Management of Waste in Laboratory
This chapter presents the approaches and methods for the management and ultimate disposal of laboratory wastes. These wastes may contain chemical hazards as well as multi-hazardous compounds containing the combination of biological hazards, radioactive and chemical hazards (Ho & Chen, 2018). According to Wang et al (2017) an effective waste management strategy aims at maximizing safety while lowering the environmental impacts. This effectiveness is considered from the time of purchase of raw materials utilized in the laboratory to the disposal of the resulting wastes from the laboratory processes. There are number of activities and processes for managing laboratory chemicals and wastes to ensure their probable adverse impacts on the environment are minimized, and maximum safety assured. This chapter presents a discussion of the laboratory waste management strategies, starting with a description of the type of laboratory wastes followed with a discussion of the approaches that can be implemented in the management of the different types of chemical wastes. A discussion of the qualifications, competencies and role of personnel in the management of laboratory wastes is also presented.
Laboratory waste are classified into two major categories, non-hazardous and hazardous wastes. Hazardous wastes according to () refers to the chemical, biological and radioactive waste that are dangerous to both humans and the environment. Handling of such wastes requires a high level of competency from the laboratory waste management personnel. Also, the management of such wastes requires the adoption of methods and strategies that will minimally impact on the environment
Hazardous laboratory waste is waste that poses severe threat to the environment and human health if not disposed of properly. According to the Environmental Protection Agency (APA) wastes that are considered hazardous has four major characteristics, ignitability, corrosivity, reactivity and toxicity. Having an ignitability characteristic means that the wastes have a flashpoint of less than 60 degrees Celsius, are non-liquid materials that cause fires, or are ignitable compressed oxidizers and gases. Wastes with corrosivity characteristics are acidic liquid wastes having a pH value of 2 or less and basic liquids wastes with a pH value of 12.5 and above, such wastes can corrode steel, thus labelled as corrosive hazardous wastes. Reactive hazardous wastes refer to wastes that are unstable under standard conditions and thus can react with water to product toxic fumes. These kinds of wastes also have the capability to explode or detonate when heated. Lastly, toxic hazardous wastes include wastes that are dangerous to human health when inhaled, swallowed or absorbed. Such wastes can also leach through soil and cause serious contamination of the soil and groundwater.
Non-hazardous waste refers to laboratory wastes that do not cause direct threat to the environment or human life. However, such wastes cannot be dumped into a sewer line or receptacles for the fear of causing blockages that will become environmental hazards. .
The goal of the waste management strategies is to reduce the effects of the hazardous and non-hazardous compounds on the environment and on humans. Different methods can be employed to deal with the problem. The waste management hierarchy as postulated by () shows the methods of dealing with hazardous wastes in their order of preference. The most preferred option focus on reducing the amount of waste being released from the laboratory to prevent pollution in the first place. This approach is implemented through source reduction of the resulting wastes from various laboratory processes.
Nevertheless, not all wastes can be eliminated through source reduction or reuse, as such, other approaches have been proposed to deal with the generated wastes. The second option of managing such wastes include refining, recycling or recovering the wastes to be used in various processes. The second approach is also effective in lowering the rates of pollution since the wastes do not reach the environment and are acquired and utilized in other settings, before reaching the environment or landfills. Unfortunately, the second approach has also proven ineffective and impossible to achieve in the management of some kinds of wastes. As a result, other strategies have been postulated that focus on treating the wastes to minimize their toxicity and potential for causing adverse effects on humans and the environment. The last option of managing the wastes is by disposing the hazardous and non-hazardous wastes in landfills or incineration followed with a propped disposal of the residual ash.
As much as each of the identified methods may be vital in the management of wastes at certain times, it is important that the laboratory personnel always try to “move up the management hierarchy”. Waste reduction should be the cornerstone of the efforts made towards the management of laboratory wastes of their probable adverse effects on humans and the environment is to be curtailed.
As illustrated above, there are four tiers to the management of hazardous laboratory waste. The four strategies entail source reduction and prevention of pollution, reuse of materials or their redistribution, treatment, reclamation or recycling of materials within the wastes, and disposal of the wastes through treatment, land burial or incineration. While the first two tiers are considered the most effective in the management of hazardous laboratory wastes, the last two tiers are also important in providing safety and environmental benefits. A discussion of each of the four tiers to laboratory hazardous waste management is advanced herein.
