ASSESSMENT OF PHYSICO-CHEMICAL PROPERTIES OF SURFACE WATER OF SHITALAKHYA RIVER NEAR POLASH, NARSINGDI, BANGLADESH

Md. Abdul Mottalib 1* , A. N. M. Al-Razee 2 , Md. Nurul Abser 3 and E.U.M. Aman 2 . 1. Institute of Leather Engineering and Technology, University of Dhaka, Dhaka-1209, Bangladesh. 2. Department of Analytical Chemistry and Environmental Science, Central Training Institute for Chemical Industries, Polash, Narsingdi-1611, Bangladesh. 3. Department of Chemistry, Jahagirnagar University, Savar, Dhaka, Bangladesh.

This study was carried out to examine the physico-chemical properties of the surface water of Shitalakhya River. Total thirty samples were collected from Polash-Ghorashal area in Narsingdi, Bangladesh and were analyzed for physico-chemical properties such as Temperature, pH, EC, Total Alkalinity, P-Alkalinity, DO, BOD 5 , COD, NH 3 -N, NO 3 -N & SiO 2 to monitor the level of water quality of the River. Obtained results of the present study shows that most of the parameters exceed the maximum permissible limit in pre-monsoon and dry season. Ammonia was found to be the major pollutant of the River. Overall of the seasons NH 3 -N and BOD 5 exceeded the allowable limit for aquatic life and the highest concentration of NH 3 -N (342.99 mg/L) was recorded along the River in pre-monsoon near at the point source of UFFL. Among the thirty samples, seventeen samples showed P-alkalinity probably due to hydroxide alkalinity. In pre-monsoon the DO value (2.59-3.82 mg/L) was found to be stressful for aquatic life though the value changes in winter season when it became highest (6.6-5.86 mg/L). From the statistical point of view temperature, pH, alkalinity, EC, COD, BOD 5 , Ammonia-N, NO 3 -N and SiO 2 are positively correlated to each other while with DO, most of the parameters are negatively correlated. The results reflect the poor effluent quality generated by Urea Fertilizer Factory (UFF) and indicates that the water of Shitalakhya River is not safe for drinking purposes, fisheries, recreational activities and various industrial uses particularly in Winter, Dry and Pre-monsoon seasons of the year. Monshiganj. The Shitalakhya River is the major source of drinking water for the ever-expanding pollution of Dhaka city so the Dhaka Metropolitan Development Program has suggested to initiate environmental protection measures to prevent pollution of Shitalakhya River [2]. The River receives effluents from five jute mills, two fertilizer factories, one sugar mill, one cement industry, one textile industry, one dairy plant, two food processing industry, one hardboard mill, one paper mill and one thermal power plant within 13 km range of its flow in Ghorashal region. Among these industries, Polash Urea Fertilizer Factory, Urea Fertilizer Factory and Ghroshal Thermal power plant are considered as the KPI (key Point Installation). In industry, surface water is used for cooling, process, steam generation, safety and other miscellaneous purposes. The average consumption of surface water by Polash Urea Fertilizer Factory, Urea Fertilizer Factory and Ghroshal thermal power plant are 15600, 28800 and 28,80,000 t/d respectively from Shitalakhya River at polash region.
As far we know, there are very few published reports on the physicochemical parameters of surface water of Shitalakhya River [3][4]. The objective of the present study was to investigate the impact of Fertilizer Factories effluent on the river water and thus to provide an updated report on the state of water quality of the Shitalakhya River. Due to the industrial pollutants, sometimes died fish was found to float on the surface water of the River in the vicinity of Urea Fertilizer Factory that had been recorded [5]. Thus, it is important to determine the intensity of pollution by inventorying the physicochemical parameters and their spatial and temporal variation in water of Shitalakhya River. This study represents the level of water quality parameters such as Temperature, pH, Total alkalinity, P-alkalinity, Conductivity, COD, BOD 5 , DO, NH 3 -N, NO 3 -N and SiO 2 in surface water of Shitalakhya River at Polash region.

