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Reducing water and waste costsin fruit and vegetable processing
GG
280
This Good Practice Guide was produced by
Envirowise
Prepared with assistance from:
Ashact Ltd
Reducing water and waste costsin fruit and vegetable processing
Summary
The UK fruit and vegetable industry generates significant amounts of waste water,wasted raw material and packaging. Implementing a systematic waste minimisationprogramme can reduce waste costs by up to 25%. This can represent 1% of businessturnover. These savings can often be achieved by changes in good housekeepingpractices and by implementing no-cost and low-cost measures resulting in immediatesavings or payback periods of less than two years.
The industry uses large quantities of water, most of which leaves factories as trade effluent.Water supply costs and trade effluent charges are expected to continue to rise. Reducing waterconsumption and minimising effluent strength and volume therefore make good business sense.Measures to reduce water use can often achieve a 20 - 50% reduction in water-related costs andmake a valuable contribution to any waste minimisation programme.
This Good Practice Guide is concerned with fruit and vegetable processing after harvesting andhow companies can save money by reducing, re-using and recycling waste. It does not giveinformation on waste disposal, energy efficiency and agricultural practices.
The Guide describes practical measures to eliminate, reduce, re-use and recycle waste and givesadvice on how to eliminate waste through effective conservation of produce. Industry Examplesthroughout the Guide illustrate how fruit and vegetable processing companies have alreadysaved money by implementing a systematic approach to waste minimisation.
The Guide explains how to:
■ produce process maps and prepare an overall mass balance;
■ identify sources of waste;
■ calculate the true cost of waste;
■ look for opportunities to reduce water and waste costs;
■ implement a systematic waste minimisation programme;
■ continue to improve your environmental performance.
Preventing waste in the first place, ie before value is added to your product, will give the greatestsavings. However, significant cost savings and environmental benefits can still be achieved byreducing, re-using and recycling waste. Remember, any reduction in water and waste costswill go straight to your bottom line.
Contents
Section Page
1 Introduction 11.1 Why minimise water and waste? 11.2 How much can I save? 1
2 Carrying out a waste review 52.1 Step 1: prepare a mass balance 52.2 Step 2: add detail 72.3 Step 3: identify costs 9
3 General measures to reduce your waste costs 113.1 Managing your waste minimisation programme 113.2 Eliminate waste 153.3 Reduce waste 163.4 Re-use waste 173.5 Recycle waste 193.6 Continual improvement 20
4 Measures to reduce waste by conserving produce 224.1 Preventing food spoilage 224.2 Washing and sanitising 24
5 Action Plan 265.1 Further help and advice 27
Appendix Blank forms 29
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Introduction
1.1 Why minimise water and waste?
Water and waste form a significant part of the operating costs of many fruit and vegetableprocessors. These costs will continue to rise above the rate of inflation because of:
■ increases in water supply and effluent costs as a result of higher wastewater treatmentstandards;
■ increases in the landfill tax to £15/tonne by 2004;
■ action to meet targets in the landfill directive to reduce the amount of biodegradable wastegoing to landfill disposal;
■ stricter controls on packaging waste;
■ implementation of the Integrated Pollution Prevention and Control (IPPC) regulations in the UK.
The average cost of mains water for industrial uses increased by 18% between 1997 and 1999.Trade effluent charges have increased, on average, by 16%. This trend is likely to continue aswater companies seek to recoup the large investment required to upgrade sewage treatmentworks to meet higher environmental standards.
Landfilling your waste is becoming an increasingly expensive option. Reducing, recycling orcomposting your waste will save you money while helping to protect the environment. Minimisingwaste is also a key aim of the IPPC directive, which will apply to the UK food industry by 2008.
Packaging waste is another important issue for the industry. Companies with an annual turnoverof £2 million and which handle over 50 tonnes/year of packaging materials are now obliged totake responsibility for recovering and recycling a specified proportion of the packaging wasteassociated with goods they process or sell1.
1.2 How much can I save?
Waste is not just unwanted materials that need to be disposed of. It also includes:
■ wasted raw materials;
■ unnecessary or excessive use of chemicals and water;
■ wasted packaging;
■ wasted time and effort;
■ wasted energy.
The total cost of waste (see Fig 1) can be 5 - 20 times more than your actual disposal costs andcan range from 5 - 20% of your production costs. Every process you undertake generates wasteand is, therefore, a target for waste minimisation.
For the latest advice about the environmental legislation governing your operations,contact the Environment and Energy Helpline on freephone 0800 585794.
1 Producer Responsibility Obligations (Packaging Waste) (Amendment) Regulations 1999.
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The true cost of waste makes up an average 4% of a typical business’ turnover. Mostcompanies can achieve savings of at least 1% of turnover by implementing a systematicwaste minimisation programme.
Companies often think that waste costs are much less than they really are. For example, in arecent survey ten companies estimated their waste to cost a combined total of £500 000/year.However, the actual cost turned out to be £13 million/year. Many companies have achievedeffective waste reduction through simple no-cost and low-cost measures with payback periodsof less than a year.
The fruit and vegetable industry generates substantial amounts of wasted raw material. Onsome processing lines, as much as 50 - 60% of produce (by weight) is discarded. Water use infruit and vegetable processing varies enormously. Companies that have not implemented anywater saving measures can often reduce water and effluent costs by 50%. Companies that haveimplemented some measures - but not adopted a systematic approach - can typically achieve a20% decrease in water and effluent costs.
There is a priority in the way waste should be dealt with to maximise cost savings and thebenefits to the environment (see Fig 2). Understanding the waste hierarchy will help you toidentify the most cost-effective savings to be made in your company. Eliminating waste is thebest option. The next best option is to minimise waste production at source. Followingreduction, you should aim to re-use. Waste can also be recycled or given/sold to someone thatcan find a use for it - thus saving you the cost of disposal.
Wastedwater
Wastedpackaging
Lost product■ Raw material loss
■ Lost profit from sale of product
■ Water charges
■ Landfill charges
■ Operation of site’s effluent treatment plant or trade effluent charges
Effluenttreatment
Fig 1 The true cost of fruit and vegetable wastes
Assume that a fresh salads processing company with a £2 million turnover makes 5%,or £100 000 profit each year. Waste costs the company around £60 000, or about 3%of turnover, as a result of unnecessary material costs (reduced yield) and disposalcosts. Reducing these costs by only 10% will put £6 000, or an extra 6%, on thebottom line. In many companies it will be possible to reduce waste by 25% or more,adding at least 15% to the profit.
Waste reduction increases profits
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■ Minimise waste at source through reducing material losses and improving process efficiency,and:
- reduce raw material costs;
- reduce the strength and volume of your effluent, thus reducing effluent treatmentand disposal charges;
- reduce solid waste disposal costs.
■ Re-use waste streams, and thus reduce disposal costs.
■ Recycle where re-use is not possible.
This Good Practice Guide describes tools to help you review your processes and identify optionsfor reducing waste. The Guide is concerned with fruit and vegetable processing after harvestingand how companies can save money by reducing, re-using and recycling waste. It does not giveinformation on waste disposal, energy efficiency and agricultural practices.
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3
45
WASTEONLY
Eliminate
Reduce
Re-use
RecycleDispose
Product
Material
Fig 2 The waste hierarchy
For general advice on waste minimisation and all other environmental issues, contactthe Environment and Energy Helpline on freephone 0800 585794.
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Fisher Foods employs 750 people at its Methwold site in Thetford and has an annualturnover of £45 million. The main production lines are prepacked mixed leaf saladsand shredded lettuce. An extensive monitoring programme was undertaken toprepare process maps and identify raw material costs. These amounted to £20 million/year. When the results of the study were reviewed at the site’s regularwaste management meetings, three areas were identified for priority action:
■ Unnecessary disposal of good quality off-cuts. Off-cuts of cabbage, carrots andlettuce are now used, where possible, in other products for retail outlets. Thisrepresents savings of £50 000/year.
■ Unsuitable process control. The spin-drying process damaged produce, whichthen had to be discarded. Operating conditions were reviewed and optimised tokeep produce damage to a minimum. The speed, time and acceleration rate ofthe drying cycle were adjusted, while the temperature was left the same.
■ Unsuitable process design. Mechanical handling damaged produce, which thenhad to be discarded. Use of redesigned raw material cage liners and installationof a new lifting and tipping machine have minimised damage and achievedsavings of £250 000/year.
Implementing these and other changes has produced total cost savings of£400 000/year. This saving represents almost 1% of the company’s turnover. Manyof the changes involved adjusting existing systems rather than large capitalinvestment.
Waste minimisation programme saves 1% of turnover
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5
Carrying out a waste review
Significant cost savings can be achieved for little or no investment simply by improvingyour housekeeping and operating practices.
Understanding material flows through your process is the key to achieving these cost savings.This Section explains how to carry out a waste review to:
■ determine your current situation;
■ identify opportunities where you can make immediate or large savings.
Section 3 describes a range of practical measures to reduce waste costs, while Section 4considers how to eliminate waste by preventing spoilage.
The waste review involves:
■ preparing a mass balance for your process;
■ adding the detail;
■ identifying the costs.
Various tools are provided in the Appendix for you to photocopy and use in your waste review.
2.1 Step 1: prepare a mass balance
Start by drawing a flow diagram showing the main steps in your process. A typical example forfruit and vegetable processing is shown in Fig 3. Be thorough - consider both your core businessand support operations. Also remember to include seasonal activities, eg provision of a canteenor other facilities for short-term employees.
Fig 3 Example flow diagram from a fruit and vegetable processor
Sanitise
Harvest Sort Trim Wash
Peel, cut, grate,shred etcRinseBlanch
Cool Package StoreFreeze
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Now look at each process step in turn and identify all of the inputs and outputs for that step.Use the waste opportunity checklist in the Appendix to help you identify your sources of waste.List the inputs and outputs for each step on a process map like the one shown in Fig 4 forsanitising. This list will be useful later in the waste review when you calculate quantities andcosts (see Sections 2.2 and 2.3).
Once you have looked closely at the inputs and outputs for each step in your process, you cansummarise the information for the whole process in a mass balance diagram. An example isshown in Fig 5. A water balance is a numerical account of where water enters and leaves yourbusiness and where it is used within the business. It typically contains information about theamount of water used by each main process and may, for some processes, be very detailed.Presenting the water balance as a diagram makes it easy to understand and use as amanagement tool. This is the first step of a waste review and may highlight areas where youcan make immediate savings.
SANITISE
SANITISE
SANITISE
SANITISE
SANITISE
SANITISE
SANITISE
SANITISESANITISE
■ Cold potable water■ Sodium hypochlorite■ Citric acid solution■ Ascorbic acid solution■ Activated carbon for air scrubbers■ Electricity, eg to power water chiller and dosing system■ Labour■ Maintenance etc
■ Wastewater■ Fruit and vegetable juice■ Soil/dirt/micro-organisms■ Residual hypochlorite■ Gas emissions■ Spent activated carbon from air scrubbers■ Wasted energy■ Maintenance waste, eg replaced parts
INPUTS
OUTPUTS
Fig 4 Typical process map for sanitising
PROCESS
WASTE
WASTE
Product
EnergyEmissionsto air
Solid waste TradeeffluentDamaged
and off-specproducePeelingsPackagingUsedconsumables
Chargesdepend onvolume andstrength
Raw materialsProduceSanitiserCommercial washing agentAntioxidants
PackagingPalletsWooden boxes/cratesCardboardPolythene/netting
ConsumablesMob capsApronsEar defendersGloves
Utilities or servicesWater (incl. cooling water)EnergySteamCompressed air
Fig 5 The mass balance approach
Contact the Environment and Energy Helpline on freephone 0800 585794 for detailsof other free tools and advice to help you identify and record sources of waste.
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Although solid wastes often affect effluent costs by increasing effluent strength, it is a good ideato look at water issues separately. For example, prepare one mass balance for water andwastewater and another for solid materials and wastes. Fig 6 shows a simple water massbalance for fruit and vegetable processing.
Walking round your site at different times will help you to identify the main areas where wateris used. Try to do this during different shifts and during periods of non-production, eg whenmachinery is switched off and out-of-hours. A walk-round review of your site will also help youto identify where solid waste, eg packaging, is occurring.
Good Practice Guide (GG152) Tracking Water Use to Cut Costs describes a step-by-stepapproach to generating a water mass balance. GG152 is available free of charge through theEnvironment and Energy Helpline on freephone 0800 585794.
