Waste treatment processes prior to land disposal of hazardous waste
The five waste management processes include a chemical, biological, thermal, and physical examination and separation and encapsulation. Chemical waste management processes involve the addition or removal of chemicals from waste to produce a less hazardous chemical by neutralization or stabilization. For example, acid wastes are neutralized with an alkali. Another chemical method entails precipitation which is normally applied to wastes with heavy metals to make them less mobile and insoluble. The precipitation process depends on the compositions of the heavy metal in the waste.
Biological management is the use of microbes to mineralize organic waste. For example, hazardous phenols can be broken down by the use of some bacteria such as Pseudomonas. Thermal treatment entails the application of heat to make the waste less hazardous and reduce its volume. Incineration is a procedure for thermal management in which different temperature parameters are used based on the type of waste. For example, wastes with volatile chemicals such as oils, paint thinners, and solvents are incinerated at high temperatures.
Encapsulation entails stabilizing and incorporating wastes with solid materials before being taken to the landfills. For example, beryllium can be encapsulated in concrete. Separation, on the other hand, entails sorting out material that can be recycled from hazardous waste. Finally, the physical inspection process is the examination of wastes to ascertain that the wastes are properly treated before the land disposal.
Key pollutants in air emissions from incinerators of hazardous waste and their sources
Some of the key pollutants from incinerators include heavy metals, carbon monoxide, and polycyclic aromatic hydrocarbons. The heavy metals are released into the air during combustion in the form of different chemical forms. For example, they are released as soluble salts such as sulfates or silicates which are less soluble. The sources of the heavy metals are the organic wastes that may contain lead, chromium, or cadmium. It is important to note that there are many concerns related to incineration as a waste management process. For example, in most cases, there is no complete combustion which leads to the release of harmful products to the air. For example, hydrochloric acid in the air has been associated with incomplete combustion. Other dangerous products are dioxins and furans. Dioxins are produced when compounds that have chlorine are incinerated. Carbon dioxide is termed as a pollutant if it is not well dispersed during the incineration. However, high emissions from factories have been found to contribute to the greenhouse effect. Another key pollutant of incineration is particulates of organic materials that contain heavy metals such as silica. The sources of hydrochloric acid, dioxins, furans, and carbon monoxide are hydrocarbon and chlorine compounds. The result of high-temperature incineration is usually ash which can be disposed of in the landfills.
Advantages of industrial boilers as a method of incineration of hazardous waste
Some of the advantages of industrial boilers are that they combust waste for energy recovery. The energy is taken to the areas of use in the form of steam, heated gasses, and fluids. The energy is used to power different operations of the factory. Boilers stabilize and reduce the volume of solid waste. For instance, solid hazardous wastes are burned at very high temperatures to stabilize them. In the process, the vapor is produced which is released in the air. The use of boilers cuts expenses that could be incurred to transport the wastes to another area for management. Also, the heat can be used to power the industry or sold to nearby buildings. Due to the stabilization, boilers help in ensuring that the wastes do not produce a lot of leachates once taken for the land disposal.
The potential health and safety risks associated with the use of boilers are the leakages in which some hazardous wastes can be released to the air. Some wastes in the boilers have radioactive properties and toxic gasses that can be emitted into the air accidentally. Boilers present risks to the operators as there are occupational risks of coming into contact with the wastes.
Underground Injection Control Program and its impact on the disposal of hazardous wastes via underground injection
The Underground Injection Control (UIC) programs are regulatory measures taken to ensure that waste disposal in landfills does not contaminate underground sources of drinking water. This is based on the understanding that many people in rural areas depend on underground sources of drinking water. In the U.S., the UIC program is based on EPA regulations that monitor injection wells in class I, IV, and V. The class I wells are designed to ensure that wastes are injected deep into impervious rock formations that are below the underground sources of drinking water. This ensures that the uppermost sources of drinking water are protected. Class IV injection wells are used in the dispose of hazardous and non-hazardous wastes above geologic formation that contain underground drinking water; this can be septic systems, dry wells, and surface runoff drainage. On the other hand, class V wells are used for non-hazardous waste disposal.
The main impact of UIC is that it ensures that wastes are pre-treatment before land disposal. It also leads to the categorization of wastes based on their risks to ensure safe disposal. Nevertheless, there are concerns about environmental ramifications especially with findings by hydrogeologists that the flow of water can reach the wells.
Leachate management, drainage materials, and leachate removal systems for a secure hazardous waste landfill
Leachate management entails comprehensive monitoring of waste from the production, treatment, design of the landfill, and its operation to ensure that quantity and quality of leachate does not have a huge impact on the environment. For instance, ensuring that landfills are left as dry as possible to avoid percolation and leaching by lining them with a cap to ensure that leachate does not get to the surface. It is an elaborate process aimed at controlling the quantity and quality of leachate as the basis of the long-term operation of a landfill. It entails designing a system that generates, collects, and treats the leachate.
The materials used in the landfill should be permeable to ensure that the leachate can filter to a collection system. They should not lead to clogging; therefore, they should provide high flow drainage capacity. The materials can be low permeability synthetic liner or soil liner that controls the flow of liquids to the leachate. The quantity of leachate formed is directed to a collection system. This is a containment facility that is used to collect and remove leachate from the landfill. The main aim is to prevent gas and leachate from getting into the environment in significant quantities. The removal system is designed to reduce the buildup of leachate or saturation and is normally at the base of the landfill. The system collects the leachate for treatment or to ensure alternative secure disposal.