AIR

The most common air emissions in wood processing or furniture industry:

• particulate matter, which generates during processing - polishing wood, spraying, using or handling of dust or powder;
• VOC from applying solvent based adhesives, coatings - handling, loading and mixing processes involving organic solvents and organic solvent borne coatings, all cleaning operations using organic solvent borne cleaning fluids, handling and storage of waste organic solvents and organic solvent contaminated wastes, coating and drying processes;
• isocyanates from the preparation, application and curing of polyurethane coatings;
• emissions from boiler houses.

The most common air emissions in printing industry:

• VOC from using in fountain solutions, solvent based inks and solutions - printing, gluing, all cleaning operations using organic solvent borne cleaning fluids; handling and storage of waste organic solvents and organic solvent contaminated wastes;
• particulate matter, which generates during processing un handling
• emissions from boiler houses.

The most common air emissions in metal processing industry:

• particulate matter, which generates during processing - cutting, drilling, spraying, using or handling of dust or scraps;
• VOC from applying solvent based paints and coatings - powder coating, spray-painting, handling, loading and mixing processes involving organic solvents, thinners, paint catalysts and organic solvent borne coatings; all cleaning operations using organic solvent borne cleaning fluids, handling and storage of waste organic solvents and organic solvent contaminated wastes, coating and drying processes;
• emissions from boiler houses.

The chapter mainly focuses on VOC emissions, their occupational and environmental risks, since they are largely contributing to photochemical smog, some are toxic and cancer causing, some contributes to high level (stratospheric) ozone depletion and global warming.

• How do I know I use VOC?
• How to identify hazardous VOC in the preparation?
• Guidance on estimation and reduction of diffuse VOC emissions:
  http://193.219.133.6/aaa/Tipk/tipk/4_kiti%20GPGB/53.pdf

Furniture industry

• Properly set-up and adjust equipment , e.g. air and fluid pressure should be high enough but no higher than needed to provide good atomization.
• Less viscous coating materials are easier to atomize, and they can be atomized at lower pressures. There are two ways to control viscosity: by dilution with a solvent and by heating. Heating the coating material to the desired viscosity instead of diluting it with solvent can give comparable atomization with lower VOC emission potential.
• The spray pattern should be optimized to the workpiece size, shape, and orientation. Slender pieces should be coated with a narrow pattern while a larger pattern can be used for larger pieces.
• The piece to be painted should be positioned to make spraying as comfortable as possible for the operator, and small pieces should be positioned such that overspray from one piece will fall onto another piece.
• Train the operator regularly (at least twice a year) for good finish quality and efficient material usage. Operators should be trained to use the proper spray techniques such as gun position, motion, triggering and overlap:
• if spray gun is held too far away, a dry spray and decreased transfer efficiency may result, while the paint may run and sag if the gun is held too close to the piece;
• to reduce uneven paint coverage, the operator should hold the gun perpendicular to the workpiece as much as possible; a sweeping arm motion will usually keep the gun in the proper position;
• proper triggering, i.e., the gun is triggered with each stroke, reduces material usage and finish defects. The stroke should be started before the trigger is pulled, and the trigger should be released before the end of the stroke;
• Equipment Maintenance:
• spray guns need to be kept clean and lubricated daily to keep them operating properly;
• when cleaning the gun in solvent, immerse only the tip of the gun;
• replace worn parts since they can significantly reduce painting trancfer efficientcy.
• Substitute chemicals to prevent and minimize emissions:
• water borne coatings (low organic solvent content);
• higher solids content coatings (! resist the temptation to thin the coatings by adding solvent, better reduce viscosity by heating);
• low-VOC coating;
• powder coatings;
• organic solvent free liquid coatings;
• radiation cured coatings (for example, ultra violet and electron beam).
• Change technologies , if needed:
• high-volume/low-pressure (HVLP) spray equipment ? provides transfer efficiency as high as 40 to 65 percent compared to 20 to 40 percent for conventional air spray technology;
• airless and air assisted airless systems ? material consumption reduced; waste volume from spray booth cleanup reduced;
• electrostatic spray systems ? waste reduction from wiping stain compared to conventional spray units;
• flat line finishing ? waste reduction in VOCs;
• UNICARB system using super-critical carbon dioxide (CO 2 ) in place of some organic solvents to apply coatings to wood, metal, and plastic materials ? improve finish quality with fewer coating applications, no VOC;
• UV-curable coatings can be applied using spray equipment, roll coaters, or curtain coaters;
• replace water-based paint booth filters with dry filters ? dry filter will double paint booth life and allow more efficient treatment of wastewater;
• Recover and reuse or recycle materials either on-site, off-site to reduce reduce waste management costs and raw material purchases:
• reuse cleaning solvent for painting lines and equipment as a reducer for the next batch of the same or darker color;
• flush equipment first with dirty solvent before final cleaning with virgin solvent;
• distilling "dirty" solvent and reuse it for cleaning is another common practice;
• recycle wet spray booth wash water by removal of paint solids;
• recycle spent solvents with recovery units including:
• small on-site solvent recovery still to recycle spent lacquer thinner;
• small in-house still to recycle methylene chloride;
• in-house still to recycle xylene;
• batch distillation unit to recover xylene from paint equipment cleaning;
• batch distillation to recover isopropyl acetate generated during equipment cleaning;
• recovery system for solvents contained in air emissions;
• solvent recovery system to recover and reuse spent methyl ethyl ketone
• Use multi-purpose materials ? it may decrease employee confusion, reduces the number of rarely-used products and therefore potentially reduces out-of-shelf-life waste.
• Storage and handling of organic solvents and materials containing organic solvents:
• use of enclosed mixing and storage vessels;
• collect and store wood coatings and thinners in closed containers;
• keep lids on containers closed during working operations;
• label containers.

