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Water Quality In Mumbai Chlorinated Compounds In Potable Water

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  • 1. Water Quality in Mumbai: Chlorinated Compounds in Potable Water Dr.Prashant Bhave1 , Sourabh Kulkarni2 ABSTRACT: Present study attempts to focus on the determination of chlorinated compounds like free chlorine, total chlorine, mono-chloramines and chlorine dioxide (Cl- , NH2Cl, ClO2) in drinking water with the help of spectrophotometer using N,N diethyl-p-phenylenediamine (DPD) method as per the “Standard methods for examination of Water & Wastewater”. The reagent, stock solutions, standard solution and calibration curve was developed as per the standard method (DPD method). The developed reagents accuracy was checked with the commercially available kit/reagents (HACH spectrophotometer reagents). Sample was collected randomly from different areas/ locations of Mumbai City. The results were compared against the standards given by Govt. of India, WHO, and USEPA. Keywords: Disinfection, Chlorination, DPD method, Spectrophotometer, Disinfection by- products (DBPs) INTRODUCTION Drinking water is essential for life, yet it can be a source of exposure to pathogens and chemical, physical and radiologicalcontaminants [1]. For waterborne pathogens, including bacteria, viruses, and protozoa, drinking water is a major contributor to human exposures[1]. A California think tank reported that as many as 76 million children could die worldwide from water-borne diseases by 2020 if adequate safeguards are not taken [2]. It is reported that of the 1.42 million villages in India, 1, 96,813 villages are affected by chemical contamination of water [Deccan Helard, 2005]. Delhi’s water supply is among the worst in many big cities of the developing world [2] . The Central Pollution Control Board has found that the tap water in Delhi contains carcinogenic substances and the toxic quotient is five times higher than the standards [2] .So, it is accepted globally that the quality of water is the most important from health point of view and to control the spread of diseases. There is various disinfection techniques used globally such as by ozone, UV rays etc[4,6]. But they are expensive for treating high volumes of water. The most popular disinfectant used all over the world from five decades has been chlorine, but in recent years the chlorine has become a less popular due to the formation of disinfection by- products(DBPs) including Trihalomethane (THMs) and Chloramines which results in health problem[4]. It is well-known that chlorination of drinking water leads to the formation of disinfection by-products (DBPs) including chloramines (referred as combined chlorine) or trihalomethanes (THMs) (florentin et al, 2011).The formation of DBPs occurs with natural or imported (xenobiotic) organic and inorganic materials present in the water (florentin et al, 2011).Chlorine is produced in large amounts and widely used both industrially and domestically as an important disinfectant. It is most commonly used disinfectant and oxidant in drinking-water treatment [WHO, 2000]. Chlorine is widely used as a disinfectant due to its effectiveness as a oxidising compound, cost effective than UV or ozone disinfectant, disinfection is reliable, provides residual concentration, removes odour, taste [WHO, 2000]. It is a less popular due to its formation of by-
  • 2. products; less effective in high pH, residual is unstable in water [WHO, 2000]. Chlorine in water combines with natural organic compounds NOM to yield a large range of Chlorine disinfection by-products (DBPs) such as trihalomethanes(THMs), haloacetic acids (HAAs), chlorophenols, phenolic acids, chlorinated quinines exhibits potentially carcinogenic, teratogenic and mutagenic activities to human health [Rosalam, 2007]. Killing effect of chlorine dioxide on bacteria is similar to or better than that of liquid chlorine at wider range pH [Junali et al, 1996]. Disinfection Water treatment processes such as, coagulation, flocculation, sedimentation, filtration, aeration and water softening are designed to produce water that are aesthetically acceptable and economical [CPHEEO, 1999]. The chlorination process in the drinking water distribution system (DWDS) has been practicedin many countries to encounter the water borne diseases [Rosalam, 2007].The mechanism of killing pathogens depends largely on the nature of the disinfectant and on the type of microorganism and destruction can be done by damage to cell wall, alternation of cell permeability, Changing the colloidal nature of the cell protoplasm, Inactivation of critical enzyme systems responsible for metabolic activities [CPHEEO, 1999]. Type, condition, concentration & distribution of organism to be destroyed, type & concentration of disinfectant, chemical & physical characteristics of water to be treated, contact time available for disinfection, Temperature of water also affect the efficiency of disinfection [CPHEEO, 1999]. Chlorination Chlorine reacts with water to form hypochlorous acid (HOCl) and hydrochloric acid (HCl) according to equation [Bhole, 2001]. Cl2 + H2O HOCl + H+ + Cl- This hydrolysis reaction is reversible. The hypochlorous acid dissociates into hydrogen ions (H+ ) and hypochlorite ions (OCl- ) according to equation HOCl H+ + OCl- HOCland OCl- depend on the pH and temperature. more than 99% of the free chlorine is HOCl at pH 5 and similarly more than 99% is OCl– at pH 10 [Rosalam, 2007]. The HOCl is 80 to 100 times stronger than OCl- in-term of disinfecting the pathogens [CPHEEO, 1999]. The organic and inorganic compounds can be ammonia, nitrite, nitrate, amino acid, and suspended solids. When hypochlorous acid reacts with organic compounds, the disinfections capability of the HOCl becomes weak and form combine chlorine. [Rosalam,2007, CPHEEO, 1999]. Cl2 + H2O HOCl +HCl NH3 + HOCl NH2Cl+H2O NH2Cl + HOCl NHCl2+ H20 NHCl2 +HOCl NCl3+H20.[Bhole, 2001] The combine available chlorine possesses some disinfecting properties though to a lower degree than the free available chlorine. Other reactions are [Kumar et al, 2012] a) Carbon C + 2Cl2 +2H2O 4HCl + CO2 b) Hydrogen Sulfide H2S + 4Cl2 + 4H2O H2SO4+ 8HCl H2S + Cl2 S + H2O
  • 3. c) Methane CH4 + 4Cl2 CCl4 + 4HCl d) Manganese MnSO4 + Cl2 + 4NaOH MnO2 + 2NaCl + Na2SO4+ 2H2O MATERIALS AND METHODS The DPD method was used for the determination of chlorinated compounds such as free chlorine, total chlorine, monochloramine, chlorine dioxide in potable water. The DPD method is applicable to natural and treated waters at concentrations from 0.2- 4 mg/L [Standard methods, 1995]. Apparatus: 1) (HACH) DR 2400 spectrophotometer and distilled water throughout the experimental work. 2) All glassware used werechlorine demand free glassware. 3) Pipettes for 0.1ml, 1ml and 10 ml capacity and conical flasks. 4) Reagent bottles brown amber glassware for 350ml, 500ml & 1000ml capacity. 5) Analytical balance GF series GF 300, wensar make pH meter. Reagents preparation: Separate glassware was used for the preparation of reagents, so to avoid interferencesand the reagents were stored in the brown amber bottle to maintain the strength. All chemicals were of reagent grade and deionised water was used throughout.Phosphate buffer solution was prepared by dissolving 24 g anhydrous disodium hydrogen phosphate, Na2HPO4, and 46 g anhydrous potassium dihydrogen phosphate KH2PO4, in distilled water and adding 800 mg disodium ethylenediaminetetraacetate dehydrate(EDTA)in 100 mL distilled water. These two solutions combined and diluted to 1 litre with distilled water. The pH of phosphate buffer was maintained to 6.2-6.5.[Standard methods, 1995]. Mercuric chloride (HgCl2) was omitted due to environmental considerations even though it has been shown that its presence can suppress interfering reactions (Carlsson et al, 1998). The DPD reagent was prepared by dissolving 1.1 g DPD Sulphate in 1000 ml H2O with 200 mg EDTA and (1+3) H2SO4to maintain the pHof two. Sulphuric acid solution (1 + 3) was prepared by slowly adding 10 ml of H2SO4 (sp. gr. 1.84) to 30 ml of distilled water [Standard methods, 1995].Like the (1+5) H2SO4 was also prepared. The Ferrous ammonium sulphate (FAS) of normality 0.00282 was prepared by dissolving 1.106 gm. Fe (NH4)2. (SO4)2.6H2O to 1 ml (1+3 H2SO4) and make to 1 lit and standardise by as per standard method. It is required as a check on any absorption of potassium permanganate by distilled water while preparing the standards for calibration of spectrophotometer. The Sodium arsenite solution was prepared by dissolving 5.0 g NaAsO2 in distilled water and diluted to 1L it is required to find the interference of Manganese in water [Standard methods, 1995]. The 10% glycine solution which is necessary for determination of chlorine dioxide is prepared. Barium di - phymylamine indicator (10%) was prepared as it is required for the checking of normality of ferrous ammonium sulphate and 85% conc. phosphoric acid was also used to check normality of FAS. Stock Potassium Permanganate Solution was prepared by placing 0.891 g KMnO4 in a volumetric flask and diluted to 1 L. This stock potassium permanganate solution was used for the calibration of spectrophotometer. The HACH 2400 spectrophotometer was used for detection.as it has advantages as Wavelength range 400- 680 nm, automatic wavelength selection, photometric resolution as 0.001 absorbance, 0.1% transmission and touch screen display with
  • 4. read out modes transmission, absorbance, and concentration. The wavelength was used for this methods is 515 nm [Standard method, 1995]. Calibration of Spectrophotometer: Figure 1: Calibration graph for DPD method. The calibration of spectrophotometer is done by the use of potassium permanganate solution. Potassium permanganate solution (0.891 g/l) - This solution was made by adding 0.891 g of potassium permanganate to a 1000 ml volumetric flask. 1 ml of this solution is equivalent to 1 milligram of chlorine, i.e. 1000 mg/l as chlorine [Standard method, 1995]. Potassium permanganate solution (0.0891 g/l) - This solution was made by adding 10 ml from above made stock solution to 100 ml distilled water. This solution is equal to 100 mg/l as chlorine. The standards for chlorine are prepared as per the following details as they are made from the ranges of 0 to 2 mg/l concentration- Adding the 1 ml from (0.0891g/l) solution to 100 ml distilled water. This is equal to 1 mg/l as chlorine equivalent. Then the colour was developed by first placing 5 ml phosphate buffer and DPD indicator to the flask and adding the above prepared 100 ml sample in the flask [Standard methods, 1995]. Like this the chlorine standards are prepared for equivalent range from 0.05 mg/l to 2 mg/l. Then the calibration curve is prepared by using the standards. The standards made are added to 10 ml sample for appropriate to spectrophotometer cell holder. Then the calibration graph is set to the spectrophotometer for the detection of parameters. Sample collection: The samples were collected randomly from the various areas of Mumbai city from greater Mumbai Municipal Corporation area. Sampling was done as per the standard sampling procedure [CPHEEO, 1999]. The brown amber 350 ml glass sampling bottles were used.The samples were collected from the residential area, commercial areas and public places as railwaystation platforms as from drinking water fountain. The sample no.1 was collected form residential areas, sample no.2 was collected from commercial areas and sample no 3 was drawn from the public places (railway stations). Sample analysis: The analysis procedure was followed as per the standard DPD method. The volume of sample was taken as 10 ml which is appropriate to the spectrophotometer cell holder. The free chlorine was determined by the first placing the 0.5ml phosphate buffer, DPD indicator and 10 ml potable water sample to the cell. The concentration was determined against blank as no addition of reagents. The total chlorine as it includes the free and combine chlorine was determined by the adding 0.5 ml phosphate buffer, DPD indicator, 1mg potassium iodide crystals and 10 ml potable water sample. The free chlorine will not react in presence of the potassium iodide. Therefore immediately the colour was measured for the free chlorine. The
  • 5. two minutes time period was given for the development of the colour for total chlorine analysis. The phosphate buffer pH was maintained to the 6.2-6.5 as the chlorine is more effective within this range of pH.In this DPD method after addition of potassium iodide to the sample the chlorine and chloramines are liberate iodine from the potassium iodide. The colour of the solution was changed and the difference in colour or intensity of colour was determined by spectrophotometer. The most common interference for the determination of free and total chlorine was manganese. The determination of manganese as an interfering agent was carried out by using sodium arsenite [Standard method, 1995]. The one mg of potassium iodide KI was added to the 100 ml free chlorine concentration to determine the concentration of monochloramine in potable water sample. Chlorine dioxide was measure by adding the glycine reagent to the 10 ml potable water sample. The aminoacetic acid removes the interference of chlorine from