2.2 Step 2: add detail
The flow diagram of your business operations and the series of process maps form the basis ofthe waste review. The next step is to add the detail. This can be divided into:
■ recording data;
■ quantifying inputs and outputs.
2.2.1 Recording data
Inventories help to record the information and data collected during the preparation of the massbalance(s) in a systematic manner. These records will be a useful reference during your wasteminimisation programme. They will also help you, should you wish to implement anenvironmental management system (EMS).
Water addedto product
Water in
Leaks to ground Effluent
Evaporation
Fig 6 Simple water mass balance
Remember:What goes in must come out ... somewhere.
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Process inventoryBegin by producing a detailed list of your processes. Fig 7 shows an example process inventory.A blank copy of this inventory is given in the Appendix for you to photocopy and use at yoursite. You may want to note the location of each process and/or give it a reference number foruse on all paperwork associated with the waste review and ongoing improvements.
Input and output inventoriesNow focus on the inputs and outputs for each process.
■ Photocopy and use the blank forms provided in the Appendix to prepare an input and anoutput inventory for each process.
■ Using the process map, list all the inputs and outputs (raw materials, utilities, wastes etc) onthe appropriate inventory. Be as thorough as possible - don’t just list the items you think areexpensive.
These inventories give you somewhere to record the quantities and costs for each input andoutput.
2.2.2 Quantifying inputs and outputs
To determine the true cost of waste and the potential cost savings from reducing waste you needto calculate the size of each input and output.
Fig 7 Example inventory of processes
INVENTORY OF PROCESSES
Site: ABC Foods Prepared by: A. Manager
Page: 1 of 1 Date: 28 January 2000
Process: Location/reference number:
Harvesting Field
Sorting and trimming (field) Field
Transport Transport
Pre-cooling Bay 1
Cold store Store
First wash Bay 2
Steam peeling Bay 3
Cutting Bay 3
Second wash Bay 4
Sanitising Bay 4
Rinsing Bay 4
Centrifugal dewatering Bay 4
Packaging Bay 5
Cold store racking Bay 6
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■ Look at existing paperwork held on-site, eg meter readings, utility bills, purchase ledgers andwaste disposal records.
■ Ask the relevant people both inside and outside the company, eg purchasing manager, wastemanager and suppliers.
■ Take simple measurements, eg using a bucket and a stopwatch to measure waterconsumption or weighing the amount of solid waste produced over a known period of time.
■ Use consistent units to keep calculations simple and free from errors.
■ Add the data to your input and output inventories.
2.3 Step 3: identify costs
Now take your inventories of inputs and outputs and calculate the costs associated with eachprocess step.
■ Gather information on unit costs from sources such as purchase orders, utility bills andcharges for special waste consignments and sending waste to landfill.
■ Keep the units simple and consistent. Link amounts to a unit of production, eg £/tonne oflettuce.
Fig 8 shows part of a filled-in inventory of inputs and Fig 9 shows part of a filled-in inventory ofoutputs. Similar blank inventories are given in the Appendix for you to photocopy and use atyour site.
Waste Mapping: Your route to more profit (ET219) explains how to quantify yourinputs and outputs. Good Practice Guide (GG152) Tracking Water Use to Cut Costsdescribes how to measure flows and calculate water use. These free publications areavailable through the Environment and Energy Helpline on freephone 0800 585794.
Fig 8 Part of an example inventory of inputs
INVENTORY OF INPUTS
Process: Sanitising Prepared by: A. Manager Date: 28 January 2000
Type Amount used Unit cost (£)
Chlorinated water 3 m3 of mains water (containing £2.04 mains water/tonne of 2.4 litres of hypochlorite lettuce £0.79 hypochloritesolution) per tonne of lettuce solution/tonne of lettuce(hypochlorite contains 14-15% Total = £2.83/tonne of lettucefree chlorine)
Fig 9 Part of an example inventory of outputs
INVENTORY OF OUTPUTS
Process: Sanitising Prepared by: A. Manager Date: 28 January 2000
Type Amount produced Unit cost (£)
Sanitising 3 m3 of wastewater per tonne of £2.91 effluent charges/tonne of wastewater lettuce lettuce
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2.3.1 Prioritise
Rank your inputs and outputs in order of cost. Prioritising will make your waste minimisationprogramme more cost-effective. A small reduction in a major area could give much greatersavings than a large reduction in a minor area.
Your inventories will give you a good basis for continual improvement. When you have reducedthe more expensive wastes, other waste streams will move up the ranking.
Calculating the cost of waste from different processes highlights the increasing value of materialsas they pass through successive processing stages. For example, potatoes discarded after theyhave been peeled, sliced, blanched and cooled will have a higher value, ie £/tonne, than eitherraw potatoes or potatoes discarded after the initial wash.
If you need help to carry out any of the steps of the waste review, contact theEnvironment and Energy Helpline on freephone 0800 585794.
G’s Marketing Ltd employs 140 people at its fresh vegetables production site atSoham in Cambridgeshire. There are four main production lines: onion, broccoli,leek and celeriac. Annual turnover in 1997 was around £18 million. Process mappingallowed the company to develop a mass balance of the site’s operations. Thishighlighted areas where savings could be achieved. These included:
■ Eliminate waste at source. Customer specifications required broccoli to betrimmed to produce uniform-sized florets. This resulted in substantial off-cuts.Much of this waste was used for animal feed, but the management felt that analternative use could be found for good quality broccoli off-cuts. Expanding itsproduct range to include packs of florets enabled G’s to increase the raw materialyield significantly.
■ Reduce the amount of waste generated.
- The standard trays used to package leeks were larger than necessary.Replacing these with half-size trays reduced pallet movements by 45%. Thisresulted in a saving of around £1 600/year.
- Half-size plastic liners were used to replace standard liners on the celeriac andfennel packaging lines. This resulted in a saving of around £400/year,equivalent to 40 000 half-size liners.
■ Re-use the waste that is generated. Fennel arrived at the site packaged in cardboardboxes. Previously, these boxes were sent for landfill disposal. However, G’s identifieda supermarket chain that was prepared to receive celeriac consignments in usedboxes. Re-using 7 000 boxes/year achieved savings of £1 000/year.
■ Recycle water to minimise consumption. Most of the water used at the site wasfor washing the celeriac. Now, the wash water is recycled throughout the dayand then discharged to a sedimentation lagoon. At the end of the day, theproduction line is rinsed with fresh mains water. This procedure keeps water useto as low as 1.8 m3/day.