Hazard reduction is regarded as a significant part of pollution prevention. Such waste management approach is encouraged in laboratories that mostly deal with hazardous compounds. From a scientific point of view, it is highly feasible to lower the volume of the hazardous characteristics of chemicals used in various laboratory procedures and chemical reactions. According to () hazard reduction reactions can be included in the last steps in an experimental sequence, to minimize the amount of hazardous chemicals released as wastes. Significant economic benefits can be attained by performing a hazard reduction procedure as part of an experiment. Such benefits are attained when the necessity to accumulate, store transport and treat hazardous wastes are eliminated.
Reduction of the hazardous wastes is achieved when the laboratory personnel keep up-to-date chemical inventories, order small quantities of hazardous materials, and conduct experiments that lower the chance of waste release from the processes.
Reduction of hazardous wastes begin with a good book keeping of chemicals. Every laboratory is expected to establish a chemical inventory system within the laboratory. The system should include all the chemicals in the laboratory, detailing the name of the chemical, chemical abstracts services, procurement date, expiry date and the quantity. The laboratory manager has the responsibility of updating the required quantity of each chemical every three months and making the necessary adjustments. Comparing the quantity of stock and the volumes consumed provided a better guidance on the quantities that should be purchased annual. Procuring the right quantity is vital in ensuring that there are no unnecessary wastes from expired chemicals or reagents. Table 1 below, highlights how such comparisons can be made.
|Different chemicals recorded||Stock (kg/year)||Consumption (Kg/Year)|
Table 1:Average Volume of Chemical Consumption per year
After developing the computerized inventory, it is possible to initiate a chemical exchange program with the manufacturers. Such a program will enable the laboratory manager to request for new chemicals that have been depleted, while requesting for the manufacturers to uptake the unused chemicals. The arrangement is effective in reducing the amounts of unused chemicals from the laboratory as well as enabling to achieve maximum cost-savings.
This is another process that can be adopted in reducing the amount of hazardous chemicals in the laboratory. According to () the process entails substituting hazardous chemicals with non-hazardous chemicals in certain laboratory programs and processes. The table 2 below shows processes where hazardous chemicals can be substituted with non-hazardous chemicals.
|Type of experiment||Instead of these chemicals||Use|
|Agar rose gel staining||Ethidium bromide||Fluorescent dyes or crystal violet|
|Glassware cleaning||Chromic acid solutions||Biodegradable surfactants, strong corrosive solutions, sonic baths|
|Kjeldahl digests||Mercury salt||Mercury-free catalysts (copper sulfate)|
|Storage of biological specimen||Formaldehyde||Ethanol|
Recycling and reclamation of materials from waste is another waste management method that can be adopted in the control and management of laboratory wastes. The recycling process is done to enable the laboratory manager utilized some of the materials reclaimed from the resulting wastes. Different methods can be adopted in recycling and reclaiming hazardous chemical wastes. Methods such as neutralization, distillation, digestion, encapsulation and other thermal treatment methods can be adopted in the recycling and reclamation of materials from laboratory wastes. The expense and the practicality of these processes is largely dependent on the nature of the material as well as its volume. Treatment and recycling of materials is more preferable than disposal of the wastes in the landfills or through incineration. As reported by () the recycling process ensures that minimal wastes are released into the environment, contributing to maximum savings on costs to the laboratory.
Examples of recycling processes includes treatment of high and low pH wastes with water to obtain various salts that can be used in other laboratory processes, and treatable waste water that will have minimal adverse effects if released into the environment. Encapsulation of wastes containing mercury is another example of material reclamation since it can lead to the recovery of some mercury molecules and release of waste water that have minimal adverse effects on the environment. Filtration of aqueous-based waste is also vital in lowering the volume of the wastes and releasing wastewaters that can be safely treated in a sewage treatment facility.
Disposal of chemical hazardous wastes can be done in sanitary sewer, landfills or incinerators for further treatment. While the disposal in the sewer system was initially considered an effective waste management method, its use in the current times has been prohibited. The environmental concerns associated with the disposal of the wastes in the sewer system have markedly changed the custom. In fact, most academic laboratories have eliminated sewer disposal as a waste management strategy since it causes major risks to the surrounding communities, based on the fact that most wastes being released into the environment are hazardous chemicals.
