Assessment of the Effluents of Basra City Main Water Treatment Plants for Drinking and Irrigation Purposes

: A severe water scarcity challenge is facing Iraq, which is predominantly due to the absence of water management policies, negatively impacting the water quantity and quality provision from the Tigris and Euphrates Rivers. Moreover, these practices have led to the intrusion of the Arabian Gulf salinity wedge into the Shatt Al ‐ Arab River (SAR), which is the main water source for most water treatment plants (WTPs) in Basra city. In addition, the inadequate management and operation for most WTPs is another reason for the deterioration of water quality provided to Basra province. Accordingly, the aim of this study is to evaluate the performance of the main WTP within Basra province and to subsequently make recommendations for decision ‐ makers to come up with new management strategies and policies. The effluents from eight WTPs were selected to study the quality of water supply for Basra city during the period between January 2018 and December 2018. The results showed that all WTPs were inadequate to treat raw water for drinking or irrigation purposes mainly due to the very bad raw water quality provided by the SAR as well as the lack of maintenance for such plants, resulting in very low removal efficiencies for various water contaminants. measured parameters were pH, turbidity, EC, alkalinity, total hardness (TH), calcium (Ca), magnesium (Mg), Cl, sulphate (SO 4 ), TDS, sodium (Na) and potassium (K). The results indicate that SAR water is very poor for domestic, industrial and irrigation purposes


Introduction
Water is a vital natural resource for life to continue on earth. Therefore, the provision of safe water is essential for community life [1,2], since more than 80% of human health issues relate to insufficient sanitation and low-quality drinking water [3,4]. Raw water treatment and purification by removing chemical and microbial contaminants as well as the undesirable physical constituents such as taste and odour are essential to provide water fit for human consumption [5]. Raw water can be treated using various treatment processes such as flocculation, sedimentation, filtration and disinfection, which should be undertaken in treatment plants to produce safe water for communities [6]. Regular evaluation of the water treatment plant (WTP) performance by monitoring the treated water quality is essential to ensure that the produced water is within legal thresholds. Treated water during all seasons. These earlier studies indicate the importance of this study to assess if the water quality situation has changed in the meantime.
In 2018, the shortage of water sources and the poor water quality in Basra province highlighted the necessity for decision-makers to invest more into WTPs [19]. Basra is the second largest city in Iraq and is positioned downstream of the Euphrates-Tigris River system, with a population of more than two million inhabitants [20,21]. In this governorate, the SAR serves as the main source for water supply. Most WTPs are located alongside this river. There are several treatment plants in Basra city. Most of them are conventional and old treatment plants, which are relying on the coagulationfiltration treatment process [20].
The key aim of this study is to evaluate the performance of the main WTP of Basra city, since there are insufficient previous studies covering this important issue relating to the public health and the environment of Basra governorate. The main corresponding objectives are to: (a) assess the quality of raw water supplied by various sources to the treatment plants; (b) evaluate the treated water quality for various application purposes, such as portable drinking water and agricultural irrigation water; (c) calculate the water quality index for raw and treated water to evaluate the efficiency of the WTP; and (d) make recommendations of interest to international water managers. Findings will contribute to the understanding of generic compliance challenges with national and international guidelines and standards.

Study Area
A steady increase in the population to more than four million people living in Basra city, coupled with a deterioration of water quality, has led to the most serious urban water supply problem in Iraq. The Shatt Al-Arab River (SAR) is the main water source, which is a natural river that passes through Basra governorate with a flow rate ranging between 25 and 75 m 3 /s. Municipal, industrial and agricultural sources discharge into the river. As a result, the total dissolved solids (TDS) levels in the river were almost three times the maximum acceptable standards for potable water. The Sweet Water Canal (SWC) was constructed as a temporary measure in the late 1990s to provide an improved water supply. However, it is now the only significant source of low TDS water, because the SWC was originally designed as a fully lined concrete channel to minimize losses and guarantee the delivery of the designed capacity to Basra.
The untreated water, coming from the SWC, flows to a specific point of the reservoir called R-Zero, which is located just west of Basra city. Some of the water is treated near R-Zero, but the majority is pumped to the intakes of existing WTPs in Basra. The Governorate of Basra has several WTPs; the majority is located near the SAR. Most of these plants are either old conventional plants or use multiple package units made up of many compact units installed in the 1990s. They require major rehabilitation to bring them up to a suitable standard of performance [9].
The intake of the SWC is at Bada'a near Ash Shatra on the Gharraf River, which is a branch of the Tigris north of Al Nasiriyah in the Governorate of Dhi Qar. Most of the plants are constructed close to the SAR, and can also draw raw water from it, if required [20]. The SAR was Basra's original raw water source, and hence, all main WTPs were constructed on its banks. However, the reduction of freshwater flow from the Tigris and Euphrates Rivers over time resulted in seawater intrusion advancing inland. This led to an increase of the salinity within the SAR water. Moreover, the Iraqi river systems have been used as a point of discharge for agricultural drainage water and sewage, which has further aggravated the problem of insufficient water quality in the SAR. For example, TDS levels in SAR increased from an average of 1792 mg/l in 1997 to an average exceeding 3000 mg/l in the year of 2001. This has been followed by a significant increase to about 10,000 and 20,000 mg/l in the years of 2009 and 2018, respectively [20].
The SWC was designed to deliver 8.5 m 3 /s, but it is currently operating at approximately 6.0 m 3 /s, which is equivalent to 518,400 m 3 /d [20]. Two open rectangular reservoirs were constructed 8.0 km north of R-Zero and have a total capacity of 75,000 m 3 , which is equivalent to a two-day supply for Basra centre and nearby districts. These reservoirs are used just for storage of the water that comes from the SWC and used in times of water shortage. No active treatment of the waters in the reservoirs that might improve the water quality has been undertaken [20], as shown in Figure 1.

