11. Emissions control
Emissions control related appropriate measures for biological waste treatment.
1. You must review your activities to identify opportunities to minimise and where possible contain, treat and abate emissions.
2. All air and emissions treatment (including gas clean-up) must be engineered, commissioned and validated by a chartered engineer.
3. Equipment must be tested, operated and maintained following manufacturers recommendations, operational requirements and design criteria.
4. When determining the complexity of the control measure you need to apply you must consider if you need to comply with mandatory AEL. Otherwise you can follow a risk based approach and must consider the:
- inventory of emissions
- type or composition of emissions, for example dust, bioaerosols, odour, organic compounds or litter
- source of emissions
- site location and proximity to sensitive receptors
- the impact on any sensitive receptors
- likelihood of release, taking account of seasonal and process variations
- measures you can take that will break the source pathway receptor relationship
The following measures apply to all processes and operations.
1. You must identify, characterise and control all emissions from your activities that may cause pollution. This includes all emissions to air and water (including emissions to sewer) from your facility.
2. Your emissions inventory must include information about the relevant characteristics of the emission to air and water, such as:
- flammability, lower and higher explosive limits and reactivity
- other substances present that may affect the waste gas treatment system or plant safety (for example, oxygen, nitrogen, water vapour, dust)
- average and maximum values and variability of flow, pH, temperature, and conductivity
- average and maximum concentration and load values of relevant substances and their variability – for example, COD and TOC, nitrogen species, phosphorus, metals, priority substances or micro pollutants speciated organic compounds and ammonia
- data on bio eliminability – for example, BOD, BOD to COD ratio, Zahn Wellens test, biological inhibition potential (such as, inhibition of activated sludge)
The following measures apply to all processes and operations.
We may set emission limits and monitoring requirements in your permit, based upon your emissions inventory and environmental risk assessment. We may set additional limits and monitoring requirements for certain processes, for example dust and total volatile organic compounds.
1. Where you are required to monitor emissions to comply with the requirements of your environmental permit you must follow our monitoring guidance.
2. For relevant emissions to water or sewer identified by the emissions inventory, you must monitor key process parameters (for example, waste water flow, pH, temperature, conductivity, or BOD) at key locations. For example, these could either be at the:
- inlet or outlet (or both) of the pre treatment
- inlet to the final treatment
- point where the emission leaves the facility boundary
1. You must monitor and record meteorological conditions or have access to meteorological data for the site location. This is so you can forecast wind speed, air temperature and wind direction.
2. You must put weather monitoring stations at appropriate locations on your site.
3. You should calibrate meteorological monitoring equipment every 4 months or follow manufacturers’ recommendations.
1. You must take measures to minimise the release of bioaerosols from your process.
2. You must document potential bioaerosol emission sources and identify measures to minimise their release. Measures include, for example:
- processing waste promptly and monitoring it according to defined processing conditions
- taking corrective measures to address unfavourable conditions
- using slow-speed shredders in sensitive locations with misting devices fitted or carrying out these activities in covered areas
- taking into account meteorological conditions when managing activities
- avoiding activities such as turning and shredding in unfavourable meteorological conditions
- stopping activities when the wind is blowing in the direction of sensitive receptors
- dampening haul roads and processing areas and stopping activities when the wind is blowing in the direction of sensitive receptors
- using static aeration and covering piles where possible and practicable
3. If your facility is within 250 metres of a sensitive receptor, you must:
- write and implement a site specific bioaerosol risk assessment
- monitor bioaerosols to make sure that the control methods you have stated are effective
4. You must implement the control measures identified in your risk assessment. You must also consider the exposure of staff and visitors and take measures to avoid or reduce prolonged exposure to bioaerosols.
The following measures apply to all processes and operations.
1. You must develop and implement an odour management plan.
2. Where you expect odour pollution at a sensitive receptor, or it has been substantiated, you must monitor:
- using dynamic olfactometry following EN 13725 to determine the odour concentration
- to EN 16841 1 or 2 to determine the odour exposure
- to an alternative ISO, national or other international standards
3. You must review your odour management plan as part of your environmental management system. It must include all of the following elements:
- actions and timelines to address any issues
- a procedure for doing odour monitoring
- a procedure for responding to identified odour incidents, for example, complaints
- an odour prevention and reduction programme designed to identify the source(s), to characterise the contributions of the sources and to implement prevention and reduction measures
The following measures apply to all processes and operations.
