Pilot of an Anaerobic system and Constructed Wetland for domestic wastewater treatment in Pune

Population served (in PE): 1600 PE (assuming 200l/p/d) for wastewater management; 4-5 farmers served with irrigation water / More than one hectare land served with treated water

System capacity: 50m3/day

In steady-state operation since 08/2022

Hand-over from PAVITR to long-term owner: 01/2024

Input: Screened domestic raw wastewater from student hostels and staff quarters pumped from an existing sewage treatment plant (STP)

Output: Treated water for irrigation purposes

Flow scheme: (Preliminary treatment: screening at existing sewage treatment plant)

Anaerobic primary settler - Anaerobic baffled reactor + Anaerobic filter - Sub Surface HFCW- Dual-Media-Filter + UV treatment

This pilot system is located on the premises of SUHRC Symbiosis Campus in the town Lavale in the suburbs of Pune, Maharashtra. Raw wastewater comes from hostels and staff quarters with a population of around 1600 inhabitants that produce about 300m³ of domestic wastewater per day. After being screened at a local STP, 50 m³/day of the generated wastewater are pumped to the pilot system. This pilot is used to provide treated wastewater for irrigation on nearby farmland.

These were the main steps we took for realising this pilot project:

Identification of potential pilot sites and preparation of the pilot’s preliminary design/set-up based on

• consideration of general topography and site assessments taking into account availability of space, availability of wastewater, availability of reuse sites, availability of skilled labour and experienced contractor etc.
• baseline data collection and analysis at several points in time: wastewater characterisation and soil data to characterize treatment requirements on the one hand side, and nutrient needs of receiving soils on the other hand side.
• these data were complemented by a GIS-based topography survey and mapping of the area. Here, among other factors, also the regulatory compliance with the CPHEEO norms were critical for the identification of potential irrigation fields.

Selection of final project site and specification of location based on

• stakeholder engagement and collaboration: to discuss aspects around land ownership of the required land for the treatment facility and for reusing the produced treated water. Eventually leading to signing of Memorandum of Understanding (MoU) with the farmer whose fields were used for the irrigation research activities.
• public consultation.
• environmental impact assessment.

The most decisive factors for the final site selection turned out to be the ownership of the land the treatment system is installed on, and the availability and accessibility of close-by land for reusing the produced treated water for irrigation. This also pertained to how easy or difficult it was to establish clarity about existing roles and responsibilities.

Finalisation of design

Whereas the anaerobic system was designed by NEERI, the HFCW design was carried out by IRIDRA

Tendering and construction

A tender was floated for the selection of a contractor and all required materials for installation of the system were purchased in India. Construction was supervised by ESF and SIU staff.

Start-up phase and preparation of operation and maintenance

To be fully functional, the anaerobic system requires time to develop active microbial biomass and the HFCW requires time for initial plant development. During this time, the operation and maintenance phase was prepared involving an operator training and the provision of respective O&M materials and routines.

On-going monitoring and evaluation

Being a research site, regular system monitoring was continued by SIU and ESF also after steady state operational status was achieved.  

At this pilot, stakeholder engagement started in early project stages for identifying potential sites and finding agreements with the respective land-owner. For the finally selected site this was SIU management. Also, recurring meetings with the farmer who eventually was supposed to apply the treated effluent took place. Target of these meetings was to sensitise him and his workers, but also to identify an accessible and appropriate location for the irrigation. During the discussions with SIU management and the farmer, also agreements were reached regarding the responsibilities each involved party would take throughout the pilot’s implementation and O&M phase.

The following stakeholders were involved in these respective roles/capacities:

• SIU project team: administrative project implementation on-site; contact point for community members; on-site system monitoring and trouble-shooting.
• ESF project team: Supervision of construction works and start-up phase and also for regular monitoring.
• NEERI and IRIDRA technical experts: design of Ansys and HFCW, remote troubleshooting during start-up phase of constructed wetland
• Farmer of neighbouring fields: The helper farmer was appointed to perform all the farming activities.

A general learning concerning the engagement with stakeholders was the necessity to start on-boarding of (potential) target stakeholders as early as possible and to tailor communication to suit to different stakeholder groups. The engagement process should be continual throughout the implementation process, offer participation opportunities, and address concerns of the targeted stakeholders as well as help to identify and highlight potential benefits of the project for them. Transparency and accountability should be guiding principles that should be followed throughout.

For the duration of PAVITR, day-to-day operation was carried out by one skilled operator/farmer who is present on-site on a daily basis. Training of operator was organised by SIU and the owner of the farmland,

For maintenance tasks like major cleaning activities or seasonal plant harvesting, additional workers are employed who are instructed SIU. For the anaerobic system, a third-party desludging service will be employed around every three years.

Wastewater and soil sampling and analysis as well as monitoring of the crop growth was carried out by the PAVITR project staff at SIU and ESF. Supervision of the operator and ad-hoc trouble-shooting was also covered by SIU staff, supported by ESF.

For the long-term O&M of the system, day-to-day operations are planned to be taken over by SIU campus administration who will employ an operator to be present on a daily basis on-site. System monitoring will be taken care of by Symbiosis.

Some general remarks about important aspects to take into consideration when setting up the O&M phase:

• the operation and maintenance manual should be prepared in local language,
• the checklist sheets should be made handy for regular maintenance,
• the training should be provided in local language,
• the easy SOP flowcharts should be available on site in local language.

At the time this case study was compiled, these preliminary observations were made:

• the test results of the treated effluent show that parameters are within the permissible limit except for Total Phosphate.
• the maturity stage of Phyto plants from the wetland effects the system performance.

No negative impact on soil/fruits with the application of reuse of treated wastewater, whereas the yield is increased with application of reuse of treated wastewater.

At this site, the main product is treated wastewater, and the bi-product is sludge. The dry sludge can be used as fertiliser for agriculture. The treated wastewater has nutrients, so it is assumed to save cost on fertilisers. However, the following barriers were met when realising the reuse potential.

• The cost of freshwater is very less because of the subsidized rate of governments - so selling treated wastewater is challenging.

Awareness to use such treated water among farmers is much needed.