Industry Specific Practices
An asterisk (*) next to a listed practice indicates that industry reviewers considered it a particularly good suggestion based on effectiveness and effort/expense required to implement.
Analytical & Clinical Laboratories
Also see:
- General Solvent & Cleaning/Degreasing
Good Housekeeping & Operating Practices
- * Use computer tracking to keep records of chemical inventories, chemical purchases, and waste generation (Consider using already-developed chemical inventory system software packages.)
- Do dry runs of experiments to avoid spillage and waste
- * Practice wastestream segregation by avoiding mixing non-hazardous with hazardous waste
- * Consolidate partly-filled bottles in lab packs
- Compact lab debris to reduce volume
- * Establish a student and employee education program using posters, fact sheets, and visits by lab safety committees (very important)
- * Train laboratory technicians on ordering less chemicals, alternatives to reduce chemical usage, the importance of proper waste disposal, and proper waste identification (very important)
- * Use microglassware and microlab techniques (this has led to a 100-fold reduction in some laboratories’ solvent generation)
Material Substitution
- * Use washable cloth rags instead of paper towels for cleanup a and small spills, and contract with a commercial launderer to "recycle" rags (try to find one which recycles its washwater)
- Substitute less hazardous chemicals in experiments (e.g. alcohol for benzene; sodium hypochlorite for sodium dichromate; cyclohexane for carbon tetrachloride; stearic acid for acetamide in phase change and freezing point depression experiments; and dichloromethane for chloroform)
- * In cleaning laboratory glassware, substitute specialty detergents for sulfuric and chromic acid cleaning solutions
Materials Recovery
- Let solids in used solvents settle, then decant off liquid for reuse as a first rinse/presoak for dirty brushes or equipment
- Exchange unused/uncontaminated chemicals among laboratory facilities
- Recycle and reclaim chemicals when possible (e.g. photo chemicals and flammable liquids)
- Recycle solvents with onsite distillation unit if there is sufficient quantities to make it cost-effective
- Recover platinum, palladium, and rhodium contained in catalysts
Process Modifications
- Use instrumental analysis rather than wet chemistry
- Decompose carbon disulfide using hypochlorite
- Oxidize inorganic cyanides using aqueous hypochlorite
- Neutralize strong acids with tap water and agricultural lime and strong bases with muriatic acid
Sources (Appendix A): S6, S13, S14
Automotive Repair
Also see:
- General Solvent & Cleaning/Degreasing
- Painting, Coating, & Stripping
Good Housekeeping & Operating Practices
- Become a "zero discharger" (eliminate industrial discharge to sanitary sewer)
- Minimize the inventory of fluids and chemicals
- Drain and replace motor oil, coolant, and other fluids in a designated area which is not connected to the storm drain or sanitary sewer
- Place drip trays under leaking autos (even if you suspect leaking has ceased); cars with unclipped hoses, unscrewed filters, or other removed parts; and hot tanks, cleaning tanks, and parts washers
- Use large low-brimmed pans under cars where mechanics are working
- Reduce equipment leakage through more frequent scheduling of preventive maintenance
- Place clean-up supplies in convenient, easy-to-locate areas around the shop
- * Minimize cleanup wastes:
- Use squeegees and rags for small spills
- Use "hydrophobic" (absorbs oils, not water-based liquids) mop to separate spilled oil from antifreeze/water and place recovered liquids in waste oil drum and waste antifreeze container for recycling
- Use a wet/dry vacuum for larger coolant spills and put recovered liquid in waste antifreeze drum
- Preclean excessively soiled parts when using a hot tank
- Place parts washers/solvent sinks near working areas and install spill basins
- Remove hot tank solids and recharge solution
- Prevent need for intense cooling system flushes by changing coolant more frequently
- * Reduce spills and sloppy work areas through employee incentive programs such as:
- Bonuses/prizes for safety violation-free months
- Posting photographs of poor/good employee work areas
- Using employee spill/accident record as one criteria in determining pay increases
Material Substitution
- Use longer-lasting synthetic oils
- Substitute water-based cleaners for solvent cleaners
- Purchase re-refined oil and antifreeze for use in your shop (if meets appropriate standards, warranty, etc.)
Materials Recovery
- Use an industrial laundry service for shop rags and uniforms (Keep rags in a covered container and do not saturate. Try to find a service that recycles its wastewater.)
