Review of odour monitoring and control techniques at rendering plants

1. Review of odour monitoring and control techniques at rendering plants Nigel Gibson

2. I have been involved with odour measurement, modelling and control since 1991 and now run one of the UK’s UKAS accredited olfactometry labs. My experience with this topic area is based on work at a number of rendering plants: Alba Proteins (formerly Wildriggs). A Hughes and Son, animal rendering facility, Skellingthorpe. Banham Compost (formerly Pimlotts). Chetwynd Animal by-Products, Cardigan. Fairfield Piggeries. Fats and Protein, Lancaster. John Knights ABP Mayfield Rendering, Bromsgrove. JG Pears animal rendering facility, Newark and Market Harborough. Peninsular Protein, Great Torrington, Devon. P Waddington animal by-products facility, Bradford. Sun Valley foods, Hereford. Isle of Man Animal By Products plant. National By-Products (Ireland). My work extends to providing expert support for operators, regulator and stakeholders Who am I

3. Project context • Background, • Objectives. What’s in the report, • Its structure, • Contents, • Key findings, • Recommendations. Delegates are expected to have read the report, so today’s presentation will only provide an overview of the project deliverable Overview of session

4. Just to remind ourselves why we are here All rendering plants have the potential to emit offensive odour, but not all odour emitted from a rendering plant is equally offensive. Regulators need to implement IPPC/IED [EPR 2010]. The key requirements to be addressed are: • Best Available Techniques (BAT) should be applied in relation to preventative measures against pollution. • No significant pollution should be caused. • The permit should include all measures necessary for compliance, including in situations other than normal operating conditions. This report shows that with careful design of the plant and full commitment from the operator a rendering plant can be operated without causing significant numbers of odour complaints Before we start ……..

5. Rendering facilities account for a large proportion of all complaints received from members of the public. The public expects regulators to deal effectively with odour levels they find unacceptable – treating these odours as pollution and taking appropriate enforcement action to ensure that operators deal with the sources of odour in a timely fashion (or temporarily or permanently shutting down these facilities if they are either unwilling or incapable of bringing the impact of odour emissions to a level that is considered acceptable). Cost regulation? Need a good grasp of what BAT is in terms of odour control? Need good understanding of objective odour assessment techniques? Background to the project

6. Dealing effectively with odour levels that the public finds unacceptable is fairly straightforward when a facility operator is violating specific conditions of their permit. This may not always be the case. The source of an offensive odour may not be readily identifiable, or is an occasional emission from non-contained sources where either the facility is operating within its permit conditions or the relevant condition is a general ‘odour boundary’ condition. Need for practical odour management and control Understanding what has worked Background to the project

7. Compliance violations involve the regulator taking some sort of action against the facility operator – frequently in response to a complaint from the public. When odour releases are slight or negligible and the facility operator is in compliance, then more effective engagement with the impacted public by both the regulator and the facility operator may be the most appropriate strategy. Not all odour from a rendering plant are highly offensive therefore there is a need to manage stakeholder expectation? Background to the project

8. A regulator has to balance site regulation with stakeholder expectation. Some stake holder comments [not included in the report]: “Intensity of odour has also declined but the intensity of the smell varies, but on most occasions it is sufficiently strong to make you gag. Moreover, the emissions affect your mental and physical well being, depress your appetite, and force you to remain indoors (although the smells often penetrate into even a modern, double-glazed home).” “Sheer frustration dealing with terrible odours. Lack of respect for residents by the Plant management.” Background to the project

9. To identify best practice for implementing existing guidance for the control and monitoring of odour emissions, and recommend additional activities that complement and enhance existing guidance and improve performance. The report Seeks to elaborate on the technical guidance that has been prepared by Europe and transpose through national sector guidance. Uses case studies to reinforce best practice. Purely provides supporting material. Overall objective of the project

10. To take stock of the legal landscape with regard to odour, and identify, explain, and recommend specific, objective and concrete permit conditions that can be used to deal with any unacceptable levels of offensive odour. The report goes on to look at the types of legal action involving odour. This is designed to show you the types of problems encountered elsewhere and how they were dealt with. Overall objective of the project

11. To assess odour control techniques/technologies, in order to aid their effective and appropriate application. The report provides advice on techniques/technologies used to minimise odour emission. We provide some technical material on the techniques/technologies, and give an indication of how effective it has been. We also give some advice on what to watch out for and also how to monitor the situation. Overall objective of the project