Process mapping highlights savings opportunities
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General measures to reduce yourwaste costs
This Section describes a range of practical measures to reduce waste and thus save money.
Apply the questions in Fig 10 to each waste stream in turn, starting with the priority wastesidentified by your waste review (see Section 2.3.1). Tackling waste at the earliest level of thewaste hierarchy as possible, ie eliminate > reduce > re-use > recycle, will give the greatest costsavings. A checklist of no-cost and low-cost measures to reduce water and waste costs is givenin Table 1. Measures to eliminate waste by conserving produce, eg preventing spoilage andeffective sanitising, are considered in Section 4.
Before making any changes to your cleaning and washing regime, you must ensure that allrelevant hygiene standards will be met. Refer to your trade association guidelines, eg the ChilledFood Association Guidelines for Good Hygienic Practice in the Manufacture of Chilled Foods,ISBN 1 901 798 00 3.
Measures to reduce packaging use and costs are summarised in Table 1. For more advice, seeGood Practice Guide (GG157) Reducing the Cost of Packaging in the Food and Drink Industry.GG157 and other free publications on packaging are available through the Environment andEnergy Helpline on freephone 0800 585794.
3.1 Managing your waste minimisation programme
The success of any waste minimisation programme depends on involving everyone in the company.
■ Set up a waste minimisation team with members from all levels and departments.
■ Ask the team to prepare a policy statement accompanied by some realistic no-cost and low-cost options to reduce waste. These should show how significant savings can be madeimmediately and will help to generate interest in the scheme.
■ Obtain senior management approval for the policy statement and the waste minimisationprogramme. Making waste minimisation part of the company’s work policy encourageslong-term commitment.
■ Keep everyone informed about progress and changes to work practices. Provide training asnecessary and ensure everyone understands the benefits of minimising waste.
Can you eliminate waste at source?
Can you re-use the waste generated?
Can you recycle the waste generated?
Dispose of the waste correctly - notingthe cost for subsequent waste reviews.
Can you reduce the amount of waste generated?
No
No
No
No
Implement waste saving measure
Fig 10 Following the waste hierarchy
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33
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nolo
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Min
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W
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d Ef
fluen
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C
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w-c
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mea
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wat
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te c
ost
s
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The role of the management team is explained in Good Practice Guide (GG27) Saving MoneyThrough Waste Minimisation: Teams and Champions. GG27 is available free of charge throughthe Environment and Energy Helpline on freephone 0800 585794.
3.2 Eliminate waste
Eliminating waste at source is not only the best way to prevent pollution, it is often the mostcost-effective option. Rotating chemical stocks and buying only the quantities you needeliminates out-of-date chemicals. Avoid excessive chemical use by weighing chemicalsaccurately and using automated dosing.
Customers that demand a certain size of produce can lead to otherwise good quality wholeproduce or off-cuts being wasted - at a substantial cost. Try discussing a change in specificationwith the customer or find additional customers with less stringent specifications or alternativeend-products such as soups and ready-meals.
Damp floors covered with discarded produce provide perfect conditions for microbial activity. Itis, therefore, important to keep floors clean, dry and free of produce. To contain produce andavoid it being dropped on the floor, fit guards to conveyor belts and trays below machines.
Using a hose to clean floors and surfaces can consume a large volume of water, especially if thehose is left unattended or forgotten. Use brushes, squeegees and scrapers to remove solids fromareas before they start to dry out, thus minimising or often eliminating the need for water.Caked-on dirt can take longer to remove and lead to corrosion if the slurry has a high acid, alkalior salt content, eg acidic fruit juices generated during minimal processing, use of sodiumhydroxide during caustic or lye peeling, and salt dipping to remove moisture from vegetablesprior to freezing.
Hoses left unattended or forgotten are a common source of unnecessary water use. Alightweight trigger-grip nozzle attachment can cost as little as £25 and is easy to fit. Releasingthe trigger-grip switches off the water, thus eliminating unnecessary use. For more informationabout trigger nozzles and other water saving measures, see Good Practice Guide (GG154)Reducing the Cost of Cleaning in the Food and Drink Industry and Good Practice Guide (GG67)Cost-effective Water Saving Devices and Practices2.
A team of employees was set up at G’s Marketing Ltd’s fresh salads production siteat Barway in Cambridgeshire to look at opportunities to reduce waste on the celeryline. The celery was previously hand-collated and check weighed. Installing a multi-head weighing machine at a cost of £100 000 resulted in savings of £110 000/year.This represents a payback period of 11 months. Savings were achieved by:
■ lower product give-away as a result of accurate weighing;
■ reduced use of packaging film due to use of smaller bags;
■ reduced labour costs.
Closer control of weighing and packaging brings substantial savings
2 Both Guides are available free of charge through the Environment and Energy Helpline on freephone0800 585794.
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3.3 Reduce waste
Waste can always be reduced. If the payback seems poor, check that all the hidden costs andbenefits have been taken into account. Also, bear in mind that operating costs (eg rawmaterials, water supply, energy, transport, landfill fees and effluent charges) and externalpressures for improvement, eg stricter legislation, will continue to increase.
3.3.1 Choice of process
Careful process selection and design can significantly reduce your water, effluent and solid wastecosts without compromising process quality.
You will also reduce waste costs if you optimise trimming procedures and process conditions,remove soil from produce in the field, remove soil from produce mechanically (but withoutdamaging it) and monitor chemical use.
A factory in Manchester, employing 100 people, manufactures jam on threeproduction lines. Little was known about how water was used on-site as only incomingwater was metered. Water consumption and flow rates were monitored for 24 hoursusing a bucket-and-stopwatch approach. Cleaning was identified as an area of highconsumption; in particular, hosepipes in the fruit room were found to use 17% of thesite’s water consumption. This resulted in water supply and effluent costs of£9 700/year. Trigger nozzles were fitted to the hosepipes and operators trained in theiruse. The attachments and training cost only £100, but resulted in savings of £3 000 -£4 000/year. The payback period was, therefore, less than two weeks.
Trigger hoses reduce water costs significantly
Water use and waste arisings were compared for wet and dry caustic peeling at a plantprocessing 72 tonnes/day of table beet. For the same quantity of produce processed,dry peeling reduced water use by 75% and solid waste by 90% compared to wetpeeling. In addition, the effluent generated during dry peeling contained 88% lesssuspended solids, 94% less COD3 and 93% less BOD4 than that from wet peeling.
