103
7. Sunlight: Sunlight helps in the purification of surface water body by adding
oxygen through photosynthesis. Besides this, the UV rays from the sun can
disinfect the water to some extent.
8. Adsorption: Solid surface of soil, rock, mineral, vegetation can adsorb pollutants depending on the chemical properties of solids.
9. Absorption: Some pollutants will be absorbed by abiotic component of environment and some others may be absorbed by living organism.
10. Biogeochemical cycles: Complex biogeochemical cycles through series of
physical, chemical and biological activity would change the pollutants to an
extent wherein pollutants will not harm environment.
11. Sedimentation: Some pollutants may settle in water body without further travelling in the environment.
12. Filtration: Filtration in natural set-up can occur when water infiltrates through
soil strata vertically and moves through voids in soil horizontally.
Worldwide, numerous regions suffer from water shortage, as well as contamination. The infiltration and subsurface storage of river and rainwater can decrease
water stress. Artificial groundwater recharge, combined with plant purification,
bank filtration and/or the use of subsurface dams, as well as artificial aquifers, is
especially beneficial in areas where layers of gravel and sand exist below the surface
of earth (Balke and Zhu 2008).
The nature is so diverse that it provides the needs of all living organisms.
Different organisms have different requirements with respect to habitat, nutrient
requirement, temperature, light, oxygen, etc. The organisms have flourished and
colonized according to environmental set-up. The nutrition of one animal may be
poison to another. The nitrate which is very much essential for plant growth may
lead to health hazard in case of humans. Hence, wetlands formed in plant-nutrientrich (e.g. nitrate, phosphate and so on) slow-flowing or stagnant water will help
wetland plants to get their nutrition, while the other organisms on downstream get
relatively pure water for their survival (Figs. 5.2 and 5.3).
Varying flow either due to change in seasons or flow gradient would make settleable solids settle making the rest of relatively pure water flow further.
Wetlands which are referred as kidneys of nature are identified late by humans
for usefulness. Wetlands adjacent to water bodies were occupied by humans for
building civilization, thereby sacrificing self-purifying system established by nature
over the period of time. The wetland which was not occupied for building structures
became dump yard for wastes generated by humans (Fig. 5.4).
5.2 Engineering Control
Water and wastewater treatment in engineering control is similar to what happens in
self- purification process of water in nature; but the treatment happens in engineered
structures. The time and space required for the treatment depends on energy input to
5.2 Engineering Control
7. Sunlight: Sunlight helps in the purification of surface water body by adding
oxygen through photosynthesis. Besides this, the UV rays from the sun can
disinfect the water to some extent.
8. Adsorption: Solid surface of soil, rock, mineral, vegetation can adsorb pollutants depending on the chemical properties of solids.
9. Absorption: Some pollutants will be absorbed by abiotic component of environment and some others may be absorbed by living organism.
10. Biogeochemical cycles: Complex biogeochemical cycles through series of
physical, chemical and biological activity would change the pollutants to an
extent wherein pollutants will not harm environment.
11. Sedimentation: Some pollutants may settle in water body without further travelling in the environment.
12. Filtration: Filtration in natural set-up can occur when water infiltrates through
soil strata vertically and moves through voids in soil horizontally.
Worldwide, numerous regions suffer from water shortage, as well as contamination. The infiltration and subsurface storage of river and rainwater can decrease
water stress. Artificial groundwater recharge, combined with plant purification,
bank filtration and/or the use of subsurface dams, as well as artificial aquifers, is
especially beneficial in areas where layers of gravel and sand exist below the surface
of earth (Balke and Zhu 2008).
The nature is so diverse that it provides the needs of all living organisms.
Different organisms have different requirements with respect to habitat, nutrient
requirement, temperature, light, oxygen, etc. The organisms have flourished and
colonized according to environmental set-up. The nutrition of one animal may be
poison to another. The nitrate which is very much essential for plant growth may
lead to health hazard in case of humans. Hence, wetlands formed in plant-nutrientrich (e.g. nitrate, phosphate and so on) slow-flowing or stagnant water will help
wetland plants to get their nutrition, while the other organisms on downstream get
relatively pure water for their survival (Figs. 5.2 and 5.3).
Varying flow either due to change in seasons or flow gradient would make settleable solids settle making the rest of relatively pure water flow further.
Wetlands which are referred as kidneys of nature are identified late by humans
for usefulness. Wetlands adjacent to water bodies were occupied by humans for
building civilization, thereby sacrificing self-purifying system established by nature
over the period of time. The wetland which was not occupied for building structures
became dump yard for wastes generated by humans (Fig. 5.4).
5.2 Engineering Control
Water and wastewater treatment in engineering control is similar to what happens in
self- purification process of water in nature; but the treatment happens in engineered
structures. The time and space required for the treatment depends on energy input to
5.2 Engineering Control