Solid Waste Management Pyramid 1t4h42

Solid Waste Management Pyramid Apodaca and Azucena

The Solid Waste Management Pyramid

}

Treatment/ Waste Disposal

Most Preferred

Reuse Recycle

}

3R’s

Source Reduction (Reduce)

Resource Recovery

Incineration Landfilling

Least Preferred

Source Reduction (Reduce) • Source Reduction is the first tier of the solid waste management pyramid. • Often called waste prevention, means consuming and throwing away less. • Includes purchasing durable, long-lasting goods and seeking products and packaging that are as free of toxics as possible. It can be as complex as redeg a product to use less raw material in production, have a longer life, or be used again after its original use is completed. Because source reduction actually prevents the generation of waste in the first place, it is the most preferable method of waste management and goes a long way toward protecting the environment.

Source Reduction (Reduce) • Source reduction can be applied by companies at the design and production phases to minimize the amount of materials in products and packaging, and deliver products using natural resources as efficiently as possible. Source reduction can also be applied by food-service and hospitality establishments through minimizing the use of single-use disposable containers, providing reusable cutlery and encouraging the use of reusable take-out containers, including coffee cups, beverage containers and “to-go” boxes.

Source Reduction Example • A laundry detergent flexible pouch weighs 85 percent less than a plastic bottle. The amount of packaging is 84 percent less.

Reuse • This is simple; reduce waste by not wasting something, but reusing it. • It is the action or practice of using something again, whether for its original purpose (conventional reuse) or to fulfill a different function (creative reuse or repurposing). • This can be combined with the top level by replacing something disposable with something reusable. But most commonly, it means to quite literally reuse something.

Reuse Example

Advantages of Reuse • Energy and raw materials savings as replacing many single use products with one reusable one reduces the number that need to be manufactured. • Reduced disposal needs and costs. • Refurbishment can bring sophisticated, sustainable, well paid jobs to underdeveloped economies.

• Cost savings for business and consumers as a reusable product is often cheaper than the many single use products it replaces. • Some older items were better handcrafted and appreciate in value.

Disadvantages of Reuse • Reuse often requires cleaning or transport, which have environmental costs. • Some items, such as freon appliances, infant auto seats, older tube TVs and secondhand automobiles could be hazardous or less energy efficient as they continue to be used. • Reusable products need to be more durable than single-use products, and hence require more material per item. This is particularly significant if only a small proportion of the reusable products are in fact reused.

• Sorting and preparing items for reuse takes time, which is inconvenient for consumers and costs money for businesses. • Special skills are required to tweak the functional throughput of items when devoting them to new uses outside of their original purpose.

Recycling • It is the process of converting waste materials into new materials and objects. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions. • Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution (from incineration), and water pollution (from landfilling).

Recycling • It is the preferred option when reuse is not an option, if an item is broken, or in a poor condition that means it can't be reused. • Recycling contrasts with reuse in the fact that recycling tends to break an item down to its raw materials before making them into something else. In the milk bottle example, reusing involves washing and refilling, while recycling would involve grinding the glass and melting it again, turning the raw material into a different grade of glass.

Recycling Example

Treatment And Disposal of Solid Waste • Treatment: – Incineration – Gasification and Pyrolysis – Open Burning • Disposal – Sanitary landfills – Controlled dumps

– Bioreactor landfills •

Other – Composting – Recycling

Resource Recovery • Waste-to-energy (WtE) or energy-from-waste (EfW) is the process of generating energy in the form of electricity and/or heat from the primary treatment of waste. • WtE is a form of energy recovery. • Most WtE processes produce electricity and/or heat directly through combustion, or produce a combustible fuel commodity, such as methane, methanol, ethanol or synthetic fuels

Waste-to-Energy (WtE) Plant • a facility that uses solid waste materials (processed or raw) to produce energy. • WtE plants include incinerators that produce steam for district heating or industrial use, or that generate electricity; they also include facilities that convert landfill gas to electricity.

Incineration • the most common WtE implementation • a waste treatment process that involves the combustion of organic substances contained in waste materials. • Incineration and other high temperature waste treatment systems are described as "thermal treatment".

• Incineration of waste materials converts the waste into ash, flue gas, and heat. • Incinerators are used for this process.

Incineration

Important Points Regarding Incineration • Supplying of solid waste should be continuous. • Waste should be proper mixed with fuel for complete combustion. • Temperature should not be less than 670 ˚C.

Advantages and Disadvantages of Incineration Advantages

Disadvantages

• Most hygienic method.

