Assessment of Surface Water Quality of River Kali-east: A Tributary of River Ganga in Uttar Pradesh, India

River Kali-East, a tributary of river Ganga, is a non-perennial river of India which is highly driven by the discharge of sewage and industrial euent. Twenty-seven locations on the entire stretch (approx. 550 km) of river Kali-East were monitored which indicated that color varied as 20-200 Hazen, dissolved oxygen (DO) as 0-8.16 mg/l, biochemical oxygen demand (BOD) as 6.6-410 mg/l, chemical oxygen demand (COD) as 22-1409 mg/l, total suspended solids as 38-4386 mg/l, total dissolved solids as 180-2536 mg/l and fecal coliform as 4.9 × 10 2 - 34 × 10 7 MPN/100 ml. High BOD and COD in the river revealed untreated/partially treated industrial discharge into the river and the self-purication capacity of the river Kali-East has been inhibited for a long distance by heavy and undiminished inux of domestic sewage into the river. Twenty-six drains discharge a total organic load of 148 tonnes per day into the river. Maximum pollution load was contributed by Odean Nala (42%) in Meerut district. This study recommends strict regulatory norms for discharge of industrial euents by the industries in the catchment area of the river, reduction in sewage treatment gap by utilizing alternative treatment technologies (such as constructed wetlands) and proper dilution of polluted river water to improve the overall quality of the river. latifolia, Phragmites australis (Cav.) Trin. ex Steud. and C. esculenta. Apart from metals, the average removal eciency of physico-chemical characteristics, i.e., conductivity, TDS, BOD, TSS, NO 3 -N, NH 4 -N and PO 4 -P in winter and summer season were observed from 55.3–91.61% to 64.8– 94.1%, respectively. Phytoremediation could also prove successful for the treatment of industrial wastewaters. Rai and Tripathi (2009) reported

Considering these issues, the present study was carried out with following objectives: (i) to carry out a comprehensive evaluation of surface water quality of river Kali-East from its origin to the con uence with river Ganga; and (ii) to evaluate the status of pollution load and treatment in the catchment area of river Kali-East.

Description of the study area
Kali-East river is a non-perennial tributary of the holy river Ganga in India. The ow in the river is mainly due to industrial wastewater discharge or rainfall. It originates in Khatauli town (29°16'45.09"N, 77°47'18.96"E) in Muzaffarnagar district of Uttar Pradesh state of India where the ow in the river is attributed to a sugar mill drain. Thereafter, it traverses a distance of approximately 550 km through the districts of Meerut, Hapur, Ghaziabad, Bulandshahar, Aligarh and Kasganj in Uttar Pradesh. The river Kali-East meets river Ganga in Kannauj district of Uttar Pradesh at 27°0'45.34"N, 79°59'6.76"E. In the catchment area of river Kali-East, various industries (sugar, distillery, chemical, pulp & paper, and textile) are located. Climate is humid sub-tropical with predominantly three seasons namely summer season (March-May) which is extremely hot, winter season (November-February) which is cold and rainy season between June and October. The temperature in the area varies from 0 to 50°C. The Bay of Bengal branch of the Indian monsoon is the major bearer of rain in this area with an average annual rainfall of 840 mm. Approximately, 80% of the annual rainfall is received from the south-west monsoon during July to September.
Geologically, the study area lies within the Ganga-Yamuna inter uve. The top stratum consists of approximately 1.3 km thick layer of quaternary alluvium. Alluvial deposits are sub-divided into older and younger alluvium. Younger alluvium is restrained to river passages and the surroundings of the low-lying areas which is generally ooded during the monsoon season. The alluvium in this area encompasses alternate beds of sand and clay with occasional inter-beds of calcareous concretions. The granular zones consist of various sand grades varying from ne through medium to coarse sands (Singh 2004;Umar et al. 2008).
For the present study, 27 monitoring locations on river Kali-East were selected starting from its origin in Khatauli (Muzaffarnagar) to its con uence with river Ganga in Kannauj. During its course, 26 drains with different sources (domestic/industrial/mixed) meet with the river. At two locations, freshwater Ganga canals (upper and lower Ganga canals) meet with the river which decreases the pollution load in the river. The sampling locations on river Kali-East were selected in such a way so that the effect of the receiving wastewater from drains on the river can be assessed. The sampling locations on the river, drains and freshwater canals are shown in Fig. 1 and Supplementary Figure S1.

