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Management of Non-hazardous Waste (Intro (humans created pdts not found in…
Management of Non-hazardous Waste
Intro
humans created pdts not found in natural world e.g. CFCs, plastics
prob.s w/ disposal exists: waste generation accelerated since Industrial Revolution + growing pop in cities
waste is excreted by organism/thrown away by society bc no longer useful & if kept, may be detrimental (its constituents may still be useful to another)
too much waste disposed in a place can contaminate/pollute env-> hazard to health, safety, welfare->need careful management
World Bank: generate 1.2kg of Municipal Solid Waste (MSW) per city dweller per day
Concepts
EF
land area & natural resources capital on which city draws to sustain its pop. & prod. structure
measurement of sustainability: numerical indication of amt. of resources used to support consumption of city dwellers-> waste
SG's EF in 2012 is 6.1gha per person, when global avg. is 2.84gha
wealthy cities have cap. to draw resources from beyond their immediate regions (e.g. imports)-> urban EF usually 2-3x larger than geographical area they occupy
limitations: EF depends on where. city boundary is drawn quality & range of stats vary from cities. particular gaps of city dwellers contribute disproportionately to EF
global consumption is uneven & inefficient, NOT there is a lack of resources
Urban Metabolism
sum of technical & socioeconomic processes that occur in cities, resulting in growth, energy prod., & waste elimination
usually linear in cities:
large inputs of consumer gds (made from raw materials), energy (coal, oil, nuclear, fossil fuels), food
large outputs of waste (inorganic, organic, gas emissions)
linear form is disruptive of natural cycles, promotes waste & undermines goal of SUD
circular metabolism: less inputs & outputs, more recycling
Daly Rules: pollution & wastes must be emitted no faster than natural systems can absorb them, recycle them, or render them harmless
Comparison btw EF & UM
UM: quantify amt.s of materials & energy that flow thru a city EF: takes add. step of estimating area of productive terrestrial & aquatic ecosystems required for UM to happen
Brundtland Report: limits imposed by...
ability of biosphere to absorb effects of human activities
Classification of Waste
solid, liquid, gas, energy (noise)
sources (human activities): fuel combustion, industrial processes, agriculture etc.
DCs concerned w/ disposing (difficulties + costs)
LDCs concerned w/ collecting, usually 1/3-1/2 of solid wastes generated in cities uncollected
Strategies
Incineration
hazards: release harmful emissions (BUT can be reduced by improving combustion techniques, sorting wastes, fitting pollution control devices)
limitations: site selection + pressure on land (incineration generates ash, which is usually buried in landfills). costly
can be combined w/ energy recovery (waste-to-energy incinerators) e.g. 24% of Denmark's energy, in 2007
controlled burning of waste @ high temp., designed to attain its complete combustion
success: less than 1% of h/h waste ends up in landfills in Sweden. half converted into energy (2.2M tonnes)
3R's
in DCs, more formalised recovery & recycling schemes e.g. recycling bins
scavenging in dumpsites in LDCs provides employment e.g. in Asia & Latin America, 2% of pop. earn a livelihood by scavenging, recovering materials to sell for reuse/recycling
what affects quantities of materials recycled is cap. of recycling plant & equipment, & size of mkt for recycled materials
realisation of econ. value of certain wastes promotes 3R's
success: Denmark's waste taxation system (h/hs & industries): within 10 years of implementation, 26% reduction of waste & reached recycling rate of 61%
limitations: hard to change lifestyle
failure: in SG, only 1/2 of "recycling pile" is recycled, due to contamination & non-recyclable items found
Landfill
hazards: leakage of toxic leachates (contaminate surface & ground water), leaving refuse open to air (rats, bacterial infestation), methane (fire hazard but can be renewable fuel)
limitations: pressure on avail. space & opposition from locals (dirty, foul smelling, pests & diseases)
e.g. 64% waste in OECD countries to landfills in 1995 but expected to reach 50% by 2020
success: Semakau: offshore landfill. perimeter lined w/ impermeable membrane & leachate is treated-> no H2O pollution. has recreational activities, like bird watching . home to > 700 types of plants, animals
where waste is dumped e.g. Smokey Mountains. however, quantities disposed are declining as recycling rates improve in some countries
failure: Payatas Landfill in Metro Manila. produced 26kg of Pb annually, threaten H2O supply as near dam & river. landslide 30m high, 100m wide killed >200 ppl in 2000
if properly designed & managed, little harm-> sanitary landfills
(sites where waste is isolated from env. until it is safe. considered when it has completely degraded biologically, chemically and physically)
e.g. Semakau Landfill