UA5 C3 Liquid and Solid Emissions Obj 6.docx
Transcript
Environment and Climate Change Canada defines “disposal” and “treatment” as follows: Disposal: The final disposal to landfill, land application or underground injection, either on the facility site or at a location off the facility site; transfer to a location off the facility site for storage or t...
Environment and Climate Change Canada defines “disposal” and “treatment” as follows: Disposal: The final disposal to landfill, land application or underground injection, either on the facility site or at a location off the facility site; transfer to a location off the facility site for storage or treatment prior to final disposal; or movement into an area where tailings or waste rock are discarded or stored, and further managed to reduce or prevent releases to air, water or land, either on the facility site or at a location off the facility site. The disposal of a substance is different from a direct release to air, water or land. Treatment: Subjecting a substance to physical, chemical, biological or thermal processes at a location off the facility site prior to final disposal. Several methods of disposal have been used through the years. Landfill was a quick and easy way to hide thousands of drums of hazardous material. The risk was not well assessed, as numerous old landfill sites are now leaking dangerous materials into waterways. Encasement and burial at sea has been used, but this merely moves the hazard to another location. Deep well injection has been used to dispose of hazardous liquids into subsurface rock formations thousands of feet below the Earth’s surface. This practice is a vast improvement over landfills, but again the hazard is only moved to another location. The USEPA has restrictions regarding the land disposal of hazardous wastes (including Industrial and Municipal Waste Disposal Wells). The restrictions prohibit hazardous waste disposal unless the “waste has been treated to become non-hazardous or the disposer can demonstrate that the waste will remain where it has been placed for as long as it remains hazardous, which has been defined as 10,000 years by regulation.” Diluting liquid waste in order to stay within regulatory limits is not permitted. There are other technologies and strategies that treat liquid waste to make disposal more effective. These treatment methods include: • Physical treatment • Chemical treatment • Biological treatment • Thermal treatment Physical Treatment Non-hazardous liquid waste can often be treated by dewatering and sedimentation, using settling ponds. Water can be removed from solid components by centrifuges, filtration, or other similar processes. Centrifuges work on the same principle as cyclone separators, but can be more complex in operation. Centrifuges are used in industries such as wastewater treatment, oil and gas, and sewage treatment. Chemical Treatment In a chemical treatment, chemicals can be added to liquid waste to neutralize highly basic or acidic liquids. Chemicals that cause precipitation, coagulation, and flocculation of matter are commonly used in wastewater and water treatment plants. There are also many types of oxidation processes. These processes can change organic and inorganic compounds into less hazardous forms. Biological Treatment Industrial effluent and wastewater that have significant organic components may be treated by anaerobic digestion, which is a biological treatment. This reduces the amount of organic matter and the amount of waste. Thermal Treatment The only certain way to destroy many organic materials is through complete combustion. This is accomplished in high temperature incinerators, which is a form of thermal treatment. Environment and Climate Change Canada states: “incineration is a type of thermal treatment that is recognized as an effective and environmentally sound disposal method for a wider range of wastes”. Incinerators can destroy liquid waste; however, they might produce gaseous emissions that require further treatment. Even with incineration, close control and vigilance is necessary to assure complete destruction of the waste. Handling Liquid Waste Transportation of hazardous liquids for disposal must be done carefully, in compliance with regulations, and with attention to the possible consequences. Crude oil, gasoline, liquefied petroleum gas, solvents, fuel oils, lubricating oils, heat transfer oils, and hundreds of liquid products present unique hazards if spills or leaks occur. Spills in lakes, streams, oceans, or environmentally fragile areas cause environmental damage, even if relatively small amounts are involved. Each liquid must be handled according to information on current material safety data sheets. Neutralizing cleanup and disposal procedures should be followed. Appropriate clothing, tools and containers must be employed and personnel working on the cleanup must be thoroughly decontaminated and monitored for effects—even after the cleanup is complete. Operation of industrial plants provides an opportunity for solid and liquid waste to harm the environment. Knowing from where these emissions and effluents originate is the first step in controlling them. An understanding of how waste treatment and handling systems are designed to work, and to what waste product they are best applied, is essential. With this knowledge, Power Engineers can operate these systems properly and according to regulatory requirements. Careful selection, operation, and monitoring of emission and effluent control systems can minimize the impact of plant operation on the environment.
