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Water quality variations and control technology of Yamuna River
Em'ironmental Pollution (Series A) 37 (1985) 355-376
Water Quality Variations and Control Technology of Yamuna River
Devendra Swaroop Bhargava Division of Environmental Engineering, Department of Civil Engineering, University of Roorkee, Roorkee 247667, India
ABSTRACT A one-man water quality survey of the Yamuna River of the Indogangetic plain was undertaken to determine the variations in the quality of this river along its course during both summer and winter seasons, The variations in water quality are discussed with regard to the several water quality parameters, and a water quality index representing the integrated effect of the concentrations and relative importance of the parameters is used to denote degradation of the river quality. Stretches of the river are identified which require quality upgrading. A comprehensive strategy is presented for improving the water quality of the river.
INTRODUCTION The Yamuna is one of the important rivers of the Indogangetic plain. It originates as an upland river from Yamnotri in the Himalayas and in its upper reaches carries large amounts of suspended inorganic material. Smaller quantities of the dissolved substances occur in the summer when snow melt and runoff constitute the flow. In winter, this situation is, however, reversed because the underflows, springs, seepage, etc., make up the greater part of the river's volume. The water quality of the Yamuna River thus undergoes significant natural change during the two major seasons of the year. There is considerable human activity of various kinds along the course 355 Environ. Pollut. Set. A. 0143-1471/85/$03.30© ElsevierApplied SciencePublishersLtd, England, 1985. Printed in Great Britain
356
Devendra Swaroop Bhargava
of Yamuna River, including domestic, commercial, agricultural and industrial activities, and, as a result, different types of waste material enter the river, continuously altering its water quality. It is significantly degraded when it passes through the major urban centres such as Delhi, Mathura, Agra. The effect is more severe in the summer months when the river volume is comparatively low. The river water quality is also considerably changed by its tributaries. The most important of these, the Chambal, brings about an improvement in the water quality of the Yamuna which, like any other river, also undergoes self-purification along its course. The Yamuna River is used for a variety of activities, all affected to varying degrees by the degraded water quality. To improve the usefulness of the river, a comprehensive pollution control strategy and policy needs to be evolved for implementation at a national level.
WATER QUALITY SURVEY OF YAMUNA RIVER The Yamuna River system is shown in Fig. 1, together with its various tributaries and the major urban centres from its origin to Allahabad where it merges into the Ganga, the most important river of the Indogangetic plain. A one-man water quality survey of Yamuna River (Bhargava, 1977) was undertaken along its entire course during summer and winter to investigate variations in the Yamuna water quality, the related implications for the various beneficial uses, and to work out a suitable strategy for controlling its pollution status. Portable equipment such as portable-size incubators, pressure cookers, balance (Dial-O-Gram), conductivity meter, galvanic cell oxygen analyser, pre-calibrated turbidity disc, thermometers, etc., together with the necessary glassware, chemicals and other accessories were carefully packed into boxes for transportation to the various stations along the river. Temporary laboratories were set up at each sampling station. Observations for some of the water quality parameters could be made directly at the river site. For the remaining parameters river samples were collected for analysis in the temporary laboratories. The turbidity and suspended material were interpreted indirectly from a measurement of the depth of light penetration (DLP). For this purpose, a l0 cm diameter weighted metal disc coloured red and white in alternate quadrants was used (Bhargava, 1983a). Such a disc was considered
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superior to the standard Secchi disc from the point of view of visibility and to maintain a vertical position in the flowing water. The DLP used in this study is the depth in centimetres of this disc below the water surface at which it just becomes invisible. The observations of the various water quality parameters at the upstream and downstream sides of the sampling stations are presented for both seasons in Table 1. Photographs of the water surface at each sampling point were also taken in order to correlate the photographic optical density (POD), determined from the analysis of the photographs, with conventional pollution parameters (Bhargava, 1983e). Integrated effect of the water quality parameters
The various beneficial uses of water were grouped into five categories according to their quality requirements, viz. (1) swimming, bathing, drinking without treatment, etc; (2) public water supplies; (3) agriculture; (4) industry; and (5) culture, wildlife, non-contact recreation, boating,
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20 (19)
17 (18) 20
18 (18) 18
20 (19) 20
15 (14) 15
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W S
W
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1"0 56
0.2528 31
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0-5
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Velocity DLP DO (m s 1) (cm) (rag litre-l)
a u/s, upstream; d/s downstream; S, summer; W, winter.
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u/s
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28 (29) 29
30 (30) 30
30 (31) 32
20'5 (23) 19
29 (30)
d/s
u/s
d/s
u/s
d/s
u/s
d/s
u/s
S
Temperature (°C) b
Hamirpur
Agra
Mathura
Delhi
Dak Patthar
Station
a
--
3.3
5.9
14-0
12.0
12"0
7'0
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5"2
2-6
5"4
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2-6
8.0
6-0
6.1
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1-35
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36
43
67
115
89
87
32"5
4.5
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72
69
77
285
304
203
200
63"3
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-
466
630
770
700
660
658
364
196
140
200
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424
417
457
670
666
615
613
344
260
150
165
W
BOD Chloride Conductivity (rag litre 1) (rag litre ~) (m mhos era-l)
TABLEI Obse~ationsalongtheYamunaRiver
152
192
254
232
204
204
184
104
52
70
S
142
144
148
228
223
216
214
172
140
72
92
W
Hardness as CaCO 3 (mg litre 1)
22
79
+2400
540
+2400
+2400
+2400
70
350
+2400
S
280
70
33
1 600
280
84
920
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170
14
70
W
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1"4
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0"6
0"6
0-8
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Coliform Nitrogen MPN (rag litre-l) (lOOml 1)
61
53
22
33
31
44
51
70
82
59
S
55
74
72
34
49
50
50
45
71
89
93
W
Overall WQI
e~
oo
23 11
2
69 65
71
59 44
56 64
63 28
84 82
W 99 91 70 35 58 62 58 47 79 82 78
40 79 69 42 47 23 32 21 79 89 --
--
71
63
8 43
28 25
93 74
94 96
S
W
S
46
47
41
8 8
8 8
78 53
94 94
W
Agriculture
--
76
65
49 41
45 43
58 55
47 79
S
65 68
71
51 49
46 46
55 62
91 82
W
Industry
WQI values JOt various benej4cial uses Public water supplies
u/s, upstream; d/s, downstream; S, summer; W, winter.
85
u/s d/s
u/s d/s
Agra
35 14
Allahabad
u/s d/s
Mathura
57 27
69
u/s d/s
Delhi
35 67
S
Swimming, drinking without treatment, bathing, etc.
Hamirpur
u/s d/s
Dak Patthar
Station
T A B L E
Computed Values of the WQI in the Yamuna River°
--
72
68
92 88
89
69 65
51 35
90 45
72 58
81 75
99 98
83 91
65 50
W
S
Fish culture, wildlijb non-contact recreation, boating
t~
Devendra SwaroopBhargava
360
etc. (Bhargava, 1983d), and a water quality index (WQI) was used to evaluate the suitability for each category of use: n
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Variations in Yamuna River water quality.
a
1200
II II
III III
II --
II
IV IV
III IV
II III
III II
S
II I1
II
III Ill
III III
II III
I I
W
II --
Ill
V III
IV IV
I II
I I
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llI II1
III
V V
V V
II II1
I I
W
Agriculture
II --
II
III III
Ill III
IIl III
III I1
S
II II
II
III Ill
III III
III lII
I I1
W
Industry
River class ]or the beneficial uses Public }cater supplies
a u/s, upstream; d/s, d o w n s t r e a m ; S, s u m m e r ; W, winter.
Allahabad
II --
II
u/s d/s
II
IV IV
u/s d/s
Agra
Hamirpur
III III
III IV
u/s d/s
Mathura
III 1V
III IV
u/s d/s
Delhi
II II
III II
W
u/s d/s
S
Swimming, drinking without treatment, bathing
Dak P a t t h a r
Station
TABLE3 Water QualityClassoftheYamunaalongitsCourse"
II --
I1
III III
II III
II III
II I
S
I II
II
II II
II II
I IIl
I I
W
Fish culture, wildlife, non-contact recreation, boating
taa
~-
"~
362
Devendra Swaroop Bhargava
to the use, andf/(Pi) is the sensitivity function of the ith parameter, which depends on the concentration and importance value of a parameter for a given use. The WQI ranges from 0 (worst water) to 100 (best water) (Bhargava, 1983d). The WQI values for each category of use at various points along the Yamuna River in both summer and winter are presented in Table 2. The overall WQI at a given point has also been computed from
TABLE 4
Acceptable BeneficialUses in the Various Zones of the Yamuna River Acceptable (Classes I and 11 only) beneficial uses
Stretch of the Yamuna River
Summer
Winter
Dak Patthar Delhi
Public water supply, agriculture, fish culture, wildlife, non-contact recreation, boating
All except industrial
Delhi-Hamirpur
Nil
Fish-culture, wildlife, non-contact recreation, boating
Hamirpur-Allahabad
All except agriculture
All except agriculture
these data by assuming equal weighting of all the beneficial uses (Table 1). If desired, different weightings could be assigned for the different uses at a given point, on the basis of the relative cost of each use for evaluation of the overall WQI. The variations in the Yamuna water quality in respect of the several water quality parameters and the overall WQI are presented in Fig. 2. Each beneficial use was graded into a class: I (excellent), II (good), III (satisfactory), IV (poor) and V (unacceptable) for corresponding WQI values of 90 + , 65-89, 35-64, 11-34, and - 1 0 , respectively (Bhargava 1983d) (Table 3). Table 4 gives acceptable uses for the various zones of the Yamuna River.