Printing industry

• Press Cleaning:
  • wipe excess ink off before cleaning equipment with solvents;
  • substitute high VOC cleaners with low VOC cleaners containing no more than 30% VOC by weight. Use those with a lower vapour pressure and higher flash point à they are divided in to 4 groups according to their flash points:
    • < 21ºC à are not allowed to use in printing industryà very fast evaporation, vapors are harmful for health. High explosion risk.
    • 21ºC – 55ºC à flammable, high evaporation, vapours are harmful for health. Not allowed to use on new presses.
    • > 55ºC à low evaporation, vapours are harmful for health. Flammable, but the flame point is high.
    • > 100ºC à non VOC, are highly recommended to use on printing presses, e.g. vegetable based cleaning agents.
  • change from a petroleum oil-based ink to a vegetable oil-based ink such as soy or linseed oil;
  • install automatic cleaning systems reduce cleaner consumption by removing excess ink à also prevent ink build-up which requires stronger cleaning solutions;
  • try to use one type of solvent for all purposes à will improve recycling capabilities;
  • schedule jobs by colour à clean the ink tray only when changing colours or if ink might dry out between runs;
  • applying solvent directly to roller blanket with a squeeze bottle. Also squeeze used towels à reuse the liquid for initial cleanup, followed by clean solvent for final cleanup.
• Photochemcicals
  • install floating lids to exclude air and reduce evaporation and contamination à can double the life of the solution;
  • to reduce the amount of oxidation of developer solution, add glass marbles to bring the liquid level up to the brim each time the liquid is used à will extend the chemical's useful life and the life of the bath.
• Platemaking:
  • use laser plate-making with an electronic imaging system;
  • reduce drag-in of contaminants, reduce drag-out of solutions by adding dripborads and extending drip time;
  • use nonhazardous developers and finishers;
  • increase use of direct-to-plate technologies that allow preparation of plates from computer images without intermediate steps, i.e., replace the current image-making operation with a "computerized electronic prepress system" for type-setting and copy preparations.
• Printing and Silk Screening:
  • use water-based, soybean oil, UV-curable or electron beam drying inks in
  • preference to solvent-based;
  • dedicating presses for various ink colours, if feasible;
  • filling ink fountains with only enough ink for the run or shift and returning unemulsified links to their containers;
  • use fountain solutions that do not contain isopropyl alcohol (IPA) or have low concentrations of IPA in the dampening solution by adding small volumes of alternative chemicals such as glycols or glycol ethers;
  • adding leftover coloured inks to black ink;
  • reformulating the composition of the fountain or the solution used to eliminate isopropyl alcohol;
  • using non-toxic inks, free of heavy metals (lead, barium, cadmium and chromium;
• Finishing:
  • use water-based adhesives rather than solvent-based;
  • minimize coatings and adhesives that hinder recycling;
  • use mechanical binding methods instead of glues or adhesives.
• Recover and reuse or recycle materials either on-site, off-site to reduce waste management costs and raw material purchases:
  • flush equipment first with dirty solvent before final cleaning with virgin solvent;
  • distilling "dirty" solvent and reuse it for cleaning is another common practice;
  • recycle empty containers by purchasing ink in bulk containers that are returned to the supplier for refilling;
  • recover waste solvents on-site with batch distillation if quantities warrant, or utilize professional solvent recyclers;
  • install solvent hoods to recapture solvent losses from presses;
  • recycle used and leftover inks;
  • for silkscreen operations, recapture printing ink by squeezing screen prior to washing
• Use multi-purpose materials à it may decrease employee confusion, reduces the number of rarely-used products and therefore potentially reduces out-of-shelf-life waste.
• Storage and handling of organic solvents and materials containing organic solvents:
  • segregate spent solvent according to colour and type of ink. Reuse the collected wastes to thin future batches of the same ink;
  • use of enclosed mixing and storage vessels;
  • collect and store in closed containers;
  • keep lids on containers closed during working operations;
  • label containers.