Study area:-
The study was conducted near the effluent channels from two Fertilizer industries -the Urea Fertilizer Factory  1b). An engine boat was used for traveling into the River and samples were collected from a depth of about 20-25 cm below water surface. Two liter polypropylene bottles were used for water sample collection. Before taking final water samples, the bottles were rinsed three times with the water to be collected.

Results and Discussion:-
The collected samples were analyzed for the physico-chemical properties like Temperature, pH, Total alkalinity, Palkalinity, EC, DO, BOD 5 , COD, NH 3 -N, NO 3 -N and SiO 2. The temperature, pH and conductivity of water samples were measured immediately after collection at spot area [6]. Standard methods [7], [8], [9] and [10] were adapted for laboratory chemical analysis for the water quality parameters. Modified winkled method was used for the determination of dissolved oxygen. The results of different parameters are shown in Fig. 2.

Statistical analysis:-
To establish the association among the parameters statistical analysis was performed by using the software MS Excel and Pearson's correlation (r) by SPSS (18.0 version). .621 ** .618 ** 1 ** Correlation is significant at the 0.01 level (2-tailed). * Correlation is significant at the 0.05 level (2-tailed). N=No. of Samples Temperature:-Temperature of the study samples varied from 22.0ºC to 43.0ºC along the Shitalakhya River during the sampling period. Lowest temperature 22ºC was recorded at100 meters distance from the point source of UFFL in winter season while highest temperature 43ºC was recorded at the outfalls of effluent of Urea Fertilizer Factory in pre-920 monsoon and the average temperature was also high in the pre-monsoon of the overall five seasons because huge amounts of turbine condensate were drained to the river. At the sampling point F SW2 situated near the point source of Urea Fertilizer Factory, the temperature ranged 32.5-43ºC in five seasons that is most vulnerable. In a previous study Kabir [11] reported that the temperature of Shitalakhya River water at Narayanganj ranged from 19.7 to 32.2ºC. Azam et al. [12] studied the water quality parameters of the four river systems in the Sundarbans and found the temperature seasonally varied from 23.36⁰C to 30.3⁰C and Islam et al. [4] found the temperature of water ranged from 28 to 32⁰C in Shitalakhya River in June-July, 2007. The results of present investigation are higher than the findings of Azam et al. [12] and Islam et al. [4]. In very low temperature fish growth stops and in extremely high temperature fish will die [13]. From the statistical point of view temperature is significantly positive correlated with alkalinity, electrical conductivity, BOD 5 , COD, NH 3 -N, NO 3 -N while it has significantly negative correlation with DO. The obtained results indicate that the temperature of Shitalakhya River along the Fertilizer Factories area are within acceptable limit except the point source of UFFL where process steam condensate (20 t/h) from Urea plant, condensate drain from reflux drum (10 t/h) and boiler blow down (08 t/h) from ammonia plant process are continuously drained.

pH:-
The pH of water samples ranged from 7.15 to 9.75. In the pre-monsoon the sampling was carried out during high tide so that sample points only F SW1 and F SW2 had high pH (9.1 to 9.75) that exceeded the allowable limit for fishing purpose. At the sampling station F sw2 , pH value exceeded the limit for surface water standard of aquatic life [14] and WHO drinking water standard [15] in all the five seasons. The pH of water samples was mostly alkaline due to effluent containing NH 3 from Urea Fertilizer Factory. The pH value (7.15-9.75) of the present study is higher than the previous study (7.5 to 8.4) that was performed by Islam et al. in June-July, 2007 in Shitalakhya River [4]. Therefore the pH of the Shitalakhya River water is not suitable for aquatic growth, the optimum ranges of pH for aquatic life is 6.8 to 9.0 [14].

