Read Here: : Possible remedies for burning issue of Kathmandu roads: Dust generation

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: