Suraj Shah, Khce
Dust arising from development is additional to background dust concentrations. If not adequately controlled dust emissions from developments may lead to increases in dust concentrations beyond the site boundary, which may affect local amenity and influence local air quality.
It is more effective to
address dust emissions at the design and planning stage of new development
proposals, than to seek to deal with dust problems retrospectively. Likewise it
is more effective to deal with potential dust emissions at source, rather than
once airborne. However, in context of Nepal system, the solution is searched
once problem is in its high phase and it becomes the headlines of national
daily. So, as an engineering student I am
writing some major remedies with their
economic value to dust generation which is becoming a major health issue to
Kathmandu valleys people.
They are as follows:
WATER:
Water is considered as
one of the cheapest method for dust control but with the frequent application
rates and equipment used in spraying and scarcity of water in context of valley
its optional has to be thought. In generally, the effectiveness of water spray
depends upon weather and traffic and may be effective from 30 minutes to 3
hours.so with the frequent application cause rise in capital and cause way
slippery and cause potholes. If water is used as dust palliatives it should be
used with surfactants or wetting agents or mix with less salts.
HYGROSCOPIC
SALTS:
It may be next option
for valley as water is scare in a dry
period generally (falgun to jesth) hygroscopic salts are typically chloride
salts and suppress dust by attracting moisture from the air, keeping the road
surface moist. They are generally applied as surface sprays or mixed in,
followed by a final wash (rates vary according to material type, preparation
and traffic). When the atmospheric moisture falls below 70% relative humidity,
the hygroscopic chlorides cease to function, whereas the deliquescent chlorides
cease to function at about 30–40% relative humidity. The products are thus
climate sensitive, and Jones (1998) reports their limitation to a climate
region encompassing Gauteng Chloride salts are able to have their
water-attracting functions recharged with a few hours of adequate moisture and
humidity.
PETROLEUM RESIN:
The next solution is Petroleum (emulsified or
sulphonated petroleum) resins are derived as a by-product of the oil refining
industry; emulsified petroleum resins are formulated as dust suppressants and
stabilizers. Binding agents added to the emulsified petroleum resin (derived
from paraffinic crude oil) formulation, which penetrate the wearing course and
bind the material, preventing them from becoming airborne. In addition, wetting
agents, emulsifiers and dispersants are added to increase the penetration and
spreading of the product. The
application methodology is dependent on the wearing course material
characteristics, usually an initial mix-in application would be required followed
by maintenance spray-on applications.
TAR
AND BITUMEN EMULSION PRODUCTS:
The
last discussed technical solution is Tar-based products are derived from coal
tar distillates to which solvents are added to improve penetration. Bituminous
based products are based on 80/100 penetration grade bitumen with solvents
added. Emulsifiers and wetting agents may be added to enable the product to be
mixed with water and applied as a mix-in product, followed by spray-on
maintenance applications, at an application frequency and dilution dependent on
the product itself, material type, preparation and traffic types and volumes.
The palliative works by binding the wearing course material, but performance is
sensitive to the quality of the wearing course material.
The graph showing comparisons
of these products:
However other technique
like traffic management ;reducing speed ,reducing traffic volume.
REFERENCES:
dec.alaska.gov/air/anpms/Dust/topten_dustctrl2.htm
amponash-dacosta.pdf
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