Assessment of the Water Quality Index of water body at Pravarasangam, Maharashtra

Assessment of the Water Quality Index of water body at Pravarasangam, Maharashtra

Dinkar V Aware*a Madhukar E Navgire*b and Haribhau R Aher* c

aDepartment of Chemistry, Shri Dnyaneshwar Mahavidyalaya, Newasa, Dist-Ahmednagar, M.S., India, Affiliated to University of Pune.

bDepartment of Chemistry, Jijamata College of Science and Arts,Bhende, Dist-Ahmednagar, M.S., India, Affiliated to University of Pune.

cDepartment of Chemistry, P.V.P.College, Loni, Dist-Ahmednagar, India, Affiliated to University of Pune.

Abstract

The present study was intended to calculate water Quality Index (WQI) of surface water of Pravarasangam, in order to ascertain the quality of water assessed for public consumption and other purpose. Physicochemical parameters were monitored for the calculation of water quality index for rainy and winter seasons. Investigation has been based on different parameters namely pH, conductance, TDS, chlorides, nitrate, sulphate, phosphate,alkalinity, hardness, BOD and DO. Keywords: River Prawara, Physico-Chemical parameters, water Quality Index.

1. Introduction

   The fresh water is of vital concern for mankind, since it is directly linked to human welfare. The surface water bodies, which are the most important sources of water for human activities are uniformly under severe environmental stress and are being threatened as a consequence of developmental activities. Pravarasangam is the one of the back water station of the largest earthen dam, Jiakwadi. It is historical place of Lord Shiva, situated at the conflict of Mula and Godavari River. This station is a holy place, hence throughout the year various human activities are taking place. The water from this station is used mainly for drinking purpose for the Newasa city and nearby other forty villages. Adequate amount of water is available at this station throughout year. It is with this background, the present work was undertaken between July2008 and January 2009.

   Water quality index provides a single number that express overall water quality at a certain location and time, based on several water quality parameters. The objective of water quality index is to turn complex water quality data into information that is understandable and usable by the public. A single number cannot tell the whole story of water quality; there are many other water

   quality parameters that are not included in the index. However, a water quality index based on some very important parameters can provide a simple indicator of water quality. In general, water quality indices incorporate data from multiple water quality parameters into a mathematical equation that rates the health of a water body with number.

2. Study area

   The Pravara river in Newasa, in Ahmednagar district is located in survey of India topological sheet number 47, 7/14 and lies between latitude 190 32 to 190 37 N and longitude 740 49 to 750 1E [1]. As the area falls in semi-arid zone, it receives moderate rain fall during the monsoon (average rain fall 56 cm) and have generally dry climate. But due to the availability of water from Mula left cannel, Bhandardara dam and back water from Jayakwadi dam (Nathsagar) plenty amount of water present at this station throughout year.

3. Materials and Methods

   Water samples were collected twice every month during morning hours between 8 a.m. and 10

   a.m. pH and dissolved oxygen were monitored at the sampling spot while conductivity, total dissolved solids, total alkalinity, total hardness, chlorides, nitrates, phosphate, and BOD were analysed in the laboratory according to APHA (2005) and Trivedy and Goel (1986) [2,3].

   In this study, for the calculation of water quality index, eleven important parameters were chosen. The WQI has been calculated by using the standards of drinking water quality recommended by the Word Health Organisation (WHO) Bureau of Indian Standards (BSI) and Indian council for Medical Research (ICMR) [4, 5,6].

   Water Quality Index (WQI):

   Water quality index, indicating the water quality in terms of index number, offers a useful representation of overall quality of water for public or for any intended use as well as in the pollution abatement programs and in water quality management. Horton (1965) defined water Quality Index (WQI) as a reflection of composite influence of individual quality characteristics [7]. The following steps of evaluation of WQI have been used from the point of view of the surface water for human consumption, and it is calculated by weight arithmetic index method (Brown et. al 1972) [8].

   Calculation of sub index or quality rating (qn):

   Let there be `n` water quality parameters

   and quality rating or sub index (qn) corresponding to nth parameters is a number reflecting the relative value of this parameters in the polluted water with respective to its standard permissible value. The qn is calculated using following expression.

   qn = 100 [(Vn – Vio) / ( Sn – Vio)]

   Where,

   qn =Quality rating for the nth water quality parameter.