The Environment Agency views all abatement and gas clean up systems as point source channelled emissions regardless of whether they are open or have a stack.
1. To reduce point source emissions to air (for example ammonia, dust, organic compounds and odorous compounds) from your biological treatment process, you must use one or more of the relevant abatement techniques, such as:
- bio filtration, bio trickling or bio scrubbing
- scrubbing (for example wet or chemical)
- adsorption, for example activated carbon
- thermal oxidation
- fabric filter – for mechanical biological treatment to remove dust
2. You must assess the fate and impact of the substances emitted to air, following the Environment Agency’s air emissions risk assessment methodology.
3. To make sure the abatement system is effective in treating odorous and other emissions you must monitor and maintain your abatement to achieve optimum conditions at all times.
To demonstrate effective control, monitoring and assessment may include the following parameters:
- gas flow or loading rate
- bacterial viability (applicable to bio-oxidisation treatment systems)
- pH
- acid growth (indicated by pH)
- gas temperature
- pollutant removal efficiency rate
- chemical injection (redox potential – applies to chemical scrubbing and bio-oxidisation systems)
- spent solutions (for waste recovery or disposal)
- humidity or moisture content
- back-pressure
- thatching and compaction of media in biofilters (thatching is forming a natural barrier to prevent the ingress of additional water to the surface layer)
- channelling (preferential pathways for gas flow) and vegetation growth in biofilters
- ammonia, hydrogen sulphide and odour concentrations (in both input and exhaust gas streams)
- energy requirements for providing adequate and continuous airflow
4. You must observe trends and changes over time which could indicate that additional maintenance or replacement is needed.
5. You must have:
- procedures to deal with a loss in abatement efficiency due to toxic compounds
- a program of filter media replacement which is informed by performance and condition
- a program to replenish chemical reagents in abatement scrubbers
- procedures for commissioning new filter media or abatement
6. At least once a year, you must carry out an efficiency assessment of your abatement system.
Biofilters (open and closed fixed bed systems)
The following measures apply to all processes and operations.
7. You must use a filter bed material that is suitable for maintaining bacterial communities and that will hold its structure integrity.
8. You must consider water retention capacity, bulk density, porosity, surface area, nutrient viability and particle size.
9. The biofilter must be connected to a suitable ventilation and air circulation system. It must provide uniform waste gas distribution through the bed and enough residence time to make sure treatment takes place.
10. You may need to pre-treat the waste gas before it enters the biofilter, for example, with a water, acid or alkaline scrubber. You must make sure you pre-treat the waste gas if chemicals in untreated gas can poison the biofilter, for example ammonia.
11. You should design biofilters on a modular basis so they can keep operating during staged refurbishment.
12. You must drain any liquid which accumulates in the base of the biofilter to an appropriate leachate collection or treatment system.
13. The pipework to the biofilter must be made from corrosion resistant materials. It must incorporate low drain points to prevent the build-up of condensate, corrosion and loss in efficiency.
14. You must monitor your biofilter for the following:
- gas inlet temperature (inlet and outlet on closed systems)
- gas inlet flow rate (inlet and outlet on closed systems)
- filter media moisture
- thatching and compaction using back-pressure measurement
- pH (this should be monitored from the biofilter drainage effluent)
- gas inlet humidity
- gas inlet and outlet concentrations for ammonia, hydrogen sulphide and odour
- bacterial viability
15. You must visually monitor your biofilter for:
- vegetation, moss and fungus – the media must be in good condition and clear of vegetation, you can use a photographic record of the media bed to see how it changes over time
- media depth to identify decomposition and compaction over time – you can do this using vertical rulers located in the biofilter bed
- surface condition – to identify any channelling, gaps or signs that the biofilter bed is shrinking
- irrigation – to identify wet and dry spots and the uniformity of any sprinkler systems
16. You must maintain your biofilter with a vigorous and healthy microbial community operated at optimum designed values. You should periodically review:
- media health, for example bacterial viability, particle size distribution and depth
- volumetric air flow or surface air flow distribution in open biofilters
- emission removal efficiency, for example odour removal
Calculate removal efficiency using the concentrations sampled from the biofilter inlet and outlet.
