Dayanand Park - Nagpur

The Dayanand Park case study is a further case study of the invalid link, which aims to optimise the use of different urban water flows by treating each of these flows via modular natural systems appropriate for urban and peri-urban areas of India.

Dayanand Park is one of the well-maintained parks managed by the Nagpur Improvement Trust (NIT), the Development Authority of Nagpur, Maharashtra. About 1500-2000 people use the garden daily for recreational and leisure activities, such as yoga, laughter club, jogging and play area for children. The water requirement to maintain the garden is approx. 100 – 120 m³/day, stemming currently from groundwater resources and - due to the depletion of groundwater levels during the summer season – also from untreated sewage, posing a huge health risk for the park users.

The aim of this project is to treat the necessary water before re-using it, providing sewage management for at least 1000 population equivalent (p.e.), and improving the safety and health of the population and workers. The solution proposed are natural treatment technologies integrated into the existing landscape, more precisely different combinations of horizontal flow and vertical flow subsurface constructed wetlands (CWs).

CWs are wastewater treatment technologies, which emphasize the processes happening in natural wetlands in order to improve their treatment capacity (KADLEC AND WALLACE 2008). A CW is a shallow basin filled with some sort of filter material (substrate), usually sand or gravel, and planted with vegetation tolerant of saturated conditions. Wastewater is introduced into the basin and flows over the surface or through the substrate (UN-HABITAT 2008). The mechanisms that occur in CW systems for wastewater treatment are complex and include chemical, physical and biological processes. CWs are used worldwide to treat various types of wastewater. They have proven to be efficient at achieving not only conventional water quality parameters but also have a great potential for the elimination of emerging organic contaminants (HIJOSA-VALSERO et al. 2010).

Various CW configurations exist (such as subsurface, vertical flow wetlands (VFCW); subsurface, horizontal flow constructed wetlands (HFCW); superficial flow constructed wetlands; aerated engineered wetland (AEW)), which may be combined in order to increase their treatment efficiency, especially nitrogen removal. The configurations used at Dayanand park are based on VF- and HF-CWs. The various combinations are HF-HF, HF-VF, VF-HF, VF-VF and AEW, each of equal capacity, which will be integrated into the existing landscape in order toprevent the use of raw sewage, improving health and safety for park users.The technical characteristics are the following:

• Proposed quantity of wastewater to be treated: 100 m³/d (sewage management for at least 1,000 p.e.).
• Type of treatment system:
  • Primary treatment: three stage septic tank.
  • Secondary treatment: 5 different combinations of various SSF VF and HF CWs.
  • Tertiary treatment: disinfection (UV).
•  Designated end-use: gardening/irrigation to prevent the use of raw sewage.

This case study will offer great opportunities for research, because it allows monitoring and comparing five different CW treatment lines treating the same wastewater under Indian conditions. Furthermore, it will act as a good example of how natural treatment systems can be transformed via landscape architecture into attractive ecosystem services with high performance potentials and positive effects on the quality of life. As the site is located in a public park close collaboration with appropriate stakeholders (NIT, park users) is essential to ensure success of the project and create an overall supportive environment.