Ricardo-AEA © Ricardo-AEA Ltd Nigel Gibson Review of odour monitoring and control techniques at...

Ricardo-AEA

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Nigel Gibson

Review of odour monitoring and control techniques at rendering plants

© Ricardo-AEA LtdRicardo-AEA in Confidence2

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


• 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


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 ……..


• 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


• 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



• 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?



• 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.”



1. 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


2. 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.



3. 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.



• 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


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


• 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.


• 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.


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


• 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


• 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.


• 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.



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 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


• 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


• 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


• 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




Aspect Summary of responsesWhere does the raw material come from? Direct from slaughterhouse: 63%

From transfer facility: 8% From both: 29%

How many sites have formal mechanisms for controlling the quality of raw materials entering the site?

Yes: 62% No: 38%

Does this mechanism material to be rejected on grounds of odour? Yes: 54% No: 46%

Time period before dispatch Immediately: 25% Within 1 hour: 50% When transport becomes available: 25%

Storage arrangements while awaiting dispatch Left in covered trailer until removed from site. Materials would be loaded back into vehicle delivering and sent off-site. Rejected material not stored on site, it is not unloaded from the carrier. Any material to be rejected is pumped to lorry in an enclosed area. The material is stored in containers that are covered and sealed.

If raw material is rejected from a particular source, would this prohibit that source from supplying material in future?

Yes: 20% No: 60% Investigated/dealt with on a case by case basis: 20%

On arrival is the raw material immediately unloaded in the raw material area?

Yes: 75% No: 25%

Is raw material allowed to be stored outside? Yes: 35% No: 65%

If raw material is allowed to be stored outside how many delivery vehicles are allowed on site and for how long?

No outside storage after 30 minutes: 33% Up to 4 vehicles allowed for 20 minutes: 33% 2 vehicles may be parked for up to 8 hours: 33%

Are the same raw-material handling systems applied to all raw material types handled on site?

Yes: 48% No: 52%

Additional material provided Blood delivered directly into a specified tank. Fallen stock, blood and all other raw material are handled separately. Fallen stock that need samples removed from their brains or hides/pelts

removed prior to being rendered are allowed to be tipped on the floor. Offal and blood pumped from tanks; feathers in a wet system.


• 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


• 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


• 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


• 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


• Summary of industry practice

Implementation of BAT – containment

Aspect Summary of responses

Is there an airlock serving the raw material area?

Yes: 39% No: 61%

How are the buildings enclosing the raw materials and processing area fabricated?

single skinned: 71% double skinned, with insulation: 19% double skinned, without insulation: 10%

How is the negative pressure within the buildings designed?

Set using air changes per hour (ACPH) : 86% Monitoring negative pressure: 14%

Additional material provided Where variable ACPH rates are applied: 1.9 ACPH when there is one cooker operational (based on flow to biofilter). However, as

some addition extraction is applied directly to plant and equipment and is fed to the thermal oxidiser (TO), the total ACPH may be slightly higher.

ACPH by area: Raw Material Room 4; Dryer Room 9; Press Room 22. ACPH by area: RM Reception 2.6; Effluent Treatment Room 1.3; Filter Room 28.5; Meal

Lorry Loading Area 11.5; Meal Grinding & Sterilising 6.1; Process Area 4.8; Area above Cooker 25.1; Crushing Area 7.2.

ACPH by area: Raw Materials Building 10; Process Building 10; Meal Building 5.Where fixed ACPH rates are applied: Rates applied range from 2 to 10 ACHPWhere negative pressure is monitored: Monitoring negative pressure: 9 to -11 Pa; negative pressure monitoring is used to adjust

extraction rates.


• Summary of industry practice

Implementation of BAT – containment

Aspect Summary of responsesIs raw material deposited into a lidded hopper which allows air to be extracted directly from the raw material storage?

Yes: 21% No: 79%

What equipment is fully enclosed and extracted directly to an odour-control system?

Cooker: 94% Steriliser (where used): 84% Presses/centrifuge: 83% Meat and bone meal (MBM) coolers/grinder: 58%

Other plant which is enclosed and extracted to an odour-control system

Raw material bins, blood/waste water/tallow tanks. MBM handling system. Decanters/buffer tanks/bins.


• 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


• 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.


Material intake

Poultry processing

Storage

Meat outloading

Cooking Room Thermal oxidiser

Air lock


• 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.



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


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


Summary of impact assessment approaches used by operators

Implementation of BAT - active odour control -– risk assessment

Aspect Summary of responsesHow was (were) the height of the stack(s) serving the main odour control plant determined?

