MUNICIPAL SOLID WASTES

MUNICIPAL SOLID WASTES MUNICIPAL SOLID WASTES

“Wastes are only raw materials we’re too stupid to use.” -Arthur C. Clarke

Solid waste: any unwanted or discarded material that is not a liquid or a gas. Sources: 98.5% is from (1) mining (2) oil and natural gas production (3) agricultural (4) sewage sludge, and (5) industrial activities used to produce goods and services for consumers 1.5% is municipal solid waste (MSW also called garbage) from home and businesses in or near urban areas. (Facts: It is about 200 million metric tons (440 billion pounds) per day (twice as much as 1970). It is enough to fill a bumper-to-bumper convoy of garbage trucks encircling the globe almost eight times) Disposal: 54% is dumped in landfills, 30% is recycled or composted, and 16% is burned in incinerators

For urban environment Refuse: the discarded solid wastes material resulting from normal community activities, including garbage, rubbish, ashes, street refuse, dead plant and animal matter, and solid industrial wastes. (fact: In 1970, US generate more than 200 million tons of refuse per year). Table 6.2 sample municipal refuse composition in US. The composition has changed greatly during the last 30 years. Garbage (organics) has declined from 65% to only 12% of total weight. A relative increase in combustible material has increased the heating value of refuse about 1000 Btu per pound, increasing the economic incentive for incineration.

Solution/disposal 2006 U.S. MSW Generation

WASTE DISPOSAL: BURN, BURY OR DUMP

1. BURN Incineration is a waste treatment technology that involves the combustion of organic materials and/or substances. The city of Commerce incinerator consumes 400 tons of trash per day and produces 10 megawatts of electricity, enough for 20,000 homes.

SYSAV incineration plant in Malmö, Sweden capable of handling 25 tonnes per hour household waste. To the left of the stack, a new identical oven line is under construction(March 2007). An example of a low capacity, mobile incinerator Spittelau incineration plant in Vienna Municipal solid waste in the furnace of a moving grate incinerator capable of handling 15 tons of waste per hour. The holes in the grate elements supplying the primary combustion air are visible.

Products from incineration: Gas products: Dioxin (a heterocyclic organic compound with the chemical formula C4H4O2; in general refers to a class of super-toxic chemicals) and furans (heterocyclic organic compound): serious health hazard (no longer emitted using new gas cleaning technology). CO2 and others such assulfur dioxide, hydrochloric acid, heavy metals and fine particles (PM2.5) Solid products: toxic fly ash and incinerator bottom ash: the fly ash constitutes more of a potential health hazard than does the bottom ash because the fly ash often contain high concentrations of heavy metals such as lead, cadmium, copper and zinc as well as small amounts of dioxins and furans Odor pollution can be a problem with old-style incinerators.

Combustion/Incineration (thermal treatment)-turn wastes into energy Burning MSW can generate energy while reducing the amount of waste by up to 90 percent in volume and 75 percent in weight. Canada Singapore Russia French west Indies

2. BURY Landfills: A landfill, also known as a dump or tip (and historically as a midden), is a site for the disposal of waste materials by burial and is the oldest form of waste treatment. Resource Conservation and Recovery Act The Resource Conservation and Recovery Act (RCRA) was enacted by Congress in 1976 and amended in 1984. The act's primary goal is to protect human health and the environment from the potential hazards of waste disposal. In addition, RCRA calls for conservation of energy and natural resources, reduction in waste generated, and environmentally sound waste management practices. Under the Resource Conservation and Recovery Act (RCRA), landfills that accept MSW are primarily regulated by state, tribal, and local governments. EPA, however, has established national standards these landfills must meet in order to stay open. Municipal landfills can, however, accept household hazardous waste. The number of landfills in the United States is steadily decreasing—from 8,000 in 1988 to 1,754 in 2006. The capacity, however, has remained relatively constant. New landfills are much larger than in the past. Fresno Sanitary Landfill (1937)

Sanitary landfills are sites where waste is isolated from the environment until it is safe.It is considered when it has completely degraded biologically, chemically and physically. As a minimum, four basic conditions should be met by any site design and operation before it can be regarded as a sanitary landfill: • Full or partial hydrogeological isolation: if a site cannot be located on land which naturally contains leachate security, additional lining materials should be brought to the site to reduce leakage from the base of the site (leachate) and help reduce contamination of groundwater and surrounding soil. If a liner - soil or synthetic - is provided without a system of leachate collection, all leachate will eventually reach the surrounding environment. Leachate collection and treatment must be stressed as a basic requirement.• Formal engineering preparations: designs should be developed from local geological and hydrogeological investigations. A waste disposal plan and a final restoration plan should also be developed.• Permanent control: trained staff should be based at the landfill to supervise site preparation and construction, the depositing of waste and the regular operation and maintenance.• Planned waste emplacement and covering: waste should be spread in layers and compacted. A small working area which is covered daily helps make the waste less accessible to pests and vermin.