   Vn = Estimated value of nth parameters at a given sampling station.

   Sn = Standard permissible value of the nth parameters.

   Vio = Ideal value of nth parameters in pure water.

   i.e. 7.0 for pH, 14.6 mg/l for DO and 0 for all other parameters.

   pH value calculation through water quality rating evaluation:

   Ideal value of pH is 7.0 where 8.5 is the permissible value of water (i.e. polluted water), therefore, quality for pH is calculated from the following relation.

   qpH = 100 [(VpH – 7) / ( 8.5 7)]

   Where VpH = observed value of pH.

   DO calculation through the water quality rating equation:

   QDO = 100 [(VDO 14.6 / (5 14.6)]

   Calculation of unit weight: Wn = K / Sn

   Where,

   Wn = unit weight for the nth parameters, Sn = Standard value of for the nth parameters,

   K = constant of proportionality

   The overall water quality Index was calculated by aggregating the quality rating (qn) with the unit weight linearly.

   WQI = qn Wn / Wn

   Table 1: Water Quality rating for drinking water (Chaterjiee and Raziuddin 2002)

   Sr. No	WQI level	Water quality rating	Possible Use of Water
   1.	0-25	Excellent	All-purpose like potable, industrial, agricultural,
   2.	26-50	Good	Domestic and agricultural
   3.	51-75	Poor	Agricultural, industrial
   4.	76-100	Very Poor	Agricultural
   5.	100	Unfit for drinking	Not much possible agricultural can be used only after proper treatment

   Table 2: Drinking standard recommended by agencies and unit weights

   ICMR

   Sr. No.	Parameters	Standards (Sn)	Recommended Agency	Unit weight (Wn)
   1.	Conductance	300	ICMR	0.3710
   2.	TDS	500	ICMR/ISI	0.0037
   3.	pH	7-8.5	ICMR	0.2190
   4.	Chlorides	250	0.0074
   5.	Nitrates	45	ICMR	0.0412
   6.	Phosphate	25	ICMR	0.0618
   7.	Sulphate	150	ICMR	0.0103
   8.	Alkalinity	120	ICMR	0.0155
   9.	Hardness	300	WHO	0.0051
   10.	BOD	5	ICMR	0.3723
   11.	DO	5	ICMR	0.3088

   * All the values are expressed in unit mg/L except conductance in µS/cm

4. Result

   Table 3: Seasonal variation of the physico-chemical parameters of the water body

   Sr. No.	Parameters	Rainy season	Winter season
   1.	Conductance	373.4	299.78
   2.	TDS	244.3	196.75
   3.	pH	7.6	8.22
   4.	Chlorides	98.5	82.38
   5.	Nitrates	1.3	0.62
   6.	Phosphate	0.4	0.28
   7.	Sulphate	2.5	3.28
   8.	Alkalinity	37.3	49.09
   9.	Hardness	48.4	64.80
   10.	BOD	1.14	2.10
   11.	DO	7.72	8.27

   Table 4: Calculation of Water Quality index in Rainy season

   Sr. No	Parameters	Observed Value	Standards (Sn)	Recommended Agency	Unit weight (Wn)	Quality Rating (qn)	Wnqn
   1.	Conductance in µS/cm	373.4	300	ICMR	0.3710	124.467	46.177
   2.	TDS	244.3	500	ICMR	0.0037	48.860	0.181
   3.	pH	7.6	7-8.5	ICMR	0.2190	40.000	8.760
   4.	Chlorides	98.5	250	ICMR	0.0074	39.400	0.292
   5.	Nitrates	1.3	45	ICMR	0.0412	2.889	0.119
   6.	Phosphate	0.4	25	USPH	0.0618	1.600	0.099
   7.	Sulphate	2.5	150	ICMR	0.0103	1.667	0.017
   8.	Alkalinity	37.3	120	ICMR	0.0155	31.083	0.482
   9.	Hardness	48.4	300	WHO	0.0051	16.133	0.083
   10.	BOD	1.14	5	ICMR	0.3723	22.800	8.488
   11.	DO	7.72	5	ICMR	0.3088	71.667	22.131
   					1.4161	400.566	86.828
   Water Quality Index = Wn qn / Wn = 61.315