Dry peeling scores over wet peeling
One of Fisher Foods’ sites produces bags of mixed leaf salads and shredded lettuce. Rawmaterial costs of £20 million/year meant that improved raw material yield was anobvious priority area for the company’s waste minimisation programme. Trimmingswere identified as one of the main areas of waste. When current practice was reviewed,the company found that trimming was often excessive. To overcome this problem,operators were given training and the trimming lines began to be supervised.Photographs of correct trimming procedures were displayed in the trimming areas toguide operators. The scheme cost £30 000 to implement, but resulted in cost savings of£100 000/year. This represents a payback period of 3.6 months.
Training results in cost savings
3 Chemical oxygen demand.
4 Biochemical oxygen demand.
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3.3.2 Process location
Off-site processing can significantly reduce the amount of waste that needs to be disposed of,thus saving you money and effort.
Consider sorting, trimming and washing produce in the field and then ploughing the soil andwaste produce back into the field. This eliminates handling and disposal costs at the factory. Thenumber of lorry trips needed between field and factory is also reduced.
Cold storage and processing areasConsider vacuum-chilling produce before it is stored, as this means no chilled water is used orcontaminated.
Select machinery for such areas carefully. Waste heat from machines in cool processing areasplaces extra demands on plant chiller systems, thus incurring extra costs.
3.3.3 Water use and effluent generation
Effluent strength increases if solid waste comes into contact with water, eg trimmings washedto drain with a hose. Removing the solid waste, eg using a coarse screen, avoids you having topay unnecessary effluent treatment and disposal costs.
When designing or changing a process, select equipment and techniques that reduce water use,solid waste and effluent volume and strength.
Consider using separate water systems or countercurrent rinsing to achieve better control oftreated water use. For example, a factory processing salads installed three separate watersystems. Only one of the water systems used chlorinated water. Intermediate storage andfiltration allowed water to be re-used for leaf washing, while countercurrent rinsing was used toconserve water during herb washing.
Consider using spray systems to minimise water use during processing. For example, a vegetableprocessing company found that delivering water to an integrated blancher-cooler tunnel systemwith a spray system used much less water than blanching and cooling baths. The system wasalso less labour-intensive, as the baths also had to be emptied regularly.
3.4 Re-use waste
Re-use is less cost-effective than eliminating or reducing waste, but it can still give you costsavings and environmental benefits. Re-use may be either direct or after minimal treatment, egfiltering through a coarse screen. Segregating different waste streams increases the potential fortheir re-use or recycling. It may also reduce your disposal costs by making the waste easier totreat or subject to lower disposal charges.
The potato slicers at a snack food company require running water. However, fullflow costing about £100/week for each unit (1996 prices) was not necessary. Flowrestrictors costing about £1 each were installed to reduce the flow and save water.
Reducing water flow saves money
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A large volume of produce exudate can be released from produce during processing in the formof fruit juice, starch and sugars. If the produce is conveyed in water, this fluid combines with thewater to generate a wastewater with a high chemical oxygen demand (COD). Such wastes willincrease your trade effluent charges significantly. Reducing the volume of conveying waterallows this wastewater to be segregated and combined with discarded produce to form a semi-solid waste. This can then be sold as animal feed. Benefits include reduced water supply costs,reduced trade effluent charges and conversion of a waste to a saleable by-product.
Water used during fruit and vegetable processing can be re-used in various ways, eg:
■ Water used in flumes, eg for conveying solid waste, can be re-used following suitabletreatment.
■ Screening water to remove grit, stones and other debris allows it to be re-used, eg for rinsing.
■ Ultrafiltration can filter out macromolecules, eg proteins and fine colloidal material, whilenanofiltration takes out smaller molecules such as sugars. Both methods remove COD. Moreinformation can be found in Good Practice Guide (GG54) Cost-effective MembraneTechnologies for Minimising Wastes and Effluents and Good Practice Guide (GG37) Cost-effective Separation Technologies for Minimising Wastes and Effluents. Both are availablefree of charge through the Environment and Energy Helpline on freephone 0800 585794.
■ Storing water can also be cost-effective. For example, one salads processor stores up to halfa season’s demand for water (including returned flume water) in reservoirs. The water is thenused for irrigation.
■ Another factory re-uses approximately 90% of its water through a filtration and carbonadsorption system. Water use is monitored per kg of product as a key performance indicator.
■ Rinse water can often be re-used by rinsing produce in a series of tanks or stages. Lowerrates of water use per kg of product are achieved with countercurrent rinsing (see Fig 11)because the produce is rinsed initially in dirty water and then in progressively cleaner water6.
In 1996, Hillsdown Holdings plc set up a waste minimisation club for its companies inEast Anglia. One of these companies, Smedley’s Fresh Foods, produces a wide rangeof chilled foods at its site in Pinchbeck. The site has an annual turnover of around£20 million and employs 270 - 380 people. Production includes salads and ready-to-eat salad snacks.
A survey of current practices found that the chilled water used to cool potatoes afterblanching was discharged to drain on a once-through basis. Investigations revealedthat this water could be used repeatedly for cooling (up to four times) before beingdischarged. Although new machinery costing £9 000 had to be installed to achievethis, the reduction in water use produced savings of £15 000/year in lower water andeffluent costs. This represents a payback period of less than 8 months5.
Water re-use reduces water and effluent costs
5 See Group-wide Waste Minimisation Club Success: A demonstration at Hillsdown Holdings plc (ET182),available free of charge through the Environment and Energy Helpline on freephone 0800 585794.
6 For more information about countercurrent rinsing, see Case Study Rinsing and Chemical Recovery SystemAchieves Large Savings (NC11) from the Environment and Energy Helpline on freephone 0800 585794.
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3.5 Recycle waste
If waste cannot be re-used, consider options for reprocessing, recycling in-house or recycling off-site. Although these options may be less cost-effective than others higher up the wastehierarchy (see Fig 2), they may still have cost and environmental benefits compared to disposalto landfill or discharge as trade effluent. Segregation of different waste streams is againimportant.
Compost excess, spoiled or off-specification product. For advice on composting, contact theComposting Association (Tel: 01933 227777; www.compost.org.uk) or the BIO-WISE Helpline onfreephone 0800 432100 (www.dti.gov.uk/biowise).