17. You must carry out periodic sampling to make sure your abatement system is functioning as designed and is able to treat and mitigate emissions.
18. You must re-mix or replace biofilter media, either during planned routine maintenance or more frequently if your monitoring assessment identifies it is needed.
For other key monitoring parameters and information on biofilters, see Understanding Biofilter Performance and Determining Emission Concentrations under Operational Conditions.
Pre-treatment abatement scrubbers
The following measures apply to all processes and operations.
19. You must select the most appropriate aqueous absorbing solutions for treating pollutants in the waste gas stream. Where you have identified a mix of pollutants you may require a multi-stage process.
Flow rates must allow for sufficient gas residence time and minimise carry-over of scrubbing solution into the waste gas stream.
20. You must monitor your abatement scrubber for the following:
- gas temperature and flow rate, inlet and outlet
- moisture content or humidity
- back-pressure, for packing scrubbers
- pH of scrubber solution
- chemical injection rate (redox potential)
21. You must continuously monitor the scrubber solution for:
- flow rate
- pressure
- temperature
- pH
You should periodically measure the inlet and outlet of the scrubber for:
- ammonia
- hydrogen sulphide
- odour.
Activated carbon
The following measures apply to all processes and operations.
22. You must monitor your activated carbon filter for the following parameters:
- inlet and outlet gas temperature and flow rate by continuous monitoring
- inlet moisture content or humidity
- back-pressure
- carbon bed temperature
- ammonia
- hydrogen sulphide
- odour
23. You must make sure you either replace or regenerate the carbon before saturation.
24. You must make sure the concentrations of volatile organic compounds within the gas stream are below their lower explosive limit.
25. You must make sure you follow the manufacturers’ recommended maximum operating temperature.
26. You must use a cooling system if you exceed the upper temperature limit.
27. You must minimise particulates in the waste gases before they reach the carbon filter.
28. You must not allow exothermic reactions when maintaining activated carbon filters.
29. You must store activated carbon safely to prevent spontaneous combustion. You must store it following supplier or manufacturers’ recommendations.
Stacks and vents
The following measures apply to all processes and operations.
30. Stack or stack and vents must release at an appropriate height, temperature and velocity to make sure the emissions disperse well. You must use dispersion modelling to demonstrate the emissions do not impact on sensitive receptors.
31. You must install a suitable monitoring point on stacks and vents with appropriate safe access.
32. You must monitor emissions following the Environment Agency guidance on monitoring stack emissions.
Emission limits
The Environment Agency will set release limits in your permit considering:
- your emissions inventory
- the associated emission limits (AELs) set out in the Waste Treatment and Storage BAT Conclusions
Unless there is a site-specific reason not to, we set emission limits in the permit at the upper limit of the BAT AEL range. Emission limit values may need to be stricter depending on:
- the location of sensitive receptors (such as residential properties)
- the stated design of the abatement plant
For abatement plant designed to reduce odour emissions, BAT Conclusion 34 gives an option on AELs which the Environment Agency sets as an emission limit. We will usually set a limit for odour where the plant is designed for that purpose. But we may also set limits for ammonia if:
- the location means there is a need to
- the plant is designed to also reduce ammonia
All abatement plants should be designed to reduce odours and, where required, ammonia. For new abatement plant, the limits are set based on plant design or the BAT AEL, whichever is less.
Multiple emission limits may be required:
- to maintain the effectiveness of abatement plant as designed
- if the waste gas inventory or predicted inventory identifies odour and ammonia as relevant
- to protect people and the environment
When we set limits for both ammonia and odour, you should monitor these emissions periodically. This is to demonstrate that the abatement plant keeps performing as designed through its:
- operation
- maintenance
For existing biowaste sites, we will regulate based on the operator’s odour management plan (OMP). Operators should demonstrate the existing abatement plant is effective and does not present a risk of odour pollution. The OMP should set out:
- a schedule for periodic monitoring of odour from the abatement plant to demonstrate it is operated and maintained as designed
- the actions needed if performance of that plant drops
When the Environment Agency confirms odour pollution, we may set an emission limit for odour:
- within the BAT AEL range
- at a level which will prevent or minimise odour complaints
Also, if monitoring data shows odour concentrations are greater than the upper BAT AEL for odour, it may indicate that abatement plant is not able to treat odour concentrations to the level understood as achievable under the waste treatment BREF. This may require you to:
- refurbish or replace the odour abatement plant
- apply to vary the environmental permit
The following measures apply to all processes and operations.
