Solid And Liquid Wastes Environmental Health Cover 2 Top

Solid And Liquid Wastesph 385environmental Healthcover 2 Topics In Th

Solid and Liquid Wastes PH 385 Environmental Health Cover 2 topics in this chapter – disposal of solid wastes and treatment and processing of liquid wastes. What are some reasons why we should be concerned about waste disposal? Term waste is used to describe materials that are perceived to be of negative value. Hazardous waste refers to by-products of society that can pose a substantial or potential hazard to human health or the environment when improperly managed. It possesses at least 1 of 4 characteristics (ignitability, corrosivity, reactivity, or toxicity), or appears on special EPA lists. Pollution is the introduction into the natural environment by humans of substances, materials, or energy that cause hazards to human health, harm to living resources and ecological systems, damage to structures and amenities or that interfere with the legitimate uses of the environment. Almost all people dislike pollution, but some of these same people do not recognize that they contribute to the pollution problem through their own consumption practices. History The concept of waste management is relatively recent. Before the 1900s, the individual was responsible for discarding wastes. Since then, the waste management industry in the US has evolved to the point where individuals discard waste without thinking about its ultimate fate. Read passage of NYC solid waste disposal in the 1900s. Early methods of waste disposal were primitive and consisted of dumping garbage into rivers. Growing Solid Waste Problem Trash or garbage is also called municipal solid waste (MSW). From the US (residents, business) generated about 236 million tons of MSW before recycling. This is about 4.5 lbs. of waste per person per day. Increasing trend and expense of disposing of MSW is increasing as well. Landfills are filling up and closing causing an increase in disposal fees known as tipping fees. Less developed areas also show increasing trends in the amount of solid waste produced. MSW Stream Components of the MSW stream include packaging, furniture, clothing, bottles, food waste, papers, batteries, and organic materials. Table 12-1 categories of Solid Wastes Usually not included in MSW are construction material wastes, sewage sludge, non-hazardous industrial wastes. EPA Hierarchy for MSW management Source Reduction Recycling Disposal Source reduction (waste prevention) refers to reducing the amount of waste created, reusing whenever possible and recycling what is left. Through source reduction, the amount of solid waste that must be deposited in landfills is limited. Example include backyard composting, smaller packages for products reducing amount to be discarded, refillable bottles, longer-lasting tires for vehicles, “pay as you throw” system where amount paid for trash pickup is proportionate to amount generated. Recycling or reuse is the process of minimizing waste generation by recovering and reprocessing usable products that might otherwise become waste. Disposal including waste combustion (with energy recovery) and landfilling. MSW Disposal Recycling Composting Landfilling Incineration Four main dimensions Recycling Reduces greenhouse gas emissions Prevents water pollution Decreases need for new landfills Preserves raw materials and energy Employment opportunities Define recycling Advantages listed Recycling aluminum cans, paper, and bottles Rate of recycling in the US has increased from 6.4% in 1960 to 30.6% in 2003. Missouri has developed a recycling program that has resulted in diverting 41% of its solid waste stream. Composting The controlled decomposition of organic materials, such as leaves, grass, and food scraps, by microorganisms. Composting produces a useful material that resembles soil and can be used in gardening. About ¼ of household wastes consists of clippings from gardens and food waste. Table 12-2 lists acceptable and unacceptable compost materials. Composting breaks down organic material through physical and chemical processes. Microorganisms such as beetles and earthworms aid in decomposing the materials if adequate oxygen and water are present. Temperatures of compost piles can reach 90-140º F killing off bacteria, weed seeds, and insect larvae. Some critics of composting do not believe that pathogens are sufficiently eliminated. Massachusetts has one of the most successful composting programs in the US. Yard and food waste are composted preventing 37,500 tons of waste from entering landfills and saving about $2 million each year. Check out the Berea Ecovillage Landfills 4 major parts Leachate Air pollution and groundwater contamination Megafills Materials that cannot be recycled or composted need to be deposited in landfills. Composed of 4 major parts: bottom liner (dense layer of clay sealed with plastic sheeting to contain hazardous material leaks) system to collect leachates (leachate sump collects leachates and further treats) cover appropriate location to minimize groundwater contamination Leachate is a liquid produced as water seeps through wastes, collecting contaminants. Garbage is piled up in rows that are 10-20 feet high and bulldozers help to compact the garbage. At the end of the day, garbage is covered with soil and other materials to protect from scavengers. After the