- Contract with recycling services for used oil and antifreeze (or recycle antifreeze onsite if you have/use large volumes)
- Recycle solvents with a service that replaces dirty solvent with fresh on a regular or "as-need" basis, or use an onsite distillation unit if there is sufficient quantities to make it cost-effective
- Reclaim and reuse all freon
Process Modifications
- Use a fluid brake cleaning method instead of a vacuum to contain asbestos more effectively (fluid is recirculated)
- Use high temperature ovens and dry abrasives (shot blast) for parts cleaning (be sure meets local air emission restrictions)
Radiator Repair-Specific:
Take a look at the Vendor Directory for companies which sell recirculating radiator flush booths and other equipment
- * Use a radiator flush booth that recirculates flush water
- * Reduce wastewater by:
- Increasing pressure and decreasing water flow in (non-recirculating) flush booths
- Adding fresh water only to the test tank - as test tank water becomes unusable, transfer it to the recirculating flush booth, then transfer it to the hot tank/ultrasonic cleaner for use in radiator precleaning
- Capture water spills with a wet/dry vacuum and transfer to the hot tank
- Settle solids from test tank water when cloudy and reuse water
- Recover test tank water, recirculated flush booth water, and spilled water with chemically-assisted filtration rather than adding to hot tank (save water and energy if hot tank is turned off earlier)
- * Only use hot tank when necessary - use smaller tanks with ultrasonic cleaning for light jobs
- Monitor and maintain boil-out tank to keep at optimum operating conditions
- When emptying boil-out tank, remove the solids, reuse the liquid, and reconstitute the bath
- * To extend the life of water used in the recirculating flush booth, minimize dragout
from hot tank:
- Install hang bars over tank
- Blow residual caustic solution back into hot tank using compressed air
- Pre-rinse radiator over hot tank using pressurized spray
- Solder over drip pan rather than over test tank
- Use a zinc-free flux and lead-free solder
Sources (Appendix A): S4, S5, S13, S16, S22
A Mountain View, CA
auto repair shop has been very successful in minimizing waste generation. See their Case Study.
Construction-related Activities
Also see:
- Automotive Repair
- General Solvent & Cleaning/Degreasing
- Painting, Coating, & Stripping
Good Housekeeping & Operating Practices
- Cover all raw materials (especially plaster and other powders), by-products, containers, wastes, and dumpsters with tarps, plastic sheeting, or roof structure to prevent rainwater contamination and sunlight deterioration
- Hazardous waste/materials storage:
- Keep lids closed on containers
- Store on a diked concrete pad when possible to improve spill containment
- Surround with a berm or secondary containment
- Store in garages or sheds with secondary containment during rainy periods
- Vehicle and equipment maintenance:
- Maintain vehicles and heavy equipment and inspect frequently for oil, fuel, or other fluid leaks
- Refuel and perform routine vehicle and equipment maintenance in one designated area
- Perform major maintenance, repair jobs, and washing offsite
- Use drip pans and drop cloths to catch drips, splashes, or spills, and dispose of properly
- Use hand pumps or dispensers to reduce the risk of spilling liquids such as gasoline and kerosene
- If vehicle fluids, paints, solvents, etc. leak or spill:
- Clean up immediately using dry cleanup methods (absorbent materials, cat litter, and/or rags - reuse until spent)
- Contain large spills immediately and notify the appropriate agencies
- Cover areas containing spill residues to prevent stormwater from contacting contaminants
- Substitute water-based for oil-based paints and coatings
- Replace solvents with film-free biodegradable cleaners for cleaning operations such as preparation of marble, metal window frames, or other substances for application of adhesives
Material Substitution
- For cleaning applications where biodegradable cleaners are inappropriate (such as cleaning electrical contacts), use water soluble solvents
- Use non-chlorinated strippers instead of methylene chloride to remove varnish, paints, sealers, and finishes from wood, concrete, and metal surfaces (takes approximately 30 minutes rather than a few)
Materials Recovery
- Use an industrial laundry service for rags (Keep rags in a covered container and do not saturate. Try to find a service that recycles its wastewater.)
- Contract with recycling services for used oil and antifreeze (and purchase re-refined oil and antifreeze for use in your vehicles)
- Use a solvent recycler that replaces dirty solvent with fresh on a regular or as-need basis
- Let solids in used solvents settle, then decant off liquid for reuse as a first rinse/presoak for dirty brushes or equipment
- Recycle reusable materials onsite or contract with recycling service(s) (Recyclable materials include concrete, asphalt, metal scrap, solvents, degreasers, cleared vegetation and topsoil, paper, rock, and vehicle maintenance materials such as oil, antifreeze, batteries, and tires.)