Water quality of Yamuna River
363
R E S U L T S A N D DISCUSSION
Temperature variations The temperature was lowest at Dak Patthar, the station close to the Himalayas from where the river originates, and varied identically in both seasons, rising sharply from Dak Patthar to Delhi at a rate of about 5 °C 100km-1 in summer and 2°C 100km-1 in winter. The summer rate is higher due to a greater difference in the river and ambient temperatures at Dak Patthar when compared with Delhi, where the river almost reaches equilibrium with the ambient temperature. In the winter months, the river temperature is slightly higher than the ambient temperature due to the higher temperature of the sub-surface water which constitutes the major flow of the river, and the variations of river and ambient temperature are therefore identical. The magnitude of temperature rise at urban centres due to wastewater outfalls depends on the ratio of the wastewater discharge rate to the river discharge rate. Downstream, the temperature falls due to evaporation and radiation. The average cooling rate, for example, is seen in both seasons to be around 1 °C 100km-~ in the Delhi-Mathura reach of this river, and 3°C 100km -~ in the Mathura-Agra reach. The impounding reservoir between upstream and downstream of Dak Patthar also receives cooler groundwater in summer months, as a result of which the downstream temperature is lowered. A higher microbial activity, and hence greater assimilation rate of the organic pollution, results in summer months than in the winter although the higher temperature makes bathing more comfortable during the summer months.
Variation in DLP The D L P (representing the clarity of the river water) is very high upstream of Dak Patthar where the river originates as an upland river in winter (when the discharge is comprised mostly of infiltering clearer groundwater) when compared to summer (when the snow melt runoff carrying a large suspended load reaches the river). However, the impounding reservoir at Dak Patthar tends to remove the turbidity, as a result of which the D L P stabilises to around 50 cm downstream of Dak Patthar in both seasons. The inflow of wastewaters between Dak Patthar and Mathura results in a drop of clarity in both seasons. At Delhi, where large
364
Devendra Swaroop Bhargava
amounts of wastewater outfall into the river, significant bioflocculation with extracellular polymers (excreted by bacteria in their endogenous phase) acting as excellent coagulants (Pavoni et al., 1972) takes place (Bhargava, 1983c), and results in a rise of clarity from upstream to downstream of Delhi in both seasons. The river having acquired significant extracellular polymers by the time it reaches Mathura, the bioflocculation causes a further increase in clarity thereafter, in both seasons. Due to greater bacterial activity in summer months, the clarity rise is more significant. The clarity observations alone cannot be relied upon to interpret the pollution status of a river, because low clarity may be caused by the discharge of inorganic suspended matter, while suspended and colloidal portions of the discharged organic materials may be removed due to bioflocculation, resulting in an improvement of clarity (or turbidity)---although the biochemical oxygen demand (BOD) would increase on account of the dissolved portions of the discharged organic material. The velocity variation would significantly affect the D L P caused by inorganic suspended material (Bhargava 1983a). The organic material causing turbidity is affected very little by velocity variation (Table 1), which shows that the D L P variation is insignificant in spite of variations in velocity between Delhi and Agra, where considerable amounts of organic matter enter the river. In this stretch of the river, the stream velocity is low and cannot sustain large amounts of inorganic material. Due to higher clarity, the river maintains a high aesthetic appearance from Dak Patthar to Agra in winter, and from Agra to Allahabad in summer. Greater clarity would also mean deeper light penetration, which would encourage higher photosynthetic activity in the river. DO and BOD variations
The variation patterns of the dissolved oxygen (DO) and BOD in the river are identical in both seasons. Higher BOD values all along the river in the summer months compared with the corresponding values in the winter were due to the smaller summer river flow. For obvious reasons, the DO values were higher in the winter. The retention time of the impounding reservoir at Dak Patthar has an equalising effect on both these parameters. The BOD in the reservoir becomes stabilised due to selfpurification mechanisms (such as settling, mixing, assimilation, etc.), to a value around 2mg litre-1 in both seasons, as a result of which its downstream value decreases in summer but increases slightly in the
Water quality o] Yamuna River
365
winter. The DO similarly stabilises to around 7.9 mg litre- 1, causing the downstream value to increase slightly in summer, but to decrease in winter. In both seasons, on an average long-term basis, the BOD increases from Dak Patthar to Agra but decreases thereafter, while the D O slightly decreases from Dak Patthar to Agra but afterwards increases. This is due to large organic load inputs from point and non-point sources and their stabilisation and natural removal from Dak Patthar to Agra, and vice versa from Agra to Allahabad. The less polluted Chambal River plays a significant role in decreasing the BOD and increasing the DO beyond Agra. At almost all urban centres along the Yamuna River, the BOD rises steeply immediately after the wastewater outfalls in the river. Such rises are sharper and greater in summer when the river volume discharge is reduced. As a consequence, the D O also drops sharply below the wastewater outfalls. The flow velocity in the Yamuna is low (extremely low in the Delhi region) enough to sustain algal growth which contributes part of the oxygen needed to maintain high BOD input during the summer months. Delhi has several outfalls and the BOD in the Yamuna rises to as much as 60 mg litre- 1 below the Najahgarh drain outfall in summer. This value is reduced to as low as 5 mg litre- 1 after a distance of about 6 k m due to bioflocculation and the extremely fast self-purification of the Yamuna (Bhargava, 19830. The DO as a consequence was found to drop to extremely low values, even touching zero, after some wastewater outfall drains, but due to the river's extremely high reaerating ability, the DO was able to recover significantly in a short distance (Bhargava, 1983c). Because a significant drop in the river DO takes place only after some distance from the waste outfall point, by which distance the BOD is considerably reduced, DO alone cannot therefore be used to define the pollution status of a river. The set of B O D - D O values would indicate the self-purifying ability of the river apart from its pollution status. F r o m the consideration of BOD and DO, the Yamuna River at most urban centres remains unfit for bathing, fish culture, etc. Several cases of mass fish mortality have occurred in Delhi. One of the water works situated at Okhla downstream of Delhi provided extensive treatment (including heavy pre-chlorination) to the river water which had a B OD of about 6-8 mg litre- ~. Although the Okhla treatment plant was involved in public controversies several times, no waterborne epidemic could be
366
Devendra Swaroop Bhargava
attributed to this water works. The Yamuna River water upstream of the urban centres is utilised after appropriate treatment for public water supply at almost all the urban centres situated along it. The river's high BOD assimilation capacity has been fully exploited for wastewater disposal purposes and this results in an economy ofwastewater treatment COSTS.
Variations in chloride, hardness and conductivity Chlorides, hardness and conductivity remain at their lowest values in both seasons at Dak Patthar, with similar variation in both seasons. The higher chloride content along the entire river in winter is due to a greater contribution from the sub-surface water as compared to that from the exposed rocky material during the summer months. In winter it rises steeply between Delhi and Agra as this stretch of the river is regenerated almost entirely from groundwater infiltration (Bhargava, 1983b). Hardness and conductivity are contributed from the sub-soil as well as surface minerals (such as limestone and dolomite), and therefore are seen to be of almost equal magnitude in both seasons along the entire river. Due to changes in soil characteristics, the hardness is slightly higher in the Dak Patthar-Agra reach in the winter, but after Agra it is higher in the summer. In both seasons, hardness increases in the Dak Patthar-Agra reach due to the undersaturated (negative Langelier Index) character of the river water, but decreases after Agra due to oversaturation of the water (Bhargava, 1977). For conductivity, such a reversal takes place at Delhi. The decreasing trend in both seasons in the concentrations of chloride, hardness and conductivity from Agra onwards is due to the changed sub-soil and exposed rocky material characteristics and to the entry of the Chambal River which carries a significant discharge with low dissolved mineral content (Deb & Chadha, 1964). The larger discharge from the Chambal in winter makes this decrease more significant in winter than in summer. After Hamirpur, however, these dissolved mineral contents are maintained at more or less uniform levels in both seasons. The discharge of wastewater (which contains higher concentrations of dissolved minerals) in significant volumes causes an increase in the river concentrations of chloride, hardness and conductivity. At Delhi, significant amounts of groundwater (of higher chloride content) are used for domestic industrial, private and municipal purposes, new residential colonies, Jhuggis Jhomparies (unhygienic clusters of huts without any
Water quality of Yamuna River
367
organised water supply or drainage), and other habitations around the town. The whole of this used groundwater finds its way into the Yamuna as part of the municipal and industrial wastewater, as a result of which the chloride content of the Yamuna rises in both seasons (Bhargava, 1983b). The increase in the chloride content at Delhi is 35 mg litre - 1 in winter and 28 mg litre-1 in summer. The greater upswing in winter is because of added groundwater infiltration into the Yamuna. In contrast, at Agra, the chloride content in the Yamuna decreases downstream of the town by about 20 mg litre - 1 in winter and about 50 mg litre - 1 in summer, because of a lower chloride content of the groundwater in the Agra region (Pathak et al., 1976). A greater decrease during the summer months suggests a larger industrial use of cooler groundwater. The effect of groundwater on the Yamuna chloride content at Allahabad is insignificant because of the very large flow rate of the Yamuna at Allahabad. The high chloride content of the Yamuna between Mathura and Agra during the winter months renders the Yamuna water less suitable for agricultural purposes.