Drain
Produce
Fresh water
Rinse ARinse BRinse CRinse D
Fig 11 The principle of countercurrent rinsing
In 1993, a snack food company began a major operations review to improveperformance. A Water Action Group consisting of managers, shift operators and thesite adviser used a bucket-and-stopwatch approach to study the ideal flow rates foreach piece of equipment. When the results of this water audit were reviewed, thecompany realised that substantial savings could be made if wastewater streams weresegregated prior to on-site treatment. The wastewater streams were treated toremove solids and oils, which were then processed into animal feed cake.
Three main waste streams were identified, ie:
■ potato wash water;
■ cold starch water;
■ hot starch water containing oils.
The potato wash water is now re-used after grit is removed and the cold starch wateris recycled after the good quality starch has been recovered. Water recyclingreduced water consumption by 19%. This is equivalent to 165 000 m3/year or£90 000 in water supply costs.
Segregating wastewater streams saves money
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3.6 Continual improvement
Use your mass balance (see Section 2.1) as a tool for regular assessments of your waste andwater costs. Use your figures from your initial waste review as a base-line.
Monitoring processes by taking regular measurements will allow you to identify annual andseasonal trends and calculate costs. Unexpected changes should be investigated and, ifnecessary, action taken to rectify problems, eg a water leak or faulty machine.
Compare your findings to your base-line. If necessary, discuss and set new targets forimprovement. As well as accounting for changes in operating practices, inputs, outputs andcosts, this gives you the opportunity to consider new technical developments in the fruit andvegetable industry. Implementing changes and monitoring the effects establishes a cycle forcontinual improvement (see Fig 12).
A fruit and vegetable processor supplying wholesale and retail outlets found aparticular problem with the sticky, semi-liquid waste generated when melon seedsare removed during processing.
Until recently the melon seed waste was tankered off-site three times a week fordisposal to landfill. This cost £14 820/year. Owing to the increase in demand formelon portions, the frequency and, therefore, the cost of disposal was set toincrease.
Wastes from the process lines are normally combined. Solid waste is dewatered in acentrifuge and sold as animal feed to local farms. The effluent is sent to drain. Themelon seeds, which have a high feed value, would be removed from the wastestream during dewatering but the associated fruit juice would not. The high COD ofthe fruit juice would then increase the site’s trade effluent costs.
To overcome the problem of increased disposal costs, the melon seed waste is nowstored in holding tanks. It is then fed through a comminutor into a skip to which thedewatered solid waste from the other vegetable lines is added constantly. The resultis a ready-mixed high quality animal food supplement. The equipment cost £20 000to buy and £5 000/year to run. The net saving of £9 820/year resulted in a paybackperiod of just over two years.
Segregating waste streams produces cost savings
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REVIEW✓
✓
START
ABCD
✓
Compare
Measure
Waste review
Implement
Set new targets Brainstorming
Fig 12 Using the mass balance as a tool for continual improvement
For further advice on management issues and how to set up an environmentalmanagement system, contact the Environment and Energy Helpline on freephone0800 585794.
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Measures to reduce waste byconserving produce
Premature and/or unnecessary product loss result in lost sales and increased disposalcosts. Understanding the factors that influence shelf-life will help you to save money by:
■ minimising spoilage;
■ changing the way processes are operated;
■ improving process efficiency;
■ decreasing the need for repeated washing and rinsing.
4.1 Preventing food spoilage
Some of the factors that reduce the quality of fruit and vegetables are outlined below, togetherwith recommended methods to reduce deterioration.
4.1.1 Controlling natural processes and process conditions
Fruit and vegetables continue to respire after harvesting, leading to excessive tissue softeningand the generation of off-flavours.
■ Precool produce (see Table 2) to reduce the rate of the chemical reactions that cause produceto deteriorate after harvesting and during ripening. For example, the rate of respiration at10°C is half that at 20°C.
■ Optimise the use of antioxidants to inhibit the tissue oxidation that causes off-flavours.
Microbial spoilage is another problem that can be solved through simple, practical measures.Microbial growth depends on factors such as temperature and the availability of water andnutrients. The growth of some microbes can also be affected by pH. Some fruits have a pHrange that is detrimental to the growth of bacterial pathogens, but yeasts and moulds can stillgrow, so spoilage is still an issue. Some bacteria (eg Listeria monocytogenes and Salmonellaspp.), yeasts and moulds can grow at low temperatures.
Prevent microbial spoilage of produce by:
■ Precooling produce (see Table 2). To minimise pathogen uptake, the temperature of theproduce should ideally be 10°C lower than the temperature of the wash water. Recentstudies7 suggest that if the temperature of the produce is higher than the temperature of thewash water, pathogens are readily drawn up into the cells of the produce through the skinand, to a greater extent, via surface lesions. Both result in rapid spoilage.
■ Cleaning processing equipment regularly to minimise microbial contamination8.
7 See Zhuang, R-Y, Beuchat, L and Angulo, FJ (1995). Fate of Salmonella montevideo on and in raw tomatoesas affected by temperature and treatment with chlorine. Applied and Environmental Microbiology. Vol 61,pages 2127-2131.
8 For further information see Good Practice Guide (GG154) Reducing the Cost of Cleaning in the Food andDrink Industry.
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4.1.2 Control handling
The rate of deterioration can increase rapidly if produce is damaged through incorrect handling.Bruising results in tissue breakdown, while surface lesions encourage microbial infection.
Manual handling of produce■ Maintain high levels of operator hygiene. Make regular checks on operator hygiene issues
and maintain hygiene stations.
■ Ensure that operators keep their fingernails short to prevent produce damage.
■ Handle produce gently to minimise bruising. For large produce, handle items singly tominimise bruising.
Mechanical handling of produce■ Handle produce gently to minimise bruising during loading and unloading of machinery.
Bruising causes the produce to decay during transit to customers, leading to rotten and off-spec produce at the end of the journey.
■ Convey produce as a single layer on conveyor belts to minimise bruising due to contactbetween produce.
4.1.3 Use the right tools for the job
The type of equipment used can have a dramatic effect on the extent of deterioration. Selectingthe best equipment for the process will reduce the amount of waste produce and chemical use.Gentle removal of wash water is crucial to optimising the shelf-life of produce.