Sources (Appendix A): S6, S13, S17
Dry Cleaning
Good Housekeeping & Operating Practices
- Substitute low temperature laundering for dry cleaning when applicable
- Routinely check the following areas for liquid leakage:
- Hose connections, couplings, and valve machines
- Saturated lint from lint basket
- Door gasket and seating
- Pumps and storage tanks
- Filter sludge recovery
- Distillation unit
- Filter head gasket and seating
- Water separators
- Cartridge filters
- Diverter valves
- Check baffle assembly in cleaning machine weekly
- Check air relief valves for proper enclosure
- Adjust in-and-out condensing coil temperature on heater to within 10°F of each other
- Periodically replace the seals on dryer deodorizing and aeration valves
- Repair holes in air and exhaust ducts
- Replace faulty gaskets on cleaning machine door or tighten enclosure
- Clean lint screens regularly to avoid clogging fans and condensers
- Open button traps and lint baskets only briefly as necessary for cleaning
- Allow only batch discharge of decant water from separator after visual inspection (may not be acceptable to POTW)
Materials Recovery
- If a "dry-to-dry" non-vented system is not used, install a carbon adsorption unit to reclaim solvent from air emissions
- * Install solvent distillation unit to reclaim solvent
- Recycle solvents from filters and cartridges (e.g. steam strip)
- Use a reclaiming dryer to reduce solvent losses
- Utilize azeotropic conditioning to recover solvent (supercondenses the solvent)
- Use a halogen leak detector
- * Use an automated solvent system to eliminate overuse of solvent, soap, sizing, and brightener, and ensure appropriate removal and distillation of dirty solvent (expensive)
Process Modifications
- Retrofit "dry-to-dry" vented systems to non-vented systems to reduce solvent vapor losses and increase recovery
- Replace older systems with a "dry-to-dry" non-vented system (expensive) (Financing Available! See "CLEAN" Program)
- Use a refrigeration/condensation system
- Install solvent leak detectors to monitor for vapor losses
- * Encourage manufacturers to:
- Redesign separators with baffles and decant taps to reduce perchloroethylene (PCE) entrainment and afford better decanting of water
- Provide double-walled tanks
Sources (Appendix A): S12, S13, S22
A Santa Clara, CA
dry-cleaner has taken proactive steps to meet pending air quality regulations and reduce
perc use. See their Case Study.
General Solvent Use & Cleaning/Degreasing
General Solvent Use:
Good Housekeeping & Operating Practices
- Store fresh or used solvents in covered containers (properly vent as needed)
- Use an industrial laundry service to clean contaminated rags (Store rags in a closed container. Do not saturate. Try to find a service which recycles its wastewater.)
- Avoid spraying, showering, or splashing solvents
- Minimize the number of different solvents used and segregate different solvents (as specified by recycler) to enhance reuse and recycling opportunities
Materials Recovery
- Reuse spent solvents (e.g. use spent high-grade solvents in lower-grade uses; allow solids, such as paint, to settle in used solvent and decant liquid solvent for reuse)
- Use a solvent sink service that replaces dirty solvent with fresh on a regular or as-need schedule for equipment and parts washing
- Recycle spent solvent with an onsite distillation unit if quantities are sufficient to make it cost-effective
Parts Cleaning/Degreasing Operations:
Good Housekeeping & Operating Practices
- Turn off solvent flow and cover or plug solvent sink/tank when not in use
- For tanks that are used continuously, install lids with "silhouette entries" (openings closely match the shape of items being cleaned)
- Maintain solvent quality by:
- Properly maintaining equipment to prevent water contamination
- Allowing only dry parts to enter the cleaning operation
- Adding chemical stabilizers to solvent to keep it from going acidic
- Minimize drag-out of solvent by:
- Allowing parts to drain adequately
- Using drip racks above solvent sink or degreaser to allow adequate drainage of heavy parts
- Using drain boards or drip guards to direct spillage back into tank
- Monitor sludge volume and remove:
- Sludge bottom buildup from soak tank when contaminants reach 10% of solvent quantity
- Organic materials when they are 10 % by weight of a cold cleaning operation or 25 % by weight of a vapor degreasing operation
- Metal fines (such as zinc or aluminum) immediately
- When using vapor phase cleaning, take the following measures to ensure that parts are