Variations in coliform MPN (most probable number) and nitrogen (ammonia) The coliform variation is almost identical in both seasons. The summer values are higher than those in winter, due to the greater volume of domestic wastewater in summer. The coliform counts are very high at urban centres because of discharge ofwastewaters from domestic sources. Due to the natural death rate of coliforms, their numbers decrease between the urban centres unless there are fresh additions from non-point domestic wastewater sources. The ammoniacal nitrogen accompanies an increase in the ratio of total plate count to the coliforms. The coliform content is high between Delhi and Agra, so that the Yamuna River is not suitable for bathing, swimming or other contact recreational uses. This presents a serious situation because almost all the religious centres to which people go for bathing (including inhaling the raw water for mythological-religious objectives), and camps, fairs, recreation, etc., are situated between Delhi and Agra. Perhaps the Indian people have developed a natural immunity or have such immense faith in their religious pursuits that they do not contract diseases even after drinking water polluted with such high coliform counts. During the river survey people were observed at several places drinking the raw untreated river water in connection with religious rites. I was rebuked when I tried to
368
Devendra Swaroop Bhargava
inform some of them of the dangers and risks involved. At one place, I witnessed some youngsters brushing their teeth with river water just downstream of a waste outfall sewer. This is perhaps how they become immune to the dangers of drinking bacterially contaminated water. In the circumstances, it would be in the interests of public health to plan (at a national level) and urgently execute a comprehensive pollution control strategy and programme for the Yamuna, the sacred river of the Hindus.
Identifying the sensitive stretches of Yamuna Figure 3 gives the WQI for the various beneficial uses of the Yamuna for both seasons. Assuming a WQI greater than 65 (that is, not lower than Class II for any use) as the limit for the river to be of some value for use, the exploitable uses for the various stretches of the Yamuna River are indicated in Table 4. This can also be seen in Fig. 3, in which the dashed lines denote each beneficial use at a WQI value of 65. A study of Table 4 shows that the Yamuna can be exploited for public water supplies, agriculture and fish culture, in both seasons from Hamirpur to Allahabad, and for fish culture alone in winter from Delhi to Hamirpur. As pointed out earlier, the Delhi-Hamirpur stretch is most critical because of the occurrence of religious centres. If the water quality can be improved in this stretch, the quality of the Yamuna from Hamirpur to Allahabad would automatically also improve. Since the greatest degradation of the Yamuna takes place at the Indian capital Delhi, which is the largest urban centre along its course, efforts should mainly concentrate on improving the quality of the water at Delhi, where the overall WQI drops from 70 to below 50 in both seasons. The overall WQI remains above 70 from Dak Patthar to Delhi in both seasons, but is reduced to below 65 (that is, Class III and below) at all points downstream of Delhi in both seasons (except for the small stretch of Hamirpur to Allahabad in winter). The Delhi-Hamirpur stretch involves three major urban centres, viz. Delhi, Mathura and Agra. The best strategy would be to include all these in the priority programme for improving the Yamuna water quality in the order Delhi, Agra and Mathura, as the overall WQI is seen to drop on an average basis for the two seasons by 22.5 at Delhi, by 13 at Agra, and by 6.5 at Mathura. It is expected that the cost of such a programme would be proportional. Table 1 also shows that the upgrading of river water quality
Water quality of Yamuna River
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Variation in the W Q I values for the various beneficial uses in Y a m u n a River.
370
Devendra Swaroop Bhargava
required in terms of the overall WQI (to attain at least a value of 65) downstream of these urban centres would be 14 and 20 at Delhi, 43 and 31 at Agra, and 34 and 15 at Mathura for summer and winter, respectively. These upgradings in the overall WQIs (43 at Agra, 34 at Mathura and 20 at Delhi) would make the Yamuna fit for overall use in both seasons.
Technological measures for enhancing Yamuna quality The programme for enhancing the Yamuna quality should not only be implemented at all the urban centres situated along the river, but also at all possible identifiable non-point sources of wastewater entering the river. This would require an extensive survey of the entire catchment area of the Yamuna River basin. However, as pointed out, the order of implementation should depend on the magnitude of the overall WQI value that is lost at each urban centre. Such control of the Yamuna River quality would involve several approaches, broadly grouped into defensive and offensive. The defensive approaches would aim at reducing the pollution load on the river (so that its self-purification capacity is not overburdened) through proper planning, treatment and disposal of the wastewaters. Such approaches would include the following programmes. Wastewater collection
A master plan of the urban centre of the river local basin should be utilised for evolving a comprehensive plan for the collection of wastewaters. Particular attention should be paid to segregation of the wastewaters having different and specific characteristics. Storm water should as far as possible be collected separately, taking care to exclude all other wastewater. Industry should be advised to segregate wastes requiring special treatment and provide separate collection lines for (i) industrial wastes requiring special treatment, (ii) domestic wastewaters for transporting to the municipal sewerage system, and (iii) storm waters for disposal into nearby open drains or the storm drainage system if one exists. Wastewater treatment
All wastewaters collected should be subjected to an appropriate treatment before their final disposal into the river. Industry should be advised of the satisfactory treatment of special wastes.
Water quality of Yamuna River
371
Advances in inplant practices Industry should be advised to: (i)
Reduce their waste load generation. This can be done through: (a) modification and efficient use of raw materials used in industrial production so as to produce the least offensive and least volume of waste (b) employing the latest process technologies and modifications to suit local conditions, enabling a reduction in the generation of waste loads (c) attempting a recovery system for wastes which would eliminate or reduce the waste load as well as give returns in the form of by-products (d) trying a modification of the waste generation process with the object of getting the least obnoxious and least bulk of wastes (e) practise the re-use of effluents and re-cycling ofwastewaters. (ii) Reduce the peak flows of waste through load equalisation techniques. (iii) Reduce the pollution potential of wastewater through neutralisation. (iv) Tailor industrial production according to the assimilation capacity of the receiving rivers. This should, however, be practised only in emergency situations after full consideration of economic losses for industry and the gains of the municipal corporations from the water resources thus protected.
Temperature control in power plants Nuclear power plants and electric power plants along the Yamuna River, such as the thermal power plants at Delhi which discharge wastewater at significantly high temperatures into the rivers and cause thermal stress in the river system, should modify their cooling systems and discharge their wastewaters after spraying them into the air before release into the river, or use other techniques to normalise the wastewater temperature.
Planning and zoning of disposal outJalls The outfall points carrying the wastewaters for disposal into the river should be properly planned so that they are located at a point where the river has maximum waste assimilation capacity and ability. This aspect is important, particularly because rivers vary in their self-purification
372
Devendra Swaroop Bhargava
character from stretch to stretch and a proper design of the number and spacing of wastewater outfalls for best assimilation is highly technical. Although it is economical to treat all the wastewater at one point, it may in some situations be more appropriate to dispose of all the effluent through several properly spaced and designed outfalls.
Improved agricultural practices The agricultural practices (crop raising, poultry and livestock farming) ~¢hich result in the release of organic matter, fertilizers, pesticides, herbicides, etc., into the rivers through land runoff, erosion and land drainage systems should be improved to reduce the organic, nutrient and Loxic loads on the river system. To achieve these improvements, the fertilizers, pesticides, herbicides, etc., reaching the river should be reduced by (i) an efficient, optimal and economical use of these chemicals, (ii) erosion control in the fields, and (iii) disposal of organic wastes generated From this practice onto agricultural land.
