Bacteriological and Physiochemical Analysis of Drinking Water in Hilla City , Iraq

Abstract

This study was carried out from 6 th December 2008 to 5 th April 2009 . In order to ascertain the drinking water quality in Hilla city for human consumption, bacteriological and physiochemical characterizations were evaluated. The data for bacterial counts showed that the total aerobic bacteria count (TAB) were between 0-70 /100ml, total coliform (TC) 0-2/100ml , fecal coliform (FC) 0-2/100ml , fecal streptococci (FS) 0-2/100ml , while for physiochemical analysis revealed that the chlorine were between 3-5.8 mg/L, turbidity 2.8 7.5 NTU, pH 6.9 7.5 and biological oxygen demand (BOD) 3.1 14.8 mg/L. These findings indicated that the water after treatment at the plants was suitable for human drinking, but at the points of use in houses was unsuitable for drinking during the study period. Introduction : Drinking water quality has always been a major issue in many countries, especially in developing countries and the high quality of water sources were required for drinking purpose (Assembly of Life Sciences, 1977). Good drinking water quality is essential for the well being of all people. Unfortunately in many countries around the world, some drinking water supplies have become contaminated, which has impacted on the health and economic status of the populations (Anonymous, 1992). Contaminants such as bacteria, viruses, heavy metals, nitrates and salt have find their way into water supplies as a result of inadequate treatment and disposal of waste, industrial discharges, and over-use of limited water resources (Amund and Odubella ,1991). The proportion of waterborne disease outbreaks associated with the distribution system failures has been increased over the years (Moe and Rheingans, 2006). So, water is unfit for drinking if there is any coliform bacteria (Edema et al., 2001), According to the data of WHO (2006) approximately, 250 thousand of people die every day all over the world due to diseases (typhoid, cholera, dysentery, etc.) caused by unhealthy water usage. The problems in water sources have become directly one of the most important problems in human lives (Kosek et al.,2003). The main subject to supply the water is attainability and the development of management strategies and the efficient developing cost of water providing systems (Prasai et al.,2007). Every person needs approximately 2 liters of clean drinking water and this amount reaches to approximately 12 millions m 3 /day for the world population (Yassi et al.,2001). Considering the above facts, the present research was undertaken to determine the bacteriological contamination indicators and physiochemical analysis of drinking water after treatment at the plants and the points of use in the houses of Hilla city. Materials and Methods 1. Collection of samples The drinking water samples of plants and points of use in houses were collected bimonthly from the taps of stations as mentioned in Table 1 . Samples for bacteriological analysis were collected according to APHA (1998) using sterile borosilicate glass bottle under 1 Dept. of Biology , College of Science , University of Babylon ; 2 Dept. of Biology , College of Science for Women , University of Babylon ; 3 Babel Directorate for water. RESEARCHES of THE FIRST INTERNATIONAL CONFERENCE (BABYLON AND RAZI UNIVERSITIES) ( 2011) 821 ISSN 2072-3875 sterile conditions, water ran from an inside tap for several minutes before filling the sample containers and then transported into refrigerating bags then they were analyzed in the lab. within 24h . While, the chlorine, turbidity, pH and BOD of the samples were measured during the collecting of the samples (APHA, 1998). Table 1. The number and name of the stations used in this study. Station No. Station Name 1 New Hilla plant 2 Old Eltayara plant 3 Burnun plant 4 Al Imam plant 5 Al Kafl plant 6 point of –use in Bab Al Hussien 7 point of –use in Al Tahmaziyah 8 point of –use in Burnun 9 point of –use in Al Imam 10 point of –use in Al Kafl 1Bacteriological analysis Several culture media were used for isolation of bacteria such as nutrient agar (Oxoid) for total aerobic bacterial count, MacConkey agar (Himedia) for coliform count and brain-heart infusion agar (Himedia) for fecal streptococci count. These media were sterilized in an autoclave at 121 0 C for 15 minutes. Samples were cultured on the prepared medium in duplicate and incubated aerobically at 37 0 C for TBC, TC and FS. and at 45 0 C for FC . The colonies were counted and expressed as colony forming units per100 milliliter (cfu/100ml) of the samples as described by APHA (1998). Various biochemical tests were carried out for bacterial identification (Macfaddin , 2000). 