Alkalinity:-
Total alkalinity level varied from 50.4-1811.9 mg/L as CaCO 3 . The highest (1811.9 mg/L) and second highest (998 mg/L) level of alkalinity were recorded in the pre-monsoon and dry season respectively near the point source of UFFL. The P-alkalinity was also detected in this study. Over the all seasons P-alkalinity was high near the point source F sw2 of Urea Fertilizer Factory and highest was recorded (535.7 mg/L as CaCO 3 ) in pre-monsoon due to outfall of ammonia containing effluent from the UFF and showed hydroxide alkalinity. For fishing purpose maximum recommended range of alkalinity is 200 mg/L [16]. Table 1 reveals that Alkalinity is significantly positively correlated with pH (r = 0.717), NH 3 -N (r = 0.990), NO 3 (r = 0.959), EC (r = 0.867), COD (r = 0.734), BOD (r = 0.649) and SiO 2 (r = 0.671). The alkalinity observed in this study is higher than those found in Yamuna River of Agra city the range was 175 -310 mg/L [17] and in the grab samples of effluents from nitrogenous fertilizer Factory at Kota the range was 50-350 mg/L [18].

Electrical Conductivity (EC):-
The results of conductivity of the current study were found ranged from 131.6 to 2292 µS/cm those are shown in fig.  2(a). The chart revealed that the conductivity of surface water exceeded the recommend value of FAO drinking water standard (1000 μS/cm) in winter, dry and pre-monsoon season at the outfall of UFFL's effluent. Maximum value was recorded in pre-monsoon (2290 µS/cm) due to discharge of Fertilizer Factories effluent, increased concentration of ions, less flow of water and increased evaporation. Minimum value (131.6 µS/cm) was recorded at the 800 m (F SW6 ) downstream from the UFF point source in monsoon due to shut down of Fertilizer Factories at that period and dilution effect for high flow of water. Table 1 [19]. The EC values found in the present study is higher than those found in Ganges, Brahmaputra and confluence where the maximum and minimum electric conductivity values were 471 µS/cm & 222 µS/cm and 195 µS/cm &120 µS/cm respectively [20].

Chemical Oxygen Demand (COD):-
Chemical Oxygen Demand (COD) varied from 10 mg/L to 60 mg/L along the Shitalakhya River in the five seasons. The highest (60 mg/L) and second highest (40 mg/L) value of COD were recorded at 3 to 4 meter distance from the point source of UFF and PUFF respectively in the pre-monsoon due to oil bearing effluents such as lube oil, seal oil from compressors and heavy duty pumps were drained to the River through point source and minimum was recorded (10 mg/L) in the 20 meter upstream from the point source of UFF in monsoon due to dilution effect and high flow of water in the River . Table 1  The temperature of the water can also contribute to high BOD levels for example warmer water usually will have a higher BOD value than colder water. The highest BOD was recorded for the river water adjacent to Urea Fertilizer Factories discharge point. The BOD values of all seasons were exceeded the permissible levels for aquatic life. The permissible limit for BOD for drinking water is 0.2 mg/L, for recreation 3 mg/L, for fish 6 mg/L and 10 mg/L for irrigation [19]. Another standards showed that BOD < 1 mg/L indicates pristine streams, < 5 mg/L unpolluted natural streams, 5-8 mg/L moderately polluted streams [21]. So the BOD values were not support for fish culture and irrigation activities and not suitable for drinking purpose. Islam et al. [4] found the BOD values ranged from 9-14 mg/L in Shitalakhya River whereas Hadiuzzaman et al. [22] found 11-16 mg/L BOD in Shitalakhya River and 22-54 mg/L in Balu river. The BOD values of present study nearly similar to the BOD values of Balu River and higher than the study carried out by Islam et al. [4].