Environmental control I'he various pollutants reach the river through drains carrying urban runoff. An impression of a clean or dirty city is obtained from the river quality near the city, implying that efforts should be made towards a zleaner environment. Attention should therefore be paid to public and private sanitation, efficient refuse collection and disposal systems, and ~treet cleaning. The offensive approaches should aim at the fullest exploitation and improvement in the waste assimilative capacity of the river, so that the river quality can be enhanced. Some of these approaches would include Lhe following.
Drought control l'he river quality and the assimilative capacity vary significantly from flood to drought conditions. During the latter, normally in the summer ~vhen greater amounts of wastewaters are generated due to increased ~ater demand, the river quality worsens, and would be improved if the low flow river conditions were augmented. The effectiveness of low flow augmentation would, however, depend on the type of waste, condition of :he river water, location of the sources of wastewater and the location 3f the reservoir used as a means for low flow augmentation and drought control. The cost component of reservoir storage for the flow
Water quality oJ' Yamuna River
373
augmentation would form only a small percentage of the total cost of the multi-use reservoir. The storage reservoirs would store the flood water and release it in a regulated manner. Such a release during dry weather would therefore help to maintain the river at a desired quality level. Such reservoirs may also be used for hydroelectric plants, and in such cases the peak discharges from the plants would have an adverse effect on river quality. As an alternative to reservoirs, pumped storage reservoirs could also be used to augment the low flow conditions. Reservoir storage, apart from use in augmenting low flows, also affects the quality of the stored water, as was discussed for the reservoir at Dak Patthar. During storage in such reservoirs, the biodegradable matter and pathogens are reduced, the suspended solids settle out, and cool water is available in the summer for industrial cooling purposes. Because back flow conditions used to be created by the larger drain flow at (summer) times of minimum river flow conditions, a reservoir was created at the downstream end of the Wazirabad water works at Delhi mainly to protect raw water intake from possible contamination by the Najafgarh drain, situated a few metres downstream of the intake point. However, this reservoir could also be used for augmenting the low flow of the Yamuna River at critical times, at least to prevent fish mortality.
Regulated release of stored wastes Another approach in the maintenance of river quality along the urban centres on the Yamuna during dry weather river flow conditions is to store the generated wastewater which can be released in a regulated manner, depending on the flow conditions in the river and the desired quality goals for the river. The wastewaters could be stored in lagoons/oxidation ponds where they become partly purified (Bhargava, 1984). This can also be a suitable alternative in situations where a municipality is too poor to afford complete wastewater treatment, and where pollution control programmes are at a planning or execution stage. This approach would be suitable for Delhi and Agra, where large spaces could be made available for such storage and partial treatment of the wastewater, until such time as the planning and execution of the comprehensive pollution control programmes are completed.
River developments The river development works should be directed towards increasing the discharge in the rivers and modification of river configurations to improve
374
Devendra Swaroop Bhargava
the surface area, bed slope, velocity, etc., for better re-aeration and selfassimilative capacity. Considerable scope of this kind exists on the Yamuna River at the identified urban centres.
Diversion of drains The drain outfalls into the river could be diverted (through pumping if necessary) to locations where the stream has a better waste assimilative capacity. The drains to be diverted should be chosen particularly from those stretches of the river which are to be improved and made more suitable for beneficial uses. This approach would improve the Yamuna in some of its stretches at Delhi, where about twenty large and small drains are discharged into the river.
Treatment of drainage channels The pollution load on the river can be reduced by encouraging treatment of the wastewaters carried through the drains. Water hyacinth, which has a significant potential for purifying wastewater of all types and reducing the toxic as well as organic loads of the wastewater, could be harvested in selected stretches of the drains carrying wastewater (Sagar & Bhargava, 1981). Very coarse screens should be installed at both the ends of selected stretches of the drains to prevent the flow of water hyacinth into the river. The configuration of the drains should also be improved to increase reaeration, which could be further enhanced by installing artificial reaerators in the drains. This approach should be attempted in a few selected drains, particularly the Najafgarh drain at Delhi which has a long course before its outfall into the Yamuna River.
Improving the assimilative capacity of rivers The rivers can take up greater pollution stress and be maintained at a better quality through artificial aeration, which can at times be more effective than advanced wastewater treatment. Some of the common devices that can be conveniently used include diffusion aerators (oxygen transfer takes place through the train of bubbles generated by pumping compressed air through the diffusers placed at the river bottom; the efficiency of this system would depend on the river depth, fineness of the bubbles, and the spacing of the diffusers) and mechanical surface aerators (oxygen transfer takes place due to the negative pressure created by a rotating aerator impeller placed at the water surface, and due to the increased interfacial area between the air and the water). This approach is, however, costly.
Water quality of Yamuna River
375
Better use of assimilation capacity
For an optimal utilisation of the assimilation capacity of a river, a rational effluent distribution policy should be followed. The distribution should correspond in time (regulated discharge in relation to the river flow), and in space (pumping the wastewater to selected discharge locations in relation to the oxygen budgeting in the river).
CONCLUSIONS It would be most desirable to adopt both defensive as well as offensive strategies simultaneously in order to achieve the best results. Some strategies for improving the Yamuna quality at Delhi alone have been presented elsewhere (Bhargava, 1982). Depending on the finance available, the appropriate strategies should be selected from the above series of options for an efficient pollution control at each urban centre along the river.
Practical applications The methodology presented for identification of the river stretches requiring control of their water quality could be employed to devise pollution control programmes. The river standards could also be specified in terms of the water quality indices depending upon the intended use of the river. For administrative purposes, a river classification based on the water quality indices would be useful.
ACKNOWLEDGEMENT The author is grateful to the Indian Institute of Technology, Kanpur for providing facilities for this study.
REFERENCES Bhargava, D. S. (1977). Water quality in three typical rivers in UP--Ganga, Yamuna and Kali. Thesis presented to the Indian Institute of Technology, Kanpur, India, in partial fulfilment of the requirements for PhD degree.
376
Devendra Swaroop Bhargava
Bhargava, D. S. (1982). Improving the Yamuna for Delhites. Int. Symp. on Food Industry and the Environment, held at Budapest, Hungary, 9-11 September 1982. Bhargava, D. S. (1983a). A light penetration model for the rivers Ganga and Yamuna. Int. J. Develop. Technol., 1, 199-205. Bhargava, D. S. (1983b). Effect of subsurface water on Yamuna water quality at Delhi. J. environ. Engng Div., Instn Engrs, lndia, 64, 33-4. Bhargava, D. S. (1983c). Most rapid BOD assimilation in Ganga and Yamuna rivers. J. environ. Engng, Am. Soc. Civil Engrs, 109, 174-88. Bhargava, D. S. (1983d). Use of a water quality index for river classification and zoning of Ganga River. Environ. Pollut, Ser. B, 6, 51-67. Bhargava, D. S. (1983e). Very low altitude remote sensing of the water quality of rivers. Photogram. Engng & Remote Sensing, J. Am. Soc. Photogram., 49, 805-9. Bhargava, D. S. (1984). Monographs for aerobic stabilisation pond (oxidation pond) design. J. environ. Engng Div., Instn Engrs, India, 64, 81-5. Deb, B. C. & Chadha, S. P. (1964). A stud),' on the quality of Indian river waters. Tech. Mem. IRDI, Government of India, Central Water and Power Research Station, Poona. Pathak, B. D., Venkatesan, S. & Bhattacharya, S. C. (1976). Recent findings of groundwater exploration in Uttar Pradesh. Geological Survey of India, 125th Anniversary Celebrations, Lucknow, November 1976. Pavoni, J. L., Tenney, M. W. & Echelberger, W. F. Jr (1972). Bacterial exocellular polymers and biological flocculation. J. War. Pollut. Control Fed., 44, 414 31. Sagar, G. & Bhargava, D. S. (1981). Water hyacinth: An aid to sewage treatment. Proc. int. Symp. on Water Resources Conservation, Pollution and Abatement, held at Roorkee, India 11 13 December 1981, 259-68.
Water Quality Variations and Control Technology of Yamuna River
Devendra Swaroop Bhargava Division of Environmental Engineering, Department of Civil Engineering, University of Roorkee, Roorkee 247667, India
ABSTRACT A one-man water quality survey of the Yamuna River of the Indogangetic plain was undertaken to determine the variations in the quality of this river along its course during both summer and winter seasons, The variations in water quality are discussed with regard to the several water quality parameters, and a water quality index representing the integrated effect of the concentrations and relative importance of the parameters is used to denote degradation of the river quality. Stretches of the river are identified which require quality upgrading. A comprehensive strategy is presented for improving the water quality of the river.