garbage is covered, anaerobic bacteria aid in the decomposition of organic materials and produce methane gas. This gas can be useful energy if recovered. Hazardous wastes such as pesticides and medical wastes should not be disposed of in MSW sites. Landfills can cause air pollution and groundwater contamination especially older designs that are not well sealed. Leachate may contain toxic heavy metals such as lead, cadmium and arsenic or solvents and cleaning agents that may enter the groundwater. Landfills generate methane, VOCs and other gases which pose a fire hazard and contribute to greenhouse gases. EPA standards increased the safety of landfills by establishing construction standards in 1988. Reduce leaching of chemicals, minimize air pollution, and limit access by scavengers that could spread disease. About 10,000 small landfills were combined into 3,500 larger landfills known as megafills which take in ,000 tons of trash every day. Text box lists Federal standards. Incineration Another method for disposal of MSW. Incineration can be used to generate energy while reducing the volume and weight of waste. Fig. 12-10. This plant can burn about 2250 tons of MSW per day at about 2500 degrees. At this temp. glass and aluminum melt. Metals from the residues of combustion can be recycled into scrap metal and the remaining ash is deposited into landfills. This plant generates enough energy to provide electricity to 40,000 homes. Disadvantage of incineration is that some facilities produce hazardous emissions such as PCBs and carcinogenic substances. May cause air pollution or be deposited on the ground. Hazardous Wastes Hazardous materials used in the home Medical waste Industrial hazardous waste Radioactive waste Mining and extraction wastes Hazardous wastes are legally disposed of in the US by discarding them on the surface of the land, storing them in slurry ponds, dumping them into landfills, and incinerating them. Originate from the following sources: Home: pesticides, cleaning products, automotive products, paint, and flammable products Medical: chemicals, infectious agents, radioactive materials Industrial: toxic chemicals, solvents, heavy metals, and residues Radioactive: materials from nuclear fuel and uranium processing Mining: acids and heavy metals Worldwide about 400 million tons of HW produced each year. The developed countries produce most of the hazardous wastes and sometimes ships them to developing countries that accept cash payments, but many of these developing countries do not have adequate facilities for safe disposal which endangers the local population and environment. In 1989 a treaty titled the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal came into effect under the United Nations. The purpose is to regulate international transport of HW and promote safe disposal. Uncontrolled HW sites Superfund Uncontrolled HW sites are a major concern for PH and the environment in the US. About 40,000 of these sites have been reported to federal agencies and about 1300 are on the National Priorities List (EPAs list of the most serious uncontrolled or abandoned HW sites identified for possible long term remedial action under Superfund. List is based on a score the site receives from the Hazard Ranking System. Superfund mandates cleanup of HW sites in the US. Federal fund provided through the CERCLA to clean up uncontrolled or abandoned HW sites as well as accidents, spills, and other emergency releases of contaminants into the environment. Toxic chemicals present in hazardous wastes may enter the drinking water supply and through biomagnification may enter the food chain. Love Canal EPA Removes Love Canal From Superfund List For Release: Thursday, September 30, 2004 (#04152) New homes at Love Canal New York, NY --The U.S. Environmental Protection Agency (EPA) today finalized its decision to remove the Love Canal site in Niagara County from the Superfund National Priorities List (NPL). All cleanup work at the site has been completed, and follow up monitoring conducted over the past 15 years and continuing today confirms that the cleanup goals have been reached. Through a series of plans, EPA, together with the New York State Department of Environmental Conservation, contained and secured the wastes already disposed of in the canal so that they are no longer leaking into surrounding soils and groundwater and also revitalized properties in the neighborhood surrounding the canal. The Love Canal incident represents a situation in which HW entered the water, air, and soil and is significant to EH b/c it is identified with hazardous chemical exposures and their possible harmful influences on human health. The Love Canal is located near Niagara Falls, NY. It was excavated in the 1890s for a proposed hydroelectric power project that was never completed. The Occidental Chemical Corp. Used the site from to dispose of about 20,000 tons of toxic waste (dioxin, pesticides, and other organic compounds) sealed in metal drums. The Love Canal was covered and deeded to the Niagara Falls Board of Education in 1952 and became an area of construction of homes and schools. In the 1960s and 70s, the presence of toxic chemicals were observed and residents complained of adverse health outcomes. The Love Canal incident created the Superfund which enforces that the responsible parties must assume liability for