To minimise deterioration during the mechanical processing of produce, consider the following:
■ Cutting may cause less damage than steaming, which can cause scalding, generate off-flavours and reduce nutritional quality.
■ Recent studies have shown that peeling carrots with a sharp blade, rather than abrasionpeeling using a carborundum drum, resulted in a reduced rate of product spoilage and areduced requirement of antioxidants in the wash water.
■ Use antioxidants in the wash water to suppress browning, but do not use more thannecessary. Minimising the use of antioxidants will reduce wastewater strength and thusreduce trade effluent charges.
Method Description Applications*
Hydro-cooling Heat is removed from the Asparagus, beet, broccoli,produce through direct carrot, cauliflower, celery, contact with cold water. cherries, peas, radish,
raspberries, sweet corn
Vacuum-cooling The surface of the produce Suitable for leafy vegetablesis moistened with water and and heat-sensitive fruits,then placed in a vacuum to eg cabbage, cherries,induce evaporative cooling. lettuce, raspberries and spinach
Air-cooling Cold air flows over the Aubergine, beans, cucumber, produce to allow rapid peppers, tomatocooling without freezing.
* Precooling is not appropriate for some tropical and sub-tropical fruit.
Table 2 Common methods used for precooling
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■ Removing wash water gently is an important part of optimising the shelf-life of the produce.For example, some studies have shown that centrifugal drying can cause less bruising thanother drying processes. However, the centrifugal rate and drying time may need to beassessed and optimised9.
4.1.4 The importance of correct installation and maintenance
The advantages of choosing the best equipment may be lost if you do not install and maintain itproperly. Good maintenance is essential for all machines and all manual or hand-held equipment.
■ Keep blades clean to maintain a good cutting action. Cutting the surface of produce duringpeeling, cutting and peeling releases tissue fluid that can cause browning and encouragemicrobial contamination.
■ When using cutting and shredding machinery fitted with blades, keep blades sharp. Dullblades cause more tissue damage and are harder to clean10.
■ Clean machines regularly to minimise microbial loads.
■ Service equipment regularly to prevent unnecessary damage to produce. Vibrations caused byloosened fittings result in a jagged cutting action. This damages the produce, resulting ingreater fluid loss. The strength of the wastewater is increased, thus increasing effluent charges.
4.2 Washing and sanitising
4.2.1 Washing needs and options
Effective washing and decontamination of fruit and vegetables are hard to achieve. However,inadequate washing and microbial decontamination shorten the shelf-life of produceconsiderably. This results in more solid waste and increased disposal costs.
A survey of 250 food processors handling raw fruit and vegetables11 found that chlorine was themost commonly used sanitising agent (76% of companies) compared to potable water only(20%), commercial produce wash (3%) and aqueous organic acids (1%).
4.2.2 Chlorine-based sanitising agents
Chlorination or disinfection of the wash water is most useful to keep the wash water clean andprevent cross-contamination. Washing in chlorine can reduce the levels of micro-organisms 100-fold at best, and is sometimes as effective as washing with potable water alone12.
It is important to use the optimum concentration of hypochlorous acid. Minimising the use ofsanitising agents will reduce wastewater strength and thus reduce trade effluent charges. If it istoo high, the produce may be bleached and its flavour tainted. This will lead to product beingwasted. In addition, raw material costs and trade effluent charges may increase.
9 New Approaches in Improving the Shelf Life of Minimally Processed Fruit and Vegetables, Trends in FoodScience and Technology, June 1996, Vol 7, pages 179-187.
10 Microbiological tests on swabs from dull blades have shown a higher number of aerobic viable countscompared to those from sharp blades.
11 Review of Current Industry Practice on Fruit and Vegetable Decontamination, Campden & Chorleywood FoodResearch Association (CCFRA) Review No. 14 (1999).
12 Beuchat, LR (1998). Surface Decontamination of Fruits and Vegetables Eaten Raw: A review. Food Safety Unit,World Health Organisation WHO/FSF/FOS/98.2.
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Monitor on-line■ Install on-line monitoring of ‘available’ chlorine. This can help to prevent excessive chemical
use. Several sensor types may be available; consult your chemical supplier for advice on thechoice of a continuous on-line system.
Reduce organic load before chlorinationChlorine-based compounds bind readily to forms of organic material, eg soil and plant debris.
■ Remove as much organic material as possible before washing to reduce the amount ofchlorine required.
Although rinsing can reduce organic loading, it is important not to overuse water. Usingturbidity sensors to monitor the clarity of wastewater is one way of controlling rinsing. Thismethod is more accurate than visual inspection and does not require supervision.
The use of turbidity sensors is described in Good Practice Guide (GG220) Low-cost ProcessControl in Food and Drink Processing, available free of charge through the Environment andEnergy Helpline on freephone 0800 585794.
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Action plan
Your next step is to draw up an Action Plan for implementing a systematic wasteminimisation programme in your company. You may want to use the checklist below todevelop your plan.
Action Person Deadlineresponsible
Set up a waste minimisation team.
Obtain senior management approval for the wasteminimisation programme.
Explain to staff the need for waste minimisation.
Implement a system to maintain staff motivationand participation.
Produce a flow diagram of your process steps and aprocess map for each step. Prepare a mass balance.
Compile inventories of processes, inputs and outputs.
Gather information:
Find copies of site plans.Locate utility meters.Identify water routes and drainage systems.Find utility bills and purchase orders/invoices.
Calculate quantities and costs of inputs and outputs.
Review the current (base-line) situation. Use it toidentify areas where you can save money by makingprocess improvements and minimising waste.
Use the waste opportunity checklist in the Appendixto help you identify opportunities for reducing waste.
Assess the costs and benefits of different measures.
Prioritise waste saving options and identify the mostcost-effective measures.
If necessary, carry out feasibility studies/pilot trials ofpossible waste saving measures.
Implement waste saving measures, starting withno-cost and low-cost opportunities to save money.
Measure inputs and outputs regularly and compareyour results with the previous base-line review.
Review progress regularly and set new targets.
Use this approach as a tool for continualimprovement.
Waste minimisation checklist
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5.1 Further help and advice
5.1.1 Environment and Energy Helpline
The Helpline (0800 585794) can:
■ Provide free, up-to-date advice on waste minimisation and environmental issues.
■ Tell you about relevant environmental and other regulations that could affect your operations.
