5. Waste treatment appropriate measures
These are the appropriate measures for waste treatment at regulated facilities with an environmental permit for treating chemical waste.
1. Waste treatment must have a clear and defined benefit. You must fully understand, monitor and optimise the waste treatment process to make sure that you treat waste effectively and efficiently. You must not treat waste to deliberately dilute it. The treated output material must meet your expectations and be suitable for its intended disposal or recovery route. You must identify and characterise emissions from the process, and take appropriate measures to control them at source.
2. You must have up-to-date written details of your treatment activities, and the abatement and control equipment you are using. This should include information about the characteristics of the waste you will treat and the waste treatment processes, including:
- simplified process flowsheets that show the origin of any emissions
- details of emission control and abatement techniques for emissions to air and water, including details of their performance
- diagrams of the main plant items where they have environmental relevance, for example, storage, tanks, treatment and abatement plant design
- details of chemical reactions and their reaction kinetics and energy balance
- details of physical treatment processes for example thermal desorption, distillation, phase separation, shredding, filtration, compaction, centrifuging, heating, cooling or washing
- details of biological treatment processes
- details of any effluent treatment
- a description of any flocculants or coagulants used
- an equipment inventory, detailing plant type and design parameters, for example, time, temperature, pressure
- waste types to be subjected to the process
- the control system philosophy and how the control system incorporates environmental monitoring information
- process flow diagrams (schematics)
- venting and emergency relief provisions
- a summary of operating and maintenance procedures
- process instrumentation diagrams
- monitoring points and monitoring schedules
3. You must have up-to-date written details of the measures you will take during abnormal operating conditions to make sure you continue to comply with your permit. Abnormal operating conditions include:
- unexpected releases
- start-up
- momentary stoppages
- shut-down
4. You should use material flow analysis for relevant contaminants in the waste to help identify their flow and fate. You should use the analysis to determine the appropriate treatment for the waste either directly at the site or at any subsequent treatment site.
Material flow analysis considers the contaminant quantity in the:
- waste input
- different waste treatment outputs
- waste treatment emissions
You should use the analysis and your knowledge of the fate of the contaminants to make sure you correctly treat and either destroy or remove them.
The use of material flow analysis is risk-based, considering:
- the hazardous properties of the waste
- the risks posed by the waste in terms of process safety
- occupational safety and environmental impact
- knowledge of the previous waste holder(s)
A treatment process may destroy certain substances in the waste. It could also put substances into the air, water or ground, or have residues which are sent for disposal. The weight of these outputs should be minimised. The treatment may produce residues for recovery or reuse and the weight of these substances should be maximised.
5. You must not proceed with the treatment if your risk assessment or material flow analysis indicates that losses from a process will cause:
- the breach of an environmental quality standard
- the breach of a benchmark
- a significant environmental impact
6. You must clearly define the objectives and reaction (chemical, physical or biological) processes for each treatment process. You must define the end point to the process so that you can monitor and control the reaction. You must define the suitable inputs to the process, and the design must take into account the likely variables expected within the waste stream. You must sample and analyse the waste to check that an adequate end point has been reached.
7. For each new reaction, you must assess the proposed mixes of wastes and reagents before treatment by carrying out a scale laboratory test mix of the wastes and reagents to be used. You must predetermine a batch ‘recipe’ for all reactions and mixes of wastes. You must also take into account the potential scale up effects, for example, the increased:
- heat of reaction with increased reaction mass relative to the reactor volume
- residence time within the reactor and modified reaction properties
Your treatment must comply with HSG143 Designing and operating safe chemical reaction processes.
8. The reactor vessel and plant must be specifically designed, commissioned and operated to be fit for purpose. The designs need to consider chemical process hazards and a hazard assessment of the chemical reactions. They also need to consider prevention and protective measures and process management, such as:
- working instructions
- staff training
- appropriate process control measures
- monitoring systems, alarms and interlocks
- plant maintenance
- checks
- audits
- emergency procedures
9. To track and control the process of change, you must have a written procedure for proposing, considering and approving changes to technical developments or procedural or quality changes.