Landfill operation. Note that the area being filled is a single, well-defined "cell" and that a rubberized landfill liner is in place (exposed on the left) to prevent contamination by leachates migrating downward through the underlying geological formation. Leachates: liquids percolated through waste piles.

Land reclamation As human overcrowding of developed areas intensified during the 20th century, it has become important to develop land re-use strategies for completed landfills. Some of the most common usages are for parks, golf courses and other sports fields. Increasingly, office buildings and industrial uses are made of a completed landfill. In these latter uses, methane capture is customarily carried out to minimize explosive hazard within the building. An example of a Class A office building (highest quality office space locally available) constructed over a landfill is the Dakin Building at Sierra Point, Brisbane, California. The underlying fill was deposited from 1965 to 1985, mostly consisting of construction debris from San Francisco and some municipal wastes. A clay cap was constructed over the debris prior to building approval. Mt. Trashmore, Virginia

Another strategy for landfill reclamation is the incineration of landfill trash at high temperature via the plasma-arc gasification process, which is currently used at two facilities in Japan, and will be used at a planned facility in St. Lucie County, Florida. The Plasma-arc gasification process is a chemical reduction process that converts MSW from its original state to a glass-like aggregate solid at the bottom, and a synthetic fuel gas, also known as syngas, at the top. Once gasification is over, the syngas is cleaned in a multi-step process, bringing it to levels near natural gas cleanliness. It is then compressed before being used as fuel for a gas turbine.

Impacts to people near landfills in the U.S. Communities near landfills are increasingly facing health consequences from air and water contamination, particularly from landfills that are poorly constructed and operated. Ground and air contamination pose a significant threat to public health for those living within three to five miles of a landfill, and will eventually degrade the environment far beyond those limits. Poorly constructed and operated landfills persist with leachate breaks, uncovered trash, and unchecked banned hazardous compounds. The U.S. Environmental Protection Agency generally relies on the states to enforce their own operating permits and federal laws. If state agencies are not aggressive, violations can worsen, multiplying negative environmental impacts exponentially. There are some notable recorded violations in the U.S., such as for a landfill in Hawaii that was fined $2.8 million in 2006 for operating violations, but this is not common. http://en.wikipedia.org/wiki/Landfill

REDUCE, REUSE, RECYCLE

Composting decomposes organic waste, such as food scraps and yard trimmings, with microorganisms (mainly bacteria and fungi), producing a humus-like substance.

Other New Technologies Bioconversion of biomass to mixed alcohol fuels: The process involves a biological/chemical method for converting any biodegradable material (e.g., municipal solid waste, sewage sludge, agricultural residues such as corn stover, sugarcane bagasse, cotton gin trash, manure) into useful chemicals, such as carboxylic acids and biofuels, such as a mixture of primary alcohols (e.g., ethanol, propanol, butanol) and/or a mixture of secondary alcohols (e.g., isopropanol, 2-butanol, 3-pentanol) Two processes: 1 - Enzymatic hydrolysis - a single source of feedstock, switchgrass for example, is mixed with strong enzymes which convert a portion of cellulosic material into sugars which can then be fermented into ethanol. 2 - Synthesis gas fermentation - a blend of feedstock, not exceeding 30% water, is gasified in a closed environment into a syngas containing mostly carbon monoxide and hydrogen. The cooled syngas is then converted into usable products through exposure to bacteria or other catalysts. After gasification, anaerobic bacteria (Clostridium ljungdahlii) are used to convert the syngas (CO, CO2, and H2) into ethanol. The heat generated by gasification is also used to co-generate excess electricity.

2. Biodrying is the process by which biodegradable waste is rapidly heated through initial stages of composting to remove moisture from a waste stream and hence reduce its overall weight. It can take as little as 8 days to dry waste in this manner. This enables reduced costs of disposal if landfill is charged on a cost per tone basis. Biodrying may be used as part of the production process for refuse-derived fuels. Biodrying does not however greatly effect the biodegradability of the waste and hence is not stabilized. Biodried waste will still break down in a landfill to produce landfill gas and hence potentially contribute to climate change.