Collection of river and drain samples
Surface river water samples were collected from 27 selected locations during the pre-monsoon season (March-May) of 2019. The detail of sampling locations on the river is presented in Table 1. Wastewater samples were collected from 26 drains discharging into the river Kali-East. The detail of drains is shown in Table 2. Wastewater samples from drains were collected before the con uence point of the drain with the river Kali-East. Samples were collected using grab sampling technique for the determination of physico-chemical (color, pH, BOD, COD, TSS, TDS, NH 3 -N and NO 3 -N) and biological (total and fecal coliform) properties of river water. Samples for color, pH, BOD, COD, TSS, TDS, NH 3 -N and NO 3 -N were collected in polyethylene bottles. Samples for DO, total and fecal coliform were collected in glass bottles. Samples for NH 3 -N were preserved with H 2 SO 4 , and DO samples were preserved with MnSO 4 and NaN 3 . After collection, samples were transferred to the laboratory in an ice-box.
For metal analysis, grab samples of water/wastewater from the river and drains in polypropylene bottles were also collected. The samples were immediately acidi ed with HNO 3 after collection to avoid precipitation.

Analysis of river and drain samples
After reaching the laboratory, river/drain samples were analyzed for physico-chemical and biological parameters following standard methods (APHA 2017). Metal (As, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Hg, Zn, Sb, Co, Se, and V) concentration in water/wastewater samples of river and drains was measured using atomic absorption spectrophotometer following standard protocols (APHA 2017).

Flow measurement in drains
The ow of wastewater in drains was measured using Ball-oat method (CPHEEO 2013). Instantaneous ow in drains was calculated as Where Q was measured in m 3 /sec; A is the average cross-sectional area of ow in m 2 ; V is the average velocity of ow in m/sec.
The average cross-sectional area of ow was calculated as where the average cross-sectional area of ow was measured in m 3 /sec; W and D are width and depth of the ow measured in m.
Width, Depth, and average surface velocity are measured thrice and average values were considered for further calculation of ow.
As ow velocity is not identical in the entire cross-section of the drain, suitable correction factors were applied so that ow is not exaggerated/over-estimated (Subramanya 2009). A factor of 0.8 was used for averaging velocity and ow width. Therefore, the resulting factor (0.8 × 0.8) ~ 0.65 was considered for ow calculation in natural drains.

Organic load of drains
Organic load in drains was calculated as where TPD is tonnes per day and MLD is million litres per day.

Quality assurance and quality control
Reliable results were guaranteed by following appropriate quality assurance protocols and procedures during sample collection, preservation, and analysis. Bottles were acid washed before the collection of samples. Samples were transported in ice-boxes to ensure data representativeness. The analytical quality was assured by using duplicate samples, reagent, and procedural blanks. The atomic absorption spectrophotometer was calibrated after every ve readings using blank and drift reagents. High calibration coe cients were maintained (r 2 ≥ 0.99) during the analysis of metals. For each metal, the limit of detection was calculated as thrice the standard deviation of blank samples.

Results
In river water, the color varied as 20-200 Hazen, DO as 0-8.16 mg/l, BOD as 6.6-410 mg/l, COD as 22-1409 mg/l, TSS as 38-4368 mg/l, TDS as 180-2536 mg/l, Cl¯ as 27-845 mg/l, NH 3 -N as 1.5-77.4 mg/l, NO 3 -N as 0.1-5.8 mg/l and PO 4 -P as 0.2-5.2 mg/l. The physico-chemical properties of river water at 27 selected monitoring locations are presented in Table 3. The color of water in uences the photosynthesis process due to differential penetration of light, energy budget, strati cation due to thermal gradients, and the aesthetic appearance of the aquatic ecosystems (Branco and Torgersen 2009). Color is a prominent feature of natural water when good quality water is produced from it for domestic and industrial purposes (Chow et al. 2007). In ltered water, the color chie y arises from the dissolved organic carbon (fraction of total organic carbon) and ferric iron (Fe (III)) Table 4. In the present study, the river was highly polluted until approximately 143 km downstream from the origin of the river. In this stretch (Muzaffarnagar to Bulandshahar district), DO was NIL and BOD was high (up to 410 mg/l). However, after the mixing of the upper and lower Ganga canal in the polluted water of the river Kali-East, the water quality improved (DO increased and BOD decreased). The DO level increased to 7.7 mg/l and BOD decreased to 15.6 mg/l before meeting the river Ganga.
In Muzaffarnagar district, high BOD (410 mg/l), COD (1070 mg/l) and TDS (1094 mg/l) in the river water downstream sugar mill drain were observed. Also, low pH (4.9) in river water indicates industrial discharge from near-by industries. In Meerut district, pronounced foul smell around the river was observed D/s Chhoiya drain and Hapur drain. The color of the river water at these locations varied as 154-178 Hazen. The foul smell in the river water may be attributed to anaerobic decomposition of organic matter present in the river.
Also, it was observed that river water U/s Chhoiya drain, D/s Chhoiya drain, and D/s Hapur drain is being utilized for irrigation of adjoining agricultural elds. Irrigation of agricultural elds with the polluted river water may deteriorate human health due to the bioampli cation of pollutants to the human food chain. In Bulandshahar district, the river water quality (BOD-186 mg/l, COD-1409 mg/l) deteriorated after the discharge of 11 drains into the river. Till Bulandshahar, there is no DO in the river. However, after traversing a distance of approximately 143 km, the river meets upper Ganga canal and the river water quality improved substantially (DO-0.8 mg/l, BOD-22 mg/l, and COD-76 mg/l) at U/s Wave Distilleries and Breweries Ltd., Aligarh after meeting the canal. In Aligarh district, the river further meets another canal i.e. lower Ganga canal and the river water quality after meeting the canal improved further (DO-5.9 mg/l and fecal coliform-490 MPN/100 ml) at U/s Kasganj drain. In Kannauj district, the DO in the river Kali-East increased to 7.7 mg/l before the con uence with river Ganga.

