Waste management
Waste management (or waste disposal) is the activities and actions required to manage waste from its
inception to its final disposal. This includes the collection, transport, treatment and disposal of waste,
together with monitoring and regulation of the waste management process.
Waste can be solid, liquid, or gaseous and each type has different methods of disposal and management.
Waste management deals with all types of waste, including industrial, biological, and household.
Waste is produced by human activity, for example the extraction and processing of raw materials. Waste
management is intended to reduce adverse effects of waste on human health, the environment or
aesthetics.
Principles of waste management
Waste hierarchy
The waste hierarchy refers to the "3 Rs" reduce, reuse and recycle, which classifies waste management
strategies according to their desirability in terms of waste minimization. The waste hierarchy is the
cornerstone of most waste minimization strategies. The aim of the waste hierarchy is to extract the
maximum practicnlal benefits from products and to generate the minimum amount of end waste; see:
resource recovery. The waste hierarchy is represented as a pyramid because the basic premise is that
policies should promote measures to prevent the generation of waste. The next step or preferred action
is to seek alternative uses for the waste that has been generated i.e. by re-use. The next is recycling
which includes composting. Following this step is material recovery and waste-to-energy. The final action
is disposal, in landfills or through incineration without energy recovery. This last step is the final resort
for waste which has not been prevented, diverted or recovered. The waste hierarchy represents the
progression of a product or material through the sequential stages of the pyramid of waste
management. The hierarchy represents the latter parts of the life-cycle for each product.
Life-cycle of a product
The life-cycle begins with design, and then proceeds through manufacture, distribution, recycle primary
use and then follows through the waste hierarchy's stages of reduce, reuse and recycle. Each stage in the
life-cycle offers opportunities for policy intervention, to rethink the need for the product, to redesign to
minimize waste potential, to extend its use. Product life-cycle analysis is a way to optimize the use of the
world's limited resources by avoiding the unnecessary generation of waste.
Resource efficiency
Resource efficiency reflects the understanding that global economic growth and development cannot be
sustained at current production and consumption patterns. Globally, humanity extracts more resources
to produce goods than the planet can replenish. Resource efficiency is the reduction of the
environmental impact from the production and consumption of these goods, from final raw material
extraction to last use and disposal. This process of resource efficiency can address sustainability.
Polluter-pays principle
The polluter-pays principle mandates that the polluting party pays for the impact on the environment.
With respect to waste management, this generally refers to the requirement for a waste generator to
pay for appropriate disposal of the unrecoverable material.
Disposal methods
Landfill
A landfill site (also known as a tip, dump, rubbish dump, garbage dump or dumping ground and
historically as a midden) is a site for the disposal of waste materials by burial. It is the oldest form of
waste treatment (although the burial part is modern; historically, refuse was just left in piles or thrown
into pits).
Incineration
Incineration is a disposal method in which solid organic wastes are subjected to combustion so as to
convert them into residue and gaseous products. This method is useful for disposal of both municipal
solid waste and solid residue from waste water treatment. This process reduces the volumes of solid
waste by 80 to 95 percent. Incineration and other high temperature waste treatment systems are
sometimes described as "thermal treatment". Incinerators convert waste materials into heat, gas, steam,
and ash.
Incineration is carried out both on a small scale by individuals and on a large scale by industry. It is used
to dispose of solid, liquid and gaseous waste. It is recognized as a practical method of disposing of
certain hazardous waste materials (such as biological medical waste). Incineration is a controversial
method of waste disposal, due to issues such as emission of gaseous pollutants
Recycling
Recycling is a resource recovery practice that refers to the collection and reuse of waste materials such
as empty beverage containers. The materials from which the items are made can be reprocessed into
new products. Material for recycling may be collected separately from general waste using dedicated
bins and collection vehicles, a procedure called kerbside collection. In some communities, the owner of
the waste is required to separate the materials into different bins (e.g. for paper, plastics, metals) prior to
its collection. In other communities, all recyclable materials are placed in a single bin for collection, and
the sorting is handled later at a central facility. The latter method is known as "single-stream recycling."