Main water Treatment Plants of Basra City
The main WTP of Basra city are shown in Table 1. Most of these plants are either conventional old plants or ones that use multiple package units (MPU) constructed in the mid-1980s to early 2000s [20]. All the WTPs were designed to satisfy the requirement of drinking water where the source of water was fully welled up at the start of the 1980s. As a result, the WTPs were functioning to a high standard. Figure 2 indicates the locations of the WTP under study. R-Zero is a reservoir located at the end of the SWC near the Basra International Airport, and provides the raw water for most WTPs. The intake of the SWC is at Bada'a near Ash Shatra on the Gharraf River, which is a branch of the Tigris north of Al Nasiriyah in the Governorate of Dhi Qar. Most of the plants are constructed close to the SAR (Figure 2), and can also draw raw water from it, if required [20].

Analysis of Water Quality
Standard methods for the examination of water and wastewater (American Public Health Association (APHA)) [22] were considered for water quality sampling and testing, unless stated otherwise. Eight WTP outflows were selected to evaluate the quality of water supplied to Basra city during the period from January 2018 to December 2018. All sampling bottles were washed with distilled water and a non-ionic detergent, soaked overnight in 10% nitric acid (HNO3) solution and then rinsed with deionized water before use. The samples were collected monthly from each plant during the studied period. They were taken from the influent and effluent taps of each WTP, collected in plastic bottles of one litre and kept within a cooled box during transportation to the laboratory. Within two hours of collection, the required physical and chemical analyses were performed. All samples were encoded by sample number, time and date of collection, name of location, geographical coordinates and any other measurements taken in situ. Three replicates for each sample location were analysed for various parameters such as aluminum (Al), K, Na, Cl, Mg, Ca, SO4, TSS, TDS, TH, alkalinity, electrical conductivity (EC), turbidity (TUR), pH and water temperature, using common procedures to assess the suitability of treated water for drinking and irrigation purposes according to national and international standards.
In situ tests were performed for several water parameters such as temperature using a digital thermometer. Electrical conductivity (mS/cm) and TDS (mg/l) were measured by using a portable digital device (METTLER TOLEDO FIVE GOTM conductivity meter (Mettler Toledo, Columbus, OH, USA)). The pH of the water samples was measured directly in the field by using the portable pH meter model SD300. Turbidity was determined with the Turbidity Meter Lovibond TB 300 IR (The Tintometer Limited, Amesbury, UK). The measurement unit was Nephelometric Turbidity Unit (NTU). All portable equipment items were calibrated in the laboratory before traveling to the sample stations.
In the laboratory, TSS measurements were carried out using the Gravimetric Method; 100-mL water samples were evaporated to dryness at 105 °C within a drying oven using a pre-weighed 100-mL beaker. After evaporation, the beakers were placed in desiccators before weighing [22]. Total hardness, Ca +2 (mg/l) and Mg +2 (mg/l) were measured by the (EDTA) complex metric titration method, as described by the APHA [22]. Sodium (Na + ; mg/l) and potassium (K + ; mg/l) concentrations were measured by the flame photometer model M410. Chloride (Cl − ; mg/l) concentrations were determined by the silver nitrate titration procedure. Sulfate (SO4; mg/l) concentrations were estimated spectrophotometrically using the barium sulfate turbidity method according to APHA [22]. Alkalinity (mg/l) and aluminum (Al; mg/l) in the water samples were measured by the Atomic Absorption Spectrophotometer model SpectroDirect LoviBond (The Tintometer Limited, Amesbury, UK). The detection limit for aluminum was 0.01 mg/l.

Data Analysis
Microsoft Excel has been applied for basic statistical analyses such as mathematical mean, standard deviation as well as the minimum and maximum values of the measured water characteristics. The IBM-SPSS Statistics Version 23.0 software (IBM, Endicott, NY,USA) was operated for more advanced statistical analyses of the results at a 5% significance level. The normality of the data was assessed using the Shapiro-Wilk test. The one-way analysis of variance and the Kruskal-Wallis H-test were applied for data that were normally and non-normally distributed, respectively. The Spearman's test was applied to assess the correlations among variables.