1. You must only use masking agents, chemical neutralising agents and topical barriers together with comprehensive process management control. Any topical chemical barrier must be approved for use.
You should use masking or chemical treatments (for example neutralising agents) to destroy or to reduce odorous compounds.
2. Using chemical treatments must not affect the quality of the compost or digestate.
3. You must take care when using masking agents (for example deodorisers) as these may cause pollution and amenity impacts.
4. You must only use topical barriers, where you can achieve the following conditions, you:
- can demonstrate you apply the barrier in line with manufacturer’s instructions
- maintain records of the application rate, time and conditions
- continue to monitor other process parameters for example, temperature and moisture
5. You must review your water-efficiency measures when considering the use of neutralising agents and topical barriers.
The following measures apply to all processes and operations.
1. You must use appropriate measures to prevent emissions of odour, ammonia, dust, bioaerosols and particulates, mud and litter.
2. You must design, operate and maintain plant in a way that prevents or minimises fugitive emissions to air, for example by:
- limiting drop heights
- using wind barriers
- using gravity transfer rather than pumps
This also applies to associated equipment such as:
- screeners
- shredders
- conveyors
- skips or containers
- building fabric, including doors and windows
- pipework and ducting
3. You must use high integrity components, for example seals or gaskets or leak test certificated PVRVs.
4. You must have a programme of work that covers the maintenance of all plant and equipment. This must also include protective equipment such as curtains and fast action doors used to prevent and contain fugitive releases.
5. You must identify the frequency of maintenance in your management system. As a minimum you must follow manufacturers’ recommendations.
6. To identify and manage wastes that could cause, or are causing fugitive emissions to air, you must do:
- pre-acceptance checks
- waste acceptance checks
- site inspections
7. When you identify any such wastes you must:
- take appropriate risk-assessed measures to prevent and control emissions
- prioritise their treatment or transfer
8. Where necessary you must use a combination of one or more of the following measures:
- cover any conveyers, hoppers, container that are outside
- store and handle the waste within a suitably enclosed area (for example bays), a building or enclosed building
- keep doors closed except when access is needed
- use an appropriate abated air circulation or extraction system to keep enclosed buildings and equipment under adequate negative pressure, locating air extraction points close to potential emission sources
- use fast-acting or ‘airlock’ doors that default to closed
- use suitable covers (these can include textile sheeting, synthetic membranes and organic materials such as straw and woodchip) – the choice of cover depends on the risk to receptors
You should install localised containment, for example air extraction over a waste shredder, to minimise and treat air.
You should install ventilation to BS EN 13779:2007 or follow the HSE Exhaust Ventilation Guide.
You must use suitably qualified engineers to design and install systems and make sure relevant standards are applied. The HSE provides guidance on selecting, using and maintaining local exhaust ventilation (LEV) correctly.
9. You must review the integrity and containment effectiveness of any building, covers and contained air systems during commissioning. You must then do this periodically following manufacturers guidelines, or at least every 2 years.
10. You must carry out assessments to recognised standards, for example BS EN ISO 9972:2015.
You can use a smoke test to identify emission leaks from buildings. This may show where you need to make improvements before you carry out a more thorough survey.
11. You must replace or repair damaged building, containers covers as soon as possible.
12. You must stop using any vessel or tanks immediately if their integrity is compromised.
13. You must regularly inspect and clean all waste storage and treatment areas and equipment, including conveyor belts. You must identify the frequency of inspection and cleaning in your management system.
14. You must take measures to prevent plant and equipment, conveyors and pipes corroding. This includes using appropriate construction materials, corrosion inhibitors and regularly inspecting and maintaining plant.
15. You must consider dampening potential sources of fugitive dust emissions with water or fog, for example when turning open windrows or on areas where traffic moves.
