03n hazardous waste print

NTU EM107 Environmental Health and Safety

3 Hazardous Waste

3.1 Hazardous Wastes Incidents

Figure 3-1: Workers in protective clothing clearing the toxic waste from a hole in the landfill on Pulau Pangkor, Perak, Malaysia. Some 92 drums containing potassium cyanide were brought there by the owner ScientificTex Sdn Bhd from Penang, Malaysia, and dumped illegally. (The Straits Times, Friday, March 24,1995)

3.1.1 Love Canal

Love Canal In the late 1800’s major electricity supply was direct current that cannot be transferred through long distances, resulting in the clustering of energy-intensive industrial development near the power source. In 1892 William T. Love developed a plan to build a canal to connect the upper and lower levels of the Niagara River, to use the power generated near this canal. An industrial complex would also be developed. The 7-mile long canal was never completed – the development of alternating current ended the need for power users to be near the power generating source – the final 2 sections of the canal each about one-quarter mile long were left unfinished.

Became a chemical landfill

Hooker Chemical purchased the site of the abandoned canal in the late 1943s and started landfilling the canal with their waste residues. What was done was “legal” at the time. Indeed Hooker Chemical did an environmental feasibility study – which concluded that the short uncompleted canal was lined with impervious clay and thus was a suitable disposal site.

A number of other companies also used the canal for disposal of their waste chemicals. In total an estimated 22,000 tons of chemicals of unknown kind were buried at Love Canal. The city of Niagara Falls

03N Hazardous Waste.doc 3-1 April 2011


deposited fly ash there. Biological warfare agents and residues may also had been buried there, an accusation the US Pentagon has denied.

In 1952 Hooker Chemical closed and capped the canal.

Sold to the city In 1953, the Niagara Falls School Board and city officials ordered Hooker Chemical to sell canal to city. Reportedly Hooker Chemical tried to dissuade the sale and not to build on the site – citing possible dangers of building over the chemical landfill - but School Board and the city were determined, and the final sale was for US$1.

In the deed Hooker stated that chemical wastes were buried there and Hooker should bear no liability for them.

A school was built

The 99th Street School was built in 1954 over the unused northern part of the canal. Following soon housing developments, and utilities that resulted in digging into the protective clay covering and laying sewer lines through the waste.

In 1978, some 97 families lived immediately adjacent to the landfill , in the homes immediately adjacent to the landfill, and the school had 410 students. In a study published in 2008, an estimated 6,200 persons were affected by the waste dump.

The aftermath Children playing at the park would occasionally pick up chunks of “rocks” and would throw them against rocks to see the brilliant explosion. These rocks turned out to be chunks of phosphorus.

Soon more horror stories abound – birth defects, mental retardation, enlarged livers, cancer, swimming pool swelling up, black stuff oozing out of basements, etc.

A large number of chemicals were found at the sites – tests showed a variety of chlorinated solvents, benzenes, toluenes, pesticides, dioxin, etc.

The superfund program

The US Superfund Program was created by the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA). With the “polluter pays” principle, the US government would take legal action to get the former owners and users of contaminated site to cleanup the contamination or pay for the cleanup. If the responsible parties cannot be identified or are now bankrupt, the costs are paid from a “Superfund” created by a tax on manufacturers of petroleum and chemicals.

Occidental Chemical paid restitution costs

The Occidental Chemical Corporation (which had become the parent company of Hooker Chemical) paid $129 million to cover the federal government's cleanup costs at Love Canal, New York.



National Priorities List

In October of 1981, the Love Canal was listed on the EPA’s National Priorities List (NPL).

Note: The National Priorities List (NPL) is the list of national priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the United States and its territories. The NPL is intended primarily to guide the EPA in determining which sites warrant further investigation.

3.1.2 Minamata Disease

Minamata Bay, Japan

Minamata was a small town facing Minamata Bay on the western coast of Kyushu, Japan. A local chemical company Chisso Corporation started production of acetaldehyde (which was used to produce plastics) in 1932. The process utilized a mercury salt and produced methyl mercury, an organic form of mercury readily incorporated into the food chain.

