Constructed wetland for wastewater treatment at Indian Agriculture Research Institute, Pusa, New Delhi



Location: Indian Agricultural Research Institute (IARI), Pusa, New Delhi Scale: Institutional Implementing organisation: Water Technology Centre, Indian Agricultural Research Institute (IARI), Pusa, New Delhi	Designed Capacity: 2.2 MLD Area : 1.42 Ha Operational since : 2012 Capital cost : 1.2 Crores O&M: Rs. 1,335 / day)



The decentralised wastewater treatment system is based on an engineered wetland technology. The aim of the project is to provide an alternate source of water for irrigation of the institute’s agricultural fields. The system treats 2.2 MLD of wastewater with an annual irrigation potential of 132 Ha. The source of the wastewater is a nearby drain carrying wastewater from the adjacent Krishi Kunj and Loha mandi Colony.



The wastewater treatment plant comprises of 3-treatment cells (each of 80 meter by 40 meter), where organic, nutrient and metal pollutant reductions (i.e. secondary and tertiary treatments) take place; besides 2-sewage wells and 1-grit chamber, where preliminary/ primary treatment takes place. Each treatment cell is stratified with a bed of gravels of varying sizes/ grades, onto which Typha latifolia – a hyper-accumulating emergent vegetation is planted. To make the whole system minimal energy consuming, a complete gravity flow of the wastewater, from the grit chamber to the treated water-collector sump of the system has been ensured. The flow of the wastewater in each treatment cell is so regulated that there is complete sub-surface flow, thereby leading to no ponding, foul smell, mosquito breeding or any direct contact with wastewater. The treated water is finally collected in an treated water-collection tank(80 meter by 40 meter by 2 meter), from where it is finally pumped, through a riser and a set of hydrants, into the irrigation network of the Indian Agricultural Research Institute farm.



Long term monitoring of treatment capacity of the constructed wetland treatment system reveals that it is capable to remove turbidity (99%), BOD (87%), Nitrate (95%), Phosphate (90%) and heavy metal (81 - 99%). In terms of standard cost-accounting, the proposed initiative has been found to be associated with Rs. 0.545 Crore per MLD of capital cost (CAPEX) and about Rs. 0.607 per Kilo litre (KL) of total O&M cost. Thus, in comparison to a comparable conventional wastewater treatment plant, the proposed initiative is associated with about 50-65% lower treatment costs. Further, in comparison to a conventional wastewater treatment plant, the proposed technology has less than 1% energy requirement and is associated with zero-chemical application and no sludge generation



Dr. Ravinder Kaur, Project Director Water Technology Centre IARI, Pusa, New Delhi E-mail: pd_wtc@iari.res.in, rk132.iari@gmail.com