16. You must prevent or minimise litter.
17. You must stop outdoor processing activities, for example waste shredding or windrow turning when weather conditions may either:
- increase the risk of impact on local receptors
- cause wind-blown litter, dust, odour or bioaerosols
If you need a dust management plan, you must develop and implement it following our guidance.
The following measures only apply to:
- anaerobic digestion (AD)
- mechanical-biological treatment (MBT)
- thermophilic anaerobic digestion (TAD)
1. You must implement a leak detection and repair (LDAR) plan. It must link to your regular monitoring, maintenance and Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) plan. You must use it to quickly identify and carry out repairs, or to replace plant and equipment.
2. The LDAR plan must include:
- a map of the site and an inventory that identifies locations (point and area sources) for potential emissions
- a method for locating unknown emission sources
- estimates of the type and volume of release from each leak location
- prioritised locations (from highest risk to lowest risk) based on the potential quantity of release, its environmental impact, and DSEAR
- your monitoring methods and frequency to quantify significant emissions
- mitigation measures
3. You must consider all potential sources of leakage within your LDAR plan, for example:
- double membrane roofs (air blower vent)
- roof and cover fixings
- pressure relief valves and vents
- feeding and digestate separation units
- gas pipes
- conveyors and presses
- compressor
- combined heat and power plant (methane slippage)
- gas upgrading plant
- grid injection
- reception storage
- digestate storage
- pits and sumps, for example condensate pits
- building containment
4. You must identify and reduce emissions of volatile organic compounds and other substances to air.
Methods for identifying leaks include:
- sniffing using organic compound analysers and bag sampling, carried out to the requirements of EN15446 standards and the US Environmental Protection Agency (EPA) Protocol for Equipment Leak Emission Estimates referenced within this international standard
- optical gas imaging (OGI) using hand-held cameras to enable visualisation of gas leaks
Methods for quantifying emissions include:
- solar occultation flux (SOF)
- differential absorption light detection and ranging (DIAL)
EN 17628 provides guidance on using multiple monitoring techniques for LDAR programmes.
Information on methane leakage from AD plants is available in:
- the Department of Business, Energy and Industrial Strategy’s Methodology to assess methane leakage from anaerobic digestion plants
- the International Energy Agency’s Methane emissions from biogas plants
5. You must include the following LDAR survey details in your LDAR plan.
Details of the site where the LDAR survey was carried out, conditions at the time of the survey, and measurement objectives, including:
- site name
- operator name
- permit number
- site processes (under normal operating conditions)
- date of the survey
- site operation on the date of the survey (for example, operating at full capacity or reduced load due to X and Y)
- weather conditions (including temperature, wind speed and wind direction)
- measurement objectives (for example, targeted processes, site areas)
Details of the organisation and personnel carrying out the LDAR survey, including:
- name and address of the monitoring organisation
- names, experience and qualifications of the personnel carrying out the monitoring
- accreditation status of the monitoring organisation
- documented procedures used for the LDAR campaign and reporting
- quality assurance or quality control criteria
- name of the person approving the report for the monitoring organisation
- the signature of the person approving the report
Details of the detection equipment used for the survey, including:
- make, model and serial number of the detection equipment used for the survey
- methane detection limit of the detection equipment (for example, ≤60g/hr (OGI cameras), <10ppm (sniffer devices))
- if an OGI camera is used, the spectral range of the camera (µm)
- certification or verification status of the OGI camera (for example, to US EPA OOOOa specifications)
- calibration certificates for the equipment (if applicable)
Details of the survey carried out, including:
- areas of the site that were surveyed
- areas of the site that were not surveyed – including a reason why those areas were not surveyed
- leak definition used for the survey (for example, 500ppm, or detectable by the specified OGI camera at Xm)
- distance from which components were surveyed
- duration of measurements, at individual components and specified site areas
Details of result monitoring, including:
- list of leaks identified during the survey
- annotated plan of site (or piping and instrumentation diagram) showing the precise locations of the identified leaks
- time when each leak was identified
- a description of each leaking component identified (for example, valve, flange and so on) – include the component reference number where available
- a photograph of the leaking component showing the leak location
- severity of the leak – the measured methane concentration or leak rate, or the risk posed due to the component type and location (or both)
- emission estimate in kg/h for each component surveyed
- total site emission rate in kg/h, including uncertainty
- any non-conformities against the quality assurance or quality control procedures
The repair schedule must include a proposed timescale for repairing the identified leaks, with justification (based on the severity of the leak or potential risk).