Methyl mercury dumped into the bay

From 1932 to 1968, Chisso dumped an estimated 27 tons of mercury compounds into Minamata Bay without treatment. “According to Eugene Smith's interview of the people who lived in Minamata, the company believed that it was much cheaper to pay off the few people who were opposed to the dumping, rather than implement an environmentally safe technique of waste removal. Therefore, since the villagers accepted this practice through compensation of money, and the government was behind the industry, the entire process appeared ethical.”

Bioaccumulation and Biomagnification

The case of Minamata disease exemplifies phenomenon known as bioaccumulation and biomagnification, where substances if not excreted or broken but stored in the tissue of organisms, would reach successively higher concentration in the higher trophic level in the food chain. For further details the reader is referred to Chapter 8 of this module Environmental Health.

Minamata Disease

Local residents depended on fish and shell fish for their protein. Strange behaviours began to emerge, cats would stagger, unable to keep their balance, they would fall into the sea and drown - residents called it "cat suicides." From the early 1950s, similar symptoms - successive loss of motor control, sometimes partly paralyzed and contorted bodies - started to emerge amongst the villagers (See Eugene Smith’s photographs).

The result of this indiscriminate disposal of mercury into the sea were thousands of people poisoned by methyl mercury - the illness became known as the "Minamata Disease". The mercury poisoning resulted from years of environmental destruction and neglect from the corporation.

Note: much of what was known about the Minamata Disease was drawn from a book written by former Life photographer, Eugene Smith, and his wife, Aileen, who lived in Minamata for several years.



3.1.3 Household Hazardous Wastes

Household hazardous wastes

A large number of household items, including aerosol cans, paints, batteries, bleach, disinfectants, cleaners, fluorescent tubes, medicines, etc are hazardous wastes. These are frequently disposed in the municipal solid waste stream, while the amount generated by each person is very small, the quantities eventually created in the municipal waste stream is significant.

A detailed discussion of household hazardous waste is beyond the scope of this module.

3.2 Tranboundary Movement of Hazardous Wastes

Formosa Plastics and Cambodia

In November 1998, a shipment of 3,000 tonnes of incinerator waste was unloaded from a Taiwanese vessel and transferred to a dumpsite near Sihanoukville, Cambodia. The dumpsite was near a village that was home to some 3,000 persons.

The plastic sheets used to hold and cover the wastes were attractive to the villagers, who would use them as roofing materials and fences. They were reportedly ripping the plastics open with their teeth to get the strings to use as clothes line. The waste was laced with mercury.

Within weeks tragedy struck – a dock worker that cleaned the vessel hold died, with many others hospitalized with symptoms of nerve damage and respiratory distress. Tests confirmed that the waste contained dangerously high levels of mercury.

Formosa Plastics Corp. had exported the wastes without consent of the Cambodian or the Taiwanese governments, a violation of the Basel Convention (see below). Formosa Plastics later admitted to paying $3 million bribe to Cambodian officials so that they could carry out the dumping.

Problem Since the 1970’s with increasing environmental awareness governments of developed countries started tightening rules of management of hazardous wastes, leading to significantly higher cost for hazardous waste disposal. Soon such hazardous wastes showed up in developing countries such as Haiti and Nigeria, which did not have the knowledge or infrastructure to manage the wastes appropriately. Often the hazardous wastes ended up illegally dumped at remote locations, or stored on unprotected land for which the owners were often paid a paltry sum as rental to store the hazardous wastes.

The Basel Convention

Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal (The Basel Convention) is a United Nations treaty designed to prevent the unauthorized transfer of hazardous wastes from developed to less developed countries by providing the Parties



the right to prohibit the import of hazardous wastes or other wastes for disposal from other Parties.

There are at present 175 parties to the treaty, with only Afghanistan, Haiti and the United States of America having signed but not ratified the treaty.

3.3 Hazardous Waste Management Hazardous waste

Hazardous wastes are wastes which by their nature and quality may be potentially detrimental to human health and/or the environment and which require special treatment and disposal.

Hazardous wastes can be liquids, solids, contained gases, or sludges, they are usually by-products of manufacturing processes or simply discarded commercial products, like cleaning fluids or pesticides. Some examples of hazardous wastes include spent acids, spent solvents, spent etchants, waste oil and waste sludge.

