Disposal and Storage of Chemical Waste

• Chemical waste - a waste that is made from harmful chemicals.
• Chemical waste may fall under regulations such as the Clean Water Act of 2004 (Republic Act No. 9275) which aims to regulate pollutant discharges into the waters of the Philippines.
• Hazardous waste is a substance that poses a hazard to human health or the environment when improperly managed.
• Ignitable – liquids with a flash point below 60oC, closed-cup test, or 65.6oC, open-cup test. Self-reactive solid materials that are liable to undergo at normal or elevated temperatures, a strongly exothermal decomposition or readily combustible solids that may cause a fire through friction.
• Flash point – it refers to the lowest temperature wherein the liquid will form a vapor in the air near its surface that will flash or ignite upon exposure to an open flame.
• Flash point is a general indication of the combustibility or flammability of a liquid.
• Closed-cup test - the flash point in the closed cup method is conducted inside a closed vessel that is not open to the outside atmosphere. The lid is sealed and the ignition source is introduced into the vessel itself, allowing for a closer approximation to real-life conditions (such as those found inside a fuel tank).
• Open-cup test - conducted in a vessel that is exposed to the air outside. The temperature of the substance is gradually raised and an ignition source is passed over the top of it until it reaches a point at which it “flashes” and ignites.
• The flash point here will vary according to the distance between the substance and the ignition source – the height of the source above the cup. The most commonly-used open cup method is known as the Cleveland open cup (COC).
• Corrosivity – generally aqueous wastes with a pH of 2 or less or 12.5 or greater.
• Reactivity – wastes that are unstable, explosive, and capable of detonation or violent reaction in water.
• Toxicity – a chemical waste that poses a hazard to health or the environment. This type of hazardous waste must be categorized as to its identity, constituents, and hazards.
• • Chemicals that can no longer be used for their intended use. Example: aged or surplus inventory
  • Mislabeled or unlabeled chemicals.
  • Abandoned chemicals.
  • Material in deteriorating or damaged containers.
  • Residuals in chemical containers
  • Diluted solutions containing hazardous chemicals
  • Debris contaminated with a hazardous materials Examples: rags, paper towels, lab diapers, gloves, etc.
• In the laboratory, chemical wastes are usually segregated on-site into an appropriate waste carboy and disposed of by a specialist contractor in order to meet safety, health, and legislative requirements.
• Laboratory wastes containers should only be filled up to 75% capacity to allow for vapor expansion and to reduce potential spills which could occur from moving overfield containers. It must also be compatible with the stored hazardous waste.
• Chemical waste category that should be followed for proper packaging, labeling, and disposal of chemical waste.
• Innocuous Aqueous Waste

  • Acid (pH < 4)
  • Alkali (pH > 10)
  • Harmless Soluble
  • Inorganic Salt
  • Alcohol containing salt
  • Hypochlorite solution
• Organic Solvent

  • Chlorinated Examples: DCM, Chloroform, Chlorobenzene, etc.
  • Non-chlorinated Examples: THF, Ethyl acetate, Hexane, Toluene, Methanol, etc.
• Red List

  • Compounds with transitional metals
  • Biocides
  • Cyanides
  • Mineral oils and hydrocarbons
  • Poisonous organosilicon compounds
  • Metal phosphides
  • Phosphorus elements
  • Fluorides and nitrites
• Solid Waste

  • Lightly contaminated

  Examples: gloves, empty vials/centrifuge

  • Broken glassware

  Broken glassware are usually collected in plastic-lined

  cardboard boxes for land filling. Due to contamination, they are usually suitable for recycling.
• NaCl may be poured down the sink.
• Some chemicals are washed down with excess water like conc and diluted acids and alkalis, harmless soluble inorganic salts, alcohol-containing salts, hypochlorite solutions, fine (TLC grade) silica, and alumina.
• Aqueous waste containing toxic compounds is collected separately.
• Waste elemental mercury, spent acids and bases may be collected separately for recycling.
• Waste organic solvents are separated into chlorinated and non-chlorinated solvent waste.
• Chlorinated waste is usually incinerated at high temperatures to minimize the formation of dioxins.
• Non-chlorinated solvent waste can be burned for energy recovery.
• Chemical materials on the “Red List” should never be washed down a drain.
• Environmental Protection Agency (EPA) prohibits disposing certain materials down any UVM drain includes:

  • Flammable liquids
  • Liquids capable of causing damage to wastewater facilities
  • Highly viscous materials capable of causing an obstruction in the wastewater system
  • Radioactive materials
  • Materials that have or create a strong odor
  • Wastewater capable of raising the temperature of the system
  • Pharmaceutical or endocrine disruptors
• Incompatible chemicals are stored in separate areas of the laboratory.
• Acids should be separated from alkalis, metals, cyanides, sulfides, azides, phosphides, and oxidizers.
• Oxidizers should be separated from acids, organic materials, metals, reducing agents, and ammonia.
• Container Compatibility

  • The container must be chemically compatible with the material it will hold.
  • Chemicals must not react with weakening or dissolving the container or lid.
  • Acids or bases should not be stored in metal.
  • HF should not store in glass.
  • Gasoline should not store or transport in lightweight polyethylene containers such as milk jugs.
• Packaging – chemical liquid waste containers should only be filled up to 75% of their capacity to allow for vapor expansion and to reduce potential spills which could occur from moving overfilled containers. This air space allows for pressure changes above the liquid in response to changes in the rate of evaporation with ambient temperature.
• Labeling – waste containers should be clearly labeled with the full details of the contents, date, and the name of the person responsible for accumulating and transferring the waste. Major components of the waste must be clearly listed and where possible the original container used to help provide hazard information.
• Storage – the containers must be in good condition and should remain closed unless waste is being added. Hazardous waste must be stored safely prior to removal from the laboratory and should not be allowed to accumulate. The container should be sturdy and leak-proof, also has to be properly labeled.
• Waste containers may be stored in laboratory areas as a temporary measure while they are being filled until they can be transferred to a designated waste storage area.
• Flammable solvent waste should be stored in a suitable flammable storage cabinet or fire-resistant container.
• Waste solvent containers should be clearly marked and coded.
• Where possible containers used to store waste chemicals in the liquid form should be stored with secondary containment, this may simply take the form of a small tray to act as a bund in the event of a spillage.