2Physiochemical analysis At the time of sampling , pH was measured using HANA digital pH meter with combine glass electrode , turbidity was done using HACH 2100p Turbidimeter , the level of chlorine was measured using HACH chlorometric with DPD and photometric method using Winkler solution for detecting of BOD (APHA1998). Results and Discussion This study was demonstrated the bacteriological and physiochemical analysis of water samples taken from different stations of Hilla city as shown in Table 1. The results of bacteriological analysis (Table 2.) exhibited that the drinking water samples at the plants after treatments were not contaminated with bacteria because the number of TAB, TC, FC and FS bacteria were similar to those of the WHO (2006), while the samples which collected from points of use in the houses were contaminated with bacteria. The potential source of coliform bacteria in water supplies result from suboptimal operation of water treatment processes or ingress of contamination from breaches in the integrate of the distribution system (Prasai et al.,2007). These include for example, leaking hatches on service reservoirs , contamination via air valves RESEARCHES of THE FIRST INTERNATIONAL CONFERENCE (BABYLON AND RAZI UNIVERSITIES) ( 2011) 831 ISSN 2072-3875 and stop valves, infiltration into mains and service reservoirs , cross connections and back flow effects . The physiochemical analysis of all water samples collected from drinking water taps were presented in Table 3. There were high levels of chlorine in all samples as pH values were also high in New Hilla and Old Eltayara plants . These values of parameters were bellowed the standard values of the WHO (2006). The current study found that the pH values of drinking water were ranged between 6.9 and 7.5 . Generally, low pH values obtained in the water might be due to the high levels of free CO2 which may be consequently affected the bacterial counts (Edema et al., 2001). For effective chlorination, pH should be less than 8.0 and this must be controlled so as to minimize the corrosion of water mains and pipes ( Soylak et al.,2002). The WHO (2006) guidelines for drinking water quality states showed that the pH range of drinking water should be between 6.5 and 8.0. The turbidity values were ranged between 2.8 to 7.5 NTU , the minimum turbidity (2.8 NTU) was observed in New Hilla plant while, the maximum turbidity (7.5 NTU) was observed in the house taps in Al Tahmaziyah. All samples have turbidity values below the permissible limited of WHO (2006). Turbidity represents an important aspect of water quality, it is seemed as the cloudiness of a liquid as a result of particulate matters being suspended within it. It is important that the high lighted by the fact that suspended solids interfere with effective chlorination/disinfection and helps to shield bacteria (Asano, 2007). Additionally, suspended solids also serve as a place of attachment for bacteria (Hurst, 1996). Chlorine values varied from 3 to 5.8 mg/L, according to WHO (2006) the permissible limited for its concentration in drinking water is 0.2 to 0.6 mg/L. The data revealed that all drinking water samples had high concentrations of chlorine . BOD ranged from 3.1 to 14.8 mg/L, this result recorded in Burnun , Al Imam , Al Kafl plants and points of use of these plants which had BOD levels >10 mg/L . BOD measures the amount of oxygen used by microorganisms, to oxidize the organic matters present within the water sample (Nielsen, 2003). Water with BOD levels < 4mg/L were seemed as clean, while those of >10 mg/L were considered unsafe (APHA,1998). The results of this study showed that certain samples of the points of use were contaminated with coliform and fecal streptococci bacteria , while the other water samples (plants water) were in the permissible limited of the WHO (2006). The concentrations of the physiochemical analysis in the drinking water samples of plants were found below the values of the guidelines for drinking water given by the WHO (2006), while the values of points of use were high than those of the WHO (2006) . Thus, it is concluded that the water after treatment at the points of use in houses of the stations was unsafe for human drinking during the study period of Hilla city. RESEARCHES of THE FIRST INTERNATIONAL CONFERENCE (BABYLON AND RAZI UNIVERSITIES) ( 2011) 838 ISSN 2072-3875 Table.2. Bacteriological analysis of the drinking water. Station No. Date Bacteria (cfu/100ml) 6.12.2008 5.1.2009 11.2.2009 5.3.2009 5.4.2009 Acceptable value for potable water (cfu/100ml) (WHO,2006) 1 total aerobic bacteria count 0 0 0 0 0 50 total coliform 0 0 0 0 0 none fecal coliform 0 0 0 0 0 none fecal streptococci 0 0 0 0 0 none 2 total aerobic bacteria count 0 0 0 0 0 50 total coliform 0 0 0 0 0 none fecal coliform 0 0 0 0 0 none fecal streptococci 0 0 0 0 0 none 3 total aerobic bacteria count 6 2 2 8 4 50 total coliform 0 0 0 0 0 none fecal coliform 0 0 0 0 0 none fecal streptococci 0 0 0 0 0 none 4 total aerobic bacteria count 6 1 8 3 12 50 total coliform 0 0 0 0 0 none fecal coliform 0 0 0 0 0 none fecal streptococci 0 0 0 0 0 none 5 total aerobic bacteria count 9 5 2 11 7 50 total coliform 0 0 0 0 0 none fecal coliform 0 0 0 0 0 none fecal streptococci 0 0 0 0 0 none 6 total aerobic bacteria count 35 63 48 52 61