Manufacturer recommendation: 3% Using HMIP D1 calculation: 16% Using air dispersion modelling of air pollutants such as nitrogen dioxide: 34% Using air dispersion modelling of residual odour: 25% Not known / Other: 22%

Is there a stack serving the odour control plant which treats the air extracted from the buildings or back-up system?

Yes: 63% No: 37%

How was the height of this stack originally determined?

Manufacturer recommendation: 8% Using HMIP D1 calculation: 12% Using air dispersion modelling of air pollutants such as nitrogen dioxide: 24% Using air dispersion modelling of residual odour: 36% Not known / Other: 20%


• 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

(b) Higher stack(a) Lower

stack

Neighbouring industrial building

Transportation interchange station


• 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


• Summary of current practice


Aspect Summary of responsesHow are the fumes from the cookers/processors and presses/centrifuges treated?

30% use condensation + oxidation in boiler.

94% use a purpose-built oxidiser.

6% use a non-thermal control technique. This represents one small site employing a biofilter.What type of purpose-built thermal oxidiser (TO) is used?

73% have a recuperative TO (i.e. the plant has a back end boiler to recover heat as steam).

23% have a regenerative TO (i.e. the plant has a heat exchange system to utilise heat to warm incoming air). What is the target residence time and combustion temperature used in the TO?

8% have operating criteria of 0.81 second 850oC

15% have operating criteria of 1 second 850oC

15% have operating criteria of 2 second 850oC

62% have operating criteria of 2 second 950oCIf oxidation is carried out in the steam-raising boiler, what is the minimum rate of boiler firing?

Range of values from medium (ca. 30%) to high fire (ca. 70%)


• Example performance data – use of steam raising boilers


Category ABP processed Plant throughput (tpa*)

Firing rate Inlet (ouE/m3) Outlet (ouE/m3) Odour reduction (%)

Cat 3 Slaughterhouse and butchery waste 120,000 90%70%55%15%

1,420,0002,390,0002,982,0001,601,000

5,70022,50019,8009,100

99.6%99.1%99.3%99.4%

15% 2,771,000 418,000 84.9%

<40% 826,400 11,200 98.6%

Cat 1-3 Fat, bone, offal, knacker, blood, poultry, food waste, feathers and fallen stock

155,000 various20%

1,667,7253,389,706

5,6396,922

99.7%99.8%

Cat 1-3 Fat, bone, offal, knacker, blood, poultry, food waste, feathers and fallen stock

150,000 Not recorded 38,820,000# 26,950 99.93%##

6,700 99.98%

48,435,000# 29,500 99.94%##

6,850 99.99%


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.



Similar data and guidance is also presented for recuperative and regenerative thermal oxidisers:

• Example performance data

• Factors influencing performance:– Combustion conditions– Odour loading



• 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


Implementation of BAT – odour control – building air

• Summary of current practiceAspect Summary of responsesHow is the air extracted from raw-materials reception and the process building treated?

Biofilter using wood chip: 44%Biofilter using other media: 11%Chemical scrubber – single stage/scrubbing medium: 7%Chemical scrubber – multiple stage, single scrubbing medium: 4%Chemical scrubber – multiple single stages/scrubbing media: 11%Carbon filter: 4%Thermal oxidiser: 15%No treatment: 4%

Where a biofilter is used, is it covered, and is the treated air discharged through a stack?

Yes: 22%No: 88%

Where a biofilter is used, is the media replaced at defined intervals?

Yes: 67%No: 33%

Where a biofilter is used, have there been problems with the management of the media (e.g. drying out, compacting)?

Yes: 38%No: 62%

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


• 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


• Summary of current practice


Aspect Summary of responsesHow are the fumes from the cookers/processors and presses/centrifuges treated when the main combustion plant is unavailable?

Back-up incinerator: 5%Condenser only: 5%Condenser + boiler:– 30%Condenser + boiler then chemical scrubber (only used until part processed material is complete): 5%Condenser + chemical scrubber: 15 %Condenser + biofilter:– 30%All inlet and outlet valves closed to contain odours:.5%No treatment: 5%

How quickly does the back-up system become fully operational?

Instantly: 50%Within 3 minutes: 15%Not specified: 35%

How often is the back-up used? Every time the system shuts down: 55%Once a week: 5%Once a month: 5%Less than once a month: 5%Never: 5%not specified: 25%

How often is the operation of back-up checked?

Every time the system shuts down: 24%Once a day: 6%Once a week: 18%Once a month: 12%Never: 12%not specified:29%

Has the performance of the backup system been tested using olfactometry?

