Fresh water scarcity and need for wastewater treatment by ICRISAT-IDC Wastewater Team

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Information about Fresh water scarcity and need for wastewater treatment by ICRISAT-IDC...

Published on September 7, 2016

Author: icrisatsmco

Source: slideshare.net

1. Fresh water scarcity and need for wastewater treatment ICRISAT-IDC Wastewater Team Introduction  Increasing population growth rate, depleting fresh water resources, finite available land and food scarcity.  The map below shows that India will become water stressed by 2025. Key Dilemmas  Lack of fresh water resulted in wastewater use in peri-urban and rural areas for agriculture.  Urgent need to recycle low quality wastewater for agricultural use.  Wastewater treatment plants in Indian urban cities have low treatment capacities resulting in partially treated wastewater.  Estimated wastewater generation i.e. class I and class II towns is 38254 MLD.  Treatment capacity in class I and class II cities is 11787 MLD.  Huge gap between wastewater generation and treatment.  Rural parts of India lack efficient wastewater treatment plants.  Past and current wastewater treatment status in India shown in Figure below. Wastewater a valuable resource  Nutrient rich wastewater generated from peri-urban and rural areas is perennial and nutrient rich containing nitrogen, phosphorus, coliforms and heavy metals-lead, cadmium, chromium and zinc.  Untreated wastewater usage for irrigation pose health hazards. Need for low cost, less energy intensive and minimal maintenance systems for wastewater re-use in agriculture.  Need to develop constructed wetlands (CWs) as decentralized wastewater treatment systems for improving wastewater quality and sanitation in rural India. What are Constructed wetlands?  Human-made engineered systems as low cost, effective in excessive nutrient reduction similar to a natural wetland and requiring minimal maintenance. 0 2 4 6 8 10 12 14 16 1988-1992 1993-1997 1998-2002 2008-2012 Wastewaterquantity (BMC) Wastewater generation Treated muncipal wastewater Not treated muncipal wastewater discharged 11553 233.7 35558 269.6 0 5000 10000 15000 20000 25000 30000 35000 40000 Class I cities Class II cities Wastewater(millionlitresperday(MLD) Treatment capacity MLD Sewage generation MLD What makes constructed wetlands effective?  Physical filtration of nutrients due to coarse sand and gravel media. Adsorption of nutrients/contaminants to surface of sand and gravel media.  Microbes present in the wastewater responsible for nutrient transformations.  Wetland plants reduce excessive nutrients through its uptake in the above-ground biomass (leaves, stems and branches) and below ground part (roots).

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