Transcript Solid Waste - Cheung Chuk Shan College

Solid Waste
are useless, unwanted or
hazardous materials resulting
from human activities
 Rubbish that may decompose e.g.
food materials
 Non-decomposable waste e.g.
metal, glass
Solid Waste
 solids from sewage treatment
 Ashes
 Large debris from construction
works
 Industrial waste e.g. chemicals
 Farm waste e.g. manure, crop
remains.
Ways of disposing solid
waste
1. Composting
 Decomposition of organic
waste by micro-organisms
 Process takes 3 weeks
before the materials can be
reused as fertilizers.
Ways of disposing solid
waste
2. Recycling
 Householders are asked to
separate the waste
 They are collected separately
for recycling.
 This reduces the volume of
waste at incinerators / landfills
Ways of disposing solid
waste
3. Landfill
 Are used to bury waste.
 At the landfill site the waste
is spread in thin layers &
bulldozed to compact the
waste between each layer.
Ways of disposing solid
waste
 The site uses concrete
linings to reduce pollution to
ground water.
 Once full, topsoil is added &
the area is often landscaped
for recreational use.
Ways of disposing solid
waste
 This is the most economic
solution provided there are
suitable sites available + they
are close to the source of the
waste
 High cost involved in
transporting waste to landfills
Ways of disposing solid
waste
4. Incineration
 The burning of waste materials
 During combustion, carbon
dioxide, sulphur oxides, nitrogen
oxides, dioxins and ash are
produced.
Ways of disposing solid
waste
 Modern installations use
electrostatic precipitators,
bag filters to remove any
fine particles
 Heat from the incineration
process has been used for
domestic heating
Ways of disposing solid
waste
 In recent years, fears of
global warming and the
release of harmful
substances, dioxins, has
made the siting of
incinerators difficult.
Ways of disposing solid
waste
 New generation of ‘energy from
waste’ (EfW) facilities are
developed
 They are cleaner than the old
incinerators
 They meet UK & EU
environmental standards
Ways of disposing solid
waste
 Energy from waste facilities
are an important source of
renewable energy. This
reduces the burden on
burning fossil fuels.
Ways of disposing solid
waste
 The ash by-product can be
recycled for use in the
construction industry. Some
will be placed in landfills.
However it will reduce the
landfill capacity needed.
Ways of disposing solid
waste
 Objections of EfW plant
 Incineration is the source of
serious toxic pollutants e.g.
dioxins
 Dioxins even at low level harm
the environment & human health
Ways of disposing solid
waste
 Incineration always produce
a toxic ash. This has to be
disposed in landfills which is
more likely to pollute water