Water Quality Index
The WQI is an arithmetical tool used to transform large quantities of water quality parameters into a single cumulatively derived number. The WQI is an indicator of the quality of drinking water for different uses [23]. In order to compute the WQI for the proposed case study, 12 physicochemical parameters (pH, EC, TDS, K + , Na + , Mg +2 , Ca +2 , alkalinity, TH, Cl − , TUR and SO4 −2 ) were considered in a three-stage process. Firstly, weights were assigned to parameters according to their perceived effects on primary health ( Table 2). A maximum weight of 4 has been assigned to parameters such as TDS, pH, SO4 −2 and EC due to their major importance in water quality assessment. Ca +2 , Mg +2 , TH, K + and Na + were given the minimum weight of 2 due to their minor effect on water quality. Other parameters, such as TUR, Cl − and alkalinity, were assigned a weight between 2 and 4 depending on their importance in the overall quality of water for drinking purposes [24].
In the second step, the relative weight (Wi) of each parameter is computed using Equation (1): where wi is the weight of each physicochemical parameter, n is the number of parameters and Wi is the relative weight. The weight (wi), the calculated relative weight (Wi) values and the WHO standards for each parameter are given in Table 2. In the third step, the quality rating scale (qi) was calculated for each parameter using Equation (2): qi= *100 (2) where qi is the quality rating, Ci is the concentration of each parameter in each water sample in mg/l and Si is the WHO standard for each chemical parameter in mg/l ( Table 2). For computing the WQI, the Sli is first determined for each parameter using Equation (3), which is then used to determine the WQI as per Equation (4): where Sli is the sub-index of the ith parameter, qi is the rating based on the concentration of the ith parameter and n is the number of parameters. Calculated WQI values are commonly classified into five categories, as shown in Table 3; excellent, good, poor, very poor and unsuitable for human consumption [25].

Efficiency of the Water Treatment Plants
In order to evaluate the effectiveness of a WTP, the efficiency of the WTP has to be calculated by using Equation (5) [6]: where ΔWQI is the difference in WQI between raw and treated water.

Cluster Analysis
Cluster Analysis (CA) includes a progression of multivariate strategies that are utilized to assemble similar objects into homogeneous groups with respect to the same properties and different from or unrelated to the objects in the other groups [26]. In this study, hierarchical agglomerative cluster analysis was performed. By this method, the levels of similarity at which observations are combined are used to build a dendrogram. The agglomerative hierarchical clustering was used with Ward's linkage method and squared Euclidean distances as a measure of similarity [27].

Irrigation Water Quality Evaluation
The excess of salt content is one of the main concerns with water used for irrigation. A high salinity content in the water will negatively affect the crop yield and degrade the soil. The quantity of water transpired through a crop is directly related to yield. Therefore, high EC in irrigation water reduces the yield potential and can result in physiological drought. Table 4 shows the criteria that are used to assess the irrigation water quality concerning salinity hazard [9]. Sodium hazard is expressed as the sodium adsorption ratio (SAR). This index measures the rate of sodium (Na) to calcium (Ca) and magnesium (Mg) ions in the water; the SAR is considered a good measure of the sodium hazard in irrigation water [9]. The continued use of water with a high SAR value leads to a degradation of the physical structure of the soil caused by excessive amounts of adsorbed sodium. SAR is calculated using the Equation (6): where Na, Ca and Mg are expressed in milli equivalent per liter (meq/l). Table 5 represents a classification of irrigation water based on the SAR values. Table 5. Irrigation water classification based on SAR values [9].
Level SAR Hazard S1 <10 No harmful effects from sodium.

S2
10-18 Appreciable sodium hazard in fine-textured soils, but could be used on sandy soils with good permeability.

18-26
Harmful effects could be anticipated in most soils and amendments such as gypsum would be necessary to exchange sodium ions. S4 >26 Generally unsatisfactory for irrigation.
The Wilcox diagram [9] was used to evaluate the suitability of water for irrigation, which is based on the combined effect of EC and the SAR. Table 6 shows the classification of irrigation water based on the effect of EC and the SAR [9]. Table 6. Classification of water according to the Wilcox Diagram [9].

