Due to the severe deterioration of the waters in the Hong Kong area and Victoria Harbor in particular, the Government took steps in recent years to deal with a problem that had become widely recognized. The "White Paper Pollution in Hong Kong-A time to act" was published in June 1989. This document outlined Government's intention to introduce complete controls on chemical waste. The Waste Disposal Regulation provides a statutory scheme of control which, if enforced vigorously, will enable Hong Kong to begin to recover itself from a serious problem that affects citizens aesthetically, economically and in terms of public health. The main objective of the control scheme is to ensure that chemical waste is property managed by all parties, from the source of production through to the place of final disposal. The Regulation provides for the definition of chemical waste, the registration of persons producing chemical waste, and control of the possession, storage, collection, transport and disposal of chemical waste. The Ordinance provides for the licensing of waste collection, transport and disposal activities and control of the import and export of chemical waste. An illustration of the scheme is shown above.

The Safety and Environmental Protection Office has registered HKUST with the Environmental Protection Department(EPD)as a Waste Producer. This procedure meets the requirement of the law and will enable the University to receive support from the Chemical Waste Treatment Center (CWTC). The Center is the first in the Territory, and is operated by Enviropace, Ltd. under contract to the EPD. The CWTC is designed to provide an integrated system for the treatment of the wide variety of chemical wastes generated in Hong Kong. All of the processing systems in the CWTC are proven technologies which are being operated in different parts of the world.

The new CWTC facility is located on Tsing Yi Island. This modem facility for processing of chemical waste is a great leap forward from the previous practice of placing untreated waste into land fills around the Territory. The entire treatment plant has just completed trial operations and will begin to receive and process waste from industry during the summer of 1993. Due to the much lower volumes, and more complex nature of waste from academic institutions, the academic institutions in Hong Kong will below on the priority list for waste pickup. The current estimate from Enviropace is that HKUST will receive support in late October or November of 1993.

The CWTC has three main treatment process systems, (1) an oily water separation, (2) physical/chemical treatment, and (3) incineration. The oily water separation process is a train of tanks and physical treatment systems. Separation is efficient and allows recovered oil to be used as fuel in the incinerator. The water is sent to biological treatment and final solid residue is sent to the incinerator or to the stabilization unit depending on chemical make-up. The waste water is first conditioned and then fed to a Sequencing Batch Reactor (SBR) for biological treatment. Organic components in the water are metabolized by the activated sludge, and the cleaned water is further processed in the carbon adsorption system. The final water meets all regulatory discharge limits.

The physical/chemical treatment process has seven components, (1) continuous neutralization, (2) waste etchant treatment, (3) chromium reduction, (4) batch neutralization, (5)other aqueous treatment, (6)catalytic oxidation procedures called PO*WW*ERTM, and finally (7) stabilization of solid residues prior to disposal in an off-site landfill. Taken together, these procedures greatly reduce the volume of the waste, recover many metals or change them to a stable state, and also catalytically oxidize carbonaceous components to carbon dioxide and water. In this manner, all residues and wastes meet strict leaching criteria and standards. High quality water is recovered from the various processes and it meets stringent regulatory discharge standards. The water is reused throughout the facilities for such things as boiler feed water make-up, rinsing, washing and chemical reagent mixing.

The incineration system consists of waste storage/blending and an incineration train and is used for destruction of organic materials and cyanide wastes. Chemical wastes received at the CWTC which require incineration are stored in tanks according to their chemical make-ups. The wastes are then blended to ensure the proper feed to the incinerator. The incinerator is an efficient high temperature combustion system that recovers waste heat for a boiler and has an air pollution control system. It is designed to handle liquids and sludges from the blend tanks and solids in burnable containers. The stack air is continuously monitored to ensure that all emission requirements are met. The incinerator ash and scrubber solids are sent to the stabilization system for treatment prior to off-site disposal.

HKUST has taken steps to conduct a comprehensive hazardous waste program. When these procedures are carried out and combined with use of the best facilities available in Hong Kong (or Southeast Asia), waste from UST will be handled in compliance with all current regulations and will be disposed of using the best treatment currently available.

(This article has been taken from June, 1993 issue of Safetywise)

With the implementation of the Waste Disposal (Chemical Waste) (General) Regulation, the disposal of chemical waste in Hong Kong is strictly controlled. Any unwanted materials that contain substances listed in Schedule I of the above regulation are regarded as chemical waste. To carry out the disposal of the newly defined waste, the Environmental Protection Department has contracted with Enviropace Ltd., to collect the waste and dispose of it at the Chemical Waste Treatment Plant at Tsing Yi Island. In this article, we would like to summarize some of the highlights of chemical waste disposal at HKUST. These include safety precautions, current waste streams, waste mixtures, the use of a chemical vompatibility test, and wastes not classified by the scheme.