Names of hazardous wastes

Hazardous wastes may be known by different names in many countries. For example, in the US and many other countries the term is simply hazardous wastes, while here in Singapore they are known as Toxic Industrial Wastes, and in Malaysia they are known as Scheduled Wastes.

Definitions of hazardous wastes - Basel Convention

Annex 1 of the Basel Convention lists wastes covered by the Convention; and Annex III lists the hazardous characteristics to be considered (explosive, flammable liquids and solids, liable to spontaneous combustion, on-contact with water emits flammable gases, oxidizing, organic peroxides, poisonous (acute), infectious, corrosives, on-contact with water emits toxic gases, toxic (chronic), ecotoxic, may yield above substances when disposed e.g. by leaching).

Also considered to be under the scope of the Basel Convention are wastes defined as hazardous by the parties involved (exporting, importing or transit countries).

Singapore Toxic Industrial Wastes

In Singapore the main regulation governing hazardous wastes is the Environmental Public Health (Toxic Industrial Wastes) Regulations. In this regulation, toxic industrial wastes are wastes which by their nature and quality are potentially detrimental to human health and/or the environment and require special management, treatment and disposal.

A list of toxic industrial wastes is available at the Singapore NEA (National Environment Agency) website: http://app2.nea.gov.sg/NEADownload.aspx?res_sid=20100505422108755681

Malaysia Scheduled Wates

Hazardous waste is defined as any waste falling within the categories of wastes listed in the First Schedule of the Environmental Quality (Scheduled Wastes) Regulation.


http://app2.nea.gov.sg/NEADownload.aspx?res_sid=20100505422108755681



The General Case

A waste will be consider hazardous by the following two ways:

Listed in regulations as hazardous wastes; or

Exhibit one or more of the following characteristics – ignitable (flash point < 60 oC), oxidizing, corrosive (pH < 2 or > 12.5, or corrodes steel at a rate > 6.35mm per year at a test temperature of 55 oC), reactive, toxic (LD50 < 500 mg/kg) or explosive.

One should note that the characteristics listed above could vary between countries.

Unknown wastes should be considered hazardous unless proven by known origin or by testing.

Management of hazardous wastes

In Singapore, the key elements for the management of hazardous wastes are:

avoid generation of intractable wastes;

encourage waste minimisation;

encourage waste reuse, recovery and recycling;

regulate collection, treatment and disposal;

monitor and audit collection, treatment and disposal; and

promote and support educational and training programmes.

In Singapore’s planning process, proposed industrial development will be screened for waste generation to eliminate the generation of wastes that cannot be safely disposed of in Singapore.

Permitting Many countries require the generator of hazardous to obtain a permit or notify the environment authorities of the generation of hazardous wastes. Likewise, companies that would like to be involved in the business of collection, transportation, storage, treatment and disposal of hazardous wastes are also required to obtain a permit before they may engage in such activities.

Typically, the companies concerned must have the knowledge and expertise to manage their hazardous wastes. In Singapore the permit holder is required to attend and passed a prescribed training (Management of Hazardous Substances conducted by the Singapore Environment Institute at NEA).

Further, only companies with the appropriate level of expertise to handle, treat and disposed of hazardous wastes may be granted licenses. Each license is also limited in its scope, i.e. the license would specify the type of waste the company may accept for treatment and disposal.

Manifest A manifest system was created by the US EPA to track the movement of hazardous waste to ensure that the waste actually reach their intended treatment and disposal facility. This system has been widely adopted by



many countries. In Singapore it is known as the consignment note system and is e-tracked.

The manifest is a form that contains detailed information about the waste, including:

generator

name and nature of the wastes (e.g. hazard classification)

quantity of wastes shipped

information about the transporter and final destination of the waste

Crade-to-grave

The concept of “cradle-to-grave” tracking system came from US regulation: the Resource Conservation and Recovery Act (RCRA).

Generators must manage hazardous wastes from the moment they are generated until their ultimate disposal.

In the paper version, multiple copies of the manifest are generated at source – the transporter signs the manifest and provide 2 copies of the manifest to the generator, who sends a copy to the environmental authority. If there are more than 1 transporter, at the handing over of the waste the second transporter is to sign and return a copy of the manifest to the first transporter, and the process is repeated until the waste arrives at the designated treatment and disposal facility. The treatment and disposal facility must returned a signed copy of the manifest to the environmental authority, and in many countries, also return a copy of the manifest to the generator. This is illustrated in the diagram below.

