Download
1 / 26
350 likes | 718 Vues
Sustainable Solid Waste Management. Definitions. Waste : any unwanted or discarded material. Waste can have three forms - Solid , Liquid or Vapor.
E N D
Definitions Waste : any unwanted or discarded material. Waste can have three forms - Solid , Liquid or Vapor. Municipal Solid Waste : wastes from homes and business in or near urban areas. In other words, municipal waste is a combination of household and commercial refuse. Waste management : collection, transport, processing, recycling or disposal, and monitoring of waste materials.
Hazardous/Toxic Waste • Hazardous waste : a waste is any discarded material, liquid or solid, that contains substances known to be : • Fatal to human and animals in low doses • Toxic, carcinogenic or mutagenic to humans or other life forms • Corrosive • Explosive or highly reactive (undergoes violent chemical reactions either by itself or when mixed with other materials)
Hazardous waste cont. • Most hazardous waste is recycled, converted to non-hazardous forms, stored, or otherwise disposed of on-site by the generators – chemical companies, petroleum refiners, and other large industrial facilities – so that it does not become a public problem. • The hazardous wastes that do enter the waste stream or the environment represent one of the most serious environmental problems. • Much of this material can be a serious threat to both environmental quality and human health.
Waste Disposal Methods • Modern waste management is focused on the 3R concept of reduction, reuse and recycling before destructing the wastes or securing the storage of wastes.
Recycling • The term recycling has two meanings in common usage. • Some times we say we are recycling when we really are reusing something, such as refillable beverage containers. • In terms of solid waste management, however, recycling is the reprocessing of discarded materials into new, useful products.
Recycling cont. • Some recycling processes reuse materials for the same purposes. • For instance, old aluminum cans and glass bottles are actually melted and recast into new cans and bottles. • Other recycling processes turn old materials into entirely new products. • Old tires, for instance, are shredded and turned into rubberized road surfacing.
Recycling cont. • Also kitchen wastes become a valuable soil amendment; steel cans become new automobiles and construction materials etc. • Japan probably has the most successful recycling program in the world. • Half of all households and commercial wastes in Japan are recycled while the rest is about equally incinerated or landfilled.
Benefits of Recycling • Recycling is usually a better alternative to either dumping or burning wastes. • It saves money, energy, raw materials, and land space, while also reducing pollution. Many recycling programs cover their own expenses with materials sales and may even bring revenue to the community. • Recycling also encourages individual awareness and responsibility for the refuse produced.
Benefits cont. • Another benefit of recycling is that it could cut our waste volumes drastically and reduce the pressure on disposal systems. • Recycling also reduces energy consumption and air pollution. Plastic bottle recycling could save 50-60% of the energy needed to make raw ones. Making new steel from old scrap instead of bauxite (aluminum ore) cuts energy use by 95%. • Reducing litter is another important benefit of recycling.
Composting • Many cities bury the organic wastes collected from municipal garbage. • They are turning it into a useful product through composting. • Composting is a biological degradation or breakdown of organic matter under aerobic conditions. • The organic compost resulting from this process makes a nutrient rich soil amendment that aids water retention, slows soil erosion, and improves crop yields. • It is an easy, inexpensive, and environmental friendly way to dispose organic wastes.
Energy from Waste • Worldwide, at least one-fifth of municipal waste is organic kitchen and garden refuse. • In a landfill, much of this matter is decomposed by microorganisms generating billions of cubic meters of methane (natural gas), which contributes to global warming if allowed to escape into the atmosphere. • Many cities are drilling methane wells in their landfills to capture this valuable resource.
Energy from Waste cont. • This valuable organic material can be burned in an incinerator rather than being buried in landfills, but there are worries about air pollution from incineration. • Organic wastes also can be decomposed in large, oxygen-free digesters to produce methane under more controlled conditions than in a landfill and with less air pollution than mass garbage burning.
Energy from Waste cont. • Millions of household methane generators provide fuel for cooking and lighting for homes in China & India. • In the United States, some farmers produce all the fuel they need to run their farms – both for heating and to run trucks and tractors – by generating methane from animal manure.
Reuse • Even better than recycling or composting is cleaning and reusing materials in their present form, thus saving the cost and energy of remaking them into something else. • For instance, auto parts are regularly sold from junkyards, especially for older car models. • In some cases, stained glass windows, brass fittings, fine woodwork, and bricks salvaged from old houses bring high prices.
Reduce • What is even better than reusing materials? – Generating less waste in the first places. • For example, excess packaging of food and consumer products is one of our greatest source of unnecessary waste. • Paper, plastic, glass, and metal packaging material make up approximately 50% of our domestic trash by volume. • Much of that packaging is primarily for marketing and has little to do with product protection.
Reduce cont. • Some environmental groups are beginning to think that we have put too much emphasis on recycling. • While recycling is an important part of waste management, we have to remember that it is actually the third “R” in the waste hierarchy. • The two preferred methods – reduction and reuse – get lost in our enthusiasm for recycling.
4. Exporting Waste • It’s not surprising that exports are attractive. • It commonly costs $1,000 per barrel to dispose of toxic waste in the U.S., but some African countries will take the barrel for $50. • Exporting of waste to Bangladesh.
5. Incineration & Resource Recovery • Faced with growing piles of garbage and a lack of available landfills at any price, many municipalities have switched to other disposal methods. • The method which they frequently turn is burning. • Another commonly used term for this technology is energy recovery, or waste-to-energy, because the heat derived from incinerated refuse is a useful resource.
Incineration cont. • Burning garbage can produce steam used directly for heating buildings or generating electricity. • Internationally, well over 1,000 waste-to-energy plants in Brazil, Japan, and Western Europe generate much needed energy while also reducing the amount that needs to be landfilled.
Incineration Plants Vienna Japan
Denmark Tokyo