• Large initial expense.

• Complete destruction of pathogens. • No odor trouble. • Heat generated may be used for steam power. • Clinkers produced may be used for road construction. • Less space required. • Adverse weather condition has no effect.

• Care and attention required otherwise incomplete combustion will increase air pollution. • Residues required to be disposed which require money. • Large no. of vehicles required for transportation.

Gasification and Pyrolysis • are two similar methods, both of which decompose organic waste materials by exposing waste to low amounts of oxygen and very high temperature. • Pyrolysis uses absolutely no oxygen while gasification allows a very low amount of oxygen in the process. • Gasification is more advantageous as it allows the burning process recover energy without causing air pollution.

Gasification

Pyrolysis

Open Burning • a legacy thermal waste treatment that is environmentally harmful. • The incinerators used in such process have no pollution control devices. • They release substances such as hexachlorobenzene, dioxins, carbon monoxide, particulate matter, volatile organic compounds, polycyclic aromatic compounds, and ash. • Unfortunately, this method is still practiced by many local authorities internationally, as it offers an inexpensive solution to solid waste.

Open Burning Example

Landfilling • A landfill site is a site for the disposal of waste materials by burial and is the oldest form of waste treatment. • Historically, landfills have been the most common methods of organized waste disposal and remain so in many places around the world. • The dumping is done with layers of 1- 2 m. • The layer is covered with soil of 20 cm thickness.

Modern Landfill

Advantages and Disadvantages of Landfilling Advantages • Simple method. • No costly plant required.

Disadvantages • Large land required. • Proper dumping site may not be available.

• No residues or by products need to be disposed.

• Odor problem.

• Separation not required.

• Leachate should be collected regularly.

• Unused land can be used. • Methane gas can be used ass fuel.

• Use of insecticides required.

• Methane gas should be collected properly. • Green house gas problem.

Sanitary Landfills • provide the most commonly used waste disposal solution. • These landfills are desired to eliminate or reduce the risk of environmental or public health hazards due to waste disposal.

• These sites are situated where land features work as natural buffers between the environment and the landfill. • For instance, the landfill area can be comprised of clay soil which is quite resistant to hazardous wastes or is characterized by an absence of surface water bodies or a low water table, preventing the risk of water pollution. • The use of sanitary landfills presents the least health and environmental risk, but the cost of establishing such landfills is comparatively higher than other waste disposal methods.

Sanitary Landfills

Controlled Dumps • are more or less the same as sanitary landfills. • These dumps comply with many of the requirements for being a sanitary landfill but may lack one or two. • Such dumps may have a well-planned capacity but no cellplanning.

• There may be no or partial gas management, basic record keeping, or regular cover.

Controlled dumps

Bioreactor landfills • are the result of recent technological research. • These landfills use superior microbiological processes to speed up waste decomposition. • The controlling feature is the continuous addition of liquid to sustain optimal moisture for microbial digestion.

• The liquid is added by re-circulating the landfill leachate. • When the amount of leachate is not adequate, liquid waste such as sewage sludge is used.

Composting • It is a process in which organic matter of solid waste is decomposed and converted to humus and mineral compounds. • Compost is the end product of composting, which used as fertilizer. • Three methods of composting:

• (a) composting by trenching • (b) open windrow composting • (c) mechanical composting

(a) Composting by Trenching • Trenches 3 - 12 m long, 2 – 3 m wide and 1- 2 m deep with spacing 2 m. • Dry wastes are filled up in 15 cm. On top of each layer 5 cm thick sandwiching layer of animal dung is sprayed in semi liquid form. • Biological action starts in 2- 3 days and decomposition starts. • Solid waste stabilize in 4- 6 months and changed into brown colored odorless powdery form known as humus.

(a) Composting by Trenching

(b) Open Windrow Composting • Large materials like broken glass, stone, plastic articles are removed. • Remaining solid wastes is dumped on ground in form of piles of 0.6 – 1 m height.

• The width and length of piles are kept 1- 2 m and 6 m respectively. • Moisture content maintained at 60%.

• Temp. increases in side pile. • After pile for turned for cooling and aeration to avoid anaerobic decomposition.

• The complete process may take 4- 6 week.

(b) Open Windrow Composting

(c) Mechanical Composting • It requires small area compare to trenching and open windrow composting. • The stabilization of waste takes 3- 6 days. • The operation involved are reception of refuse segregation shredding stabilization marketing the humus

(c) Mechanical Composting