8/2/2019 Use of Wastewater Effluent in Checking Saline Water Intrusion Into Groundwater Table

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Use of Wastewater Effluent inChecking Saline Water Intrusioninto Groundwater Table

Presentation in

Environmental Engineering on

8/2/2019 Use of Wastewater Effluent in Checking Saline Water Intrusion Into Groundwater Table

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 What is Saline Water Intrusion ?

It is the phenomenon when the Saline Water from anOceanic body enters the Underground space which

 was previously occupied by Fresh Water.

It occurs mainly due to anthropogenic reasons ie.due to uncontrolled human intervention into thenatural ground water flow.

 An imbalance between inflow & extraction of 

groundwater in an aquifer leads to Saline WaterIntrusion as the lessening of pore water pressureafter removal of fresh water leads to entry of 

 brackish water.

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Control of Saline Water Intrusion>>> Groundwater Recharge <<<

In order to combat the receding fresh water gradient &encroaching brackish water, a Hydrostatic Barrier has to

 be created in order to balance the Extraction & In-flow of  water into the groundwater aquifer. This is done through

injection of water between the source of extraction of  well-water & the saline water

However, due to shortage of water & overall escalation of cost, it becomes inevitable that most favorable input forRecharge of the Aquifer is Treated Wastewater from a

nearby Water Treatment Plant  Wastewater, which would otherwise be discharged in

running surface streams of fresh-water or the sea, is thus,utilized in a fair manner.

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Control of Saline Water Intrusion>>> Groundwater Recharge (Contd.) <<<

Natural Groundwater Recharge takes place in an area wherehuman activities such as industrial processing, agriculture,domestic practices, etc. are not present. Thus, when water is

 withdrawn from an aquifer at a faster rate than it can be

replenished, it leads to lowering of groundwater table &subsidence of the area due to aquifer collapse.

Saltwater has greater density. It wedges below the freshwater.Resultant contamination of well-water by the saline waterleads to various problems at the point of its extraction & use,such as change in soil pH, unsuitability for drinking purposes,etc. Ultimately, this can lead to less fertility of the land &thereby, a change in pattern of Human Habitation. Thus,Saltwater Intrusion has to checked at sight & in fore-sight.

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Profile of the Interface between Fresh & Saline Water

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Salt-water Interface in an unconfined coastalaquifer

X- Groundwater Level; Y- SeaLevel

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Deep-recharge Well creates a Groundwater Ridge

The Water Ridge helps in maintaining pore water pressure& thereby, maintains an isostatic equilibrium

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Situation in India

Status of Inland Salinity in different affected States

Pie-diagram shows Percentage of Area in SalineConditions out of Total Groundwater-Irrigated Area

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Other Prominent Uses of Effluent Wastewater

Industries derive more than one-fifth of their WaterRequirements from the Groundwater & the rest fromSurface Water Sources;

However, Reclaimed Wastewater fetches less than1% of the Total Industrial Requirement. It is usedmainly for Cooling Tower Systems in IndustrialUnits.

Industrial activities are the major contributors of harmful constituents in the sewage. Thus, such unitsshould be made more accountable for safe utilizationof treated wastewater, also.

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Courtesy for Data Sources :

Textbook of Environmental Engg. by Peavy & Rowe

Textbook of Environmental Engg. by Metcalf & Eddy 

 www.rt.ttu.edu  www.solinst.com;

 www.cpcbenvis.nic.in;

 www.environmental-expert.com

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Thanking You…!!! Queries requested, if any…?