12. General introduction BAT for odour control – UK and Ireland Background information on the rendering sector – the process, odour emission and complaint scenarios Sections covering the implementation of BAT for odour control • Acceptance, reception, handling and storage of raw material • Containment • Active odour abatement systems (normal/abnormal conditions, process/foul/building ventilation odour) • Inspection and maintenance Compliance monitoring Management of odour Summary of recent odour cases Appendices covering • Provisions of SG8 relevant to BAT for odour control at rendering facilities • The determination of the exhaust ventilation rates • Example planned preventative maintenance schedule • Example odour diary sheet • An example site inspection report for a rendering plant • Outline odour management plan Structure of report

13. The report draws on a number of information sources Literature search • We tried to identify papers which dealt with odour management on rendering plants. We were particularly interested in finding out how regulators deal with odour from rendering outside Europe. • Following conversation with US regulators it was apparent that • The focus of control objectives was different [ground water rather than odour] • Published guidance was relatively old [1974 !?!] • Odour control requirement and objective were less stringent than in Europe. We contacted supplier of abatement plant but were unable/unwilling to supply any information. Data sources for report

14. Results of the survey • The survey captured information on a variety of plant characteristics: • Site description • Information on odour control plant (normal and abnormal operation) • Raw material management and control of supply chain • Understanding risk of odour emission • Building design and managing negative pressure within buildings • Approach taken to setting stack heights from all odour control plant • Routine monitoring of odour and complaints investigation • Approach to public engagement • Approach taken to dealing with any odour incidents • In England & Scotland the survey was filled out by Regulators. • In Ireland the survey was filled out by both the Regulators and Operators. • In Republic of Ireland an additional questionnaire was sent to community groups, but was not included in the report. • Data was provided on 25 installations. • A summary of the information provided is included at appropriate points in the report. Data sources for report …… cont.

15. Existing guidance material [Slaughterhouse/Animal By-Products BREF ] • This document is the primary information source used to establish BAT for the sector. • Key information was extracted from this document along with references to aid navigation of the BREF, Other guidance material [food/drink/milk BREF] • Document used to provide information on certain odour control techniques. Experience of TAG/Link members. • There is a wealth of information held by regulators on the management and control of odour at rendering plants. • Within the limitation of this type of project some of this information has been incorporated in the report. Data sources for report …… cont.

16. States the overall objectives that operators must comply with. Sector guidance note SG8 • Odour boundary condition, plus • Variety of other requirements designed to ensure compliance with the OBC. Based on requirements of BREF. Irish BAT note • Defines specific benchmarks of <1.5 ouE/m3 as a 98th%ile 1 hour for new plant or <5 ouE/m3 as a 98th%ile 1 hour for existing plant, plus • Variety of other requirements designed to ensure compliance with the odour benchmark taken directly from the BREF. Section on BAT for odour control Source  pathway  receptor

17. Provides a simple outline of the process: • Raw material reception • Storage and handling of raw materials • Size reduction of raw materials • Processing of materials • Post-processing of materials • Treatment of odorous emissions • Storage of processed materials • Washing and cleaning • Effluent treatment (on site or to discharge) Section on the rendering process/sector

18. Lists the range of possible sources of odour: • Excessive build-up of raw materials or excessive residence time of raw materials at the site prior to processing • Inadequate control of odours during receipt and processing of odorous material • Inadequate building containment and/or air extraction • Loss of negative pressure in buildings through open doors, windows and compromised structural integrity • Accidental loss of containment from failed plant and equipment (e.g. extraction system failure) • Failure/Bypass of arrestment equipment resulting in discharge of odorous air or water effluent (eg. TO trip, Backup system) • Conveyor systems (e.g. raw material conveyors) • Open vessels (e.g. effluent treatment plants, lagoons) • Storage areas (e.g. raw materials reception) • Storage vessels (e.g. tallow storage) • Loading and unloading of vehicles • Vehicle washing areas • Pipework and ductwork systems (e.g. pumps, valves, flanges, pressure relief valves, catchpots, drains, inspection hatches, etc.) • Spillages and leaks • Contaminated surfaces, build-up of residues • Condensate production and handling • Burning of poor quality tallow. Section on the rendering process/sector …… cont.