Yes: 47%No: 53%


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.


Sample point Outlet (ouE/s)Non condensable flow

Post acid scrubber

Post condenser

3,900,000

1,800,000

1,200


• 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


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


Summary of current monitoring practice

Compliance monitoring – industry practice

Aspect Summary of responsesAre odour measurements carried out on the odour-control system treating process/foul air?

Yes: 76%No: 24%

What techniques are used? Olfactometry: 38%Chemical: 19%Both olfactometry and chemical: 19%Other (not specified) : 24%

Are odour measurements carried out on the odour-control system treating building extraction air?

Yes: 67%No: 33%

What techniques are used? Olfactometry: 29%Chemical: 29%Both olfactometry and chemical: 21%Sniff test: 7%Other (not specified) : 14%

Are olfactometry tests required by conditions of a permit? Yes: 33%No: 67%

Has odour modelling been carried out? Yes: 71%No: 29%

Are measurements carried out during peak production? Yes: 53%No: 47%

Have measurements been carried out during abnormal operation?

Yes : 24%No: 76%


• The report seeks to draw on established monitoring and assessment methods published elsewhere:

Compliance monitoring – techniques covered

Guidance document

SG8 Irish EPA AG5 (EPA, undated)

H4 (Environment Agency, 2011)

(Northern Ireland Environment Agency, 2012)

SEPA Odour guidance (SEPA, 2010)

Odour guidance for Local Authorities (Defra, 2010)

Techniques for odour monitoring Sniff test Section3 Section 5.4 Section 3 Section 1.6.3 Section 4.4Odour diaries Section 4 Section 5.5 - Section 4.5Olfactometry Section 2.4 Section 5.6 Section 1.6.2 App 3Chemical quantification Section 2.4 Section 5.7 Section 1.6.1 App 6Operator self-monitoring Section 2.5 Section 5.1 Monitoring of process parameters Section 5.8 Techniques for compliance monitoring Atmospheric dispersion modelling Section 3.24 App 3 Section 1.6.2 Section 4.2Regulatory compliance visits


The report summarises the principles behind a range of monitoring approaches that you may have come across:

• Use of diaries and other data gathering methods to assist in identifying the existence, cause and extent of an odour problem.

• Sniff tests, as this relates to the test included in a typical odour boundary condition, may be applied by regulators and operators.

• Testing for odour using surrogate chemical measurements (e.g. hydrogen sulphide and other reduced sulphur compounds, ammonia and amines).

• Olfactometric analysis in accordance with European Standard EN ISO 13725:2003: “Air quality. Determination of odour concentration by dynamic olfactometry”.

• The use of dispersion modelling to substantiate and develop odour measurements and survey reports.

As with other aspects of the report it provides “do’s and don’t” on each technique and considers the level of uncertainty associated with each technique.

Compliance monitoring – techniques covered


Invariably odour emissions from the rendering process will be caused by parameters within the process or the control system deviating from the ideal or normal situation.

The deviation from the normal situation may only occur for a short period, but this may be sufficient for an offensive odour to be released beyond the boundary of the site.

Good process monitoring focused on the correct parameters may show the root cause of such an emission.

Examples of the type of periodic process monitoring that may be applied are:

• Raw material delivery and inspection;

• Signs of potential blockage/damage/leakage of surfaces/sumps/interceptors/drains;

• Integrity of buildings (only those parts that can be accessed);

• Internal and external housekeeping activities;

• Maintenance/repairs/replacement carried out on critical plant;

• Depressurisation of batch cookers/sterilisers

Compliance monitoring – process monitoring


Examples of the type of continuous process monitoring that may be applied are:

Compliance monitoring – process monitoring

Odour control plant ParameterBoiler (when used for odour control) Exit temperature

Excess oxygenSteam demand of the process

Thermal oxidisers Exit temperatureExcess oxygenCarbon monoxideSteam demand of the process

Chemical scrubber pHRedox

Biofilter TemperaturePressure

Condenser Inlet and outlet temperatureExtraction system Negative pressure

Fan operation (e.g. volume flow rate)


Site inspections provide a means of critically assessing current performance of a facility against BAT.

The report suggests that there are three basic types of inspection:

• Routine inspections - the report describes that as a walk around inspection in order to carry out a thorough visual check upon compliance with licence conditions and ensure that no pollution is likely to be caused. There may a targeted focus to the inspection (e.g. completeness of records, complaints investigation)

• Incident response – may be carried out in response to complaints. The objective is to identify potential breaches of conditions or pollution at a rendering facility.