10. Where an emission is expected, all treatment or reactor vessels must be enclosed. Only vent them to the atmosphere via an appropriate scrubbing and abatement system (subject to explosion relief).
11. You must monitor the reaction to make sure it is under control and proceeding towards the anticipated result. Vessels used for treatment must be equipped appropriately, for example with high level, pH and temperature monitors. These monitors must be automatic and continuous, linked to a clear display in the control room or laboratory, and have an audible alarm. Your risk assessment may require you to link process monitors to cut-off devices.
1. Any aerosol treatment process must be fit for purpose. It must be specifically designed to:
- treat canisters and recover their materials and residues
- manage potentially flammable substances
- prevent explosive atmospheres
2. You must design and operate the treatment process (for example, the waste feed rate, duration of treatment cycle and gas or liquid extraction) so that the canisters’ residual contents are fully discharged and removed safely and efficiently.
3. You must locate the treatment plant in a designated covered area or ventilated building. This must:
- have impermeable surfaces and sealed drainage
- be located away from stored combustible materials, other sources of ignition and sensitive receptors
You must design the treatment area to avoid the potential build-up of flammable gases that are heavier than air, for example in sumps or similar sunken areas.
4. The treatment process must be:
- designed by a competent person
- carried out in an enclosed and sealed system, fitted with an appropriate gas extraction system
- provided with a means to contain or control an explosion
- strong enough to contain an explosion (typically up to 10 bar over-pressure), or have explosion relief directed to a safe space or explosion suppression fitted.
Design, operation and explosion relief provisions must satisfy the requirements of relevant health and safety legislation. The gas extraction system must be interlocked with plant operation, so that the plant cannot operate unless the system is working.
5. You must carry out the aerosol treatment process, including tipping and loading, within a controlled inert atmosphere. For example, you could use gas extraction and nitrogen gas injection to displace air from the plant and purge it before and after a treatment cycle. If the inerting system fails or high oxygen levels are detected, the treatment should stop automatically. Similarly, if you use ventilation to prevent an explosive atmosphere forming, the equipment should automatically stop operating when the lower explosion limit is approached.
6. You must make sure you have checked and sorted all canisters before feeding them into the treatment process. This makes sure you exclude incompatible or untreatable wastes (for example, expanding foams).
7. You should process batches of aluminium and steel cans separately to make it easier to recycle the metals recovered from the treatment process and prevent thermite reactions.
8. You must keep waste sorting and storage distinct and separate from the treatment process.
9. For safety, and to prevent wastes accumulating on site, you must make sure you identify available and reliable recovery or disposal routes. You should have contracts in place to take:
- the residues or materials recovered from the treatment process
- any canisters you have accepted but cannot treat on site
10. You must make sure that as a minimum, all LPG piping systems comply with UKLPG Code of Practice 22. They must be securely sealed and tested and have a procedure in place for regular inspection.
11. Containers and tanks holding liquids collected from the treatment process should be:
- compatible with the materials held
- fully earthed
- UN tested
- integrally sound
- designed and constructed to prevent the release of fugitive emissions to air (including odour) and ground, whilst allowing for emergency venting where necessary
12. You should store containers that cannot be enclosed (for example skips containing recovered metal which are open to allow ventilation and drying) in well-ventilated, covered storage areas. This will prevent:
- rainwater collecting (and becoming contaminated)
- the materials held corroding or deteriorating
13. You should not collect or hold flammable liquids in plastic drums or non-conductive plastic IBCs. Containers used to collect and hold flammable liquids from the treatment process should preferably be constructed from steel, or at least anti-static plastic. They should be designed so that they can be sealed for handling and storing. You must only use anti-static plastic containers to collect and hold flammable liquids if you are holding them separate from other wastes, within a self-contained bund.
14. You must collect, and allow to dry, any residues that remain on the recovered metals before they are stored or sent for recycling.
1. You must record in the computerised waste tracking system:
- that a waste has been treated
- what the treatment residues are and their weight
- what end-of-waste products have been made and their weight