Index Water Class Index Water Class
Very Poor

Raw Water Quality Analysis
An overview of the raw water quality provided to the main WTP assessed in this study can be seen in Tables 7 and 8. Findings showed that no Al was detected in all water sources supplied to the WTP. Water supplied to the Abu Al Khaseeb treatment plant has the highest values for K, Na, Mg, Ca, Cl and SO4, resulting in elevated EC, TDS and TH values followed by those for Al-bradiah 1 and Shatt Al Arab plants, while the lowest values were observed for the raw water supplied to the Al Shauaiba old and Al-Ribat plants followed by the Al Basra Unified plant. Slight differences in these parameter values were observed in the raw water supplied to the Shatt AlArab and Al-Garmma 1 plants (Tables 7 and  8). These findings indicated that the Abu Al Khaseeb, Al-bradiah 1 and Shatt AlArab plants were provided with raw water having the worst water quality. This is because of the agricultural industry dominant in these areas. Irrigation drainage water flows into the SAR, which is the main raw water source for most WTPs (Table 1). Moreover, the locations of the Abu Al Khaseeb, Al-bradiah 1 and Shatt AlArab plants, which are geographically situated close to the Arabian Gulf, make them the most vulnerable to saline intrusion, mainly when there is a severe water scarcity in the Basra governorate during the hot season as shown in Figure 2. In comparison, the Al Shauaiba Old WTP showed the best overall water quality, because it received raw water only from the SWC (Table 1).
Moreover, TSS and TUR values for the raw water showed a similar trend of maximum values for the Al Basra Unified plant followed by the Al-Ribat WTP, while no considerable differences in TSS and TUR were observed among other plants (Table 7). Furthermore, the alkalinity of the raw water was the lowest for the Al Shauaiba Old WTP, while no significant differences were observed among the other plants. The raw water pH was alkaline for all supplied waters (Table 7). Regarding the seasonal variation of the raw water quality (Figure 3), findings showed that for all supplied waters, there is a significant deterioration in water quality mainly during the hot season starting from June and ending in October. This is possibly due to the elevated outside temperature resulting in high water demand especially for potable and agricultural consumptions, leading to considerable reductions in the SWC waters. If supply provisions of the SWC are low, then most WTP depend on the SAR as the only raw water supply source. Additionally, during hot months, the quantity of supplied water provided to the Governorate of Basra is considerably reduced, resulting in low water levels in the SAR and subsequent intrusion of saline Arabian Gulf water to the SAR [20]. Table 7. Raw and treated water (effluent) quality parameters for the Basra city main water treatment plants during the period between January 2018 and December 2018.