Dissolved oxygen (DO):-
DO value of the current study samples varied from 2.59 to 6.60 mg/L. DO values of the study samples found in winter, dry, pre-monsoon, monsoon and post-monsoon seasons are 5.85 to 6.6 mg/L, 5.86 to 4.5 mg/L, 2.59 to 3.82 mg/L, 4.5 to 5.1 mg/L, 5.44 to 5.89 mg/L respectively. Effects of biodegradable waste discharge into a water body are largely determined by the oxygen balance of the system. It was observed that DO is comparatively higher in the winter and lower in pre-monsoon season. The lowest DO was recorded adjacent to Fertilizer Factories discharge point (F sw2 ) due to the effluents containing process steam condensate during the Factories running. The solubility of DO depends on temperature and concentration of dissolved minerals in water. As the temperature increases the oxygen saturation decreases and an increase in the concentration of dissolved salts lessens the saturation concentration of oxygen [23]. Table 1 reveals that DO is significantly negative correlated with temperature (r = -0.662), COD (-0.604), BOD (-0.452), and insignificantly negative correlated with alkalinity (-0.331), EC (-0.332), ammonia nitrogen (-0.297), nitrate nitrogen (-0.277) and silica (-0.336). The lowest DO was recorded (2.59 mg/L) near the point source of UFF in pre-monsoon and low flow of water was recorded at that point. Moreover, the data reveals that during the pre-monsoon season, the mean DO level slightly increased from 2.59 to 3.82 mg/L from upstream to the downstream of the river while in winter season its value increased from 5.86 to 6.6 mg/L. The minimum DO value requires for healthy fish is 5 to 6 mg/L, if this value decrease to 4.0 -4.5 mg/L, the water body is considered as heavily polluted [21]. The measured levels of DO never reached the acceptable level in any of the sampling stations in pre-monsoon. Its deficiency directly affects the ecosystem of a river water due to bioaccumulation and bio magnifications.

Ammonia Nitrogen (NH 3 -N):-
The amount of ammonia nitrogen varied from 1.52 to 342.99 mg/L along the River in the five seasons. The study revealed that the ammonia nitrogen also varied from 2.80 to 153.06 mg/L,10.03 to 142.87 mg/L, 9.95 to 342.99, 3.83 to 77.19 mg/L and 1.52 to138.87 mg/L in winter, dry, pre-monsoon, monsoon and post monsoon season respectively. The highest concentration was recorded at the point source of Urea Fertilizer Factory (F sw2 ) in premonsoon and lowest concentration was recorded at the 20 m upstream of UFF point source in post monsoon. It was observed that at the sampling point (F SW1 ), ammonia nitrogen concentration was so low in post monsoon and winter season because the sampling was carried out during ebb and on the other hand sampling was carried out during high tide in pre-monsoon and dry season. The table 1 indicates that NH 3 -N shows strong positive correlation with temperature (r = 0.541), pH (r = 0.714), alkalinity (r = 0.990), EC (r = 0.825), NO 3 -N (r = 0.969), SiO 2 (r =0.621), COD (r=0.698) and BOD (r=0.635) and insignificantly negative correlation with DO (r = -0.297). The concentration of ammonia-nitrogen at the point source of Urea Fertilizer Factory (F sw2 ) was higher than the other points in all seasons. This value is higher than the acceptable level (0.5 mg/L) [24]. Urea Fertilizer Factory discharges its ammonia containing effluents near the sampling point F sw2 . Another contamination source might be the process condensate containing ammonia-cal nitrogen about 20 ppm continuously drained from process condensate stripper tank at the rate of 20 t/h from urea plant are drained to the river through point source. The disposal of fertilizer industry effluents into nearby water resources poses a eminent danger especially in regard to maintenance of fish life. At 25ºC temperature and pH 7.5, maximum allowable limit of NH 3 -N for the protection of aquatic life is 0.89 mg/L and the toxicity increases with pH and temperature [25].  [3] found NO 3 -N varied from 0.2 to 1.8 mg/L in Shitalakhya River at Tarabo area in dry season while Ahmed et al. [1] found that NO 3 load of Buriganga River water during rainy, dry and summer were 0.917± 0.47, 0.43±0.61 and 0.68±0.14 mg/L respectively and that in Karnatoli River water were 0.45±0.32, 1.16±0.40 and 0.76±0.11 mg/L respectively. The chart reveals that at the point source of Urea Fertilizer Factory (F SW2 ) concentration of NO 3 -N is abruptly high among the other points. That is due to the surface water containing ammonia (NH 3 ) which might be oxidized to nitrate (NO 3 -) catalyzed by two ubiquitous bacterial groups. The first reaction is oxidation of ammonium to nitrite by ammonium oxidizing bacteria (AOB) represented by the "Nitrosomonas" species. The second reaction is oxidation of nitrite (NO 2 -) to nitrate by nitrite-oxidizing bacteria (NOB), represented by the Nitrobacter species. Table 1 indicates that NO 3 -N shows the strong positive correlation with NH 3 -N (r = 0.969), Alkalinity (r = 0.959), EC (r = 0.811) & also positive correlation with temperature, pH, COD, BOD and silica and negative correlation with DO (r = -0.277). The present findings is also higher than the previous studies of Hadiuzzaman et al. [22] and reported that NO 3 concentration in Balu River was 0.4 to 1.05 mg/L and Shitalakhya River was 0.1 to 3.5 mg/L. However, Alam et al. [26] found that the concentration of NO 3 in Buriganga River ranged from 8.0±0.5 to 12.2±0.4 mg/L in rainy season and 8.0±0.5 to 12.2±0.4 mg/L in dry season those are higher than the present study.