cleanup of environmental hazards that they cause. Both the chemical corp. and the city of Niagara paid more then $20 million to former residents of the Love Canal site. More than $200 million was paid to NY state and the federal government for cleanup of the site. In the 90s, the site was declared free from toxic waste and the original neighborhood was repopulated. Medical Waste Any solid waste that is generated in the diagnosis, treatment, or immunization of human beings or animals, in research pertaining thereto, or in the production or testing of biologicals. The US produces more than 3.5 million tons of medical waste each year. Table 12-3 has examples. A hazard associated with MW is the potential injury by sharps (needles) which can transmit infectious agents via accidental needle sticks. The greatest danger from MW is to those who are exposed at the point where the wastes are produced. MW are permitted to be deposited in landfills as long as workers are prevented from coming into contact with the waste during disposal. MW may also be decontaminated by chemicals, incinerated, irradiated, or autoclaved. Safe Disposal of HW HW may be temporarily held in storage at waste transfer stations. HW are usually transported by trucks or rail tank cars to waste storage facilities which use containers, tanks, or containment buildings. Some communities offer programs for the collection of household HW so they can be disposed of properly. These programs help reduce the amount of HW dumped down the drain or into landfills not designed for toxic materials. 2 common disposal methods for HW include landfills and injection wells. Landfills are used most frequently and are designed with heavy liners and systems for leachate collection to protect the groundwater. HW injection wells, HW are injected deep underground under extremely high pressure. Sewage Processing and Disposal Sewage is defined as the wastewater generated by people in homes and businesses. To prevent the spread of disease and damage to the environment, municipalities in developed countries pipe sewage to sewage treatment plants (places where wastewater is treated with chemicals and bacteria to produce clean water that can be returned to rivers and other waterways). During the middle ages, the Romans constructed a system of underground tunnels for transporting sewage to the Tiber River, and aqueducts carried fresh water into the city. During medieval times, people discarded human waste into the streets which flowed through open gutters. Human and animal wastes were not separated from the drinking water supplies allowing the wastes to seep into water wells. Waterborne diseases could be spread rapidly. During the 19th century, methods for sewage treatments began to improve. In the mid 1800s, NYC installed a system of sewers that drained into nearby rivers and during the 20th century the sewage was processed to remove sludge which was dumped about 100 miles offshore into the ocean. Sewage Treatment Preliminary processing Primary, Secondary, and Tertiary Phases Modern technology for sewage treatment removes solids, deactivates microbes, and produces wastewater that can be returned safely to waterways or be reused. Sewage treatment involves preliminary processing which screens for large solids and grit removal by reducing the flow. Primary stage is settlement of suspended solids; aims to remove large materials which can be composted or shipped to landfills Secondary stage is biological treatment through aeration and filter beds; promotes microbial digestion of organic material that remains in the sewage Tertiary stage involves removing remaining solids and microorganisms from the liquid portion of sewage by filtration through sand and charcoal filters and disinfection of microorganisms by using chlorine or UV radiation. Most areas in the US require that wastewater received at least secondary treatment. Sewage Disposal Composting Toilets Septic Systems Animal Wastes Composting toilets convert human waste into soil like material that must be buried or hauled away for disposal. They require little water to operate and contain and deactivate pathogens in human waste. Septic systems distribute sanitary waste below the surface and are typically comprised of a septic tank, distribution box, and drain lines. Table 12-4 They are common on-site method for disposal of sewage especially in rural areas. Most systems are designed for a 20-30 year life and eventually fail because the lines are clogged and the soil loses its ability to digest waste. Periodic inspections and pumping of the tank are routine maintenance that prolongs the life of the system. Modern practices of raising livestock involves crowding animals into confined areas to maximize efficiency. This produces substantial amounts of manure, urine and carcasses. These materials introduce environmental hazards such as buildup of nutrients on the land, surface contamination, and water pollution from runoff. Workers in charge of cleaning holding areas, disposing wastes, and handling animals directly may be exposed to diseases tissue or inhale contaminated materials. A study found slurry from pig waste that was disposed on agricultural soil showed Salmonella contamination for up to 2 weeks after deposited. An estimated 75% of antimicrobial agents destined for animals find their way back into the environment through waste.