■ Send you copies of relevant Envirowise publications.
■ Suggest other sources of information.
■ Arrange for a specialist to visit your company if you employ fewer than 250 people (at thediscretion of the Helpline Manager).
Table 3 lists some of the many Envirowise publications available free of charge through theEnvironment and Energy Helpline on freephone 0800 585794 or via www.envirowise.gov.uk
Topic Publication title and reference number
General waste ■ Cutting Costs by Reducing Waste: A self-help guide for minimisation growing businesses (GG38C)
■ Saving Money Through Waste Minimisation: Teams andChampions (GG27)
■ Waste Minimisation Pays: Five business reasons for reducingwaste (GG125)
■ Finding Hidden Profit - 200 Tips for Reducing Waste (ET30)
■ Waste Mapping - Your route to more profit (ET219)
■ Waste Account - count the cost of waste for your business...and measure your savings (ET225)
Packaging ■ Cutting Costs and Waste by Reducing Packaging Use (GG140)
■ Choosing and Managing Re-usable Transit Packaging (GG141)
■ Reducing the Cost of Packaging in the Food and DrinkIndustry (GG157)
■ Unpack those Hidden Savings - 120 Tips on ReducingPackaging Use and Costs (ET250)
■ Packing Line Savings in the Food and Drink Industry (GG243)
Reducing ■ Saving Money Through Waste Minimisation: Reducing Waterwater costs Use (GG26)
■ Tracking Water Use to Cut Costs (GG152)
■ Cost-effective Water Saving Devices and Practices (GG67)
■ Reducing the Cost of Cleaning in the Food and Drink Industry(GG154)
■ Cost-effective Separation Technologies for Minimising Wastesand Effluents (GG37)
■ Cost-effective Membrane Technologies for Minimising Wastesand Effluents (GG54)
Reducing raw ■ Saving Money Through Waste Minimisation: Raw Material Usematerial use (GG25)
■ Low-cost Process Control in Food and Drink Processing (GG220)
Table 3 Useful Envirowise publications
55
sect
ion
27
5.1.2 Other sources
Campden & Chorleywood Food Research Association (CCFRA)Chipping CampdenGloucestershire GL55 6LDTel: 01386 842000Fax: 01386 842100www.campden.co.uk
Composting AssociationAvon HouseTithe Barn RoadWellingboroughNorthamptonshire NN8 1DHTel: 01933 227777www.compost.org.uk
app
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ix
28
Blank forms
These forms are intended for you to photocopy and use as you wish to reduce water andwaste costs in your company.
■ Waste opportunity checklist
■ Inventory of processes
■ Inventory of inputs
■ Inventory of outputs
29
Waste opportunity checklist for fruit and vegetable processing
Department Area Possible waste
Field Field Off-spec produce ❑operations Trimming/sorting produce ❑Transport Field and Unnecessary transport of excess
processing site materials ❑Incoming Loading bay Off-spec produce ❑materials Wooden boxes/crates/pallets ❑
Polythene wrapping ❑Produce losses to floor ❑
Storage Cold storage Off-spec produce ❑Produce losses to floor ❑Produce damage ❑Leaks from chiller system ❑Heat gain ❑
Chemical stores Out-of-date materials ❑Damaged containers ❑Chemical spillage ❑Surplus materials ❑
Production Trimming/sorting Off-spec produce ❑precooling, washing Produce losses to floor ❑sanitising, rinsing Solid waste ❑dewatering, drying Soil/dirt ❑blanching, freezing Glass/metal/plastic ❑dehydrating, packaging Trimming/sorting produce ❑
Wash water ❑Rinse water ❑Peeling/grating/cutting waste ❑Excess chemicals ❑Leaking valves/taps/pipework ❑Taps/hoses left unattended ❑Excess/off-spec/damaged packaging ❑
Energy Building, processes Lights left on ❑Machines left running ❑Air leaks from compressors ❑Inefficient motors/pumps ❑Inefficient use of vacuum ❑Inefficient space heating ❑Excess hot/chilled water ❑Heat not recovered for re-use ❑Doors left open ❑Insufficient/inefficient insulation ❑
Domestic Toilets, canteen, on-site Leaking taps/pipework ❑water laundry, hygiene stations Taps left running ❑
Excessive pressure/flow ❑Toilet cistern overflow ❑
Support Offices, workshops, Toiletries ❑services laboratory, hygiene Office paper ❑
stations Protective clothing/gloves ❑Chemicals; acid/alkali ❑Lubricants ❑Scrap wood/metal ❑
GG280 published by Envirowise Helpline 0800 585794
30
Inventory of processes
Site: Prepared by:
Page: of Date:
Process: Location/reference number:
GG280 published by Envirowise Helpline 0800 585794
31
Inventory of inputs
Process: Prepared by: Date:
Input Input Amount used Unit cost Input costref no. name (quantity/time) (£/quantity) (£/time)
GG280 published by Envirowise Helpline 0800 585794
32
Inventory of outputs
Process: Prepared by: Date:
Output Output Amount Unit cost Output costref no. name (quantity/time) (£/quantity) (£/time)
GG280 published by Envirowise Helpline 0800 585794
For further informationplease contact the
Environmentand EnergyHelpline0800 585794
Envirowise - Practical Environmental Advice for Business - is a Government programmethat offers free, independent and practical advice to UK businesses to reduce waste atsource and increase profits. It is managed by AEA Technology Environment and NPLManagement Limited.
Envirowise offers a range of free services including:
Free advice from Envirowise experts through the Environment and EnergyHelpline.
A variety of publications that provide up-to-date information on wasteminimisation issues, methods and successes.
Free, on-site waste reviews from Envirowise consultants, called Fast Track Visits,that help businesses identify and realise savings.
Guidance on Waste Minimisation Clubs across the UK that provide a chance forlocal companies to meet regularly and share best practices in waste minimisation.
Best practice seminars and practical workshops that offer an ideal way toexamine waste minimisation issues and discuss opportunities and methodologies.
© Crown copyright. First printed March 2001. Printed on paper containing a minimum of 75% post-consumer waste.This material may be freely reproduced in its original form except for sale or advertising purposes.
Harwell International Business Centre | 156 Curie Avenue | Didcot | Oxfordshire | OX11 0QJE-mail: helpline@envirowise.gov.uk Internet: www.envirowise.gov.uk
Practical Environmental Advice for Business
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