INTRODUCTION The Yamuna is one of the important rivers of the Indogangetic plain. It originates as an upland river from Yamnotri in the Himalayas and in its upper reaches carries large amounts of suspended inorganic material. Smaller quantities of the dissolved substances occur in the summer when snow melt and runoff constitute the flow. In winter, this situation is, however, reversed because the underflows, springs, seepage, etc., make up the greater part of the river's volume. The water quality of the Yamuna River thus undergoes significant natural change during the two major seasons of the year. There is considerable human activity of various kinds along the course 355 Environ. Pollut. Set. A. 0143-1471/85/$03.30© ElsevierApplied SciencePublishersLtd, England, 1985. Printed in Great Britain
356
Devendra Swaroop Bhargava
of Yamuna River, including domestic, commercial, agricultural and industrial activities, and, as a result, different types of waste material enter the river, continuously altering its water quality. It is significantly degraded when it passes through the major urban centres such as Delhi, Mathura, Agra. The effect is more severe in the summer months when the river volume is comparatively low. The river water quality is also considerably changed by its tributaries. The most important of these, the Chambal, brings about an improvement in the water quality of the Yamuna which, like any other river, also undergoes self-purification along its course. The Yamuna River is used for a variety of activities, all affected to varying degrees by the degraded water quality. To improve the usefulness of the river, a comprehensive pollution control strategy and policy needs to be evolved for implementation at a national level.
WATER QUALITY SURVEY OF YAMUNA RIVER The Yamuna River system is shown in Fig. 1, together with its various tributaries and the major urban centres from its origin to Allahabad where it merges into the Ganga, the most important river of the Indogangetic plain. A one-man water quality survey of Yamuna River (Bhargava, 1977) was undertaken along its entire course during summer and winter to investigate variations in the Yamuna water quality, the related implications for the various beneficial uses, and to work out a suitable strategy for controlling its pollution status. Portable equipment such as portable-size incubators, pressure cookers, balance (Dial-O-Gram), conductivity meter, galvanic cell oxygen analyser, pre-calibrated turbidity disc, thermometers, etc., together with the necessary glassware, chemicals and other accessories were carefully packed into boxes for transportation to the various stations along the river. Temporary laboratories were set up at each sampling station. Observations for some of the water quality parameters could be made directly at the river site. For the remaining parameters river samples were collected for analysis in the temporary laboratories. The turbidity and suspended material were interpreted indirectly from a measurement of the depth of light penetration (DLP). For this purpose, a l0 cm diameter weighted metal disc coloured red and white in alternate quadrants was used (Bhargava, 1983a). Such a disc was considered
Water quality oj Yamuna River
Scale
Dak
patthar
0
[
eDehradun
3~
t
357
1:5,000,000 100
[
J
200 I
,
300 km l
• Ha ridwor
lew • Ih i ~
2~
Mothura'~ A gro~,~ "~,=41 _~ ~ 0~_.~'I/
~o-
•Kannauj
x
• Lucknow
Gorakhpur
Kanpur
2~
2~
I
78"
I
82°
I 86 o
Fig. 1. Yamuna River stream system.
superior to the standard Secchi disc from the point of view of visibility and to maintain a vertical position in the flowing water. The DLP used in this study is the depth in centimetres of this disc below the water surface at which it just becomes invisible. The observations of the various water quality parameters at the upstream and downstream sides of the sampling stations are presented for both seasons in Table 1. Photographs of the water surface at each sampling point were also taken in order to correlate the photographic optical density (POD), determined from the analysis of the photographs, with conventional pollution parameters (Bhargava, 1983e). Integrated effect of the water quality parameters
The various beneficial uses of water were grouped into five categories according to their quality requirements, viz. (1) swimming, bathing, drinking without treatment, etc; (2) public water supplies; (3) agriculture; (4) industry; and (5) culture, wildlife, non-contact recreation, boating,
18 (19) 20
20 (19)
17 (18) 20
18 (18) 18
20 (19) 20
15 (14) 15
W
W S
W
S
68
0"1 27 28
1"0 56
0.2528 31
30
0.4
0-5
0-35
0-5587
0.7573
59
49
44
0.22 0.6 31 41
0"25 0"5 43 44
0"22 0'6 23
0"3
0"02 0.01 36 47
0'1
0"6
7.0
6.5
5-7
7.1
7"4
7"5
8"0
7"5
7"9
1"6 2"3 13 102 7"4
S
8-4
8.7
8.3
8.3
9"2
9"2
8"6
2"2
8"5
7"9
8-0
W
Velocity DLP DO (m s 1) (cm) (rag litre-l)
a u/s, upstream; d/s downstream; S, summer; W, winter.
d/s
29 (31) --
u/s
Allahabad
28 (29) 29
30 (30) 30
30 (31) 32
20'5 (23) 19
29 (30)
d/s
u/s
d/s
u/s
d/s
u/s
d/s
u/s
S
Temperature (°C) b
Hamirpur
Agra
Mathura
Delhi
Dak Patthar
Station
a
--
3.3
5.9
14-0
12.0
12"0
7'0
10'0
5"2
2-6
5"4
S
3.0
1.9
2-6
8.0
6-0
6.1
3-0
4"5
2"9
1"65
1-35
W
36
43
67
115
89
87
32"5
4.5
2"8
2"5
S
72
69
77
285
304
203
200
63"3
30"0
5"0
5-5
W
-
466
630
770
700
660
658
364
196
140
200
S
424
417
457
670
666
615
613
344
260
150
165
W
BOD Chloride Conductivity (rag litre 1) (rag litre ~) (m mhos era-l)
TABLEI Obse~ationsalongtheYamunaRiver
152
192
254
232
204
204
184
104
52
70
S
142
144
148
228
223
216
214
172
140
72
92
W
Hardness as CaCO 3 (mg litre 1)
22
79
+2400
540
+2400
+2400
+2400
70
350
+2400
S
280
70
33
1 600
280
84
920
+ 2400
170
14
70
W
1"4
1"4
1"1
1"2
1'0
0"6
0"6
0-8
0"4
1.0
1"1
W
Coliform Nitrogen MPN (rag litre-l) (lOOml 1)
61
53
22
33
31
44
51
70
82
59
S
55
74
72
34
49
50
50
45
71
89
93
W
Overall WQI
e~
oo
23 11
2
69 65
71
59 44
56 64
63 28
84 82
W 99 91 70 35 58 62 58 47 79 82 78
40 79 69 42 47 23 32 21 79 89 --
--
71
63
8 43
28 25
93 74
94 96
S
W
S
46
47
41
8 8
8 8
78 53
94 94
W
Agriculture
--
76
65
49 41
45 43
58 55
47 79
S
65 68
71
51 49
46 46
55 62
91 82
W
Industry
WQI values JOt various benej4cial uses Public water supplies
u/s, upstream; d/s, downstream; S, summer; W, winter.
85
u/s d/s
u/s d/s
Agra
35 14
Allahabad
u/s d/s
Mathura
57 27
69
u/s d/s
Delhi
35 67
S
Swimming, drinking without treatment, bathing, etc.
Hamirpur
u/s d/s
Dak Patthar
Station
T A B L E
Computed Values of the WQI in the Yamuna River°
--
72
68
92 88
89
69 65
51 35
90 45
72 58
81 75
99 98
83 91
65 50
W
S
Fish culture, wildlijb non-contact recreation, boating
t~
Devendra SwaroopBhargava
360
etc. (Bhargava, 1983d), and a water quality index (WQI) was used to evaluate the suitability for each category of use: n
rl--[
-I ~/"
:LI
w0,
i=I
in which n is the number of water quality parameters considered relevant i
t20
,
,
,
1
"~
60 60
18
~.0
i7
20 13
,
,
,
~ummef ......
Winter
....
'- . . . . . .
,
I I
L
-"
,s"
~0.000
,
[
I
;;o~2o
"P ...........
I000 100 250 ~ ¢J 10 150 8 0 0
50 400 300 2OO s
I00 O 125
A
~-
Chloride
'8
7.5 2.5 12
"6
~
. . . . . . . .
"S -= . . . . . . . -Lp -1
100 50
"3
0 35 l I
.~ ; ." k"
j
~
_
g
E
=~
0 10
Z 5
(.;, 8
:l: 7
~-"~'--, 0 200
•;
g
~
E
~
g
=_
.E
~
;
~ 0 43
O
6
~ S
~'''T "a /-00
~
--Distance
Fig, 2.
"
I
'
cn
2
-"
Temperature
5
~
~
-- %- " DO
-2
0
I
...................
25
E
¢1
~ ........ f°'t-
,
i 600
,
I 800
~ "-i*''rl 1000
~
~
o~ s t a t i o n s
E
in
km
1
Variations in Yamuna River water quality.
a
1200
II II
III III
II --
II
IV IV
III IV
II III
III II
S
II I1
II
III Ill
III III
II III
I I
W
II --
Ill
V III
IV IV
I II
I I
S
llI II1
III
V V
V V
II II1
I I
W
Agriculture
II --
II
III III
Ill III
IIl III
III I1
S
II II
II
III Ill
III III
III lII
I I1
W
Industry
River class ]or the beneficial uses Public }cater supplies
a u/s, upstream; d/s, d o w n s t r e a m ; S, s u m m e r ; W, winter.