   Table 5: Calculation of Water Quality index in in Winter season

   NO	Parameters	Observed Value	Standards (Sn)	Recommended Agency	Unit weight (Wn)	Quality Rating (qn)	Wn qn
   1.	Conductance	299.78	300	WHO	0.3710	99.93	37.073
   2.	TDS	196.75	500	ICMR	0.0037	39.35	0.146
   3.	pH	8.22	7-8.5	ICMR	0.2190	81.33	17.812
   4.	Chlorides	82.38	250	ICMR	0.0074	32.95	0.244
   5.	Nitrates	0.62	45	ICMR	0.0412	1.38	0.057
   6.	Phosphate	0.28	25	USPH	0.0618	1.12	0.069
   7.	Sulphate	3.28	150	ICMR	0.0103	2.19	0.023
   8.	Alkalinity	49.09	120	ICMR	0.0155	40.91	0.634
   9.	Hardness	64.80	300	WHO	0.0051	21.60	0.111
   10.	BOD	2.10	5	ICMR	0.3723	42.00	15.637
   11.	DO	8.27	5	ICMR	0.3088	65.94	20.362
   					1.4161	428.69	92.166
   Water Quality Index = Wn qn / Wn = 65.080

5. Discussion

   Water quality index of the present waterbody is established from important various physicochemical parameters indifferent seasons. The values of various physicochemical parameters for calculation of water quality index are presented in the Table 3.

   The water quality index obtained for water body in different season of study period i.e. rainy

   season and winter season are 61.315 and 65.08 respectively, which indicates slightly poor quality of water [9].

   The above water quality is also supported by the following physicochemical parameters variations observed during the different seasons of the study. The conductance of water body varies between

   299.78 -373.4 µS/cm. The higher values of conductance were observed during rainy season, the higher values of conductance might be due to the addition of different nutrients, and agricultural

   runoff in the main stream [10]. The TDS values are in the range 196.75- 244.3mg/L are lower than the prescribed limits of ICMR and ISI i.e. 500mg/l. The pH of the water indicates as an alkaline nature it varies between 7.6 and8.22. The recommended value of it by ISI is 6.5 to 8.5 and by ICMR 7.0

   8.5. The chloride concentration results in salty taste of water. Some times higher concentration of it is responsible for laxative effect to the human beings. The concentration of chloride varied between 82.38

   98.50 mg/L which are well below the prescribed limits of WHO. The nitrates are the end product of the decomposition of organic waste present in the fully oxidized water and harmful above 45 mg/L

   .In the present study nitrate in the surface water are well below the permissible limits. The seasonal average statistic shows that maximum phosphate value was seen in rainy season i.e. 0.4 mg/L while minimum in winter season i.e. 0.28 mg/L [11]. These values were very well below the prescribed limits of USPH. The sulphate may have laxative effect if magnesium ion is present at an equivalent concentration [9]. In the present study sulphate concentration is held well below permissible limits. The value of sulphate concentration ranged within 2.5- 3.28 mg/L. The alkalinity itself is not harmful to the human beings but desirable limits to 120 mg/L are always required for domestic supply of water. The total alkalinity values were within the

   37.3 49.09 mg/L. The hardness values were recorded as 48.4 64.8 mg/L, higher value of hardness were observed during winter which may be due to the low water level, this values are well below the desired limits of WHO (< 300mg/L) dissolved oxygen varied from 7.72 8.2 mg/L .The BOD values are 1.14 – 2.10 mg/L which very well below the prescribed limits indicates unpolluted water.

6. conclusion

Application of the WQI is a useful method in assessing the water quality of the surface water. In the present study application of water quality index gives comparative evaluation of water quality in the different season. The present result shows that WQI in the rainy season are lesser than winter season. Average WQI i.e.63.1975 shows that in both seasons these values are in between 50 and 75 indicates poor quality water, suitable for agricultural and industrial use and is suitable for drinking purpose after suitable treatment only.

Acknowledgments

The authors are grateful to the Principal, Shri Dnyaneshwar Mahavidyalaya, Newasa, Dist- Ahmednagar, M.S., India, for providing the all required facilities to carry out the work.

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