Pollution Prevention Options for Chemical Manufacturers

compiled by Rick Grote, ChemAlliance Staff

Pollution Prevention Checklist for Chemical Manufacturing Facilities
Prepared by Solid & Hazardous Waste Education Center (SHWEC),
University of Wisconsin-Madison Extension Program

Reacted, Polymerized or Off-spec Chemicals

Dust Emissions

Empty Containers

Tanker Heels

• Test materials first to determine whether they can be used in current manufacturing processes.
• Return obsolete materials to suppliers.
• Segregate waste streams.
• Store packages to protect from weather.
• Provide secondary containment (and possibility for recovery) for hazardous materials.
• Improve quality of feed by working with suppliers or installing purification equipment.
• Re-examine need for each raw material (e.g., reduce or eliminate by modifying process and improving control).
• Use off-spec material.
• Use inhibitors to prevent unwanted side reactions or polymer formation.
• Reformulate products from powder to pellet.
• Reuse inert ingredients when flushing solids handling equipment.
• Switch to reusable containers, tote-bins or bulk shipments.
• Recover product from tank cars and tank pumps and piping systems to transfer liquids.
• Use dry disconnects.

By-products

• Improve physical mixing in reactor by installing baffles, high rpm motor for agitator, different mixing blade design, multiple impellers, pump recirculation or an in-line static mixer.
• Distribute feeds better for better yield conversion, both inlet and outlet.
• Improve ways reactants are introduced into reactor (perfect ideal reactant concentrations before feeds enter reactor).
• Improve catalyst and continuously upgrade.
• Provide separate reactor for recycled streams.
• Improve heating and cooling techniques for reactor.
• Consider different reactor design (e.g., plug flow instead of stirred-tank back mix).
• Improve control to maintain optimal conditions in reactor (e.g., stabilize conditions in operation frequently, use advanced computer controls).
• Ensure that rubber gaskets are not cracked or worn.

• Recover seal flushes and purchase and recycle to process where possible.
• Turn off flush when not in use.
• Use seal-less pumps (can-type or magnetically driven).

• Reduce tube-wall temperature:
• Use lower pressure steam;
• De-superheat steam;
• Install thermocompressor.
• Use staged heating (waste heat, then low pressure steam, then de-superheated high pressure steam).
• Use on-line cleaning techniques (recirculating sponge balls and reversing brushes).
• Use scraped-wall exchanger for viscous streams.
• Monitor exchanger fouling.
• Use non-corroding tube.

Polymerized Waste

Vented or Flared Products

• Increase reflux ratio if column capacity is adequate.
• Add section to column (e.g., with different diameter, trays, high efficiency packing).
• Retray or repack column.
• Change feed tray for better separation.
• Insulate.
• Improve feed distribution, especially for packed column.
• Preheat column feed (e.g., by cross exchange with another stream).
• Remove overhead products from tray near top of column.
• Increase size of vapor line.
• Modify reboiler design (falling film or pumped recirculation reboilers, high-flux tubes).
• Reduce reboiler temperature (e.g., using lower pressure steam, de-superheated steam, installing thermocompressor, using intermediate transfer fluid).
• Ensure that tubes are not blocked.
• Lower column pressure.
• Improve overhead condensers (retubing, condenser replacement, supplemental vent condenser addition).
• Forward vapor overhead to next column (use partial condenser and introduce vapor stream to downstream column).

By-Products

Emissions

Degraded Product

• Establish a leak detection and repair system for all valves, pumps and seals.
• Monitor major vents (storage tanks, tankers) and flare system and recover vented products (install condenser or vent compressor).
• Avoid sending hot materials to storage.
• Change metallurgy or use lining.
• Avoid overheated lines, vessel tracing and jacketing.
• Eliminate "dead" zones
• Segregate wastes and recover.

• Replace coil, investigate alternative designs.
• Replace furnace with intermediate exchanger, use high temperature transfer fluid.
• Use existing steam superheat.

Contaminated Product

Spills

Dust Emissions

Evaporative Loss

Samples from Quality Control Testing

• Produce only the amount requested or needed.
• Substitute less toxic or non-toxic raw materials.
• Improve on-line control (e.g., with computer control system).
• Optimize daily operation.
• Automate start-ups, shutdowns and product changeover.
• Program plant to handle unexpected upsets and trips.
• Relocate process equipment and change piping configuration to avoid contamination from other sources.
• Find a market for waste product.
• Install reusable insulation.
• Redesign or modify processes and technologies to recover product and unconverted raw materials.
• Reformulate products (e.g. prepare chemicals in pellet form instead of powder to reduce dust emissions).
• Segregate and reuse dust emissions in the production process.
• Shift from batch manufacturing to continuous manufacturing.
• Regenerate catalysts.
• Review sampling frequency and procedure to reduce number and quantity.
• Recycle samples.
• Consider diversion into neutralization tanks if disks rupture on the reactor.

Mercury

• Reduce sample size.
• Review sampling procedures.
• Return unused sample to process (or client).
• Perform in-line monitoring.
• Use electronic or non-mercury thermometers.

High Water Usage

• Continuously monitor water quality and adjust chemical concentration.
• Use less toxic biocides instead of chlorine.
• Use blowdown water for non-critical cleaning applications or as fire pond water.
• Use plastic lumber to replace wooden slats.

Spent Cleaners

Rinse Water

Spent Filters

• Maximize equipment dedication.
• Improve scheduling of production of chemicals that use the same production line.
• Recover more product (e.g., through scraping down tanks, pigging or blowing lines).
• Reuse inert ingredients when flushing solids handling equipment.
• Avoid unnecessary equipment cleaning; explore feasibility of eliminating cleaning step between batches.
• Consider in line mixers instead of bulk tanks for mixing.
• Consider alternative cleaning methods (mechanical cleaning such as plastic media or dry ice blasting).
• Consider less hazardous cleaners (e.g., ultrasonic cleaning with more biodegradable cleaner).
• Standardize cleaning products used.
• Use less cleaner (by using high pressure sprays, pressurized air, steam and heated cleaning bath, etc.)
• Reclaim and reuse cleaner if feasible.
• Use multiple stage rinsing.
• Reuse rinse water.
• Clean process equipment with process fluids if possible.
• Use clearable reusable filter media

Sources:

• Chemical Manufacturing: Pollution Prevention Opportunities Checklist, Industrial Waste Section, County Sanitation Districts of L.A. County, Whittier, CA, 12/90.

• "Use These Ideas to Cut Wastes," Hydrocarbon Processing, Ken Nelson, Dow Chemical USA, March 1990.

• Fact Sheet: Pollution Prevention: Strategies for Chemical Production, Center for Hazardous Materials Research, Pittsburgh, PA.

• "A Pollution Prevention Guide for Small Chemical Manufacturing Operations" Delaware Department of Natural Resources and Environmental Control: http:/wwwdnrec.state.de.us/tdelchem.htm

• Connecticut Department of Environmental Protection Industry Specific Fact Sheets: Chemical Processing (6/93)