Allahabad
II --
II
u/s d/s
II
IV IV
u/s d/s
Agra
Hamirpur
III III
III IV
u/s d/s
Mathura
III 1V
III IV
u/s d/s
Delhi
II II
III II
W
u/s d/s
S
Swimming, drinking without treatment, bathing
Dak P a t t h a r
Station
TABLE3 Water QualityClassoftheYamunaalongitsCourse"
II --
I1
III III
II III
II III
II I
S
I II
II
II II
II II
I IIl
I I
W
Fish culture, wildlife, non-contact recreation, boating
taa
~-
"~
362
Devendra Swaroop Bhargava
to the use, andf/(Pi) is the sensitivity function of the ith parameter, which depends on the concentration and importance value of a parameter for a given use. The WQI ranges from 0 (worst water) to 100 (best water) (Bhargava, 1983d). The WQI values for each category of use at various points along the Yamuna River in both summer and winter are presented in Table 2. The overall WQI at a given point has also been computed from
TABLE 4
Acceptable BeneficialUses in the Various Zones of the Yamuna River Acceptable (Classes I and 11 only) beneficial uses
Stretch of the Yamuna River
Summer
Winter
Dak Patthar Delhi
Public water supply, agriculture, fish culture, wildlife, non-contact recreation, boating
All except industrial
Delhi-Hamirpur
Nil
Fish-culture, wildlife, non-contact recreation, boating
Hamirpur-Allahabad
All except agriculture
All except agriculture
these data by assuming equal weighting of all the beneficial uses (Table 1). If desired, different weightings could be assigned for the different uses at a given point, on the basis of the relative cost of each use for evaluation of the overall WQI. The variations in the Yamuna water quality in respect of the several water quality parameters and the overall WQI are presented in Fig. 2. Each beneficial use was graded into a class: I (excellent), II (good), III (satisfactory), IV (poor) and V (unacceptable) for corresponding WQI values of 90 + , 65-89, 35-64, 11-34, and - 1 0 , respectively (Bhargava 1983d) (Table 3). Table 4 gives acceptable uses for the various zones of the Yamuna River.
Water quality of Yamuna River
363
R E S U L T S A N D DISCUSSION
Temperature variations The temperature was lowest at Dak Patthar, the station close to the Himalayas from where the river originates, and varied identically in both seasons, rising sharply from Dak Patthar to Delhi at a rate of about 5 °C 100km-1 in summer and 2°C 100km-1 in winter. The summer rate is higher due to a greater difference in the river and ambient temperatures at Dak Patthar when compared with Delhi, where the river almost reaches equilibrium with the ambient temperature. In the winter months, the river temperature is slightly higher than the ambient temperature due to the higher temperature of the sub-surface water which constitutes the major flow of the river, and the variations of river and ambient temperature are therefore identical. The magnitude of temperature rise at urban centres due to wastewater outfalls depends on the ratio of the wastewater discharge rate to the river discharge rate. Downstream, the temperature falls due to evaporation and radiation. The average cooling rate, for example, is seen in both seasons to be around 1 °C 100km-~ in the Delhi-Mathura reach of this river, and 3°C 100km -~ in the Mathura-Agra reach. The impounding reservoir between upstream and downstream of Dak Patthar also receives cooler groundwater in summer months, as a result of which the downstream temperature is lowered. A higher microbial activity, and hence greater assimilation rate of the organic pollution, results in summer months than in the winter although the higher temperature makes bathing more comfortable during the summer months.
Variation in DLP The D L P (representing the clarity of the river water) is very high upstream of Dak Patthar where the river originates as an upland river in winter (when the discharge is comprised mostly of infiltering clearer groundwater) when compared to summer (when the snow melt runoff carrying a large suspended load reaches the river). However, the impounding reservoir at Dak Patthar tends to remove the turbidity, as a result of which the D L P stabilises to around 50 cm downstream of Dak Patthar in both seasons. The inflow of wastewaters between Dak Patthar and Mathura results in a drop of clarity in both seasons. At Delhi, where large
364
Devendra Swaroop Bhargava
amounts of wastewater outfall into the river, significant bioflocculation with extracellular polymers (excreted by bacteria in their endogenous phase) acting as excellent coagulants (Pavoni et al., 1972) takes place (Bhargava, 1983c), and results in a rise of clarity from upstream to downstream of Delhi in both seasons. The river having acquired significant extracellular polymers by the time it reaches Mathura, the bioflocculation causes a further increase in clarity thereafter, in both seasons. Due to greater bacterial activity in summer months, the clarity rise is more significant. The clarity observations alone cannot be relied upon to interpret the pollution status of a river, because low clarity may be caused by the discharge of inorganic suspended matter, while suspended and colloidal portions of the discharged organic materials may be removed due to bioflocculation, resulting in an improvement of clarity (or turbidity)---although the biochemical oxygen demand (BOD) would increase on account of the dissolved portions of the discharged organic material. The velocity variation would significantly affect the D L P caused by inorganic suspended material (Bhargava 1983a). The organic material causing turbidity is affected very little by velocity variation (Table 1), which shows that the D L P variation is insignificant in spite of variations in velocity between Delhi and Agra, where considerable amounts of organic matter enter the river. In this stretch of the river, the stream velocity is low and cannot sustain large amounts of inorganic material. Due to higher clarity, the river maintains a high aesthetic appearance from Dak Patthar to Agra in winter, and from Agra to Allahabad in summer. Greater clarity would also mean deeper light penetration, which would encourage higher photosynthetic activity in the river. DO and BOD variations
The variation patterns of the dissolved oxygen (DO) and BOD in the river are identical in both seasons. Higher BOD values all along the river in the summer months compared with the corresponding values in the winter were due to the smaller summer river flow. For obvious reasons, the DO values were higher in the winter. The retention time of the impounding reservoir at Dak Patthar has an equalising effect on both these parameters. The BOD in the reservoir becomes stabilised due to selfpurification mechanisms (such as settling, mixing, assimilation, etc.), to a value around 2mg litre-1 in both seasons, as a result of which its downstream value decreases in summer but increases slightly in the
Water quality o] Yamuna River
365
winter. The DO similarly stabilises to around 7.9 mg litre- 1, causing the downstream value to increase slightly in summer, but to decrease in winter. In both seasons, on an average long-term basis, the BOD increases from Dak Patthar to Agra but decreases thereafter, while the D O slightly decreases from Dak Patthar to Agra but afterwards increases. This is due to large organic load inputs from point and non-point sources and their stabilisation and natural removal from Dak Patthar to Agra, and vice versa from Agra to Allahabad. The less polluted Chambal River plays a significant role in decreasing the BOD and increasing the DO beyond Agra. At almost all urban centres along the Yamuna River, the BOD rises steeply immediately after the wastewater outfalls in the river. Such rises are sharper and greater in summer when the river volume discharge is reduced. As a consequence, the D O also drops sharply below the wastewater outfalls. The flow velocity in the Yamuna is low (extremely low in the Delhi region) enough to sustain algal growth which contributes part of the oxygen needed to maintain high BOD input during the summer months. Delhi has several outfalls and the BOD in the Yamuna rises to as much as 60 mg litre- 1 below the Najahgarh drain outfall in summer. This value is reduced to as low as 5 mg litre- 1 after a distance of about 6 k m due to bioflocculation and the extremely fast self-purification of the Yamuna (Bhargava, 19830. The DO as a consequence was found to drop to extremely low values, even touching zero, after some wastewater outfall drains, but due to the river's extremely high reaerating ability, the DO was able to recover significantly in a short distance (Bhargava, 1983c). Because a significant drop in the river DO takes place only after some distance from the waste outfall point, by which distance the BOD is considerably reduced, DO alone cannot therefore be used to define the pollution status of a river. The set of B O D - D O values would indicate the self-purifying ability of the river apart from its pollution status. F r o m the consideration of BOD and DO, the Yamuna River at most urban centres remains unfit for bathing, fish culture, etc. Several cases of mass fish mortality have occurred in Delhi. One of the water works situated at Okhla downstream of Delhi provided extensive treatment (including heavy pre-chlorination) to the river water which had a B OD of about 6-8 mg litre- ~. Although the Okhla treatment plant was involved in public controversies several times, no waterborne epidemic could be
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attributed to this water works. The Yamuna River water upstream of the urban centres is utilised after appropriate treatment for public water supply at almost all the urban centres situated along it. The river's high BOD assimilation capacity has been fully exploited for wastewater disposal purposes and this results in an economy ofwastewater treatment COSTS.