Al-Ribat Al Basra Unified Al Shauaiba Old Abu Al Khaseeb
Raw Water

Ions
Although Al was not detected in all raw water supplied to the treatment plants, the treated water of the WTP contained some Al (Tables 7 and 8). This is possibly due to the use of aluminum as a coagulant in the traditional treatment process of the considered plants [20]. Findings showed that the maximum Al values were detected for the Abu Al Khaseeb plant, showing an average value of 0.06 mg/l, while the minimum values were recorded for the Al Shauaiba Old plant (0.03 mg/l). The Albradiah 1, Al-Garmma1 and Al Basra Unified WTP showed similar Al values of 0.04 mg/l, while the Al-Ribat, Shatt Al Arab and Al Jubila 1 WTP had similar Al values of 0.05 mg/l. The measured Al levels for the treated water did not exceed the standards for potable use of 0.2 mg/l [29,30] and irrigation standards of 5 mg/l [30,31], according to Table 9.
The study indicated that the K values are at their maximum for treated water obtained from Abu Al Khaseeb WTP, followed by concentrations for the Al-bradiah 1 and Shatt Al Arab plants ( Table 7). The water treated by the Al-Garmma 1 plant had K values higher than those for the waters obtained from the Al Jubila 1 and Al Basra Unified plants. The Al Shauaiba Old plant has treated raw water values for K, which are significantly (p < 0.05) lower than the ones for other WTP (Table 7). Compared to the raw waters, no considerable K removal was observed in any of the treatment plants. Findings show that K concentrations significantly exceed the standards for potable and agricultural use of 8 mg/l and 12 mg/l, as indicated by WHO [3] and the Food and Agriculture Organization (FAO) [29] of the United Nations, respectively. Considering public health concerns, there are no considerable health challenges linked to the consumption of high K dosages from drinking water as reported by Sebastian et al. [31]. From an agricultural point of view, elevated K values may prevent stem damage of plants at predominantly low temperature as reported by Hakerlerler et al. [32] and Cakmak [33].
Sodium concentrations for treated waters were at their maximum for water obtained from the Abu al Khaseeb plant followed by those for the Al-bradiah 1 and Shatt Al Arab plants. The Al-Garmma 1 plant treated water leading to Na concentrations slightly higher than those for the Al-Jubila plant. Statistically, no significant difference (p > 0.05) in Na concentrations were observed for the water treated by A-Ribat and Al Basra Unified plants, while the Al Shauaiba Old plant produced water with Na concentrations, which were significantly (p < 0.05) lower than the ones for the other WTP (Table 7).  Findings showed that all treated water had Na levels that significantly exceeded the standards for drinking water, which are 200 mg/l, as recommended by ICS [26] and USEPA [30]. For people requiring a restricted Na intake, a threshold of 500 mg/day is recommended. Moreover, a value of 200 mg Na/l for drinking water has been suggested to allow for a good taste of the water (Table 9) [3]. Vomiting, nausea, thirst, convulsions, muscular twitching and possible death due to hypertension may result from orally overdosing with sodium chloride [30]. Furthermore, the treated water showed elevated Na levels that significantly exceeded the threshold for agricultural, which is 920 mg/l [30]. Only the Al Shauaiba Old plant had treated water with Na concentrations (109 mg/l) that would allow for water use in irrigation. Saline soil may be obtained when irrigated with water containing elevated Na concentrations, which will impact negatively on soil structure and permeability as well as on plant growth and productivity [34].
The Abu Al Khaseeb plant had treated water of the highest Mg concentration, which is similar to those of the Al-bradiah 1 plant followed by those for the Shatt Al Arab plant (Table 7). Statistically, there is no significant difference (p > 0.05) in Mg values for treated waters obtained from the Al-Ribat and Al Basra Unified plants. The Al-Garmma 1 WTP produced water with Mg levels higher than water from the Al Jubila 1 plant. Moreover, the Al Shauaiba Old plant produced the best effluent in terms of Mg concentrations, which were significantly (p < 0.05) lower than the ones for the other plants (Table 7). No exceedances were noted for treated water Mg values compared to the standards for drinking water, which are 50 mg/l, as indicated by ICS [26] and WHO [3], respectively. The World Health Organization indicated that drinking water portability may be impaired when concentrations of Mg plus Na sulphate exceeded 1000 mg/l [3]. In comparison, all treated waters (except for those obtained from the Al Shauaiba Old plant) had Mg values that considerably exceeded the irrigation threshold of 60 mg/l [30]. Irrigation water with high Mg concentrations may cause infiltration problems and subsequent drainage challenges for soil. The sodium impact on soil may increase when the Ca to Mg ratio (Ca/Mg) is less than one (Mg dominant water), which would reduce the yield of some crops such as sugar beets, wheat, maize and barley [29]. Regarding Ca concentrations, Table 7 shows that the maximum values were recorded for the water treated by the Abu Al Khaseeb plant followed by those for the Al-bradiah 1 and Shatt Al Arab plants. Slight differences were observed for Ca concentrations when compare to values of the Al Jubila 1 and Al-Garmma 1 plants. Statistically, the results indicated that there are no significant differences (p > 0.05) in Ca concentrations when comparing Al-Ribat and Al Basra Unified treated waters with each other, while the Al Shauaiba Old plant treated water had Ca values, which were significantly (p < 0.05) lower than the ones for the other plants (Table 7). Compared to the standard thresholds of 125 mg/l and 200 mg/l as indicated by ICS [26] and WHO [3], respectively, recommended for drinking purposes, Ca concentrations in the treated water were considerably elevated with the exception of those linked to the Al Shauaiba Old plant.
Regarding public health, Ca is important for the human body; mainly for strong teeth and bone building, activation of oocytes, contraction of muscles, clotting of blood, transmission processes, heart beat regulations and cells fluid balances. Sufficient Ca is also required during pregnancy, breast feeding and for the main growth periods of children. Calcium deficiency may result in the deterioration of bones, leading to increases in fractures (osteoporosis) as stated by Pravina et al. [35].
Compared to the irrigation standard threshold of 400 mg/l for Ca [29], results showed that all treated waters had Ca concentrations that were lower than this threshold, with the exception of the Abu Al Khaseeb and Al-bradiah 1 plants, which had treated waters of Ca concentrations slightly exceeding the threshold (Table 7). Calcium is a critical secondary nutrient for yield development as it is required in relatively large amounts for plant cell wall and temperance formations. Moreover, Ca is vital for the soil structure, as it displaces Na in the soil, resulting in soil quality improvements [29].
The Abu Al Khaseeb plant followed by the Al-bradiah 1 and Shatt Al Arab plants had waters with the highest Cl concentrations (Table 7). Statistically, no significant differences (p > 0.05) for Cl were observed in the treated waters obtained from the Al-Garmma 1 and Al Basra Unified plants when compared with the Al Jubila 1 and Al-Ribat plants, respectively, while the Al Shauaiba Old plant treated water resulting in Cl values, which were significantly (p < 0.05) the lowest. Treated water from all plants had Cl values that were considerably exceeding standard thresholds, which are 250 mg/l for drinking water, as indicated by ICS [26] and WHO [3], and 1063 mg/l for irrigation [30]. In treatment plants, Cl was added as a disinfectant to purify the water in terms of pathogens. Chlorine is available as an abundant ion in nature mainly in the form of salts. Exposure to Cl gas or liquid could be harmful even in small amounts. Highly contaminated drinking water with Cl may cause respiratory issues such as asthma and cell damage, mainly in children, as well as increasing the risk of bladder cancer [3]. Using Cl as a disinfectant is useful in managing and maintaining a drip irrigation system. However, highly chlorinated irrigation water may be toxic for plants, resulting in the slow-down of plant growth or even their death [29].
The highest sulphate concentrations were noted for the Abu Al Khaseeb plant followed by those for the Shatt Al Arab and Al-bradiah 1 plants (Table 7), while the lowest values were recorded for those waters from the Al Shauaiba Old plant followed by ones for the Al-Ribat plant. Statistically, the results showed that there is no significant (p > 0.05) difference in sulphate values when comparing treated waters of the Al-Ribat plant with those of the Al-Jubila1, Al Basra Unified and Al-Garmma 1 plants, while the Al Shauaiba Old one showed treated waters with sulphate values, which were significantly (p < 0.05) the lowest.
Compared to drinking water standards, treated waters from all plants had sulphate concentrations that considerably exceeded the thresholds of 400 and 250 mg/l for drinking water as indicated by the ICS [26] and WHO [3], respectively. According to the World Health Organization, drinking water with high sulphate concentrations may cause laxative effects mainly when the two hardness constituents (both Ca and Mg) are available [3]. Moreover, the sulphate levels for all treated waters considerably exceeded the irrigation standard of 960 mg/l [29]. High sulphate availability in the irrigation water may increase the salt levels in the soil, resulting in the reduced availability of phosphorus for plants, as reported by the FAO [29].
Water hardness is the amount of dissolved Ca and Mg in the water [3]. Similarly, the Abu Al Khaseeb and Al-bradiah 1 plants produced water of the highest hardness values followed by those of the Shatt Al Arab plant (Table 7). No significant differences (p > 0.05) were observed when comparing treated water hardness concentrations from the Al Jubila 1 and A-Ribat plants with those of the Al-Garmma 1 and Al Basra Unified plants, while the water hardness values for the treated water of the Al Shauaiba Old plant were significantly (p < 0.05) the lowest. The total hardness of water is mostly expressed as milligrams of Ca carbonate per liter [3].
The TH for the treated water had the highest concentrations for the Abu Al Khaseeb, Al-bradiah 1 and Shatt Al Arab plants (Table 7), while the lowest values were observed for the water obtained from the Al Shauaiba Old plant. No considerable differences were found when comparing the TH values for waters from the Al Jubila 1 and Al-Garmma 1 plants with those from the Al-Ribat and Al Basra Unified plants.
Concerning drinking water standards, the World Health Organization classified water based on Ca carbonate concentrations to be soft if the concentration of Ca carbonate is < 60 mg/l, moderately hard for concentrations between 60 and 120 mg/l, hard for values between 120 and 180 mg/l and very hard for values > 180 mg/l [3]. Based on this classification, treated water obtained from all plants can be classified as "very hard" (TH > 180 mg/l). Moreover, treated water from all plants (except for Al Shauaiba Old) showed TH values that considerably exceeded the Iraqi and WHO standards for drinking water, which are 500 mg/l and 300 mg/l, respectively [3,29].
Generally, seasonal variations in concentrations were the highest during hot months (June to October) (Figure 4), possibly due to the high water demand caused by elevated temperatures. Moreover, the SAR, as the main raw water source, showed deteriorations in water quality parameters during hot months as well. No significant differences were observed when comparing the inflow and outflow water properties for all parameters, indicating that none of the treatment plants were fit-for-purpose.