Chemical laboratory wastes that may be permissible for sewer disposal include wastes such as aqueous solutions that are less toxic and are biodegradable. Liquid laboratory wastes such as spend buffer solutions, caustics or neutralized mineral acids can be disposed of in the sanitary sewer. Other water-soluble non-toxic solids can also be disposed into the sewer. However, the disposable of water-miscible flammable liquids into the sewer system is severely prohibited.
As much as it may be permissible to dispose off safe laboratory wastes into the sewer system, the volume of wastes to be released should be based on the requirements set by the government. According to () different governments and states have stipulated the effluent limits for various laboratory wastes being released into the sewer system. It is imperative that the laboratory manager complies with the set requirements on the effluent limits.
The release of waste in the form of vapor to the atmosphere is not an acceptable method of waste disposal. Apparatus for operations that are expected to release vapors should be equipped with appropriate trapping devices. Also, deliberate disposal of materials through evaporation of vapor should be avoided.
Chemical hoods have been devised to aid in the safe disposal of vapor wastes. As much as the hoods are capable of transporting vapor away from the laboratory personnel, such strategy should not be considered a routine method of vapor waste disposal, since it is not highly effective. The absorbent papers included in the hoods have limited absorbing capacity, lowering their effectiveness in absorbing the harmful chemicals from the vapor. Redirection of the vapor arising from the hood to a common trapping device, is effective in completely eliminating the harmful chemicals from the atmosphere.
Incineration of the laboratory wastes is a common method of waste management. According to () incineration is done at temperatures of not less than 1200 F in rotary kilns. The technology provides for the complete destruction of organic materials, reducing the volume of the wastes that must be disposed by landfill. While incineration is considered an effective waste disposal method in relation to landfill, it is an expensive option. The fuel needed to carry out the incineration enhances the overall cost of the waste management process, since the destruction of the wastes is done at higher temperatures. Also, not all wastes can be incinerated. Laboratory wastes containing mercury cannot be incinerated forcing the laboratory management to consider alternative methods of waste disposal other than incineration.
Non-hazardous wastes are considered safe and can be disposed in the normal trash bin. The disposal of non-hazardous wastes via the normal bin or sewer can have significant reduction in the cost of waste management. However, many states and municipalities restrict the disposal of wastes in the landfills or sewer system. This is because a non-hazardous compound may be improperly labelled, exposing the people to serious harm.
It is however important to note that when any non-hazardous waste mixes with portions of hazardous material then the resulting excess must be treated as a hazardous compound. Most laboratories have put in place policies that treats all wastes as hazardous. This ensures that proper waste management strategies are put in place to manage different kinds of wastes.
3.3. Management of Multi-Hazardous Wastes
Multi-hazardous waste is a waste that presents any combination of chemical, radioactive, or biological hazards. This array of waste constituent hazards makes the management of multi-hazardous wastes difficult and complex. For example, low-level mixed waste (LLMW) is a multi-hazardous waste that contains both RCRA hazardous wastes that EPA regulates and low-level radioactive wastes (LLW or LLRW) that the USNRC regulates. The hazardous characteristics, treatment methods, and disposal requirements for these wastes are different and often incompatible. Other factors that further complicate the management of multihazardous wastes include a complex federal, state, and local regulatory framework; limited disposal options; and high disposal costs. Commercial treatment or disposal facilities for multihazardous waste from laboratories are scarce. There is little incentive for the development of a commercial market to treat and dispose of laboratory multi-hazardous waste because most of the waste that laboratories generate is unique to laboratories and small in volume. The management of multi-hazardous waste is particularly challenging for research laboratories where there are frequent changes in protocols, procedures, materials, and waste generating processes. These difficult and complex management issues can also make it difficult to promote and sustain prudent pollution prevention practices.
Medical, clinical, forensic, and environmental laboratories, and biomedical, biochemical, radiological, and other types of research laboratories generate multihazardous waste. Prudent management of these wastes is necessary to protect the health and safety of all laboratory personnel who handle, process, and store the waste for disposal, and to minimize the potential of harm to public health and the environment. A further objective of prudent management of multihazardous waste is to promote excellence in environmental stewardship. The Congress established a federal initiative for preventing or reducing pollution in the Pollution Prevention Act of 1990. This initiative can serve as a guide for developing prudent practices for managing multihazardous wastes.
The Pollution Prevention Act of 1990 established a national policy that emphasizes source reduction as the most desirable approach for preventing or reducing pollution. The policy created a new hierarchy for the management of hazardous wastes. The elements of that hierarchy are listed in order of priority and importance for accomplishing the objectives of the Pollution Prevention Act.