the determination of chlorine dioxide and after adding the 0.5 ml buffer and DPD indicator. The intensity of colour was measured by spectrometer.it is carried out at 515nm wavelength. RESULTS AND DISCUSSION: The free chlorine concentration for the potable water samples for different locations of Mumbai are as follow Table 1: Free chlorine concentration Sampling location 1 2 3 CST 0.05 0.05 0.05 Masjid Bunder 0.09 0.10 0.07 Sandhrust Road 0.11 0.11 0.11 Byculla 0.11 0.11 0.12 Curry road 0.10 0.10 0.10 Matunga 0.13 0.13 0.13 Sion 0.15 0.15 0.16 Vidyavihar 0.15 0.16 0.16 Ghatkopar 0.16 0.17 0.17 Kanjurmarg 0.18 0.18 0.20 Bhandup 0.20 0.21 0.21 Nahur 0.19 0.19 0.21 Mulund 0.20 0.19 0.19 Charchgate 0.07 0.08 0.07 Marine lines 0.08 0.08 0.08 Charni road 0.08 0.10 0.08 Grant road 0.09 0.10 0.10 The Total chlorine concentration for the potable water samples for different locations of Mumbai are as follow: Table 2: Total chlorine concentration for different areas of Mumbai Sampling location 1 2 3 CST 0.48 0.50 0.53 Masjid Bunder 0.45 0.45 0.44 Sandhrust road 0.51 0.51 0.53 Byculla 0.45 0.47 0.48 Curry road 0.67 0.68 0.68 Matunga 0.44 0.44 0.43 Sion 0.48 0.47 0.47 Vidyavihar 0.48 0.53 0.56 Ghatkopar 0.55 0.42 0.44 Kanjurmarg 0.45 0.51 0.45 Bhandup 0.40 0.42 0.42 Nahur 0.44 0.45 0.44 Mulund 0.42 0.43 0.51 Charchgate 0.33 0.32 0.36 Marine lines 0.35 0.35 0.36 Charni road 0.38 0.39 0.43 Grant road 0.44 0.50 0.43 The Monochloramine concentration for the potable water samples for different locations of Mumbai are as follow Table 3: Monochloramine concentration for different areas of Mumbai Sampling location 1 2 3 CST 0.10 0.11 0.11 Masjid Bunder 0.08 0.08 0.09 Sandhrust road 0.09 0.09 0.10 Byculla 0.07 0.09 0.08 Curry road 0.12 0.12 0.13 Matunga 0.07 0.06 0.08 Sion 0.07 0.09 0.10 Vidyavihar 0.11 0.10 0.11
  • 6. Ghatkopar 0.07 0.09 0.08 Kanjurmarg 0.03 0.06 0.04 Bhandup 0.02 0.02 0.03 Nahur 0.03 0.03 0.03 Mulund 0.02 0.03 0.08 Charchgate 0.04 0.03 0.04 Marine lines 0.04 0.04 0.04 Charni road 0.02 0.03 0.05 Grant road 0.07 0.08 0.07 The water is supplied to the Mumbai is from the Bhandup water treatment plant. The capacity of Bhandup water treatment plant is about 1950 MLD. As from the above free chlorine concentration results it is observed that the free chlorine concentration is go on continuously decreasing as the water passes through water treatment plant to the distribution system. The chlorine concentration is higher in the Bhandup, Mulund, Kanjurmarg area and after it is go on decreasing up to CST Mumbai. Water supply to Mumbai comes from Bhandup water treatment plant(WTP). The Bhandup water treatment plant(WTP) is using chlorine for disinfection, but the water is conveyed from the Bhandup treatment plant to the whole Mumbai areavia drinking water distribution network, the water supply pipelines in Mumbai are very old age and there are leakages in the water supply pipelines and are increasing day by day[Hindustan times, 2013] so, there are chances of leakages in the water distribution system which causes the contamination of organic matter through it and also due to the anaerobic decomposition in the distribution system chances of ammonia formation are there Hence chances of formation of Monochloramines in the water cannot be ignored. Table 4: Chlorine dioxide concentration for different areas of Mumbai Sampling location 1 2 3 CST 0.04 0.05 0.04 Masjid Bunder 0.06 0.05 0.06 Sandhrust road 0.03 0.04 0.06 Byculla 0.05 0.05 0.06 Curry road 0.03 0.04 0.06 Matunga 0.04 0.05 0.05 Sion 0.06 0.05 0.06 Vidyavihar 0.06 0.05 0.04 Ghatkopar 0.04 0.06 0.03 Kanjurmarg 0.06 0.03 0.06 Bhandup 0.06 0.06 0.06 Nahur 0.03 0.06 0.04 Mulund 0.03 0.06 0.06 Charchgate 0.04 0.06 0.04 Marine lines 0.06 0.03 0.05 Charni road 0.06 0.06 0.03 Grant road 0.04 0.04 0.04 VALIDATION OF RESULTS: Performance comparison: For potable water sample test were conducted using the HACH reagents kit and prepared regents, the following results were obtained. Table 3: Performance comparison of HACH vs. Prepared reagents Parameter Concentra tion as per HACH reagents (mg/l) Concentrati on as per Prepared reagents (mg/l) Free Chlorine 0.10 0.16 Total Chlorine 0.40 0.47 Monochloramine 0.02 0.09 Chlorine Dioixide 0.00 0.06 Overall, the results obtained with the prepared reagents with the prepared reagents are comparable with those obtained from the HACH reagents. However, the slight difference between the results occurs due to the presence of interfering agents which are taken care of by HACH reagents. However, even with the presence of interferences, the prepared reagents can be used for obtaining a rough about the presence and concentration of