• Full site audit – these are usually more detailed site inspections providing a comprehensive review of the site’s compliance with some or all of its permit conditions (and, in the case of noncompliance, an investigation into the reasons for the noncompliance). An audit may also include a thorough assessment of the site’s operations against its operation procedures.

Compliance monitoring – site auditing


• An example site inspection carried out is provided and includes:– Reference to a series of smoke tests which were observed– A general check of records, logs, procedures etc.– The findings of a general site work over

Implementation of BAT – site auditing

No time photos location1 13:20 1a Meal shed: very low wind speed. Lots of orange smoke seen along western eaves (side

adjacent to backyard), eastern eaves obscured, and lots of smoke also seen at southern side2 13:36 2z Meal lorry loading area: lots of orange smoke seen along western eaves (side adjacent to

backyard)3 13:40 3a Filter house/ tallow filter room: lots of orange smoke from western eaves (not from adjacent

pipe as white smoke/steam undiluted with orange) and possibly from roof ridge.4 13:50 4a DAF plant: no smoke observed.5 14:05 5a Boiler house (NB boiler off): orange smoke observed from eastern corner6 14:15 6a Press area – no smoke observed7 14:25 7a Lots of orange smoke observed exiting through roof of CG tower around the cladding inside

the parapet wall and through roof hatches.


• The objective for the management of odour is to ensure that there is continual improvement – the odour situation will be better this year that last year.

Implementation of BAT – site auditing


Management of odour

The report compares and contrasts various techniques for the management of odour:

• Management through the application of SG8/ Irish BAT guidance via the permit

• Management through a site specific Odour Management Plan

• Management through a third party audited Environmental Management System


Permitrealisationroute

Activity-specificContinuousimprovementelement

Reflectscurrentactivity BAT

Third-partyaccredited EN Standard

SG8 & Irish BAT guidance

Yes No Yes No NoAdvantages – can define permit conditions based on BAT statements. Provides sector-wide definition of BAT.

Disadvantages – no element of continuous improvement specific for odour management. Review period driven by permit updates (4 yearly) and BREF review, sector-wide consultation on changes.

OMP Yes Yes Yes No NoAdvantages - allows dynamic development of odour management in response to changes in process/experience. More operator involvement in deciding management of process perhaps than in SG8-defined conditions.

Disadvantages - Not definitively part of BAT but could be argued to be part of EMS. A poor or unsupported OMP will not aid management of installation impacts or regulatory burden.

EMS No Yes Yes Yes YesAdvantages - allows dynamic development of odour management in response to changes in process/experience. May have more operator involvement in deciding management of process than in SG8-defined conditions. External accreditation may allow move to ‘light touch’ supervision.

Disadvantages - EMS may be too generic to allow rigorous management of odour. Odour control may effectively pass partly to EMS auditors, who are unlikely to have expertise or resources to focus on odour management.

Management of odour


Management of odour

In relation to the management of odour the report concludes:

• To be effective, an OMP needs to be endorsed and operated by all levels of the installation management. The OMP needs to be a structured management tool that identifies and sets out control measures for all the operations that have the potential to release odour. It must also include mechanisms to review and address issues and ensure improvement and development of the OMP.

• Each of the three options considered in the report has benefits and draw backs.


Management of odour – practical guidance

The report provides practical guidance on the areas of plant operation and management that should be considered:

• Source identification and characterisation

• Critical path identification/definition

• Monitoring of critical parameters

• Control measures

• Site-specific odour evaluation

• Odour monitoring

• Communication

• Site management and training

• Review

The report provides an example OMP.


Management of odour – case studies

The report is re-enforced by reference to a series of case studies:

• Case study 1 – Odour management philosophy– Viewed as an integral part of the animal rendering process, not as a separate activity.

– Awareness of philosophy reinforced via regular training and updates.

• Case study 2 – Odour risk evaluation – Need to detail all potential sources/conditions which give rise to odour

• Case study 3 Data recording– Highlights benefit of recording details of process parameter in a usable format

• Case study 4 - Site liaison committee– Highlighting benefit of open relationship with stakeholder

– Operator need to be seen to deliver on promises

• Case study 5 - Dealing with complaints– Highlights benefit of attention to detail when designing odour control plant

– Illustrates benefit of building good relationships with stakeholder


Legal cases

The report

• Reviewing recent (1999 – 2011) legal proceedings relating to odour. It draws on relevant odour cases (both rendering and non-rendering) and provides examples of:– Prosecutions for breach of permit conditions;– Public nuisance action;– Planning appeals; and– Ombudsman cases;

• Almost all the cases considered demonstrate the repetitive nature of regulatory infractions arising from animal rendering operations. This suggests that the regulatory tools currently available are inadequate. A more targeted risk-based approach, which utilises a range of direct measures, might be more effective in allowing earlier intervention and avoiding cumbersome criminal processes.