Variations in chloride, hardness and conductivity Chlorides, hardness and conductivity remain at their lowest values in both seasons at Dak Patthar, with similar variation in both seasons. The higher chloride content along the entire river in winter is due to a greater contribution from the sub-surface water as compared to that from the exposed rocky material during the summer months. In winter it rises steeply between Delhi and Agra as this stretch of the river is regenerated almost entirely from groundwater infiltration (Bhargava, 1983b). Hardness and conductivity are contributed from the sub-soil as well as surface minerals (such as limestone and dolomite), and therefore are seen to be of almost equal magnitude in both seasons along the entire river. Due to changes in soil characteristics, the hardness is slightly higher in the Dak Patthar-Agra reach in the winter, but after Agra it is higher in the summer. In both seasons, hardness increases in the Dak Patthar-Agra reach due to the undersaturated (negative Langelier Index) character of the river water, but decreases after Agra due to oversaturation of the water (Bhargava, 1977). For conductivity, such a reversal takes place at Delhi. The decreasing trend in both seasons in the concentrations of chloride, hardness and conductivity from Agra onwards is due to the changed sub-soil and exposed rocky material characteristics and to the entry of the Chambal River which carries a significant discharge with low dissolved mineral content (Deb & Chadha, 1964). The larger discharge from the Chambal in winter makes this decrease more significant in winter than in summer. After Hamirpur, however, these dissolved mineral contents are maintained at more or less uniform levels in both seasons. The discharge of wastewater (which contains higher concentrations of dissolved minerals) in significant volumes causes an increase in the river concentrations of chloride, hardness and conductivity. At Delhi, significant amounts of groundwater (of higher chloride content) are used for domestic industrial, private and municipal purposes, new residential colonies, Jhuggis Jhomparies (unhygienic clusters of huts without any
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367
organised water supply or drainage), and other habitations around the town. The whole of this used groundwater finds its way into the Yamuna as part of the municipal and industrial wastewater, as a result of which the chloride content of the Yamuna rises in both seasons (Bhargava, 1983b). The increase in the chloride content at Delhi is 35 mg litre - 1 in winter and 28 mg litre-1 in summer. The greater upswing in winter is because of added groundwater infiltration into the Yamuna. In contrast, at Agra, the chloride content in the Yamuna decreases downstream of the town by about 20 mg litre - 1 in winter and about 50 mg litre - 1 in summer, because of a lower chloride content of the groundwater in the Agra region (Pathak et al., 1976). A greater decrease during the summer months suggests a larger industrial use of cooler groundwater. The effect of groundwater on the Yamuna chloride content at Allahabad is insignificant because of the very large flow rate of the Yamuna at Allahabad. The high chloride content of the Yamuna between Mathura and Agra during the winter months renders the Yamuna water less suitable for agricultural purposes.
Variations in coliform MPN (most probable number) and nitrogen (ammonia) The coliform variation is almost identical in both seasons. The summer values are higher than those in winter, due to the greater volume of domestic wastewater in summer. The coliform counts are very high at urban centres because of discharge ofwastewaters from domestic sources. Due to the natural death rate of coliforms, their numbers decrease between the urban centres unless there are fresh additions from non-point domestic wastewater sources. The ammoniacal nitrogen accompanies an increase in the ratio of total plate count to the coliforms. The coliform content is high between Delhi and Agra, so that the Yamuna River is not suitable for bathing, swimming or other contact recreational uses. This presents a serious situation because almost all the religious centres to which people go for bathing (including inhaling the raw water for mythological-religious objectives), and camps, fairs, recreation, etc., are situated between Delhi and Agra. Perhaps the Indian people have developed a natural immunity or have such immense faith in their religious pursuits that they do not contract diseases even after drinking water polluted with such high coliform counts. During the river survey people were observed at several places drinking the raw untreated river water in connection with religious rites. I was rebuked when I tried to
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Devendra Swaroop Bhargava
inform some of them of the dangers and risks involved. At one place, I witnessed some youngsters brushing their teeth with river water just downstream of a waste outfall sewer. This is perhaps how they become immune to the dangers of drinking bacterially contaminated water. In the circumstances, it would be in the interests of public health to plan (at a national level) and urgently execute a comprehensive pollution control strategy and programme for the Yamuna, the sacred river of the Hindus.
Identifying the sensitive stretches of Yamuna Figure 3 gives the WQI for the various beneficial uses of the Yamuna for both seasons. Assuming a WQI greater than 65 (that is, not lower than Class II for any use) as the limit for the river to be of some value for use, the exploitable uses for the various stretches of the Yamuna River are indicated in Table 4. This can also be seen in Fig. 3, in which the dashed lines denote each beneficial use at a WQI value of 65. A study of Table 4 shows that the Yamuna can be exploited for public water supplies, agriculture and fish culture, in both seasons from Hamirpur to Allahabad, and for fish culture alone in winter from Delhi to Hamirpur. As pointed out earlier, the Delhi-Hamirpur stretch is most critical because of the occurrence of religious centres. If the water quality can be improved in this stretch, the quality of the Yamuna from Hamirpur to Allahabad would automatically also improve. Since the greatest degradation of the Yamuna takes place at the Indian capital Delhi, which is the largest urban centre along its course, efforts should mainly concentrate on improving the quality of the water at Delhi, where the overall WQI drops from 70 to below 50 in both seasons. The overall WQI remains above 70 from Dak Patthar to Delhi in both seasons, but is reduced to below 65 (that is, Class III and below) at all points downstream of Delhi in both seasons (except for the small stretch of Hamirpur to Allahabad in winter). The Delhi-Hamirpur stretch involves three major urban centres, viz. Delhi, Mathura and Agra. The best strategy would be to include all these in the priority programme for improving the Yamuna water quality in the order Delhi, Agra and Mathura, as the overall WQI is seen to drop on an average basis for the two seasons by 22.5 at Delhi, by 13 at Agra, and by 6.5 at Mathura. It is expected that the cost of such a programme would be proportional. Table 1 also shows that the upgrading of river water quality
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required in terms of the overall WQI (to attain at least a value of 65) downstream of these urban centres would be 14 and 20 at Delhi, 43 and 31 at Agra, and 34 and 15 at Mathura for summer and winter, respectively. These upgradings in the overall WQIs (43 at Agra, 34 at Mathura and 20 at Delhi) would make the Yamuna fit for overall use in both seasons.
Technological measures for enhancing Yamuna quality The programme for enhancing the Yamuna quality should not only be implemented at all the urban centres situated along the river, but also at all possible identifiable non-point sources of wastewater entering the river. This would require an extensive survey of the entire catchment area of the Yamuna River basin. However, as pointed out, the order of implementation should depend on the magnitude of the overall WQI value that is lost at each urban centre. Such control of the Yamuna River quality would involve several approaches, broadly grouped into defensive and offensive. The defensive approaches would aim at reducing the pollution load on the river (so that its self-purification capacity is not overburdened) through proper planning, treatment and disposal of the wastewaters. Such approaches would include the following programmes. Wastewater collection
A master plan of the urban centre of the river local basin should be utilised for evolving a comprehensive plan for the collection of wastewaters. Particular attention should be paid to segregation of the wastewaters having different and specific characteristics. Storm water should as far as possible be collected separately, taking care to exclude all other wastewater. Industry should be advised to segregate wastes requiring special treatment and provide separate collection lines for (i) industrial wastes requiring special treatment, (ii) domestic wastewaters for transporting to the municipal sewerage system, and (iii) storm waters for disposal into nearby open drains or the storm drainage system if one exists. Wastewater treatment
All wastewaters collected should be subjected to an appropriate treatment before their final disposal into the river. Industry should be advised of the satisfactory treatment of special wastes.
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371
Advances in inplant practices Industry should be advised to: (i)
Reduce their waste load generation. This can be done through: (a) modification and efficient use of raw materials used in industrial production so as to produce the least offensive and least volume of waste (b) employing the latest process technologies and modifications to suit local conditions, enabling a reduction in the generation of waste loads (c) attempting a recovery system for wastes which would eliminate or reduce the waste load as well as give returns in the form of by-products (d) trying a modification of the waste generation process with the object of getting the least obnoxious and least bulk of wastes (e) practise the re-use of effluents and re-cycling ofwastewaters. (ii) Reduce the peak flows of waste through load equalisation techniques. (iii) Reduce the pollution potential of wastewater through neutralisation. (iv) Tailor industrial production according to the assimilation capacity of the receiving rivers. This should, however, be practised only in emergency situations after full consideration of economic losses for industry and the gains of the municipal corporations from the water resources thus protected.
Temperature control in power plants Nuclear power plants and electric power plants along the Yamuna River, such as the thermal power plants at Delhi which discharge wastewater at significantly high temperatures into the rivers and cause thermal stress in the river system, should modify their cooling systems and discharge their wastewaters after spraying them into the air before release into the river, or use other techniques to normalise the wastewater temperature.