Figure 3-2: Cradle-to-Grave

It should be noted that in the US, the government always views the waste as belonging to the generator, a responsibility that may go beyond the “grave”, i.e. the waste generator is responsible (in part) for the waste handler’s actions. Thus, if the handler does a poor job and pollutes the environment, the generator may be responsible for cleanup.



Storage of Hazardous Wastes

The storage of hazardous wastes should be handled in a similar fashion as the storage of hazardous substances or chemicals. See Chapter 6 for further details.

3.4 Hazardous Wastes Treatment

3.4.1 Neutralization

Significance Neither excessively acidic nor alkaline effluent is acceptable for discharge. PH levels that are not in the 6-9 range could cause corrosion and interfere with biological processes (natural and treatment system).

In some instances, downstream treatment processes may require a specific pH level, e.g. for chemical precipitation. In any case the wastewater will need to meet the pH 6-9 requirements prior to discharge.

Figure 3-10: pH control for batch neutralization of acidic wastewater

Neutralization agents for acidic wastewaters

Lime:

Low cost

Disadvantage: sludge and scale production (maintenance issues)

Sodium hydroxide (NaOH) solution (caustic soda):

More expensive; lower system capital and maintenance cost

Significantly less sludge production; sodium salts produced are usually highly soluble

Neutralization agents for alkaline wastewaters

Sulfuric acid

Economical and requires conventional materials for storage, handling and feeding



Highly corrosive – need to consider safety and material handling precautions

Could also create a sulfide problem downstream

Hydrochloric acid (HCl)

More expensive; lower system capital and maintenance cost

3.4.2 Heavy Metal Removal (Precipitation)

Significance Heavy metals in water is deleterious to health and subsequent water use.

Soluble copper causes symptoms of gastroenteritis with nausea

Chromium is carcinogenic and causes skin sensitization and inflammation of the kidney

Selenium is a poison, carcinogen and causes tool decay

Certain metals, e.g. cadmium and lead, when consumed in low dosage accumulate in the body and result in chronic poisoning

Even in concentrations that do not cause acute or chronic health issues, metals could render water unsuitable for drinking purpose due to tastes, staining and corrosion characteristics. Due to their toxicity, heavy metal could affect biological treatment systems negatively.

Figure 2-11: Typical chemical precipitation system

Typical metal hydroxide precipitation process flow

Collect wastewater in equalization tank

pH adjustment

Oxidation or reduction (as needed) or certain constituents, e.g. reduction of Cr6+ to Cr3+ (less toxic)

pH adjustment (for optimum precipitation pH)



Precipitation by adding hydroxide (OH-)

Solids separation, sludge handling

3.4.3 Oxidation-Reduction

Redox Oxidation is an increase of the oxidation state, reduction is a reduction of the oxidation state. In a reduction reaction, the reducing agent is oxidized.

Example Chromium removal from industrial wastewater involves the reduction of Cr6+ to Cr3+, using a suitable reducing agent (e.g. Fe2+ which itself is oxidized to Fe3+), then precipitating Cr(OH)3.

Cr6+ + 3Fe2+ Cr3+ + 3Fe3+

Cr3+ + 3Fe3+ + 12OH- Cr(OH)3 +3Fe(OH)3

Calculate the quantity of FeSO4 and NaOH required to remove 99% chromium in 100 L/min of a wastewater containing 200 mg/L of Cr6+. What is the quantity of sludge produced? (Atomic mass Cr = 52, Fe = 55.8, Na = 23, O = 16, H = 1, S = 32)

Cr6+ + 3FeSO4 + 12NaOH Cr(OH)3 +3Fe(OH)3 + 12Na+ + 3SO42-

Atomic mass Cr = 52, Fe = 55.8, Na = 23, O = 16, H = 1, S = 32

From the equation above, 1 mole Cr6+ reacts with 3 moles of Fe2+ and 12 moles of OH- to produce 1 mole of Cr(OH)3 and 3 moles of Fe(OH)3.