Particles
The highest TSS concentrations were observed in the outflows of the Al-Ribat, Al Shauaiba Old and Al Basra Unified plants (Table 7), while the lowest values were recorded for the treated water of the Al-Garmma 1 plant followed by the Abu Al Khaseeb and Shatt Al Arab plants. Total suspended solids removal proportions were considerably better than those of other parameters, showing the highest value of 79% for the Al-bradiah 1 plant, followed by those for the Al-Garmma 1 (67%), Al-Ribat (66%) and Al Jubila 1 (62%) plants, while the lowest removals were recorded for the Al Shauaiba Old and Shatt Al Arab plants, showing values of 27% and 35%, respectively. Furthermore, the results indicated that the maximum TUR values were measured for the treated water from the Al Shauaiba Old plant followed by those for the Al-Ribat one, while minimum values were observed for the Abu Al Khaseeb and Al-Garmma 1 plants (Table 7). Correlation analysis results show that TSS and TUR values were significantly positively (R = 0.918, p < 0.001) correlated with each other, confirming findings obtained by Hannouche et al. [36]. The results showed that some plants treated water with corresponding TUR effluent values, which exceed the permissible limit of 5 NTU for Iraqi standards for drinking water [29].
The Al Shauaiba Old plant usually showed the best water quality for treated water except for those related to suspended solids and TUR. The potential reasons for that are the high demand for water mainly at high temperature and bad weather leading plant operators to decrease the settling time in the sedimentation tanks resulting in elevated values for particles in treated water (Basra Water Directorate, personal communication on 30 July 2020).

