L 14 waste management

Lecture 14Lecture 14WASTE MANAGEMENTWASTE MANAGEMENT

HRhHRh

Waste ManagementWaste Management

WastesWastes are any unwanted or discarded material from residential, are any unwanted or discarded material from residential, commercial, industrial, or agricultural activities that may cause commercial, industrial, or agricultural activities that may cause environmental problemsenvironmental problems

Waste managementWaste management is the collection, transport, processing or is the collection, transport, processing or disposal, managing and monitoring of disposal, managing and monitoring of wastewaste materials materials

Waste management is a problem in both urban and rural areas in Waste management is a problem in both urban and rural areas in our country as elsewhere in the worldour country as elsewhere in the world

The goals of waste management:The goals of waste management:

To minimize waste quantityTo minimize waste quantity

To reduce the amount of raw materials consumedTo reduce the amount of raw materials consumed

To dispose of non-hazardous waste cost-effectivelyTo dispose of non-hazardous waste cost-effectively

To dispose of hazardous waste with minimal risk to human health To dispose of hazardous waste with minimal risk to human health

and the environmentand the environment


How Pollutants Enter the EnvironmentHow Pollutants Enter the Environment: :

Hazardous-waste pollutants from a solid-waste disposal site may Hazardous-waste pollutants from a solid-waste disposal site may enter the environment by as many as six paths:enter the environment by as many as six paths:

Methane, ammonia, hydrogen sulfide, and nitrogen gases may enter Methane, ammonia, hydrogen sulfide, and nitrogen gases may enter the atmospherethe atmosphere

Heavy metals, such as lead, chromium, and iron may be retained in Heavy metals, such as lead, chromium, and iron may be retained in the soilthe soil

Heavy metals and other toxic materials may enter food chain via Heavy metals and other toxic materials may enter food chain via plant uptake growing near the disposal siteplant uptake growing near the disposal site

Crop residue containing toxic substances returns these to the soil Crop residue containing toxic substances returns these to the soil after decompositionafter decomposition

Soluble materials, such as chloride, nitrate, and sulfate may reach Soluble materials, such as chloride, nitrate, and sulfate may reach the groundwater systemthe groundwater system

Overland runoff may transport leachate into streams and riversOverland runoff may transport leachate into streams and rivers


Early conceptEarly concept of disposal was of disposal was dilute and dispersedilute and disperse

With industrialization and urbanization early concept became inadequateWith industrialization and urbanization early concept became inadequate

A A new concept new concept known as known as concentrate and containconcentrate and contain became popular became popular

However Containers may leak or break and allow waste to escapeHowever Containers may leak or break and allow waste to escape

Modern TrendsModern Trends

Consider waste as resource out of placeConsider waste as resource out of place

Cost of raw materials, energy, transportation and land make it Cost of raw materials, energy, transportation and land make it economically feasible to economically feasible to reuse & recycle reuse & recycle this kind of resourcesthis kind of resources

Under this concept waste would not exist because of recyclingUnder this concept waste would not exist because of recycling

If produced would be reused as a resourceIf produced would be reused as a resource

This concept is referred to as the “Zero waste” movementThis concept is referred to as the “Zero waste” movement


Integrated Waste ManagementIntegrated Waste Management

A set of management alternatives A set of management alternatives includes includes thethe three R’s three R’s of waste of waste prevention, incineration, prevention, incineration, composting, and landfillcomposting, and landfill

The The ultimate objective of the ultimate objective of the three R’s of IWMthree R’s of IWM is to reduce the is to reduce the amount of urban and other wasteamount of urban and other waste

By utilizing By utilizing IWMIWM technology technology weight of urban refuse could be weight of urban refuse could be reduced to 50%, perhaps as reduced to 50%, perhaps as much as 70% by early in the 21much as 70% by early in the 21stst centurycentury

A 50% reduction by weight of A 50% reduction by weight of urban waste could be facilitated urban waste could be facilitated byby

1. Source r1. Source reductioneduction (10% reduction) (10% reduction)

2. R2. Recyclingecycling programs (30% programs (30% reduction)reduction)

3. Large scale 3. Large scale compostingcomposting programs programs (10% reduction)(10% reduction)

Two typesTwo types of recycling: of recycling: (1) (1) closed-loopclosed-loop——recycled to produce recycled to produce new products of the new products of the same type same type

(2) (2) Down cyclingDown cycling– – converted into different converted into different lower quality productslower quality products

Through intensive Through intensive recycling as much as recycling as much as 80-90% of waste might 80-90% of waste might be recovered (US be recovered (US example)example)

More realistic is partial More realistic is partial recycling that can recycling that can provide 30% reductionprovide 30% reduction

Steel crushed & baled for recycling


CompostingComposting

A component of IWMA component of IWM

A biochemical process by aerobic A biochemical process by aerobic organisms of rapid, partial organisms of rapid, partial decomposition of moist, solid, organic decomposition of moist, solid, organic waste such as lawn clippings and waste such as lawn clippings and kitchen scraps to a rich, soil-like kitchen scraps to a rich, soil-like materialmaterial

Reduces volume, can be used as Reduces volume, can be used as organic fertilizerorganic fertilizer

Nevertheless, compost can be used as Nevertheless, compost can be used as an organic soil fertilizer, topsoil, or an organic soil fertilizer, topsoil, or landfill coverlandfill cover

An active compost heap

Waste ManagementWaste ManagementIncinerationIncineration

Combustible waste is burned at 900-1000 Combustible waste is burned at 900-1000 00C to consume all combustible material, C to consume all combustible material, leaving only ash and noncombustibles to leaving only ash and noncombustibles to dispose of in a landfilldispose of in a landfill