Dissolved Silica (SiO 2 ):-
Silica concentration of the present study varied from 8.70 to 44.64 mg/L. The highest concentration was recorded at point source of UFF in pre-monsoon due to high pH and high temperature because the presence of alkalinity encourages the formation of silicate ions and increases the solubility of silica and lowest was recorded in monsoon because slowness of the dissolution process of surface water. According to Pearson correlation matrix silica shows positive correlation with pH, alkalinity, EC, COD, BOD 5 , ammonia and nitrate-nitrogen and also insignificantly positively correlated with temperature. Dissolved silica concentrations in river water depend on chemical weathering, hydrological cycle in the basin, biological process and dissolution on land and in water [27]. The concentration of silica was found in the increasing order of pre-monsoon > dry season > winter season > post monsoon > monsoon. Kennedy [28] explained that, in most cases, dilution and biological uptake by diatoms are the cause of low concentration of dissolved silica in river water. Adsorption of silica on suspended particles could also possibly remove silica from solution in the presence of electrolytes [29]. Silica is the most objectionable parameter in industrial water. Silica fouling and silica scaling of heat exchanger and equipment is a great problem. The problem of silica scaling is exacerbated in presence of low levels of polyvalent metal ions (i.e., aluminum, iron, calcium, magnesium, etc.) [30]. The maximum allowable limit for silica concentration in boiler feed water is 0.02 mg/L.

Conclusion:-
From the present study it could be concluded that the overall pollution load was significantly high in pre-monsoon than in other seasons. The results showed that the quality of Shitalakhya River water was not acceptable for aquatic ecosystem perspectives because of the parameters such as DO was minimum in pre-monsoon and higher values of BOD 5 , and NH 3 -N in all seasons. The study had also concluded that some parameters such as temperature, pH, conductivity of this river water were still acceptable in all seasons except the point source of Urea Fertilizer Factory. NO 3 -N values also was acceptable in all the seasons except at the point source area of UFF in pre-monsoon. The amount of silica was high in winter, dry season and in pre-monsoon. The analytical result shows that the river water adjacent to Urea Fertilizer Factories effluent discharge area is most vulnerable, the degree of contamination is gradually decreasing with increasing distance of point sources. The absence of fishes in the study area in winter, dry and pre-monsoon period may be due to the pollution by the effluents containing ammonia from the Urea Fertilizer Factory and Polash Urea Fertilizer Factory. Some fishes are found at monsoon may be due to migration of fish from catchments area. This study indicates that the water of the Shitalakhya River is being polluted from its surrounding point and non-point sources which include discharges from Fertilizer industries. If this situation deteriorates further, the river water might be lead to a physico-chemically dead for aquatic life. So, no permission should be given to install new industries along the bank of the Shitalakhya river without their effluent treatment plant as this river is used as a raw water source for drinking and industrial water supply. And there is the need for continual assessment of the level of pollution of this stream with a view to reduce the level of pollution via education and public enlightenment.