Haveri district in Karnataka has set up a unique inline treatment system for management of greywater from households and establishments. The technology which is both nature-based and cost effective, is successfully treating all grey water before it joins the river.
Situated on the banks of the Tungabhadra River, Kodiyal GP has a population of about 8500 with adequate water for all their needs. However, the wastewater generated in the GP would previously pollute the river that flowed alongside. The ‘Nirmal Haveri’ campaign was taken up to address this critical issue.
The pilot project was a combination of a two-stage sedimentation pond followed by a constructed wetland as inline treatment and a bypass drain to address the wet weather flow.
What is inline treatment? The system consists of a horizontal subsurface flow constructed wetland that is dependent on the treatment target and the amount and quality of the influent. The removal efficiency of the wetland and maximum possible flow are determined by the surface area and cross-sectional area of the wetland. Generally, a surface area of about 3 sqm per cum of pre and secondary treated effluent is required. Settler/ Settler and Anaerobic Baffle Reactor (ABR) / Sedimentation tanks / Sedimentation drains / Sedimentation ponds etc., can be used as primary treatment modules.
Most commonly, angular graded gravel is used to fill the bed to a depth of 0.5m. To limit clogging, the gravel should be clean and free of fines. As for the water level in the wetland, it is maintained at 5 to 15 cm below the gravel surface to ensure subsurface flow. Any native plant with deep, wide roots that can grow in the wet, nutrient-rich environment is appropriate. Phragmites australis (reed) is a common choice because it forms horizontal rhizomes that penetrate the entire filter depth.
The water level in the module is controlled using a swivel pipe or baffle wall. During the maintenance of the module, the swivel pipe can be turned down completely in order to drain out the water or wastewater inflow has to be diverted.
Interventions by RDW&SD: Rural Drinking Water and Sanitation Department (RDW&SD) Karnataka has taken up initiatives to address Greywater Management (GWM) under the Swachh Bharat Mission Grameen (SBM-G) Phase II and ODF Plus initiatives. In fact, the RDW&SD has given in-principle approval and released grants of Rs.205 crore which is 25 per cent of the total amount approved for GWM implementation under SBM (G) Phase II to 4464 GPs across the state.
In this regard, the local administration together with engineers collected the necessary data, and based on the quantum of greywater generated, conceptualized the project, and identified suitable land. Design and drawings were prepared, and necessary approvals obtained from the Zila Panchayat of Haveri before the pilot project was commissioned.
The liquid waste management system is currently functional and effectively managing greywater generated in households.
These works also aid the works under Jal Jeevan Mission (JJM) in the Department providing 55 LPCD of water of which about 70 per cent becomes wastewater. The Liquid Waste Management (LWM) structures will also ensure the sustainability of water sources.
RDW&SD has also carried out a special campaign “Swachha Grama, Swachha Parisara” during June 2020 under IEC and HRD activities, to educate the rural masses regarding greywater usage in their kitchen gardens. The advantages of reclamation of water and reducing dependency on freshwater for non-potable usage were emphasised.
The Department is also working towards the prevention of water pollution by commissioning both nature-based and cost-effective engineered technologies such as Waste Stabilization Ponds (WSP), constructed wetlands, sedimentation tanks, etc., to reduce the pollution load on the natural water sources.