Salinity
In this study, Table 7 shows the highest TDS and EC values for water obtained from the Abu Al Khaseeb treatment WTP followed by those for the Al-bradiah 1 and Shatt Al Arab plants, while the lowest values were observed for water treated by the Al Shauaiba Old plant, followed by the Al-Ribat and Al Basra Unified plants. A correlation analysis showed that TDS and EC were significantly positively (R = 0.999, p < 0.001) correlated with each other, confirming the results obtained by Rusydi [37]. However, all treated waters showed TDS concentrations that considerably exceeded the drinking water standard of 500 mg/l, as recommended by USEPA [30], resulting in very bad water quality, since the elevated TDS content in the drinking water may result in high hardness, bad taste and an elevated laxative effect.
Electrical conductivity is a parameter that is measured for an indirect indication of water salinity in the water and agricultural sectors [31]. Irrigation water standards recommend the EC to be 3 mS/cm. All treated waters had values that significantly exceeded this threshold. Irrigation with such amounts of saline water will lead to saline soils (Table 7), which are linked to reduced plant growth and associated yield quality as well as unfavorable soil permeability and structure [34]. The results showed that all plants (except the Al Shauaiba Old) provide water with TDS concentrations that are considerably higher than the drinking water standard of 1000 mg/l [29]. Generally, an increase in TDS results in elevated K and Mg (see section of treated water ions). The main reason for high TDS is the shortage of the water reaching the SAR, which leads to the intrusion of the salinity coming from the Arabian Gulf. Most WTPs in Basra are supplied by the SAR, except for plants that are far away from the river such as the Al Shauaiba Old plant. Therefore, the results showed a sudden increase in TDS and associated parameters for the months of June, July, August and September. This is due to the fact that existing WTP are conventional and lacking treatment units to reduce salinity, such as reverse osmose [9].

Alkalinity and pH
For treated water, Table 7 shows that the maximum alkalinity values were recorded for the Shatt Al Arab and Abu Al Khaseeb WTP, while the Al Shauaiba Old plant showed significantly (p < 0.05) low values. Alkalinity is an indication of the ability of waters to neutralize acids added to them. Therefore, this parameter indicates the buffering capacity of waters [3]. Dissolved hydroxides, carbonates and bicarbonates are the most important chemicals that may affect the water alkalinity [3]. According to drinking water standards [30], alkalinity with moderate levels is preferred in a water supply to control the effect of corrosively caused by acidity. The United States Environmental Protection Agency (USEPA) stated the regulation limits for drinking water alkalinity only in terms of TDS, which should be about 500 mg/l (subject to pH limitations) [30]. On the other hand, from an agricultural point of view, elevated alkalinity within irrigation water may result in increasing soil pH values, and subsequently, to a reduction in the availability of micro-nutrients and low pesticide efficiency for the protection of plants. The Food and Agriculture Organization recommended the maximum alkalinity value for irrigation water to be 100 mg/l [30].
All treated water was basic (alkaline) in character (pH > 7). However, all waters were within the recommended range by WHO [3] and ICS [26], which is between 6.5 and 8.5 for drinking water purposes. Generally, water treated by the Al Shauaiba Old plant showed the highest pH values (7.56), while the lowest ones (7.19) were observed for those waters treated by the Abu Al Khaseeb plant. This indicates the negative correlation between water alkalinity and pH values as shown statistically (R = −0.156, p = 0.128).
In water treatment system operation, the pH is considered to be one of the most important parameters. The water pH should be controlled in the different treatment stages and may not be less than 8 for satisfactory clarification and disinfection. Moreover, treated water pumped to the distribution system should be monitored and controlled at all times to avoid the risk of water mains and household pipe corrosion. Otherwise, the distributed water will be contaminated and there will be problems in water odor, taste and appearance [3]. All treated waters had pH values that did not exceed the irrigation limits, which are between 6.5 and 8.4 as recommended by FAO [29]. Figure 5 shows the spatial variation of annual WQI for the raw and treated water for all the stations. It can be seen that all stations were within the limits of unsuitable water quality except for Al-Ribat, which had treated water within the limits of very poor water quality, and the treated water of Al-Shauaiba was within the limits of good water quality. The reason behind the bad water quality of all stations except for the Al-Shauaiba plant is the effect of pollution and salinity intrusion of the Arabian Gulf into the Shatt Al Arab River, which is considered the second source of raw water for the stations that are located on its banks. In comparison, the Al-Shauaiba plant is located far away from the river and the raw water is only taken from R-Zero, which had good water quality. It can also be sees that the Abu Al Khaseeb, Al-bradiah 1 and Shatt Al Arab plants always had unsuitable water quality due to the effect of the Arabian Gulf. The locations of Al-Ribat and Al-Basra Unified were unaffected by salinity intrusion from the Arabian Gulf, but Al-Garmma 1 is located on the Al-Garmma river that is connected with the Euphrates river, which has a high level of salinity.   Table 8 show the seasonal variation of the WQI for the raw water for all WTP. It can be seen that all stations had unsuitable water quality except for Al-Ribat and Al-Shauaiba, which were within the limits of poor water quality in autumn. The improvement in water quality for the seasons winter and spring was because of the high discharge of SAR river water. In summer, a deterioration in water quality for all WTPs except for Al-Shauaiba was noted. This was due to the shortage of incoming water to the SAR from the Tigres river. From Figure 6, it can be conclude that the stations that are far from the estuary and influence the salinity wedge were of better water quality. For the Al Shauaiba Old plant, which received water only from the SWC, the water quality was better.  Figure 7 shows the seasonal variation of the WQI for the treated water for all WTP. A small improvement in water quality after the treatment can be seen. However, most of the WTP were malfunctioning, needed maintenance or were subjected to poor management.

