Mr. Sagar Kolekar will present his Ph.D. defense as per the details below:
Date: September 20, 2024
Time: 11.30 a.m.
Venue: Conference Room No 1, CTARA Office
Meeting link for online:
https://monash.zoom.us/j/83352179125?pwd=YgkQfNx02aXGw7B2swmLpZW5KoIYNw.1
Title: Domestic wastewater treatment using constructed wetland as a sustainable nature-based solution in rural areas for irrigating vegetables: A case study of tomato crop
Supervisor: Prof. Pennan Chinnasamy
Internal Examiner: Prof. T. I. Eldho
External Examiner: Prof. S. Vasantha Kumar
Chairman: Prof. Raaj Ramsankaran
Abstract:
The availability of water is decreasing, especially in areas where natural water supplies are severely depleted. Of the water uses, agricultural water use accounts for the highest, and there is a constant need to augment agricultural water resources. However, the use of treated domestic wastewater for crops is still not well understood, and in some regions, not accepted. It was found from the literature that most of the domestic wastewater that is reused for agriculture is generally only treated up to secondary treatment. In this study, a combination of artificial and natural wastewater treatment methods followed by tertiary treatment is provided. It includes an Anaerobic System (AnSys) as an artificial method and a Constructed Wetland (CW) as a natural wastewater treatment, followed by an Ultra Violet (UV) system for the disinfection of treated domestic wastewater. The site in Lavale village from Mulshi Taluka of Pune district, Maharashtra was identified for the installation of a wastewater treatment system using the Analytical Hierarchy Process (AHP), and the treated wastewater was reused for growing tomatoes as a case study. The Randomized Complete Block Design (RCBD) with two treatments (freshwater and treated wastewater) were considered for the design of the experiment. The physical, chemical, and biological properties of treated wastewater, soil, and tomato fruit have been tested. The fortnightly sampling and testing of wastewater were done at an inlet and outlet of AnSys, CW, and UV. The results indicate that the overall efficiency of the AnSys + CW + UV for the removal of biological oxygen demand (BOD), chemical oxygen demand (COD), total phosphorous (TP), total nitrogen (TN), total potassium (TK), and total suspended solids (TSS) were 93%, 92%, 70%, 75%, 60%, and 96%, respectively.
Results also indicate that the effect of water type was significant for plant height, number of branches, number of fruits, and yield of the tomato. The average crop height, number of branches, tomato fruits, and yield were 1.2, 1.97, 1.72, and 2.03 times higher for treated wastewater (TWW) as compared to freshwater (FW). All other factors (e.g., hydro climate, soil, availability of sunlight, wind) were controlled as they are in the same locations, and hence both plots, i.e., control and experiment plots were exposed to the same factors, including quantity of water, while the only difference was the quality of water (TWW vs. FW). The chemical and biological properties of soil and tomato fruits were also analysed, and it was also observed that the nutrient uptake was slightly higher for TWW soil and tomato fruits when compared with FW. The presence of heavy metals and pathogens was not observed in treated wastewater, soil, and tomato fruits. There was no negative impact on soil and fruit quality due to the application of TWW; rather, it gave the maximum yield of the tomato crop.
The cost of water per litrein the context of reuse of treated wastewater for tomato through AnSys + CW + UV, the government irrigation scheme, and water from the nearby farmer were Rs 0.018, Rs 0.014, and Rs 0.025, respectively. The benefit-cost ratios (BCR) for these options were 2.25, 0.67, and 0.50, respectively. The AnSys + CW + UV scenario had the highest financial return (including all costs) as compared to other scenarios. In addition to economic benefits, the application of treated wastewater provides a sustainable solution for enhancing tomato crop yields while conserving freshwater resources. This approach not only transforms unproductive land into fertile agricultural areas but also safeguards our natural water bodies from the harmful effects of untreated wastewater discharge. Therefore, nature-based solutions, such as AnSys combined with constructed wetland and ultraviolet purification, are key to achieving environmental and agricultural benefits, and hence government and private support should be acquired for long-term benefits.
Keywords: Treated Wastewater, Wastewater Reuse, Agriculture, Tomato, Constructed Wetlands, Nature Based Solutions