Safety Precautions

All the appropriate safety precautions should be taken when handling chemical waste, and a summary of key procedures is given here:

1. Always wear splash proof goggles, gloves and a laboratory coat when handling chemical waste.
2. To prevent possible overflow, always check the liquid level in a waste container before new waste is added. The container should only be filled to 70 to 80 % of its full capacity before removal by SEPO.
3. Use a funnel and catch tray for spill prevention and control.
4. A new waste should be poured to its corresponding container only after it has passed the compatibility test (see page 6).
5. The compatibility test should only be performed in a fume cupboard.
6. For waste that evolves fumes and vapor, the transferring of waste should be done inside a fume cupboard.
7. To prevent subsequent escape of fumes and vapors, closethe container tightly each time after the transfer of waste is completed.
8. Highly reactive compounds, water reactive compounds, concentrated strong oxidizing or reducing agents should never be mixed with other chemical waste. These chemicals should be bottled separately and will be taken care of under a different scheme. Examples of explosives include many azide compounds, nitroglycerin, picric acid, trinitrotoluene, certain nitrates, perchlorates and many other chemicals. Examples of waterreactive substances include manyanhydridecompounds, alkali metals, alkyl aluminum chloride, silicon tetrachloride, various boron compounds, and many other chemicals.
9. If chemical waste is handled outside a fume cupboard, a respirator equipped with the appropriate cartridge may be needed by the waste handler. Contact the Occupational Hygiene section of SEPO (Mr. Percy To, x 6507) for information regarding respirator selection & size fifting.
10. Whenever waste is added to a container, immediately enter the information of the new waste to the chemical waste log sheet attached to the container.

Waste Streams

Another issue is the disposal of the waste into the correct container and waste stream. Currentlythere are 11 waste streams designated and collected by Enviropace in Hong Kong. These streams are:

1. Spent Halogenated Solvents (organic chemicals and solvents that contain fluorine, chlorine, bromine or iodine).
2. Spent Non-halogenated Solvents (organic chemicals without fluorine, chlorine, bromine or iodine).
3. Spent Inorganic Acids (mineral acids such as hydrochloric acid, sulfuric acid, etc.).
4. Spent Alkalis (basic compounds such as sodium hydroxide, potassium hydroxide, ammonia containing solutions, etc).
5. Spent Lube Oils (Pump oil, lubricating oil, liquid paraffins, mineral oil, etc.).
6. Spent Fixers (photographic fixing agents used in film processing).
7. Spent Developers (developing agents used in film and photo processing).
8. Spent Metals Solution (Aqueous solutions containing metal ions or precipitates except mercury, chromium (VI), and boron. Solutions containing one or more of these three elements should be collected separately. Contact SEPO, Mr. Edmond Cheng ext 6456, for specific guidance).
9. Spent Organic Acids (organic acids such as acetic acid, propionic acid, etc. If the generation rate of organic acids is low, e.g., less than 4 L per month, the organic acids can be disposed of in containers for Spent non-halogenated solvents or "Spent halogenated solvents" respectively).
10. Spent Hydrofluoric Acid (if the amount of this acid is small, e.g., less than 30% of the total acid waste of a "Spent Inorganic Acids" container, then the hydrofluoric acid can be put into this lafter container without having to start a separate stream).
11. Spent Cyanides (the pH of this container must always be kept alkaline to prevent the evolution of the lethal gas, hydrogen cyanide).

Waste Mixtures

Since many wastes are composed of mixtures, the waste generator can classify the waste according to the major component of the mixture with certain key exceptions. The exceptions are:

1. Waste containing cyanide should always go to the cyanide waste stream.
2. Metal solutions containing chromium (VI), mercury and boron should go to containers designated for these metals. As an illustration, an aqueous solution which is 1 M in each of nickel and silver, but 0.5 M in mercury should be collected in the container for mercury waste.
3. Spent metal solutions or precipitates can also be put into "Spent Inorganic Acid" or "Spent Alkalis" depending upon the pH. If thF- pH is neutral, it should go into Spent Alkalis.
4. If the total generation rate of spent photographic fixers and developers is less than 5L per week, the spent fixer and developer can both be disposed of to a "Spent Developers" container.
5. Waste with distinctive liquid phases should be separated by decantation and disposal to the appropriate containers respectively.

Chemical Compatibility Test

A fundamental procedure that will help prevent chemical reactions between waste already in a container and new waste to be added is to perform a chemical compatibility test. Guidelines for a good standard compatibility test are given in the following steps:

1. Make sure that the air flow of the fume cupboard is "safe" and the sash is lowered to at least shoulder level.
2. This test should be performed inside a fume cupboard by an experienced person.
3. Draw 50 ml sample from the target waste container into a beaker.
4. Insert a thermometer into the beaker.
5. Slowly mix in a portion of the new chemical waste that is to be added to the container. The volumetric ratio of the wastes should be similar to that between the original container content and the new waste.
6. If bubbling, fuming or a noticeable temperature rise (1 0 degree C or more) occurs during mixing or within 5 minutes, stop the mixing, at once. These signs show that the wastes are incompatible. Store the new waste separately in another container and fill in a new individual chemical waste log sheet.
7. If no adverse reaction occurs within 5 minutes, the new waste can be safely added to the corresponding container.