DO-sag curve
The DO-sag curve in the river Kali-East is presented in Fig. 2. Considering bathing water quality criteria (pH 6.5-8.5, DO ≥ 5 mg/l, BOD ≤ 3 mg/l, and FC < 500 MPN/100 ml), the water quality of the river Kali-East was found complying with bathing water standards w.r.t.
pH except for one location namely, U/s Sugar mill drain in Muzaffarnagar. Low pH (4.9) in the river at this location may be attributed to the discharge of untreated e uent from near-by sugar industries. With respect to DO, no location in the stretch from Muzaffarnagar to Aligarh was found suitable for bathing. Due to the mixing of freshwater from the Ganga canal in the river Kali-East, the water quality in Kasganj and Kannauj before meeting the river Ganga was meeting the primary water quality criteria w.r.t. DO. Also, no location in the whole stretch of the river meets bathing water quality w.r.t. BOD. High BOD in the river is due to the discharge of untreated domestic sewage and industrial e uents from the catchment area.

For fecal coliform, only two locations, namely, (i) U/s Kasganj drain in Kasganj and (ii) at Khudaganj bridge in Kannauj were meeting
bathing water quality standards.

Biological properties of surface water of river
Total coliform (TC) and fecal coliform (FC) levels in surface water of the river were estimated (Table 3). In river water, the total coliform Kali-East before the con uence with river Ganga were 2.8 × 10 8 and 9.4 × 10 6 MPN/100 ml. The discharge of high levels of coliforms by the river Kali-East into the river Ganga increases the fecal pollution load in river Ganga which could have adverse effects on the population dependent on the water of the river Ganga for drinking and cooking purposes.

Metals concentration in surface water of river
Metals (As, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Hg, Zn, Sb, Co, Se, and V) concentration in surface river water samples are shown in Table 5.  Cr, Zn, Fe, Ni, Mn, and Pb (Chowdhary et al. 2018). The composition of wastewater generated by food and dairy and chemical industries depends upon the product-speci c raw materials.

Pollution load due to drains
Twenty-six drains (domestic and industrial) discharge wastewater into the river Kali-East accounting for total ow and an organic load of 803 MLD and 148 tonnes per day, respectively. Odean Nala is the major contributor in terms of pollution load (42%). Two drains namely the Odean Nala (25%) and Abu Nala-2 (25%) accounted for 50% of the total wastewater being discharged into the river. The district-wise distribution of drains contributing pollution load into the river Kali-East is presented in Fig. 3. Out of the eight districts, the maximum number of drains are observed in Bulandshahar i.e. 11, however, the maximum pollution load was contributed by Meerut i.e. 67.7 % of the total pollution load on the river Kali-East.
[Insert Fig. 3 here] In drains, the color varied as 37-317 Hazen, pH as 5.1-8.2, BOD as 21.8-1067 mg/l, COD as 104-1752 mg/l, TSS as 48-946 mg/l, TDS as 552-2572 mg/l, NH3-N as 5-82 mg/l and NO3-N as 0.7-4.6 mg/l. The physico-chemical properties of wastewater in drains meeting river Kali-East are shown in Table 6. High BOD (1067 mg/l), high COD (1752 mg/l), and acidic pH (5.1) were observed in the Sugar mill drain which indicated the untreated/partially treated industrial discharge into the river. Saini Village drain consisted of high BOD (385 mg/l) and high COD (893 mg/l) which may be attributed to the discharge of wastewater from paper industries in the catchment area. Also, Odean Nala comprised BOD-311 mg/l and COD-721 mg/l which may be due to industrial discharge from textile industries in the vicinity.

