ORGANIC MICROPOLLUTANTS IN THE RIVER YAMUNA AND RANNEY WELLS IN CENTRAL DELHI

Abstract

Due to prevalent use of pharmaceuticals, pesticides, herbicides, personal care products, hormones, petroleum hydrocarbons, and industrial chemicals, surface water bodies get polluted. In conventional drinking water treatment process, removal of OMPs is not been in practice. Riverbank filtration (RBF) on the other hand is able to remove/reduce the OMPs through the processes such as filtration, sorption, acid-base reaction, hydrolysis, biochemical reactions etc. RBF is a process where wells adjacent to the rivers draw water that is a mixture of ground water and filtered river water. The thesis has been organized into six chapters. Chapter 1 describes the background and motivation of the study. Contamination of fresh water resources with thousands of persistent organic micropollutants (OMPs) is a matter of concern. Challenges are that their numbers and concentrations are increasing and vary widely from place to place. Conventional water treatment processes are not adequate to remove the OMPs. Additional operations are required to remove OMPs to produce potable water. The result is an increase in the cost of drinking water. Natural filtration such as riverbank filtration (RBF) or Lake Bank filtration (LBF) is reported as a useful alternative for the attenuation of OMPs. The database related to the OMPs that are present in a polluted Indian River is not available. It, therefore, led to quantifying the OMPs in the polluted stretch of the river Yamuna in central Delhi. Also, to find out their frequencies of occurrence, and concentration ranges. It became imperative to investigate the impacts of the polluted river on the well field comprising of eight Ranney wells (RWs) in the vicinity of the study site of the Yamuna. Therefore, the focus of the study was towards the assessment of pollution, measurement of OMPs present in the water of the Yamuna River and nearby eight RWs. Experimental results and outcomes of each phase of the study are presented in four chapters (Chapters 2-5) and conclusions of the study in Chapter 6. In the first phase, the pollution of the Yamuna River along with the quality of the water from eight RWs near Akshardham temple in Delhi was assessed in the monsoon and non-monsoon of the year 2013-2014. The sampling schedule, analysis protocol, and results are presented in Chapter 2. An attempt has also been made to establish the connectivity between the river and vi RWs by monitoring the stable isotopes δ18O and δ2H of the water samples. The δ18O concentration of the river water in non-monsoon was significantly more than the monsoon. The monsoon river water coincided with the local meteoric water line (LMWL). The signature of non-monsoon river water was different from the LMWL. The water from the wells in the monsoon was marginally lighter than the non-monsoon water. Similar differences were found in the electrical conductivity (EC) of the water from the river and the RWs. The EC of non-monsoon river water was 3 to 4 times the EC of the monsoon water whereas EC of the monsoon and non-monsoon RWs water was either same or marginally different. The river and RWs water responded positively to the bacterial pollution. However, total coliform and E. coli in the well water was around 5 log less than the river water in both nonmonsoon and the monsoon seasons. The organic pollution of the river was more than the well water. The average DOC of 17 mg/L in the non-monsoon was reduced to around 2 mg/L in all the RWs except NR-I. Ultraviolet absorption at 254 nm (UV-254) and specific UV absorbance (SUVA) followed the same trend as of DOC. Results suggest that in the case of contaminated source waters, RBF is an effective pre-treatment option for the production of drinking water. However, further treatment of filtrate is necessary. In developing countries, where river waters, in general, are impacted by wastewater, agriculture runoff, identification/quantification of OMPs has not been attempted. Given diverse nature, sources and effects of the OMPs, it deemed necessary to monitor OMPs in the river and well waters. Chapters 3 and 4 present the sampling protocol and measurement of OMPs by GC-MS in the river and well waters. The occurrence of OMPs in the Yamuna water in non-monsoon and the monsoon months is discussed in Chapter 3. Chapter 4 deals with the monitoring data of OMPs in the well water. Fifty-seven OMPs that were identified included the pharmaceutically active compounds (PhACs), pesticides, endocrine disrupting chemicals (EDCs), phthalates, personal care products (PCPs), fatty acids, food additive, hormones and trace organics present in hospital wastes. The two observations that were quite noteworthy regarding monitoring of OMPs are as under: (i) Ten out of fifty-seven OMPs were detected in the monsoon but were not at all detected in non-monsoon (ii) The concentration of forty-seven out of fifty-seven OMPs was more in the monsoon samples than non-monsoon samples. vii In general, during monsoon season OMPs were present in much lower concentration in river water due to high dilution. But in the present study OMPs concentrations were found high due to surface runoff from the polluted catchment area. The reason for this contradiction could not be correlated with the octanol-water partition coefficients (log Kow), solubility, and polar/non-polar characteristics of the OMPs. It could be due to the sorption of OMPs onto the sediments in an extensive network of interconnected drains and river during the low flow (~ 19 m3/s) conditions in non-monsoon months. During the high flow conditions (~ 507 m3/s), scouring of deposited sediments possibly results in erosion and dissolution of OMPs in the river water. In general, compared to rivers of Europe and United States of America, much higher concentrations of OMPs were found in the river Yamuna. OMPs present in eight RWs were also quantified over a period of one year from Aug. 2013 to Aug. 2014. Results are presented in Chapter 4. Filtrates collected from RWs were although contaminated with OMPs, the concentrations were found to be much lower than the river water. Number of OMPs detected, their frequencies of occurrence and concentrations in RWs reduced substantially compared to river water. Among different RWs, in general, number of OMPs detected their frequencies of occurrence and concentrations correlated very well with the distance of RWs from the river. Larger the distance, lesser the number of OMPs detected and lower the concentrations. In spite of high concentrations (~ 50 μg/L) in river water of 3- acetamido-5-bromobenzoic acid, 1- dodecanethiol, diethyl phthalate, palmitic acid, and adenine, they were detected to be < 1 μg/L in samples from RWs. Only few OMPs e.g. simazine and aldrin, sometime exceeded 1 μg/L in RWs. Compared to other OMPs, in general, EDCs, PCPs, phthalates, fatty acids and food additives appeared more frequently in more number of RWs but in significantly lower concentrations than present in river water. Among hormones, only estriol detected once in RW P-4. Some of the OMPs e.g. adenine were never detected in any of the RWs. The OMPs in the river water are likely to move through the aquifer. The fate depends on the nature of the OMP as well as the characteristics of the aquifer. Keeping this in view the fate of fifteen OMPs that were frequently detected in the Yamuna River water at Central Delhi was investigated under abiotic (predominantly adsorption) and biotic (mainly biosorption/ bio-degradation) conditions in columns packed with the aquifer material. The OMPs tested on the column RBF wells. The list included pharmaceuticals and their raw materials, endocrine disruptors, steroids, OMPs found in hospital wastes, and personal care products viii structurally belonging to acrylates, neutral organics, amines, phenols and fatty acids. The findings of the column runs and experimental details are presented in Chapter 5. Columns were packed with aquifer material that was taken out from the laterals of the M-15 RW, during its cleaning operation. Among different OMPs, dimethyl maleate, benzoic acid, guanine, and lomustine were found to be more mobile than estriol, decanoic acid, 1- tridecanol, 1- eicosanol, triclosan, stearic acid and cetyl alcohol. The mobility depends on the polarity of the OMPs. The retardation factor of non-polar OMPs is more than the polar ones. However, the mobility of the OMPs is considerably restricted in the biotic column. Retardation factors (Rd) for OMPs varied widely in adsorption column from 3 to 772. In biosorption column, Rd ranged from 6 to 1692 showing better removal except for benzophenone. Core findings of the dissertation along with limitations of the investigations carried out and a short note on future scope of the work are summarized