Planning and zoning of disposal outJalls The outfall points carrying the wastewaters for disposal into the river should be properly planned so that they are located at a point where the river has maximum waste assimilation capacity and ability. This aspect is important, particularly because rivers vary in their self-purification
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Devendra Swaroop Bhargava
character from stretch to stretch and a proper design of the number and spacing of wastewater outfalls for best assimilation is highly technical. Although it is economical to treat all the wastewater at one point, it may in some situations be more appropriate to dispose of all the effluent through several properly spaced and designed outfalls.
Improved agricultural practices The agricultural practices (crop raising, poultry and livestock farming) ~¢hich result in the release of organic matter, fertilizers, pesticides, herbicides, etc., into the rivers through land runoff, erosion and land drainage systems should be improved to reduce the organic, nutrient and Loxic loads on the river system. To achieve these improvements, the fertilizers, pesticides, herbicides, etc., reaching the river should be reduced by (i) an efficient, optimal and economical use of these chemicals, (ii) erosion control in the fields, and (iii) disposal of organic wastes generated From this practice onto agricultural land.
Environmental control I'he various pollutants reach the river through drains carrying urban runoff. An impression of a clean or dirty city is obtained from the river quality near the city, implying that efforts should be made towards a zleaner environment. Attention should therefore be paid to public and private sanitation, efficient refuse collection and disposal systems, and ~treet cleaning. The offensive approaches should aim at the fullest exploitation and improvement in the waste assimilative capacity of the river, so that the river quality can be enhanced. Some of these approaches would include Lhe following.
Drought control l'he river quality and the assimilative capacity vary significantly from flood to drought conditions. During the latter, normally in the summer ~vhen greater amounts of wastewaters are generated due to increased ~ater demand, the river quality worsens, and would be improved if the low flow river conditions were augmented. The effectiveness of low flow augmentation would, however, depend on the type of waste, condition of :he river water, location of the sources of wastewater and the location 3f the reservoir used as a means for low flow augmentation and drought control. The cost component of reservoir storage for the flow
Water quality oJ' Yamuna River
373
augmentation would form only a small percentage of the total cost of the multi-use reservoir. The storage reservoirs would store the flood water and release it in a regulated manner. Such a release during dry weather would therefore help to maintain the river at a desired quality level. Such reservoirs may also be used for hydroelectric plants, and in such cases the peak discharges from the plants would have an adverse effect on river quality. As an alternative to reservoirs, pumped storage reservoirs could also be used to augment the low flow conditions. Reservoir storage, apart from use in augmenting low flows, also affects the quality of the stored water, as was discussed for the reservoir at Dak Patthar. During storage in such reservoirs, the biodegradable matter and pathogens are reduced, the suspended solids settle out, and cool water is available in the summer for industrial cooling purposes. Because back flow conditions used to be created by the larger drain flow at (summer) times of minimum river flow conditions, a reservoir was created at the downstream end of the Wazirabad water works at Delhi mainly to protect raw water intake from possible contamination by the Najafgarh drain, situated a few metres downstream of the intake point. However, this reservoir could also be used for augmenting the low flow of the Yamuna River at critical times, at least to prevent fish mortality.
Regulated release of stored wastes Another approach in the maintenance of river quality along the urban centres on the Yamuna during dry weather river flow conditions is to store the generated wastewater which can be released in a regulated manner, depending on the flow conditions in the river and the desired quality goals for the river. The wastewaters could be stored in lagoons/oxidation ponds where they become partly purified (Bhargava, 1984). This can also be a suitable alternative in situations where a municipality is too poor to afford complete wastewater treatment, and where pollution control programmes are at a planning or execution stage. This approach would be suitable for Delhi and Agra, where large spaces could be made available for such storage and partial treatment of the wastewater, until such time as the planning and execution of the comprehensive pollution control programmes are completed.
River developments The river development works should be directed towards increasing the discharge in the rivers and modification of river configurations to improve
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Devendra Swaroop Bhargava
the surface area, bed slope, velocity, etc., for better re-aeration and selfassimilative capacity. Considerable scope of this kind exists on the Yamuna River at the identified urban centres.
Diversion of drains The drain outfalls into the river could be diverted (through pumping if necessary) to locations where the stream has a better waste assimilative capacity. The drains to be diverted should be chosen particularly from those stretches of the river which are to be improved and made more suitable for beneficial uses. This approach would improve the Yamuna in some of its stretches at Delhi, where about twenty large and small drains are discharged into the river.
Treatment of drainage channels The pollution load on the river can be reduced by encouraging treatment of the wastewaters carried through the drains. Water hyacinth, which has a significant potential for purifying wastewater of all types and reducing the toxic as well as organic loads of the wastewater, could be harvested in selected stretches of the drains carrying wastewater (Sagar & Bhargava, 1981). Very coarse screens should be installed at both the ends of selected stretches of the drains to prevent the flow of water hyacinth into the river. The configuration of the drains should also be improved to increase reaeration, which could be further enhanced by installing artificial reaerators in the drains. This approach should be attempted in a few selected drains, particularly the Najafgarh drain at Delhi which has a long course before its outfall into the Yamuna River.
Improving the assimilative capacity of rivers The rivers can take up greater pollution stress and be maintained at a better quality through artificial aeration, which can at times be more effective than advanced wastewater treatment. Some of the common devices that can be conveniently used include diffusion aerators (oxygen transfer takes place through the train of bubbles generated by pumping compressed air through the diffusers placed at the river bottom; the efficiency of this system would depend on the river depth, fineness of the bubbles, and the spacing of the diffusers) and mechanical surface aerators (oxygen transfer takes place due to the negative pressure created by a rotating aerator impeller placed at the water surface, and due to the increased interfacial area between the air and the water). This approach is, however, costly.
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Better use of assimilation capacity
For an optimal utilisation of the assimilation capacity of a river, a rational effluent distribution policy should be followed. The distribution should correspond in time (regulated discharge in relation to the river flow), and in space (pumping the wastewater to selected discharge locations in relation to the oxygen budgeting in the river).
CONCLUSIONS It would be most desirable to adopt both defensive as well as offensive strategies simultaneously in order to achieve the best results. Some strategies for improving the Yamuna quality at Delhi alone have been presented elsewhere (Bhargava, 1982). Depending on the finance available, the appropriate strategies should be selected from the above series of options for an efficient pollution control at each urban centre along the river.
Practical applications The methodology presented for identification of the river stretches requiring control of their water quality could be employed to devise pollution control programmes. The river standards could also be specified in terms of the water quality indices depending upon the intended use of the river. For administrative purposes, a river classification based on the water quality indices would be useful.
ACKNOWLEDGEMENT The author is grateful to the Indian Institute of Technology, Kanpur for providing facilities for this study.
REFERENCES Bhargava, D. S. (1977). Water quality in three typical rivers in UP--Ganga, Yamuna and Kali. Thesis presented to the Indian Institute of Technology, Kanpur, India, in partial fulfilment of the requirements for PhD degree.
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Bhargava, D. S. (1982). Improving the Yamuna for Delhites. Int. Symp. on Food Industry and the Environment, held at Budapest, Hungary, 9-11 September 1982. Bhargava, D. S. (1983a). A light penetration model for the rivers Ganga and Yamuna. Int. J. Develop. Technol., 1, 199-205. Bhargava, D. S. (1983b). Effect of subsurface water on Yamuna water quality at Delhi. J. environ. Engng Div., Instn Engrs, lndia, 64, 33-4. Bhargava, D. S. (1983c). Most rapid BOD assimilation in Ganga and Yamuna rivers. J. environ. Engng, Am. Soc. Civil Engrs, 109, 174-88. Bhargava, D. S. (1983d). Use of a water quality index for river classification and zoning of Ganga River. Environ. Pollut, Ser. B, 6, 51-67. Bhargava, D. S. (1983e). Very low altitude remote sensing of the water quality of rivers. Photogram. Engng & Remote Sensing, J. Am. Soc. Photogram., 49, 805-9. Bhargava, D. S. (1984). Monographs for aerobic stabilisation pond (oxidation pond) design. J. environ. Engng Div., Instn Engrs, India, 64, 81-5. Deb, B. C. & Chadha, S. P. (1964). A stud),' on the quality of Indian river waters. Tech. Mem. IRDI, Government of India, Central Water and Power Research Station, Poona. Pathak, B. D., Venkatesan, S. & Bhattacharya, S. C. (1976). Recent findings of groundwater exploration in Uttar Pradesh. Geological Survey of India, 125th Anniversary Celebrations, Lucknow, November 1976. Pavoni, J. L., Tenney, M. W. & Echelberger, W. F. Jr (1972). Bacterial exocellular polymers and biological flocculation. J. War. Pollut. Control Fed., 44, 414 31. Sagar, G. & Bhargava, D. S. (1981). Water hyacinth: An aid to sewage treatment. Proc. int. Symp. on Water Resources Conservation, Pollution and Abatement, held at Roorkee, India 11 13 December 1981, 259-68.