Pollution Mitigation Strategy
Illegal discharge of untreated domestic and industrial wastewater increases the pollution load in the river Kali-East. Consequently, the polluted water of the river Kali-East pollutes the river Ganges after meeting it in Kannauj (Uttar Pradesh). To mitigate the pollution load on the river due to domestic sewage and industrial e uent, eleven sewage treatment plants (STPs) and one common e uent treatment plant (CETP) are constructed to treat wastewater generated in the basin of the river. The total sewage treatment capacity in the basin of river Kali-East is 181 MLD, out of which 168 MLD is located in Meerut (12 STPs) and 13 MLD in Kannauj (01 STP). For treating industrial e uent, one CETP (2.1 MLD) is located in the Pilakhua town of Hapur district. In spite of the construction of STPs, there is a huge gap (46.9%) between sewage generation and sewage treatment capacity in the catchment area of the river Kali-East.
The competent authority must ensure that all sewage treatment facilities operate at the designed capacities. Also, the up-gradation of STPs must be considered if possible. All stakeholders must ensure the treatment of sewage before being discharged into the river.
Different types of industries (sugar, textile, pulp & paper, dairy & food, distillery, and chemical industries) in the catchment area of the river are a potential threat to the water quality. Timely inspection of industries regarding the compliance of discharge standards should be carried out by the competent authority to ensure the water quality of the river Kali-East. The river water is also used by farmers for irrigation of agricultural elds (Fig. 4). This must not be practiced by the farmers to avoid bio-accumulation and bio-ampli cation of pollutants into the food chain.
[Insert Fig. 4 here] The Hon'ble NGT (Government of India) has ordered the construction of su cient sewage treatment facilities for treating drains discharging urban sewage into the river (NGT 2019b). The Hon'ble NGT also suggested the application of phytoremediation/constructed wetlands to treat drains carrying municipal sewage. In compliance with the NGT order, a total of nine locations in the catchment area of the river Kali-East may be considered for the construction of treatment wetlands to treat domestic sewage and industrial e uent (Fig. 5).

Conclusion
The water quality of the river Kali-East was assessed from its origin to con uence with river Ganga. The surface water quality indicated that biochemical oxygen demand varied as 6.6-410 mg/l, chemical oxygen demand as 22-1409 mg/l, color as  Hazen, DO as 0-8.16 mg/l, total suspended solids as 38-4386 mg/l, total dissolved solids as 180-2536 mg/l and fecal coliform as 490 − 34 × 107 MPN/100 ml. This study revealed that the river was highly polluted until approximately 143 km downstream from the origin of the river. In this stretch (Muzaffarnagar to Bulandshahar district), DO was NIL and BOD was high (up to 410 mg/l). However, after the mixing of the upper and lower Ganga canal in the polluted water of the river Kali-East, the water quality improved (DO increased and BOD decreased). The DO level increased to 7.7 mg/l and BOD decreased to 15.6 mg/l before meeting the river Ganga. With respect to DO, no location in the stretch from Muzaffarnagar to Aligarh was found suitable for bathing. Also, no location in the whole stretch of the river meets bathing water quality w.r.t. BOD. High BOD and COD in the river revealed untreated/partially treated industrial discharge into the river and the self-puri cation capacity of the river Kali-East has been inhibited for a long distance by the heavy and undiminished in ux of domestic sewage into the river. A total of 26 drains carrying sewage and industrial e uent discharge an organic load of 148 tonnes per day into the river. The maximum pollution load was contributed by Odean Nala (42%) in the Meerut district. This study recommends strict regulatory norms for industries in the catchment area of the river, reduction in sewage treatment gap and proper dilution of polluted river water to improve the overall quality of the river. The study also recommends the employment of constructed wetlands technology to treat the drains discharging wastewater into the river.
Declarations Figure 1 Map of water quality monitoring locations on river Kali-East in Uttar Pradesh state of India Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors. Schematic representation of drains and canals meeting river Kali-East in different districts of Uttar Pradesh (India) Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.

Figure 5
Proposed constructed wetland sites in the catchment area of river Kali-East Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.