There is also a draft BREF (BAT reference document) developed relevant for the printing. Although this  document is binding only for large companies (which fall under IPPC directive), also for smaller companies this document can give some ideas for the improvement of own performance: see in English http://eippcb.jrc.es/pages/FActivities.htm)

Metal industry

Metal processing has wide range of processes; this chapter is mainly focussing on surface cleaning and finishing.  

• Emissions during welding of plates cleaned with esters à no additional air pollution from the use of vegetable oil esters as cleaning agents à volatile organic solvents can be replaced by esters in approximately 50% of the cleaning activities;
• Properly set-up and adjust equipment, e.g. air and fluid pressure should be high enough but no higher than needed to provide good atomization.
• Less viscous coating materials are easier to atomize, and they can be atomized at lower pressures. There are two ways to control viscosity: by dilution with a solvent and by heating. Heating the coating material to the desired viscosity instead of diluting it with solvent can give comparable atomization with lower VOC emission potential.
• The spray pattern should be optimized to the work piece size, shape, and orientation. Slender pieces should be coated with a narrow pattern while a larger pattern can be used for larger pieces.
• The piece to be painted should be positioned to make spraying as comfortable as possible for the operator, and small pieces should be positioned such that overspray from one piece will fall onto another piece.
• Train the operator regularly (at least twice a year) for good finish quality and efficient material usage. Operators should be trained to use the proper spray techniques such as gun position, motion, triggering and overlap:
• if spray gun is held too far away, a dry spray and decreased transfer efficiency may result, while the paint may run and sag if the gun is held too close to the piece;
• to reduce uneven paint coverage, the operator should hold the gun perpendicular to the work piece as much as possible; a sweeping arm motion will usually keep the gun in the proper position;
• proper triggering, i.e., the gun is triggered with each stroke, reduces material usage and finish defects. The stroke should be started before the trigger is pulled, and the trigger should be released before the end of the stroke;
• Equipment Maintenance:
• spray guns need to be kept clean and lubricated daily to keep them operating properly;
• when cleaning the gun in solvent, immerse only the tip of the gun;
• replace worn parts since they can significantly reduce painting transfer efficiency.
• Ensure your stoving oven is operating efficiently:
• use the correct temperature and stoving time by installing infrared driers prior to the oven;
• fit and check an audible or visual alarm to prevent overheating;
• reduce air extraction rates once flammable gases have been driven off;
• Substitute chemicals to prevent and minimize emissions:
• use cleaners and coating with low toxic air pollutant and VOC content à e.g. water borne;
• for chromium electroplaters, switch from hexavalent chromium solutions, which can cause cancer, to trivalent chromium ones, which do not;
• replace cyanide in plating solutions with less toxic compounds like zinc chloride and pyro-phosphate copper.
• reduce the chemical concentration of the plating bath without compromising quality;
• water borne coatings (low organic solvent content);
• higher solids content coatings (!resist the temptation to thin the coatings by adding solvent, better reduce viscosity by heating);
• low-VOC coating;
• powder coatings;
• organic solvent free liquid coatings;
• radiation cured coatings (for example, ultra violet and electron beam).
• anti-corrosion oil used for spraying products while packing them can be substituted by an oxidation packaging paper to put in the boxes at product delivery à the unhealthy mist that was earlier spread when preparing deliveries with the oil was fully eliminated.
• Change technologies, if needed:
• use alternative metal deposition technologies to reduce or eliminate toxic air pollutant emissions;
• use mechanical scraping instead of a chemical solution to remove build-up on the part;
• replace solvent pre-cleaning operations with aqueous ultrasonic cleaning;
• some systems use a batch multi-stage cabinet spray unit - rather like a large dishwasher à to clean parts using a neutral or alkaline solution, followed by phosphating and rinsing. The need for VOC based degreasers is therefore eliminated
• minimize drag-out à lower bath chemical concentrations à proper part racking based on part shapes à reducing part rack removal speed à fog or spray rinsing over bath or capture it before rinsing and return it to the plating bath by using: drip boards; air knives; hang bars; drip tanks;
• high-volume/low-pressure (HVLP) spray equipment à provides transfer efficiency as high as 40 to 65 percent compared to 20 to 40 percent for conventional air spray technology;
• the use of coating powders instead of paint à reduces solvent emissions to almost zero, but increases the heat requirement for curing
• airless and air assisted airless systems à material consumption reduced; waste volume from spray booth cleanup reduced;
• electrostatic spray systems à waste reduction from wiping stain compared to conventional spray units;
• flat line finishing à waste reduction in VOCs;
• UNICARB system using super-critical carbon dioxide (CO2) in place of some organic solvents to apply coatings to wood, metal, and plastic materials à improve finish quality with fewer coating applications, no VOC;
• UV-curable coatings can be applied using spray equipment, roll coaters, or curtain coaters;
• replace water-based paint booth filters with dry filters à dry filter will double paint booth life and allow more efficient treatment of wastewater;
• a process using vacuum heat treatment substituted a process treating saw blades at high temperature in a bath of barium salts à stopping emissions to the air
• Recover and reuse or recycle materials either on-site, off-site to reduce waste management costs and raw material purchases:
• reuse cleaning solvent for painting lines and equipment as a reducer for the next batch of the same or darker colour;
• flush equipment first with dirty solvent before final cleaning with virgin solvent;
• distilling "dirty" solvent and reuse it for cleaning is another common practice;
• recycle wet spray booth wash water by removal of paint solids;
• recycle spent solvents with recovery units including:
• small on-site solvent recovery still to recycle spent lacquer thinner;
• small in-house still to recycle methylene chloride;
• in-house still to recycle xylene
• batch distillation unit to recover xylene from paint equipment cleaning
• batch distillation to recover isopropyl acetate generated during equipment cleaning
• recovery system for solvents contained in air emissions
• solvent recovery system to recover and reuse spent methyl ethyl ketone
• Use multi-purpose materials à it may decrease employee confusion, reduces the number of rarely-used products and therefore potentially reduces out-of-shelf-life waste.
• Storage and handling of organic solvents and materials containing organic solvents:
• maintain a high standard of housekeeping
• use of enclosed mixing and storage vessels à may be achieved by the use of closed mobile containers, containers with close-fitting lids, or, preferably, closed containers with pipeline delivery;
• during hot- dip galvanizing hygroscopic materials are unlikely to give rise to dust. Ashes from the zinc bath need to be kept dry to avoid the risk of toxic arsine gas (arsenic trihydride) being formed.
• collect and store metal surface coatings and thinners in closed containers;
• potentially dusty materials should be stored in covered containers or undercover keep lids on containers closed during working operations;
• spillages should be cleared as soon as possible and in the case of solid materials this should be achieved by the use of vacuum cleaning, wet methods, or other appropriate techniques. Dry sweeping of dusty spillages should not be permitted
• label containers.