• Operators who breach odour regulations have often breached a range of other regulations. In many cases, it is the larger rendering businesses which are responsible for repeat offences, unlike in other sectors. Regulators should be aware of factors such as regulatory history of the site, the operator’s record of compliance and any non-odour regulatory failings of the operator’s business.


Legal cases - examples

Site Type Issue Decision OutcomeDundas Brothers Limited

Various prosecutions for breach of permit

Numerous breaches of permit between 1999-2002- relating to raw material processing, spills, building maintenance and the standard of odour control equipment

Pleaded guilty Fines imposed [£23K] Permit revoked/site closed[later reopened by another operator]

Cluttons Agricultural Various prosecutions for breach of permit (2000) and ABP Licence (2007)

exceeded permitted throughput, poor record keeping, making false statements

Poor raw material management leading to decomposing material on site

Pleaded guilty Fines imposed [ £175K]

Milka v Chetwynd Animal By-Products Ltd

Private nuisance Poor site operation and odour management

Found in favour of the claimants

Compensation awarded

Sacone Environmental Limited[Glasgow & Brechin]

Various prosecutions between 1999 and 2009

Various cases relating to state/performance of odour control plant, raw materials management

Found guilty in all cases

Fines imposed [ £30K]

Fairfield Piggeries / RJ Compton & Sons

Planning appeal relating to permit application

Refused to issue permit on the basis that the operator would be unable to comply with permit conditions

Appeal dismissed

Barr v Biffa Private nuisance Whether a site operating under a EPR permit can be subject to private nuisance

Found for the claimants

A site operating under a EPR licence can still be subject to a private nuisance action



Site Type Issue Decision OutcomeUlster Farm By-Products Various prosecutions

relating to water quality and odour from 2002 on wards

Breach of ammonia limits and failure to use BAT for odour control; also issues relating to storage and handling of materials; and maintenance

Pleaded guilty Fines imposed [£105K]

Ombudsman case Failures relating to the regulation of the site

A degree of maladministration found

John Clarke Farms, Bury St Edmonds

Planning appeal relating to permit application

Refused to issue permit on the basis of historic complaints and adequacy of controls

Appeal allowed

Moy Park Prosecution relating of odour from poultry rearing

Poor practices including shed doors being left open, litter (bedding) capped and visibly damp underneath, badly maintained hard standing and no method of segregating rainwater from dirty water

Pleaded guilty Fine and costs imposed (£42K)

John Knights Appeal to vary permit Seeking permission to reduce boiler firing rate limit

Appeal dismissed

Prosecution relating of breach of permit 2008-11

Various permit breaches Pleaded guilty to permit breaches, with breaches of OBC left on file

Fine and costs imposed (£150K)



Legal material supported by a case study on “permit revocation”

• The case study describes the way the Irish EPA handle a persistently bad operator and highlighted the following problem areas– management and permit compliance leading to

serious odour

– siting of plant

– relationship with stakeholder

– Inability to upgrade OCS to control odour

• The case study showed– the need for Careful siting of plant

– the need for Increased regulatory action may be required on some sites

– That the regulatory process can be long and drawn out


Legal cases - conclusions

Example cases show they are generally decided on the basic failures in management and/or operating practices, rather than on breaches (or potential breach) of an OBC.

• Thus to mount a successful actions it is clear that the regulator must have a good understanding of the process -

Almost all of the cases above demonstrate the repetitive nature of regulatory infractions arising from animal rendering operations. This suggests that the regulatory tools currently available are inadequate, assuming that the goal of regulation is not merely to punish infractions but also to anticipate them and avoid their occurrence.

• Overcome by instilling a philosophy of self-regulation by means of improving management of odour??

Operators that breach odour regulations have often breached a range of other regulations, both environmental (e.g. water, air) and non-environmental (e.g. health and safety, competition).


Conclusion

We hope that

• The report as a whole provides additional material, which taken alongside the existing statutory guidance will aid you in improving the management and control of odour at rendering facilities.

• The information contained in the report shows that rendering plants can be operated so that their impact on the local community is minimal. In order to achieve this it is necessary to treat odour management as a principal function of the process activity rather than as a supplementary issue.

© Ricardo-AEA Ltd

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Ricardo-AEA LtdThe Gemini BuildingFermi AvenueHarwell, Didcot, OX11 0QR

Dr Nigel Gibson

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