Evaluation the water quality of the potable water network in Al-Shuala/ Baghdad City

E-mail: Zbn_asr@yahoo.com Abstract


Introduction
Water is essential for the survival of any form of life. Water scarcity is increasing worldwide and pressure on the existing water recourses is increasing due to the growing demands in several sectors such as Drinking, Bathing, Showering, Agriculture, and Industrial activities, etc. [1,2]. In general, the quality of water is equally important as the quantity. Therefore, water quality is considered as an important factor to judge environment changes which are strongly associated with social and economic development [3]. Drinking water is considered as one important topic that has been received a great attention due to the high demand of human consumption used daily [4] and is defined as having acceptable quality in terms of physical, chemical, and biological parameters so that it can be safely used for drinking, cooking and other domestic applications [5]. Some of potable water have become contaminated and that is due to the growing of population, which increased the economic activities and industrialization, as a result of that, many researchers have studied to evaluate the performance of the water treatment plants and on how to improve the quality of drinking water [6]. One of the simplest methods to assess water quality conditions is by using Water quality index (WQI) is a numeric expression used to depict the overall water quality status in a single term which represents the water quality level,that is helpful for selecting appropriate treatment technique to meet the concerned issues [7,8].
The aim of this search is to evaluate the water quality of the potable water network in Al-Shuala Baghdad city and compare them with the Iraqi standards and World Health Organization standards (WHO) for drinking water then calculate Water quality index by measurement: pH, heavy metals (lead, cadmium and iron), chlorides, total hardness, turbidity, dissolved oxygen, total dissolved solid and electrical conductivity.

Materials and methods 1. Study area
The study area is located in Al-Shuala city in the North-West part of Baghdad Iraq,This city characterized by high population density Fig. 1.

Data collection and analysis
A total of about 130 water samples were collected in pre cleaned plastic bottles of 2 liters and were analyzed for water quality parameters .Water samples are collected weekly from ten sites in Al-Shuala Baghdad city as shown in Fig.1, during period extended from the February 2015 to April 2015. In this study, evaluate the water quality index of the potable water network were chosen ten parameters namely: pH, heavy metals (lead, cadmium and iron), chlorides, total hardness, turbidity, dissolved oxygen, total dissolved solid and electrical conductivity. pH , total dissolved solid and electrical conductivity were determined with portable Multi-meter ISOLAB, turbidity was measured by turbidity meter(Thermo Orion AQ4500), dissolved oxygen was measured by Lovibondmeter (senso direct oxi 200),chloride and total hardness were determined by titrimetric method [9] and heavy metals (lead, cadmium and iron) were analyzed by flameless atomic absorption spectrometry (Shimadzu AA-6300).

Calculations of the WQI
WQI indicates the quality of water in terms of index number, which represents overall quality of water for any intended use. It is defined as a rating reflecting the composite influence of different water quality parameters [10,11]. WQI of drinking water was calculated considering ten important physic-chemical parameters using WHO and the Iraqi standards (IQS) for drinking water. For calculating WQI, the following steps were used: In the first step, unit weight (Wi) for various parameters is inversely proportional to the recommended standard (V S ) for the corresponding parameter. W i values were calculated by using the following formula [12,13]: (1) where K = proportionality constant, V S = world-widely accepted drinking water quality standard. The constant of proportionality K in the above equation can be determined from the following formula [7,14]: In the second step, Quality rating (Qi) is calculated as =100 ( 3) While, the quality rating for Ph and Dissolved oxygen (Q pH,DO ) was calculated on the basis of , 100 where, V a = value of the water quality parameter obtained from the laboratory analysis. V i = the ideal value of pH considered as equal to 7.00 and for DO considered as equal to 14.6 (mg/l) [15]. V s = value of the water quality parameter obtained from recommended standard of corresponding parameter.
This equation ensures that Qi = 0 when a pollutant is totally absent in the water sample and Qi = 100 when the value of this parameter is just equal to its permissible value. Thus the higher the value of Qi is the more polluted in the water, Table 1 shows the water quality index scale. Then, the overall WQI was calculated on the basis of weighting and rating of the different physicochemical parameters, as follows [14,16]

Results and discussion 1-Results and discussion of physicalchemical parameters
The physical and chemical parameters of analyzed drinking water is summarized in Table 2-11 at ten sites in Al-Shuala Baghdad city and in Figs. 2-11 Compares between month we took average value of parameter in each month. pH: The results show that some values of pH are within the maximum permissible limit of WHO and IQS standards and slightly higher in other values than WHO and IQS standards, reaching the highest value 8.66 in site 10 and the lowest value 7.71 in site 8.Gradually pH decreasing from month February to April (2015) as it is shown in Fig. 2. Turbidity and Dissolved Oxygen: Table3 and 4 and Fig. 3 and 4 show that all the turbidity and dissolved oxygen values were good and bellow the upper acceptable limit, reaching the highest value of turbidity 1.15(NTU) in site 7 and the lowest value 0.11(NTU) in site 6 and for dissolved oxygen the highest value 2.95 (ppm) in site 3 and the lowest value1.6 (ppm) in site 9. Chlorides:The result in Table 5 and Fig.5 shows low concentration of chloride element in some samples less than acceptable limit of WHO and IQS standards, reaching the highest value of chloride 320 (ppm) in site10 and the lowest value 80.25 (ppm) in 1. Total Hardness: The results in Table 6 and Fig.6 showed that the values ofTotal hardness in Februaryhigher in some values than WHO and IQS standardsand reach the acceptable limit in March and April (2015), the highest value of Total hardness 650 (ppm) in site 2 and the lowest value 150 (ppm) in site 8. Total dissolved solid and electrical conductivity: The result of these parameters in Table 7 and 8 and Fig. 7 and 8 shown relatively low for Total dissolved solid and electrical conductivity than acceptable limits values except two point for Total dissolved solid in site 1 and 2 in February they reached the acceptable limits. The highest value of Total dissolved solid 520 (ppm) in site 1 and the lowest value 344 (ppm) in site 4, and for electrical conductivity the highest value 773 (µS/cm) in site 1 and 2 and the lowest value 605 (µs/cm) in site 5. Heavy metals: Tables (9,10and11) and Figs. (9,10and11) show that the results of heavy metals, Cd and Pb in February Cd and Pb in February showing good result they didn't give any concentration in drinking water, in march and April the results showed that drinking water samples in site 2, 4 and 9 for Cd and site 1, 2, 4 and 9 for Pb have higher concentration than that recommended by WHO and IQS standards. The highest value of Cd is 0.00912 (ppm) in site 2 and for Pb is 0.0806(ppm) in site 1.The higher concentrations of Fe shown in most sample especially in site 9 And in February reaching the highest value 3.78 (ppm) in site 9.  0.12 0.11 0.14 0.14 0.15 0.13 0.15 0.14 0.12 0.12 0.11 0.15 0.