• Guidelines for the reduction of VOC emissions in the wood furniture manufacturing sector :
  http://dsp-psd.pwgsc.gc.ca/Collection-R/En108-4-23-2004E.pdf
• European solvents industry group - various information (publications, guidelines) about solvents, use, life cycle, environmental impacts and different ways of reducing solvent emissions:
  http://www.esig.info/index.php
• Guidance documents on substitution of solvents:
  http://ec.europa.eu/environment/air/solvents/guidance_en.htm
• Good housekeeping measures for solvents:
  http://www.envirocentre.ie/downloads/Guide%20for%20Solvents.pdf
• Guidelines, training and tools specific for SMEs in the wood sector:
  http://ex-elca2.bologna.enea.it/cm/navContents?l=EN&navID=woodProducts&subNavID=1&pagID=2
• Environmental Protection Agency (EPA) – pollution prevention opportunities in the printing industry:
  http://es.epa.gov/techinfo/facts/epa/printing.html
• Common pollution prevention practices in printing:
  http://www.p2pays.org/ref/03/02453/p2pract.htm
• Guidance document on environmentally sound technologies in the metal finishing industry http://www.escwa.org.lb/information/publications/edit/upload/tech-01-6-e.pdf
• Guidance on information on technologies and practices presented in the Environmental Technology Compilation (ETC Database) and in the BAT/BEP industry guidebooks http://cptech.dost.gov.ph/BATBEPCompilation.php
• European Database for fast Selection of Best-Practice Metal Cleaning Processes http://www.cleantool.org/
  

How do I know I use VOC?

VOC = any organic compound having a vapour pressure of 0,01kPa at 293,15 °K (19,85 °C) or having a similar volatility under particular conditions of use a look for information on physical properties in SDS section 9.

Be aware, that VOCs are not only pure solvents, they might be also in paints, lacquers, glues! - look for information on composition of the preparation.

How to identify VOC, which should be substituted?

1.  Hazardous VOC - the ones having CMR properties ( Carcinogens, Mutagens and Reprotoxic substances).
2. CMR of the Categories 1 and 2 have R-phrases R45, R46, R49, R60, R61.
3. CMR of the Category 3 have R-phrase R40.
• R40: Limited evidence of carcinogenic effects (Category 3)
• R45: May cause cancer
• R46: May cause heritable genetic damage
• R49: May cause cancer by inhalation
• R60: May impair fertility
• R61: May cause harm to the unborn child
4. Screen SDS section 2 - CMR substances have to be declared in the safety data sheet when they are contained above certain percentages:
• CMR of the Categories 1 and 2 (R45, R46, R49, R60, R61)
• > or equal 0,1 %w/w
• > or equal to 0,02 %vol/vol
• Carcinogens of the Category 3 (R40) 
• > or equal 1 %w/w
• > or equal to 0,2 %vol/vol

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