dry:
- Do not overload degreaser
- Wait for condensation to stop before removing part
- Remove parts slowly
- Rack the parts for best drainage
- Avoid degreasing porous materials
- When using a vapor degreaser:
- Work in or below the vapor zone in a vapor degreaser
- Check water separator frequently to ensure it is clean and free of debris
- Make the sure the temperature of the water exiting the condenser coils and cooling jacket is between 90° and 100° F
- Inspect degreasers for leaks daily and repair as necessary
- Reduce evaporation with increased freeboard height and blankets
- Make sure degreasing tanks have empty freeboard space above the solvent vapor zone at least 75-100 % of the tank width (freeboard=.75 or more)
- Check the freeboard - ratio daily, and any time solvent is added
- Do not locate soak tank near paint curing ovens
Materials Substitution
- Eliminate the need for protective oils and subsequent solvent degreasing by having
suppliers/customers:
- Provide "just-in-time" delivery of parts
- Use corrosion inhibiting protective films, provided they can be readily removed (e.g. organic peel coatings like polyethylene shrink-wrapping, dilute oils, organic liquids, alkaline dips)
- Use aqueous (including alkaline and caustic), terpene plant oil, or citrus-based cleaners (e.g. limonene) in place of solvents for cleaning and degreasing
- When using solvents, use less toxic solvents such as:
- Non-chlorinated solvents in place of chlorinated solvents
- Aliphatic solvents such as Stoddard solvent and naphthas in place of benzene and aromatic solvents
- Aliphatic hydrocarbons, terpenes, N-methyl-2-pyrrolidone, or dibasic acid esters in place of halogenated solvents
Process Modification
- Use multiple stage/countercurrent cleaning lines for workpiece racks to minimize waste cleaning solutions (similar to countercurrent rinse systems, i.e. use dirty solvent for initial cleaning and clean solvent for final cleaning)
- Increase solvent or aqueous cleaner performance by increasing agitation:
- Install pump and spray
- Use air sparging
- Install ultrasonic units
- Install a freeboard chiller (a refrigerated coil installed above the primary condenser coil) above the vapor zone
- Reduce or eliminate solvents for drying parts by
- Using forced air dryers rather than solvents to evaporate water from parts
- Using water soluble rinse aids (small percentage in static rinse) to reduce water adhesion and subsequent drying time
- When using chlorinated solvents in batches of 500 gallons or more, analyze the solvent and add stabilizer formulation, not fresh solvent, as required
- Replace solvent systems with:
- Mechanical cleaning or paint stripping systems
- Jet spray washers, hot tanks, and steam cleaning
- Thermal "bake-off" ovens
Sources (Appendix A): S7, S8, S12, S13, S23
Machining
Good Housekeeping & Operating Practices
- Standardize the types of fluids used in machining operations for as many applications as possible to minimize the management of different materials
- Perform regular cleaning of machines and sumps, and maintain gaskets, wipers, and seals (replace as needed to reduce potential contamination of fluid)
- Dedicate separate basins for the machining of different metals to facilitate recycling and place on wheels for easy mobility from work to storage areas
Materials Substitution
- Use:
- demineralized makeup water
- non-toxic dye penetrants
- water-based or greaseless binders
- Change to synthetic fluids with low susceptibility to contamination
- Substitute lime or borax soap for lubricating oils
- Replace standard cutting oils with biodegradable cutting oils or water soluble coolants and utilize gas coolants where appropriate
- Phase out TCA and flammable solvents and convert to water-based cleaners
Materials Recovery
- Recirculate metalworking fluids with the use of a collection basin/sump unit
- * Reuse or recycle (onsite or offsite) cutting, cooling, and lubricating oils by filtration, clarification, skimming, dissolved air flotation, coalescing, hydrocycloning, centrifugation, pasteurization, or use of specialized biocides
- Segregate and reuse scrap metal; recycle metal wastes, dusts, and sludges (see "Successful exchanges . . ." on page D-1.)
Process Modification
- * Separate water/solvent from chemical wastestreams (i.e. coolant, oily rinse water, paint, etc.) by ultrafiltration, evaporation, coalescer, or centrifuge
- Convert machines to "misters" (a device which provides a thin mist of cutting oil directly at the point of cutting)
Sources (Appendix A): S1, S13