Increasing population growth rate, depleting fresh water resources, finite available land and food scarcity.

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).