19. Background on the type of odorants emitted: • Sulphur, nitrogen and oxygen containing compounds • Aliphatic & aromatic hydrocarbons (fats and oils) Lists the common odour descriptor assigned to emissions: • ‘burnt meat/chicken’, ‘dog food’, ‘burnt fat’, ‘pork scratchings’, ‘OXO cubes’, and ‘rotten vegetables’ Provides a simple odour balance to apportion odour to the main emission types. Section on the rendering process/sector …… cont.

20. Data extracted from survey returns: Relationship between distance to nearest receptor and number of complaints: • Data shows that rendering plants can operate without causing complaint. Relationship between number of complaints and plant throughput: • Data shows that the number of complaints received is not proportional to capacity. Complaints – Not an accurate measure • Fatigue of complainants • Planned changes • Weather dependant (temp/wind direction) Section on the rendering process/sector …… cont.

21. Section split into the following areas: Acceptance, reception, handling, and storage of raw material Containment Active odour control systems: • Performance of odour-control systems treating process vapour and foul odour (cooking, pressing, and sterilising) • Treating low-intensity high-volume building extraction air • Emission control during abnormal operation Maintenance. Implementation of BAT – what we cover

22. Each section • Gives practical background information on the topic area • Why we are concerned with the topic • Factors that influence odour generation or performance • Any specific features that you should pay particular attention to • Where appropriate references to sections of the BREF. • Includes tables which cross reference with BREF, SG8 and Irish BAT note. • A summary of relevant information submitted through the survey. • Indicates the practical steps that could be considered to mitigate odour. • Gives practical advice in the form of simple case studies. These case studies were developed with the help of TAG/LINK members and direct contact with certain operators. Implementation of BAT – what report provides

23. Odour associated with the handling and storage of raw materials is directly linked to the decomposition process that commences as an animal, fish, or bird is slaughtered or dies. The rate of degradation is most affected by the temperature under which the material is stored, but the rate will also be influenced by the nature of the waste material, and how it is stored and handled while at the slaughterhouse. Thus odour mitigation must focus on raw material quality Implementation of BAT – raw materials

24. In general terms, the potential effects of raw material quality on odour will be: • Relatively low where rendering is located close or adjacent to the slaughtering or processing, and there is a relatively quick and direct flow of raw material to the rendering facility. • Relatively high in circumstances where: • raw material has been rejected on the basis of its quality and odour; • there is a delay in transfer and/or inadequate temperature control before rendering raw material, especially during warm weather; • where raw material is stored at a bulking up and mixing temporary facility prior to arriving on site; and • where material has travelled some considerable distance. Other related factors such as increased moisture (e.g. if a TO is employed) or higher BOD/COD (e.g. if water is treated on site) may be important Implementation of BAT – raw materials

25. Implementation of BAT – raw materials

26. Effective management of the raw material supply chain will involve: • Liaising with raw material supplier(s) to ensure that materials arrive on site as soon as possible. • Setting acceptance criteria for raw material received at the site, especially the odours associated with raw materials, as well as specifying effective and leak-proof enclosures/covers, and implementing a procedure to check and reject non-conforming deliveries. • Setting a maximum period from production to delivery at rendering plant. • Having a contingency for rejecting unacceptable raw material Implementation of BAT – raw material management

27. Technical material supported by a case study on “Management of odour from fallen stock” Fallen stock is often in an advanced state of decay when they arrive on site. The case study shows the benefit of: • Procedures for managing odour during raw material reception and handling and maintaining the procedures to minimise the emission of any nuisance odour in relation to the handling of raw materials. • Engaging and incentivising local farming communities as this can reducing delays in receipt of fallen stock to the rendering plant, resulting in the delivery of lower odour and higher value raw materials. • Providing suitable management systems, with a range of odour control systems, can be used to provide abatement of odours from fallen stock receipt and storage. Using an appropriate odour control system delivers adequate abatement without incurring additional costs which would result from more extensive treatment of less odorous air streams, or mixed high/low odour air streams Implementation of BAT – raw materials - case studies