Efficiency of the Water Treatment Plants
The annual mean values of the water quality index and the corresponding efficiencies are presented in Table 10. It can be seen that the highest efficiency is linked to Al-Garmma 1, which was, however, only about 14%. In comparison, the lowest efficiency was noted for Shatt Al Arab, which was 1.17%. In general, all stations had bad removal efficiencies for all parameters. All plants were designed to remove turbidity and TSS as well as disinfect the water. However, plant maintenance has been neglected. In order to address the chemical pollution challenge, further advanced treatment with, for example, reverse osmosis should be considered.

Application of Cluster Analysis
Cluster analysis can be used as a tool for analyzing the relationships between water quality parameters and sampling stations. The raw and treated water quality parameters for all WTP have been processed using SPSS statistical software. The results of the cluster analysis are shown in Figure  8 for raw water. Clusters I and II consist of four stations each: Al-Ribat, Al Basra Unified, Al Jubila 1 and Al Shauaiba Old, and Al-bradiah 1, Abu Al Khaseeb, Shatt Al Arab and Al-Garmma 1, respectively. This classification indicates stations with similar raw water properties. The effect of salinity intrusion from the Arabian Gulf on the WTPs that are located near the estuary is indicated by cluster II. It is worth noting that Al-Garmma 1 is effected by the Euphrates river, which is a tributary to SAR and has bad water quality. Other stations, which are represented by Cluster I, are linked to better water quality compared to Cluster II. This is due to the source of water being either located far away from the estuary or being influenced by SWC feed. The dendrogram shown in Figure 9 groups raw water quality parameters into three statistically significant clusters: cluster I corresponds to turbidity, K, pH, Mg, alkalinity and Ca; cluster II comprises TH, SO4 , Na and Cl; and cluster III is linked to TDS and EC. Some of these groupings are intutitive in terms of some of the corresponding parameter relationships, e.g., for cluster I, an increase of pH leads to an alkalinity increase, and for cluster 3, an increase of TDS leads to an EC increase.

Irrigation Water Quality Assessment
The EC and SAR values are plotted in a Wilcox diagram ( Figure 10) for the winter season, which is considered to be the best season with regard to water quality. The water samples of Al Shauaiba Old are located in class C3-S1, which is considered as admissible regarding the Wilcox classification ( Table 6). The water has high salinity but low Na content, and can be used for irrigation for all types of soil at only a low risk of exchangeable Na. Other water samples are located in classes C4-S3 and C4-S4, which are classified as very poor in terms of water quality. Hence, the class C4 is unsuitable for irrigation. Since the winter season is considered the best season in this study, it can be summarised that none of the stations are suitable for irrigation, except for Al Shauaiba Old, which shows good water quality for all seasons.

Conclusions and Recommendations
Results show that the water quality is currently unsatisfactory for drinking purposes for all WTPs, except for Al Shauaiba Old, which shows good water quality for all seasons. The other WTPs ranged in terms of water quality between unsuitable and poor. The WTPs that are located near the estuary were worse than others. The wet season was linked to better water quality than the dry season.
The main reason for water deterioration is insufficient water quantity supplied to the city and the intrusion of a salinity wedge to the SAR, which is the main water source for most WTPs in this area. The results also show that most of the studied WTPs treat water with very low efficiency rates due to operation and maintenance challenges.
The water samples of Al Shauaiba Old are located in class C3-S1, which is considered as admissible regarding the Wilcox classification. The water has high salinity but low Na content, and can be used for irrigation for all types of soil at only a low risk of exchangeable Na. Other water samples are located in classes C4-S3 and C4-S4, which are classified as very poor in terms of water quality.
The authors recommend the following measures for improving the water quantity and quality situation for Basra and other regions facing similar challenges according to three lists of priority. High priority:

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To develop sustainable and alternative water supply sources such as constructed wetlands for raw water and wastewater treatment as well as lakes/ponds and reservoirs for rainwater harvesting.  To continuously monitor the water supply network conveying treated water to the consumers, avoiding any uncontrolled water contamination.  To establish public education plans for consumers to reduce the water demand during the hot season.
Medium priority:  To improve and control water resource management strategies to achieve adequate water supply and reduce saline intrusion challenges.  To construct water storage facilities to address water scarcity challenges.  To build water holding facilities to store access water and control flooding linked to snow melts during spring.  To manage stored water in a strategic manner to address sea water salinity wedge formation.  To construct activated carbon units to improve water color, taste and smell.
Low priority:  To build compact desalination units such as reverse osmosis at the site of the conventional water treatment plant to reduce salinity (TDS) to the appropriate levels.  To control point source pollution negatively affecting raw water quality such as domestic and industrial wastewaters as well as drainage waters due to agricultural activities.  To increasing the capacity and efficiency of water treatment plants.

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To continuously monitor WTP maintenance.  Improve the technical management capacity, budget and skill development for technicians. Funding: This research received no external funding.