May reduce the volume of waste by 75% May reduce the volume of waste by 75% to 95% (actually to 50%) to 95% (actually to 50%)

Incineration can be used to supplement Incineration can be used to supplement other fuels and generate electric powerother fuels and generate electric power

DrawbacksDrawbacks

Not a clean processNot a clean process

May produce pollution and toxic ashMay produce pollution and toxic ash

May emit oxides of nitrogen, sulfurMay emit oxides of nitrogen, sulfur

Heavy metals– lead, cadmium, mercuryHeavy metals– lead, cadmium, mercury

Carbon monoxideCarbon monoxide


Open Dumps Open Dumps

(Landfill)(Landfill)

Open dumps create Open dumps create a nuisance by being a nuisance by being unsightly, providing unsightly, providing breeding grounds breeding grounds for pests, creating a for pests, creating a health hazard, health hazard, polluting the air, polluting the air, polluting polluting groundwater and groundwater and surface watersurface water

Waste ManagementWaste ManagementSanitary LandfillsSanitary Landfills

Most common and economic method in many Most common and economic method in many countries countries

Concentrate and contain refuse (contrast to open Concentrate and contain refuse (contrast to open dumping) without creating a nuisance or hazard dumping) without creating a nuisance or hazard to public health or safety to public health or safety

It is covered with a layer of compacted soil at the It is covered with a layer of compacted soil at the end of each day of operation end of each day of operation

Covering the waste is what makes the landfill Covering the waste is what makes the landfill sanitarysanitary

The compacted layer minimizes the amount of The compacted layer minimizes the amount of surface water entering into and gas escaping surface water entering into and gas escaping from the waste and restricts continued access to from the waste and restricts continued access to the waste by insects, rodents, and other animals, the waste by insects, rodents, and other animals, such as seagullssuch as seagulls

Modern sanitary landfills are engineered to Modern sanitary landfills are engineered to include multiple barriers, such as clay and plastic include multiple barriers, such as clay and plastic liners to limit movement of leachateliners to limit movement of leachate

Environmental Impacts of LandfillsEnvironmental Impacts of Landfills A major concern with regard to A major concern with regard to

landfills is the potential water pollution landfills is the potential water pollution from the rainwater that percolates from the rainwater that percolates through the wastes, dissolving and through the wastes, dissolving and carrying away all organic and carrying away all organic and inorganic contaminantsinorganic contaminants

Many of the contaminants in landfill Many of the contaminants in landfill leachate are highly toxic and would leachate are highly toxic and would create a serious pollution problem if create a serious pollution problem if they reach the groundwaterthey reach the groundwater

The production of methane gas by the The production of methane gas by the anaerobic decomposition of organic anaerobic decomposition of organic wastes in a landfill can present a very wastes in a landfill can present a very serious explosion hazard if the gas is serious explosion hazard if the gas is not collected not collected

Possibly burned as an energy source Possibly burned as an energy source

Electricity generator powered by landfill waste

Products we Use Potentially Hazardous WasteLeather Heavy metals, organic solvents

Medicines Organic solvents and residues, heavy metals (e.g., Hg, Zn)

Metals Heavy metals, fluorides, cyanides, acid and alkaline cleaners, solvents, pigments

Oil, gasoline & other petroleum products

Oil, phenols and other organic compounds, heavy metals, ammonia, salts, acids

Paints Heavy metals, pigments, solvents, organic residues

Pesticides Organic chlorine compounds, organic phosphate compounds

Plastics Organic chlorine compounds

Textiles Heavy metals, dyes, organic chlorine compounds, solvents

Table W: Products and the Potentially Hazardous Waste they Generate (Q)

Of 70,000 chemicals approximately 35,000 are definitely or potentially hazardous to public healthUncontrolled dumping of chemical waste pollutes soil, surface water and groundwater

Hazardous Chemical Waste Management

Hazardous waste

Industrial waste


Hazardous chemical waste management is one of the most serious environmental Hazardous chemical waste management is one of the most serious environmental problemsproblems

Management involves recycling, on-site processing to recover by-products, microbial Management involves recycling, on-site processing to recover by-products, microbial breakdown, chemical stabilization, high temperature decomposition, incineration, disposal breakdown, chemical stabilization, high temperature decomposition, incineration, disposal by secure landfillby secure landfill

A number of technological advances have been made in toxic-waste management, and as A number of technological advances have been made in toxic-waste management, and as land disposal becomes more expensive, the recent trend toward on site treatment is likely land disposal becomes more expensive, the recent trend toward on site treatment is likely to continue to continue

On-site treatment will not eliminate all hazardous chemical wasteOn-site treatment will not eliminate all hazardous chemical waste

Disposal of some waste will remain necessary Disposal of some waste will remain necessary

All available technologies cause some environmental disruption All available technologies cause some environmental disruption

There is no simple solution for all waste management issuesThere is no simple solution for all waste management issues

Even with extensive safeguards land disposal cannot guarantee that the waste is Even with extensive safeguards land disposal cannot guarantee that the waste is contained and will not cause environmental disruption in the futurecontained and will not cause environmental disruption in the future

Pollution of groundwater is perhaps the most significant risk, because groundwater provides Pollution of groundwater is perhaps the most significant risk, because groundwater provides a convenient route for pollutants to reach humans and other living things a convenient route for pollutants to reach humans and other living things

End of SlidesEnd of Slides

Thank YouThank You