fires, explosions, gas exposure and confined space incidents through embedded engineering and administrative controls.
• Standardise operating practices across shifts, sites and contractors, improving training, supervision and audit readiness.
• Protect critical assets and process stability by formalising start-up, shutdown, upset condition and maintenance procedures.
• Demonstrate due diligence to regulators, insurers and clients with a documented, risk-based approach to anaerobic digestion operations.

Who is this for?

• Anaerobic Digestion Plant Operators
• Wastewater Treatment Operators
• Biogas Plant Managers
• WHS Managers and Advisors
• Operations and Maintenance Supervisors
• Environmental and Sustainability Managers
• Utilities and Infrastructure Managers
• Mechanical and Process Engineers
• Farm and Agribusiness Managers using AD systems

Hazards Addressed

• Exposure to flammable biogas and risk of fire or explosion
• Hydrogen sulphide (H2S), methane and carbon dioxide gas exposure leading to asphyxiation or poisoning
• Confined space entry hazards in digesters, tanks and pits
• Biological hazards from raw feedstocks, sludge, manures and digestate
• Pressure-related failures in gas lines, valves, and vessels
• Chemical handling hazards associated with pH correction, cleaning and dosing chemicals
• Thermal burns from heated digesters, pipework and heat exchangers
• Odour emissions and environmental releases impacting neighbouring communities
• Manual handling risks from hoses, covers, pumps and ancillary equipment
• Electrical hazards associated with mixers, pumps, CHP units and control systems

Included Sections

• 1.0 Purpose and Scope
• 2.0 References, Definitions and Abbreviations
• 3.0 Roles, Responsibilities and Competency Requirements
• 4.0 Plant Description and Process Overview
• 5.0 Hazard Identification and Risk Controls (Biogas, Biological, Chemical, Confined Space)
• 6.0 Required PPE, Safety Equipment and Gas Detection
• 7.0 Pre-Start Checks and Site Readiness
• 8.0 Normal Operating Procedure – Feedstock Reception and Pre-Treatment
• 9.0 Normal Operating Procedure – Digester Operation, Mixing, Heating and Monitoring
• 10.0 Biogas Handling – Storage, Flaring, Utilisation and Odour Control
• 11.0 Digestate, Sludge and By-Product Handling and Disposal
• 12.0 Start-Up, Shutdown and Restart Procedures (Planned and Unplanned)
• 13.0 Process Upsets and Abnormal Conditions – Troubleshooting and Escalation
• 14.0 Isolation, Lock-Out/Tag-Out and Permit-to-Work Requirements
• 15.0 Confined Space Entry Controls and Rescue Readiness
• 16.0 Cleaning, Inspection, Maintenance and Calibration Requirements
• 17.0 Emergency Response Procedures (Gas Leaks, Fire, Spills, Exposure, Structural Failure)
• 18.0 Environmental Protection Measures and Incident Reporting
• 19.0 Training, Induction and Competency Assessment
• 20.0 Recordkeeping, Monitoring Logs and Continuous Improvement
• 21.0 Document Control and Review

Legislation & References

• Work Health and Safety Act 2011 (Cth) and corresponding state and territory WHS Acts
• Work Health and Safety Regulations 2011 (Cth) and corresponding state and territory WHS Regulations
• Safe Work Australia – Code of Practice: Confined Spaces
• Safe Work Australia – Code of Practice: Managing Risks of Hazardous Chemicals in the Workplace
• Safe Work Australia – Code of Practice: How to Manage Work Health and Safety Risks
• AS/NZS 60079 (series): Explosive atmospheres (relevant to biogas areas and equipment)
• AS/NZS 2865: Confined spaces
• AS/NZS 3814: Industrial and commercial gas-fired appliances (relevant to biogas burners and CHP)
• AS/NZS 1715: Selection, use and maintenance of respiratory protective equipment
• AS/NZS 1891 (series): Industrial fall-arrest systems and devices (for work at height on tanks and structures)
• Environment Protection Authority (EPA) state guidelines for wastewater and biosolids management (jurisdiction-specific)