6. You must produce the LDAR plan using the techniques included in the following standards:
- BS EN 15446:2008, Fugitive and diffuse emissions of common concern to industry sectors – Measurement of fugitive emission of vapours generating from equipment and piping leaks
- BS EN 17628:2022, Fugitive and diffuse emissions of common concern to industry sectors – Standard method to determine diffuse emissions of volatile organic compounds into the atmosphere.
- BS ISO 15259:2023, Air Quality – Measurement of stationary source emissions – Requirements for measurement sections and sites and for the measurement objective, plan and report
The following measures apply to all processes and operations.
1. You must manage waste in a way that prevents pests and vermin.
2. You must make your pest and vermin management plan part of your environmental management system and it must include procedures for:
- inspecting for pests and vermin and for controlling them
- rejecting loads of infested waste
- treating pest and vermin infestations promptly
- storing, handling and using approved pest and vermin control products
Information on using pest control chemicals at work is available from the HSE.
Fly prevention and management
3. Making sure you implement fully all appropriate measures will proactively decrease the incident of flies on site.
4. You must have a process to count and record the number of flies on site.
5. You must have a process to investigate and resolve fly infestation.
6. You must reject maggot and fly infested waste.
7. You must make sure you have effective cleaning and housekeeping.
8. You must use fly treatment equipment and chemicals where approved and appropriate.
The HSE require that anyone using pesticides professionally should have received adequate instruction, training, and guidance in their correct use.
9. Under the COSHH Regulations (2002) you must document all activities involving pesticides (for example, storage, use and disposal). You must keep these records for a period of at least 3 years.
10. You must use all knockdown sprays, pesticides and larvicides according to the manufacturer’s instructions and licence.
You may be required to submit a pest management plan for approval by the Environment Agency.
The following measures apply to all processes and operations.
You should locate potential sources of noise (including building exits and entrances) away from sensitive receptors and boundaries.
1. You must locate buildings, walls, and embankments so they act as noise screens.
2. You must use measures to control noise, including:
- maintaining plant or equipment parts which may become more noisy as they wear out (for example, bearings, air handling plant, the building fabric, and specific noise attenuation kit associated with plant or machinery)
- closing doors and windows to prevent noise breakthrough
- avoiding noisy activities at night or early in the morning
- minimising drop heights and the movement of waste and containers
- using white noise reversing alarms and enforcing the on site speed limit
- using low noise rated equipment (for example, drive motors, fans, compressors, pumps)
- adequately training and supervising staff
- providing additional noise and vibration control equipment for specific noise sources (for example, noise reducers or attenuators, insulation or sound proof enclosures)
3. You should have a noise and vibration management plan. This must be part of the environmental management system and must include:
- actions and timelines to address any issues
- a procedure for doing noise and vibration monitoring
- a procedure for responding to identified noise and vibration events, for example, complaints
For noise, a noise impact assessment using the BS 4142:2014+A1:2019 ‘Methods for rating and assessing industrial and commercial sound’ methodology must inform your plan.
For vibration, a vibration impact assessment using the BS 6472-1:2008 ‘Guide to evaluation of human exposure to vibration in buildings. Vibration sources other than blasting’ methodology must inform your plan.
The following measures apply to all processes and operations.
1. You must ensure you have the relevant trade effluent consents in place with your local water company.
2. You must reduce emissions to water (direct or indirect) using an appropriate combination of techniques, for example:
- neutralisation
- adsorption
- stripping
- flotation
- filtration
3. You must assess the fate and impact of the substances emitted to water and sewer following the Environment Agency’s risk assessment guidance.