Source reduction: involves altering the design, manufacture, or use of products and materials to reduce the amount and toxicity of what gets thrown way. Examples: backyard composting, two-sided copying of paper, transport packaging reduction, etc. Example: Since 1977, the weight of 2-liter plastic soft drink bottles has been reduced from 68 grams each to 51 grams. Reusing items by repairing and donating to charity and community groups; Selling them is better than recycling because item dose not need to be reprocesses before it can be used again. Benefits: prevents emissions of greenhouse gases, reduces pollutants, saves energy, conserves resources, reduce costs, and reduces the need for new landfills and combustors. Facts: More than 55 million tons of MSW were source reduced in the United States in 2000: containers and packaging represented approximately 28% of the materials source reduced, in addition to nondurable goods (e.g., newspapers, clothing) at 17%, durable goods (e.g., appliances, furniture, tires) at 10%, and other MSW (e.g., yard trimmings, food scraps) at 45%. Facts: There are more than 6,000 reuse centers around the country, ranging from specialized programs for building materials or unneeded materials in schools to local programs such as Goodwill and the Salvation Army

Recycling: materials, such as paper, glass, plastic, and metals are sorted, collected, and processed and then manufactured, sold, and bought as new products. Facts: Recycling, including composting, diverted 82 million tons of material away from disposal in 2006, up from 15 million tons in 1980, when the recycle rate was just 10% and 90% of MSW was being combusted with energy recovery or disposed of by landfilling. Typical materials that are recycled: batteries (99% recycle rate), paper and paperboard (52% recycle rate), and yard trimmings (62% recycle rate). These materials and others may be recycled through curbside programs, drop-off centers, buy-back programs, and deposit systems.

Benefits: • decreases the emission of greenhouse gases • saves energy and prevents pollution (caused by the extraction and procesing of raw materials). • creates US manufactoring jobs and increases US competitiveness in the global marketplace • stimulates the development of greener technologies • conserves resources such as timber, water, and minerals and reduces the need for new landfills and combustors. • Facts: in1996, recycling of solid waste in the United States prevented the release of 33 million tons of carbon into the air-roughly the amount emitted annually by 25 million cars. • U.S. recycles 32.5 percent of its waste, a rate that has almost doubled during the past 15 years. • While recycling has grown in general, recycling of specific materials has grown even more drastically: 52 percent of all paper, 31 percent of all plastic soft drink bottles, 45 percent of all aluminum beer and soft drink cans, 63 percent of all steel packaging, and 67 percent of all major appliances are now recycled. • Twenty years ago, only one curbside recycling program existed in the United States, which collected several materials at the curb. By 2006, about 8,660 curbside programs had sprouted up across the nation. As of 2005, about 500 materials recovery facilities had been established to process the collected materials.

Impacts: • fatal accidents (e.g., scavengers buried under waste piles); • infrastructure damage (e.g., damage to access roads by heavy vehicles); • pollution of the local environment (such as contamination of groundwater and/or aquifers by leakage and residual soil contamination during landfill usage, as well as after landfill closure); • offgassing of methane generated by decaying organic wastes (methane is a greenhouse gas many times more potent that carbon dioxide, and can itself be a danger to inhabitants of an area;) • harboring of disease vectors such as rats and flies, particularly from improperly operated landfills in third-world countries; • injuries to wildlife; and • simple nuisance problems (e.g., dust, odor, vermin, or noise pollution).

Step 1. Collection and Processingfour primary methods: curbside, drop-off centers, buy-back centers, and deposit/refund programs. (Recyclables are sent to a materials recovery facility to be sorted and prepared into marketable commodities for manufacturing. Recyclables are bought and sold just like any other commodity, and prices for the materials change and fluctuate with the market.) Step 2. Manufacturing (Once cleaned and separated, they are being used in manufacturing newspapers and paper towels; aluminum, plastic, and glass soft drink containers; steel cans; and plastic laundry detergent bottles. Recycled materials also are used in innovative applications such as recovered glass in roadway asphalt (glassphalt) or recovered plastic in carpeting, park benches, and pedestrian bridges.) Step 3. Purchasing Recycled ProductsPurchasing recycled products completes the recycling loop.

Household Hazardous Waste: any product labeled: toxic, poison, corrosive, flammable, combustible or irritant that is disposed of. A complete list: http://www.epa.gov/garbage/hhw.htm

Movie in internet: http://www.storyofstuff.com/ Video at; http://videos.howstuffworks.com/medialink/4312-reduce-reuse-and-recycle-video.htm

MUNICIPAL SOLID WASTES