Environmental Engineering Reference
In-Depth Information
The United Nations Statistics Division (UNSD, 2013) defines waste as: “Wastes
are materials that are not prime products (that is products produced for the mar-
ket) for which the generator has no further use in terms of his/her own purposes of
production, transformation or consumption, and of which he/she wants to dispose.
Wastes may be generated during the extraction of raw materials, the processing of
raw materials into intermediate and final products, the consumption of final products,
and other human activities. Residuals recycled or reused at the place of generation are
excluded''.
The definitions and classifications may be based on the chemical composition, tox-
icity, the origin or the management of wastes. OECD prepared a definition for selected
categories, such as municipal waste (collected and treated by municipalities mainly
from households), hazardous waste (mainly from industrial activities) and nuclear
(radioactive) waste (generated at various stages of the nuclear fuel cycle). The present
state of the art of waste management is characterized by the existing definitions and
classifications: none of them is based on valuable contents, on the worth of the com-
ponents, their beneficial uses or reuses, etc. This kind of classification or labeling of
wastes is still missing.
Waste reduction and elimination are the most acceptable management options.
Industry, mining, and agriculture should produce, while service providers and trans-
porters act in a much more sustainable way with much less environmental impact.
This can be achieved by using global material sources more efficiently, covering energy
needs as much from renewable resources as possible and completely preventing or uti-
lizing waste if viable. To get closer to the target of sustainable waste management, i.e.,
closed-circle households, communal and industrial systems, one has to establish sepa-
rated and/or strategically combined waste streams. The term “waste stream'' indicates
a dynamic approach required to reform waste management: mapping and monitoring
all wastes and their (almost all) useful components from the place of their generation
to the end of their life cycle and finding the best pathway to those sinks where the
material or energy content of the waste is the most profitable. To be able to manage
waste this way, we must have information on the utilizable contents, the quantity and
location of the generated waste, and the location and needs of those sinks which can
utilize material and energy from the wastes. We have to assess the risks and costs asso-
ciated with the waste along the selected stream and the benefits from the use of material
and energy from the waste. Because most wastes comprise mixtures of substances, the
constituents cannot be equally utilized, and therefore, streaming should also consider
the risks and benefits of the non-target components of the waste.
“Waste hierarchy'' ranks waste management options according to their benefits for
the environment. The hierarchy of the waste pyramid is a generic frame. The actually
applied management options based on LCA (life cycle analysis), environmental risk
assessment (ERA), and socio-economic assessment (SEA) may differ from the general
options shown by the waste pyramid in Figure 6.1, i.e., the highest level solutions
recommending prevention or reuse may neither be always feasible nor be the most
beneficial.
Today's waste management system, with centralized collection, transportation,
and treatment, should be changed and substituted with more refined waste streaming.
In the current practice, nutrient reclamation, energy and material recovery as well
as organics recycling is effected in recycling centers, on landfill sites or wastewater
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