  • 7. the selected parameters for the potable water samples. Cost comparison for prepared and HACH reagents: Table 4.8 Cost comparison HACH reagents Vs. Prepared reagents. (Cost of analysis per sample) Parameter HACH Reagents (Rs.) Prepared reagents (Rs.) Free Chlorine 21/- 1.20/- Total Chlorine 21/- 1.30/- Monochloramine 104/- 1.30/- Chlorine Dioixide 35/- 1.50/- The above table shows that a reasonable accuracy of the results with the great saving in cost. However it is very important that periodic calibration of the prepared reagents is important for accuracy of result. Hence, laboratory results are acceptable. CONCLUSION: Chlorine compounds or disinfection by- products in all the Mumbai potable water samples collected from the different locations randomly shows that levels less than the Central Public Health and Environmental Engineering Organisation (CPHEEO), World health organisation(WHO) and US Environmental protection agency (USEPA) standards. The amount of free chlorine reduces as the distance from Bhandup water treatment plant increases. So, there will no health risk to human due to potable water and disinfection by- products (DBPs) in sampling locations. The study also revels on comparing the results for the above disinfection by- products (DBPs) determinations that the laboratory chemicals as given by the standard methods are fairly accurate. The cost of sample analysis is much lower. REFERENCES: [1] The water we drink, an international comparison on drinking water of drinking water quality and standards, David Suzuki foundation, Nov 2006. [2] Y.P Gupta, India's cities: Challenge for survival, The Brunei times Sunday August 5, 2007 and Y.P.Gupta, Poor water quality-a serious threat, Deccan Halard 2005. [3] Arnaud Florentin, Alexis Hautemanière, Philippe Hartemann,Health effects of disinfection by-products in chlorinated swimming pools, International Journal of Hygiene and Environmental Health, vol. 214, 461-469, 2011. [4] WHO, disinfectants and disinfectant by-products, Environmental health criteria 216, Geneva, 2000. [5] Rosalam HJ. Sarbatly and DudukuKrishnaiah, Free chlorine residual content within the drinking water distribution system, International Journal of Physical Sciences Vol. 2 (8), pp. 196- 201, 2007. [6] Huang Junli, Wang Li, RenNanqi , Ma Fang and Juli, Disinfection effect of chlorine dioxide on bacteria in water, Journal of Water Resource, vol. 31,607- 613, 1996. [7] CPHEEO, Manual on water supply and treatment, Ministry of urban development, New Delhi , May 1999. [8] A.G.Bhole, design of water treatment plants, Indian water works association, Nagpur. [9]White, G.C., Handbook of Chlorination, Van Nostran Reinhold, New York, 1972. [10] Lokeshkumar, Chlorine demand- A pollution load test, Journal of Indian water
  • 8. works association, vol.44, 20-24, Oct- Dec 2012. [11] Standard methods for the examination of water and wastewater, American Public Health Association,edition 19th 1995. [11] DR/2400, Portable Spectrophotometer instrument manual, Hach Company, USA, 2004. [12] Karin carlsson, ludvigmoberg, bokarlberg, the miniaturisation of the standard method based on the n,n'- diethyl p-phenylenediamine (dpd) reagent for the determination of free or combined chlorine, Journal of Wat. Res. Vol. 33, 375-380, 1999. [13] LudvigMoberg, Bo Karlberg, An improved N,N0-diethyl- pphenylenediamine (DPD) method for the determination of free chlorine based on multiple wavelength detection, Jurnal of AnalyticaChimicaActa , Vol. 407, 127- 133, 1999. [14] Hach,DR 2400 spectrophotometer procedure manual, method no. 8021, USA, 2004. [12] Hach,DR 2400 spectrophotometer procedure manual, method no. 8167, USA, 2004. [13] Hach,DR 2400 spectrophotometer procedure manual, method no.10126, USA, 2004. . [14] Hach,DR 2400 spectrophotometer procedure manual, method no.10171, USA, 2004. [16]Reetika Subramanian,60% rise in complaints of leaks in water pipelines, Kurla worst-hit, Hindustan times,Mumbai, 22 April 2013. [17] Sandipashar, your tap water is not safe for consumption, dna, Mumbai, 16 May 2009. [18] WHO, Guidelines for drinking water quality, fourth edition 2011. [20] USEPA, National Primary Drinking Water Regulations: Disinfectants and Disinfection By products rules and regulations, vol. 63, 1998.