Or 52 g Cr6+ : 3 x 55.8 g Fe2+ : 12 x 17 g OH- : (52 + 17 x 3) g Cr(OH)3 : 3 x (55.8 + 17 x 3) g Fe(OH)3

Amount of Cr6+ to be removed = 0.99 X 200 (mg/L) x 100 L = 19,800 mg = 19.8 g/min

Amount of Fe2+ required = 19.8/52 x 3 x 55.8 g = 63.7 g/min Amount of FeSO4 required = 63.7/55.8 x (55.8 + 32 + 16 x 4)

= 173 g/min = 173 x 60 x 24 g/day = 249120 g/day = 249 kg/day

The amount of NaOH required, and the quantity of sludge produced can similarly be worked out.

3.4.4 Carbon Adsorption

Significance Adsorption is the adhesion of dissolved substances to the surface of solid particles. It exploits the ability of certain solid materials to preferentially concentrate specific substances from a solution onto their surfaces. This can be due to either physical attractive forces (e.g. van der Waals forces in carbon and activated alumina), or chemical adsorption where chemical bonding occurs. Chemisorption has limited application in wastewater treatment.

Activated carbon is a widely used sorbent and will remove a variety of organics. It can also be used in conjunction with biological treatment where difficult-to-degrade organics are adsorbed onto powder activated carbon



(PAC) to remove them from the wastewater as well as providing significantly lengthen its retention time to enable the biomass to degrade them.

Figure 2-12: Activated carbon system schematic

3.5 Problems

1. Cyanide (CN-) is important in metal removal because cyanide forms complexes with metals and prevents them from precipitating as hydroxides. In addition, cyanide is extremely toxic and is likely to interfere or poison the biological treatment systems employed by municipal treatment plants. A common method for cyanide destruction is through chlorine oxidation at high pH. The reaction is as follows:

2CN- + 5Cl2 + 8OH- 2CO2 + N2 + 10Cl- + 4H2O

a. Propose a reason why the oxidation reaction has to be carried out at high pH. b. Calculate the daily amount of chlorine required to completely destroy cyanides in

an industrial wastewater stream containing 80 mg/L of cyanide flowing at 25 L/min. [19.67 kg/day]

2. Which of the following statements on hazardous wastes is TRUE?

a. Toxic industrial wastes as defined by Singapore regulations are industrial wastes that exhibit toxicity to human and other organisms.

b. The key benefit of the consignment note system in Singapore is the systematic collection of revenue derived from the monitoring of the movement of hazardous wastes.

c. Hazardous wastes cannot be treated using biological treatment methods. d. Transporters are required to apply for a permit for the transport of hazardous

waste. (0910S2)




3. A key concept for the management of hazardous substances is the cradle-to-grave approach. Briefly describe the approach and the key elements involved in this approach of hazardous substances management. (8 marks)(0607S2)

4. What are some parameters typically used to define wastes as hazardous wastes? (6 marks)(0809S2)

5. Briefly discuss how a permit, licensing and manifest system may be used to manage

the transport, treatment and disposal of hazardous waste. (8 Marks)(0910S2)

3.6 References 1. American University, Washington D.C., TED Case Studies: Minamata Disaster,

http://www1.american.edu/TED/MINAMATA.HTM, accessed 2 April 2011. 2. Basel Convention on the Control of Transboundary Movements of Hazardous Wastes

and their Disposal, http://www.basel.int/convention/basics.html, accessed 30 March 2011.

3. NEA, Controlled Toxic Industrial Wastes, http://app2.nea.gov.sg/NEADownload.aspx?res_sid=20100505422108755681, accessed 3 April 2011.

4. University of Minnesota, Douglas Allchin, The poisoning of Minamata, http://www1.umn.edu/ships/ethics/minamata.htm, accessed 2 April 2011.

5. Wentz C A (1995), Hazardous waste management, 2nd Ed, McGrawHill Internationsl. Prepared by: F G Ang B.Eng.(Hons) M.Eng. M.Sc.(Environmental Engineering) CIH Date: April 2011

http://www1.american.edu/TED/MINAMATA.HTM

http://www.basel.int/convention/basics.html


http://www1.umn.edu/ships/ethics/minamata.htm

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