The most common consumer products recycled include aluminum such as beverage cans, copper such as
wire, steel from food and aerosol cans, old steel furnishings or equipment, rubber tyres, polyethylene
and PET bottles, glass bottles and jars, paperboard cartons, newspapers, magazines and light paper, and
corrugated fiberboard boxes.
Re-use
Biological reprocessing
Recoverable materials that are organic in nature, such as plant material, food scraps, and paper
products, can be recovered through composting and digestion processes to decompose the organic
matter. The resulting organic material is then recycled as mulch or compost for agricultural or
landscaping purposes. In addition, waste gas from the process (such as methane) can be captured and
used for generating electricity and heat (CHP/cogeneration) maximizing efficiencies. The intention of
biological processing in waste management is to control and accelerate the natural process of
decomposition of organic matter.
Energy recovery
Energy recovery from waste is the conversion of non-recyclable waste materials into usable heat,
electricity, or fuel through a variety of processes, including combustion, gasification, pyrolyzation,
anaerobic digestion, and landfill gas recovery. This process is often called waste-to-energy. Energy
recovery from waste is part of the non-hazardous waste management hierarchy. Using energy recovery
to convert non-recyclable waste materials into electricity and heat, generates a renewable energy source
and can reduce carbon emissions by offsetting the need for energy from fossil sources as well as reduce
methane generation from landfills. Globally, waste-to-energy accounts for 16% of waste management.
Pyrolysis
Pyrolysis is often used to convert many types of domestic and industrial residues into a recovered fuel.
Different types of waste input (such as plant waste, food waste, tyres) placed in the pyrolysis process
potentially yield an alternative to fossil fuels. Pyrolysis is a process of thermo-chemical decomposition of
organic materials by heat in the absence of stoichiometric quantities of oxygen; the decomposition
produces various hydrocarbon gases. During pyrolysis, the molecules of object vibrate at high
frequencies to an extent that molecules start breaking down. The rate of pyrolysis increases with
temperature. In industrial applications, temperatures are above 430 °C (800 °F). Slow pyrolysis produces
gases and solid charcoal. Pyrolysis hold promise for conversion of waste biomass into useful liquid fuel.
Pyrolysis of waste wood and plastics can potentially produce fuel. The solids left from pyrolysis contain
metals, glass, sand and pyrolysis coke which does not convert to gas. Compared to the process of
incineration, certain types of pyrolysis processes release less harmful by-products that contain alkali
metals, sulphur, and chlorine. However, pyrolysis of some waste yields gasses which impact the
environment such as HCl and SO2.
Resource recovery
Resource recovery is the systematic diversion of waste, which was intended for disposal, for a specific
next use. It is the processing of recyclables to extract or recover materials and resources, or convert to
energy. These activities are performed at a resource recovery facility. Resource recovery is not only
environmentally important, but it is also cost-effective.[30] It decreases the amount of waste for
disposal, saves space in landfills, and conserves natural resources.[30]
Resource recovery (as opposed to waste management) uses LCA (life cycle analysis) attempts to offer
alternatives to waste management. For mixed MSW (Municipal Solid Waste) a number of broad studies
have indicated that administration, source separation and collection followed by reuse and recycling of
the non-organic fraction and energy and compost/fertilizer production of the organic material via
anaerobic digestion to be the favored path.
Sustainability
The management of waste is a key component in a business' ability to maintain ISO14001 accreditation.
The standard encourages companies to improve their environmental efficiencies each year by
eliminating waste through resource recovery practices. One way to do this is by adopting resource
recovery practices like recycling materials such as glass, food scraps, paper and cardboard, plastic bottles
and metal. Recycled materials can often be sold to the construction industry. Many inorganic waste
streams can be used to produce materials for construction. Concrete and bricks can be recycled as
artificial gravel. This topic was on the agenda of the International WASCON conference in Spain in June
2015 and on the international Conference on Green Urbanism, held in Italy 12–14 October 2016.
Liquid waste-management
Sewage sludge
Sewage sludge is produced by waste water treatment processes. Due to rapid urbanization, there has
been an increase in municipal waste water that results 0.1–30.8 kg of sewage per population equivalent
per year (kg/p.e/year). Common disposal practices of sewage sludge are incineration, composting, and
landfill.