28. To minimise the release of fugitive emissions it is necessary to ensure that as much of the rendering process is carried out within a sealed containment envelope. However, simply enclosing sources of emission is generally not sufficient to ensure that offensive emissions are prevented. It is also important to consider ventilation/extraction of air, and treatment of odorous air streams. The rate of ventilation required for effective containment of offensive odour released within a building depends mainly on how airtight the structure is. Deficiencies in the integrity of the structure and other openings such as doors, gaps around pipe work, gaps between cladding sheet etc. allow air to pass into and out of the building. The larger the gaps in the structure the greater the rate of flow of air through the building and as a consequence the greater will be the rate of extract ventilation required to contain any offensive odour. Implementation of BAT – Containment

29. The natural forces, which give rise to the movement of air through a building, are the result of wind passing through the building and temperature effects created within the building. Local extraction ventilation, can be applied to segregated air streams containing different levels of odour. The use of targeted ventilation prevents highly odorous air from plant and equipment from leaking into the building space and avoids unnecessarily contamination of the building air. This reduces the odour strength of any fugitive emission and has a beneficial effect on building air treatment requirements. Additionally, applying odour control to a small volume of concentrated air is more cost effective than treating a large more diluted odorous air stream. The overall objective of the ventilation system is to ensure negative pressure is maintained Implementation of BAT – Containment

30. Summary of industry practice Implementation of BAT – containment

31. Summary of industry practice Implementation of BAT – containment

32. Technical material supported by a case study on “Building integrity and maintenance” The case study relates to an operator who has a policy of dealing with odour control issues before they become problematic, and sees the whole of the site operation as contributory to the control of odours. Consequently, a pro-active approach is also incorporated into the site’s on-going maintenance regimes. The case study shows the benefit of: • An experienced site management team to identify the importance of building integrity and build this into the design and maintenance of the rendering plant. • Controlling of air leakage from the building to enable a satisfactory negative pressure regime to be maintained. • Implement a regular building fabric inspection and maintenance programme to ensure that building integrity is maintained. Implementation of BAT – containment - case study 1

33. Technical material supported by a case study on “Building integrity and air extraction” This case study describes the use of monitoring techniques to verify building integrity and pressure differentials at an animal rendering facility. The case study shows that • Building integrity testing is an important component of an on-going maintenance programme to ensure that the escape of fugitive odours is minimised. Appropriate in-house procedures should be documented and all results recorded and maintained for inspections. • Smoke tests and pressure differential tests provide useful tools for operators in ensuring a high standard of control of fugitive odours. Ideally, the operator should identify key locations within the process building where the pressure drops can be monitored regularly across a series of pressure transducers. Air lock Implementation of BAT – containment - case study 2 Thermal oxidiser Cooking Room Storage Material intake Meat outloading Poultry processing

34. Technical material supported by a case study on “Continuous monitoring of negative pressure” The operator has located a series of pressure transducers at key locations to monitor the pressure drop across the fabric of different parts of the process buildings. The case study • Demonstrates the benefit of negative pressure testing which provides a useful tool to demonstrate on a continuous basis whether fugitive emissions are likely to have occurred or are currently occurring /on-going. • Shows that the magnitude of outward air flow (positive pressure), monitoring should be carried out using a pressure transducer capable of reading positive and negative pressures. [see plots] • Shows that placement of the pressure monitors (transducers) is also important; typically, one monitoring device is installed per area. They should not be placed adjacent to building openings (doors or air intakes), as this may result in false readings. Implementation of BAT – containment - case study 3

35. Sources of odour The main cooking process (high-intensity process vapour/odour sources); The downstream processing of the cooked material (greaves) to separate fat from meal (high-intensity foul-odour sources); and Building ventilation air (low-intensity odour sources). The report presents information on abatement of high and low intensity odour Implementation of BAT - active odour control – risk assessment

36. Lays out key questions required to determine whether BAT is being applied: Does the operator know what the odour-control plant must achieve to avoid complaints? Is the capacity of the control plant installed (or proposed) adequate for the application? Is the technology appropriate and reliable for dealing with the nature of the odour stream to which it is applied? How reliable is the technique? What measures must be taken to ensure that the odour control plant is controlled and operated appropriately? Implementation of BAT - active odour control – risk assessment

37. Summary of impact assessment approaches used by operators Implementation of BAT - active odour control -– risk assessment

38. Technical material supported by a case study on “Advanced modelling techniques in complex urban settings ” Dispersion modelling is a well established tool, however there are limitation in the way models deal with certain situations (e.g. complex building situations). The case study showed that CFD • can be an additional, and very powerful and useful, tool to assist with investigating odour issues and designing solutions. • is limited in the range of weather conditions that can be represented. • Still requires good information on odour emissions • Modelling is expensive Implementation of BAT - risk assessment case study Neighbouring industrial building Transportation interchange station (b) Higher stack (a) Lower stack