Non-Classified Wastes

A final issue to address are those items that are not classified as chemical waste. According to the Regulation, these items include:

• Neutralized salts that do not contain hazardous compounds defined by the government regulations.
• Apparatus rinsing water and wiping tissue with low chemical contents.
• Elemental heavy metals in stableform (e.g. lead, copper, nickel).
• Household chemicals used in laboratoriesforcleaning purposes (soap, detergents).
• Dilute acids and alkalis with concentration below those defined by the regulation.

These can be disposed of as ordinary waste.

Special Wastes

Any waste containing radioactive material is collected and disposed of separately by SEPO. Please contact Dr Paul Chan (x6535) or Mr Tongo Chan (x6520) for radioactive waste related issues.

Some other materials, such as highly reactive chemicals, solid chemical wastes, gaseous materials, asbestos, and spent chemical mixtures that pose an explosion hazard are not covered by the above scheme. These are covered in a separate scheme known as Labpack Disposal that will be discussed in a future edition of Safetywise.

Finally, if there are any questions about hazardous waste please contact SEPO personnel (Mr. Edmond Cheng, x6456, or Dr. Peter Swearengen, x 651 0).

Conclusion

In conclusion, chemical wastes should always be handled with a high level of precaution. New graduate students, research assistants, and all others new to a laboratory should review and evaluate a thorough set of guidelines for the best handling procedures for various types of chemical waste. SEPO is preparing a document titled Procedures for Disposal of Liquid Chemical Waste at HKUST that will contain further details on waste handling procedures as well as more complete lists of chemical wastes defined by the Hong Kong EPD, water reactive chemicals, explosives, and examples of completion of the Waste Log Sheet. This document will be distributed to the Departmental Fire and Safety Officers (DFSOS) of the departments at the university and the intent is to make it available to all faculty and staff at the university.

The Hong Kong EPD recently conducted an audit of HKUST in regards to compliance with the Waste Disposal Ordinance (Ch. 354) Waste Disposal (Chemical Waste) (General) Regulation (September and November 1996). The results of that audit showed that representative laboratories were in violation of certain criteria of the regulation. In order to bring the university into compliance, we request that you ensure that the following conditions are met within the laboratories of your department.

For waste storage within a laboratory (Work Area) where there is less than 50 liters of chemical waste in temporary storage:

1. The standard 20L Enviropace containers must be kept within a separate spill containment tray. The tray must be able to contain at least 20% of the waste liquid volume.
2. The location of the Enviropace chemical waste containers in each laboratory must be identified with a regulation chemical waste sign, specifically, red English words and Chinese characters at least 6 cm in height on a white background.

For waste storage within a laboratory (Work Area) where there is greater than 50 liters of chemical waste in temporary storage:

1. The 20L Enviropace containers must be kept within a storage cabinet. The cabinet must contain adequate spill containment for 20% of the volume of the stored waste. The waste types must be separated by physical barriers within the cabinet to prevent mixing of any waste types that might react together. Appropriate spill containment trays meet both of the above criteria.
2. The cabinet must only be used for chemical waste, i.e., no reagent chemicals can be stored within the cabinet.
3. The cabinet must be ventilated. Vent holes at the top and bottom of the cabinet can meet this criteria.
4. The cabinet must be labeled with a regulation sign as described above.

There are standard commercial laboratory chemical storage cabinets available from CLS, for either corrosive or flammable chemicals, and these will meet the chemical waste storage requirement. These are painted with an inert, corrosion resistant paint, and are available in full size (45 gal), 1/2 size (30 gal), or in the benchtop or under bench style (15 gal). They also have spill containment built into the bottom of the cabinet. The two smaller cabinets described above fit the Enviropace 20L containers quite snugly, and require removal of the 20L container to add waste liquid.

The standard HKUST laboratory furniture under-bench cabinets also meet the waste storage requirement, and these only require the addition of vent holes and the regulation chemical waste sign. Spill containment for these cabinets can be met by the use of plastic containers available commercially in Hong Kong (contact SEPO x-6456). However, currently available spill containers will only allow up to 2, each, 20L containers within the cabinet.

Every waste generator at HKUST should adjust the chemical waste storage conditions in their laboratory(ies) to meet these guidelines. If these conditions are met, then the waste generator is in compliance with the chemical waste control laws in Hong Kong. SEPO is always glad to provide assistance if anyone has questions on the issues of hazardous waste.