Federal agencies are required to promote programs to advance this policy within their agencies and nationwide. The major research agencies within the federal government, and particularly the Department of Energy, National Institutes of Health (NIH), and EPA, are providing leadership in implementing the nation’s pollution prevention policy, and are achieving results in source reduction. For example, NIH’s low-level mixed waste (LLMW) minimization program demonstrated that a significant amount of mixed waste currently being generated can be reduced or eliminated. References found on the accompanying CD provide more detail about the source reduction and pollution prevention initiatives of those agencies, the achievements of which have encouraged academic research universities and corporate research facilities to focus their pollution prevention programs on source reduction. EHS programs at these institutions often share information on their Web sites regarding source reduction, recycling, treatment, and disposal.
Prudent waste management methods include a commitment by senior management to develop and support a waste minimization program. The program development should involve experienced laboratory personnel in planning waste minimization strategies and identifying source reduction options, such as incorporating pollution prevention goals into project proposals. Training of laboratory personnel to recognize opportunities for source reduction, reviewing research proposals to ensure adoption of available source reduction strategies, improving compliance with regulatory requirements, and institutional policy are among the new management initiatives at research institutions promoting pollution prevention. Multihazardous waste requires complex attention because of its combination of hazards and regulatory controls, as detailed in the following guidelines:
Assess the risk posed by the hazardous characteristics of the waste. A primary purpose of the risk assessment is to determine which hazardous constituent of the multihazardous waste presents the greatest risk. This knowledge can help identify source reduction and treatment possibilities to reduce the risk of the waste. An assessment that determines that a waste constituent does not present a significant risk may provide an opportunity for regulatory flexibility. For example, the USNRC or state authority may allow a licensee to manage a chemical–radioactive waste as a chemical waste without regard to radioactivity when the radioactive constituent concentration is less than what the USNRC specifies for an unrestricted area.
Minimize the hazardous constituents in the waste. Consider applying the waste minimization methods specific to each hazardous constituent of the waste. This strategy could result in reducing or eliminating one hazardous constituent from the waste stream and managing the waste as a single-hazard waste. For example, the substitution of nonignitable liquid scintillation fluid (LSF) for toluene-based LSF reduces a chemical–radioactive waste to a radioactive waste.
Determine options for managing the multi-hazardous waste. Waste management options include recycling, laboratory methods, management at institutional waste facilities, and treatment and disposal at commercial sites. Options can vary considerably between laboratories depending upon institutional capabilities and state and local laws. It may be appropriate to manage the waste in order of risk priority, from high to low risk. Options must be compatible with all hazards, and combinations of waste management methods may be limited by their order of application. Reject any combination or sequence of methods that may create an unreasonable risk to waste handlers or the environment, or that might increase the overall risk. If an option has a clear advantage in efficiency and safety, it should have highest priority. For example, if safe facilities are available on-site, hold short-half-life radioactive waste for decay before managing it as a chemical or biological waste. The EPA Final Rule on the storage, treatment, transportation, and disposal of low-level mixed waste will allow holding the waste for longer than 90 days.
Ho, C. C., & Chen, M. S. (2018). Risk assessment and quality improvement of liquid waste management in Taiwan University chemical laboratories. Waste management, 71, 578-588.
Oliveira, A. C. R. D., Braga, A. M. C. B., Villardi, J. R. W., & Krauss, T. M. (2020). Waste management in laboratories of a Brazilian public university: a challenge for environmental health and occupational health. Saúde em Debate, 43, 63-77.
Walters, A. U., Lawrence, W., & Jalsa, N. K. (2017). Chemical laboratory safety awareness, attitudes and practices of tertiary students. Safety science, 96, 161-171.
Walters, A. U., Lawrence, W., & Jalsa, N. K. (2017). Chemical laboratory safety awareness, attitudes and practices of tertiary students. Safety science, 96, 161-171.
Capoor, M. R., & Bhowmik, K. T. (2017). Current perspectives on biomedical waste management: Rules, conventions and treatment technologies. Indian journal of medical microbiology, 35(2), 157-164.
Wang, L. K., Wang, M. H. S., Hung, Y. T., Shammas, N. K., & Chen, J. P. (Eds.). (2017). Handbook of advanced industrial and hazardous wastes management (Vol. 7). CRC press.