39. For control of intense odour from the process, the report considers the use: • Boilers – treating odour as part of combustion support air. • Recuperative thermal oxidisers – using back end boilers to recover heat • Regenerative thermal oxidisers – using canisters to transfer heat to incoming odour The report provides a brief summary of the operating principle of each technique Implementation of BAT – odour control – process fume

40. Summary of current practice Implementation of BAT – odour control – process fume

41. Example performance data – use of steam raising boilers Implementation of BAT – odour control – process fume

42. The report list factors which influences the performance of oxidation using boilers for example: Poorer odour abatement performance can be expected from a system where the process demand for steam is lower than the total capacity of the boiler – capacity of the boiler is important If the boiler-firing rate varies greatly, it may be necessary to operate auxiliary burners in the boiler to maintain the temperatures necessary for oxidisation of the odorous substances – periods of no or low fire are likely to be a problem The flow rate of the organic-contaminated stream must not overwhelm the gas-handling capability of the boiler induced-draught fans. May be a problem at low firing rates The report provides guidance on what could give rise to problems. This is also provided as “do’s” and “don’ts” to reiterate good and bad practice. Implementation of BAT – odour control – process fume

43. Similar data and guidance is also presented for recuperative and regenerative thermal oxidisers: Example performance data Factors influencing performance: • Combustion conditions • Odour loading Implementation of BAT – odour control – process fume

44. Technical material supported by a case study on “Thermal oxidiser capacity” The case study compares the performance of recuperative thermal oxidation by two operators with different design philosophies: The case study identified the following problem area with the first operator • Poor maintenance of residence time • There was no monitoring of process vapour flows to the TO • The frequent plant breakdowns; • Poor quality of workmanship on the backend boiler lead to odour emission The case study showed the need for • Robust data on vapour throughput and energy balance for calculating the TO capacity requirement. • Adequacy of residence time, temperature and mixing must be demonstrated • Adequate monitoring for example during sudden changes in the mass emission of odour to the thermal oxidiser. Implementation of BAT –process fume –case study

45. Summary of current practice Implementation of BAT – odour control – building air Odour removal efficiency data as well as do’s and don’t’s on non-combustion types of odour control systems are in the report

46. During instances of oxidiser or boiler malfunction, the primary odour control plant may not be able to destroy odour effectively, leading to an abnormal operating condition. The operator must ensure that procedures are in place to ensure compliance with the odour boundary condition. Implementation of BAT – odour control – abnormal emissions

47. Summary of current practice Implementation of BAT – odour control – abnormal emissions

48. Options available include diverting process air to : A second thermal system A biofilter or chemical scrubber Another dedicated back-up system e.g. acid scrubber + carbon filter The report contains limited data on the performance of back-up systems. The report recommends that monitoring is in place to show when the back-up system is used. Implementation of BAT – odour control – abnormal emissions

49. For the effective operation of an animal by-product rendering plant, it is not just sufficient to use appropriate plant and equipment. Routine inspection by the operator will ensure that the plant and equipment is, where necessary, maintained to ensure the impact of odour from the plant is minimised. For key plant and equipment, planned maintenance by the operator is essential. This will comprise preventive maintenance (changing parts and routinely checking the function of equipment), in which the maintenance event is pre-planned and all future maintenance is pre-programmed. The operator should create a maintenance schedule for every key item or plant according to operating experience or manufacturer’s recommendation. The maintenance interval may be set based on equipment running hours or based on environmental risk. Implementation of BAT – inspection & maintenance

50. Compliance monitoring for a rendering plant is focused on demonstrating that: The process does not cause significant pollution (specifically, offensive odour) beyond the boundary of the installation, as required by an odour boundary condition. The process is operated in accordance with BAT - as defined by the conditions of the permit  for both normal and abnormal operation, when some aspect of the plant fails. The report provides: An overview of odour monitoring techniques to assess compliance with permit conditions. An overview of operator and regulatory compliance monitoring with respect to the application of, and general compliance with, BAT for the minimisation or elimination of odorous emissions from rendering plants. An overview of site inspection procedures. Compliance monitoring - overview