4. Discharges to water or sewer must comply with the conditions of an environmental permit or trade effluent consent.
Relevant sources of waste water include:
- process water
- condensate collected from a treatment process
- waste compactor run-off
- vehicle washing
- vehicle oil and fuel leaks
- washing containers, tanks and vessels
- spills and leaks in waste storage areas
- loading and unloading areas
5. If you need to treat waste water before discharge or disposal, you must use an appropriate combination of these techniques:
- preliminary or primary treatment – for example, equalisation, neutralisation or physical separation
- physico chemical treatment – for example, adsorption, distillation or rectification, precipitation, chemical oxidation or reduction, evaporation, ion exchange, or stripping
- biological treatment – for example, activated sludge process or membrane bioreactor
- nitrogen removal – for example, nitrification and denitrification
- solids removal – for example, coagulation and flocculation, sedimentation, filtration or flotation
6. You must direct wash waters from cleaning vessels to foul sewer or a contained drainage system for off site disposal or re-circulation.
You may need to pre treat the wash waters to meet any limits on the effluent discharge consent. The degree of recirculation will be limited by the water balance of your plant, the content of impurities, or characteristics of the water streams, for example nutrients.
Discharges to surface water or storm drains (except for clean, uncontaminated rainwater) are not permitted.
You should use all of the following techniques:
- segregate leachate seeping from compost piles and windrows from surface water
- re-circulate process water streams – for example, from de-watering liquid digestate, or by using water streams like surface water run-off as much as possible
- optimise the waste’s moisture to minimise generating leachate
The following measures apply to all processes and operations.
1. You must use appropriate measures to control potential fugitive emissions to land and water and make sure they do not cause pollution.
2. You must have the following measures in place in operational areas:
- an impermeable surface
- spill containment kerbs
- sealed construction joints
- connection to a contained drainage system
3. You must collect and treat separately each water stream generated at the facility, for example, surface run off water or process water. Base how you separate it on the pollutant content and the treatment needed.
4. You must make sure that you segregate uncontaminated water streams from those that need treatment.
5. You must use suitable drainage infrastructure to collect surface drainage from areas of the facility where you store, handle and treat waste. You must also collect wash waters and any spillages. Depending on the pollutant content, you must either recirculate what you have collected or send it for further treatment.
6. You must take measures to prevent emissions from washing and cleaning activities, including:
- directing liquid effluent and wash waters to foul sewer, or collecting them in a contained system for off site disposal – you must not discharge them to surface or storm drains
- using biodegradable and non corrosive washing and cleaning products
- storing all detergents, emulsifiers and other cleaning agents in suitable bunded or containment facilities within a locked storage area, or in a building away from any surface water drains
- preparing working strength cleaning or disinfection solutions in contained areas of the site and never in areas that drain to the surface water or groundwater
7. Container washing equipment must be purpose built, located in a designated area of the facility provided with self-contained drainage.
8. You must design the container wash to collect and contain all wash waters, including any spray.
9. You must use trained staff to operate the container wash and you must inspect and maintain it regularly.
10. You must have measures to prevent pollution from the on-site storage, handling and use of oil and fuel.
11. You must produce and implement a spillage response plan and train staff to follow it and test it.
12. You must have procedures and associated training in place to make sure that you deal with spillages immediately.
13. You must locate spill kits close to areas where spillages could occur and make sure relevant staff know how to use them. You must replenish the kits after use.
14. You must stop spillages from entering drains, channels, gullies, watercourses and unmade ground. You must have the following available, to use when needed:
- proprietary sorbent materials
- sand
- booms or drain mats (or both)
15. You must make sure your spillage response plan includes information about how to recover, handle and correctly dispose of all waste produced from a spillage.
16. For subsurface structures, you must:
- establish and record the routes of all site drains and subsurface pipework
- identify all sub surface sumps and storage vessels
- engineer systems to minimise leaks from pipes and make sure you can detect them quickly if they do occur, particularly for hazardous substances
- provide secondary containment and leakage detection for sub surface pipework, sumps and storage vessels
- establish an inspection and maintenance programme for all subsurface structures, for example, pressure tests, leak tests, material thickness checks or CCTV
17. You must design appropriate surfaces and containment or drainage facilities for all operational areas, taking into account:
- collection capacities
- surface thicknesses
- strength and reinforcement
- falls (of the land)
- materials of construction
- permeability
- resistance to chemical attack
- inspection and maintenance procedures
- available relevant standards of construction
18. You must have a documented inspection and maintenance programme to review the integrity of impermeable surfaces and water containment facilities. This must consider the plant and equipment manufacturers’ recommended maintenance practices.