1. College of Engineering and Technology (CEAT), International University of Business Agriculture and Technology (IUBAT), Bangladesh; haxsib@gmail.com
2. College of Engineering and Technology (CEAT), International University of Business Agriculture and Technology (IUBAT), Bangladesh; mahfuz8880009@gmail.com
3. College of Engineering and Technology (CEAT), International University of Business Agriculture and Technology (IUBAT), Bangladesh; khuzaifa26@gmail.com
4. College of Engineering and Technology (CEAT), International University of Business Agriculture and Technology (IUBAT), Bangladesh; 20106161@iubat.edu

*             Correspondence: shaaxxx.haxsib@gmail.com

Keywords: environmental issues, industrialization, Bangladesh

1. INTRODUCTION

Due to its toxic and chemical character, industrial effluent is one of the most serious environmental challenges, necessitating on-site treatment and careful management before release into the sewer system [1]. The land and environment are under immense pressure as a result of industry’s fast expansion and increased pollution. Very few people are aware of this globally increased issue, and Bangladesh, in particular, is currently in a vulnerable position [2]. Bangladesh, as a developing country, is presented with numerous major environmental issues, particularly in the area of water, as a result of rapid industrialization and urbanization, obstinate customs, poor economic situations, and a lack of understanding and technology in the country [3]. Water circumstances, such as regional and seasonal availability and quality, have a significant impact on Bangladesh’s environmental and economic progress. In terms of quality, the country’s surface water is vulnerable to untreated industrial effluents and municipal wastewater, as well as runoff pollution from chemical fertilizers and pesticides [4]. Water quality is also affected by effluent types and discharge quantities from various sectors, agrochemicals used in agriculture, seasonal water flow, and the river system’s dilution capability [5]. Bangladesh’s rapid industrialization over the last two decades has resulted in 30,000 large and small companies polluting the river system with their effluents. Pollution from industrial and municipal waste effluents, as well as agrochemicals, has reached catastrophic proportions in some bodies of water and rivers [6]. Dhaka is Bangladesh’s capital city, located in the country’s center. Five periphery rivers, including the Buriganga, Dhaleswari, Turag, Balu, Sitalakhya, and Tongi Khal, receive substantial amounts of municipal sewage and industrial effluent from Dhaka [7]. Along with the river, there are 300 outfalls of domestic and industrial effluents. The waterways are further polluted by the indiscriminate disposal of home, clinical, pathological, and commercial wastes, as well as the discharge of wasted fuel and human excreta [8]. Chemical, fertilizer, pesticides, textile, oil, power plant, ship repairing dock, cement, and tannery units are located in and around Dhaka [9]. Untreated industrial effluents, municipal wastewater, chemical fertiliser and pesticide discharge, and oil and lubricant leaks in and around river port operations threaten Dhaka river water quality. Since industrialization began in Bangladesh, pollution has skyrocketed. Konabari, Gazipur district, is Bangladesh’s largest industrial belt with several domestic and foreign industries. Every day, Konabari businesses leak massive amounts of wastewater into the surrounding land, agricultural fields, irrigation channels, and surface water, finally entering the Turag River. More importantly, dirty water kills and reduces aquatic life reproduction. Recently the Department of Environment classified the four rivers Buriganga, Sitalakhaya, Turag, and Balu as Ecologically Critical Areas (ECA) to improve ecosystems. Ecologically Critical Areas (ECA) are ecosystems that have suffered from human activities. Four rivers in and around Dhaka show the effects of urbanisation and industrialization [10]. It eventually harms humans. Heavy metals kill water flora and animals, harm the ecology, and make life harder for nearby residents. Cu, Fe, Pb, Cd, Co, Mn, Zn, and other trace heavy metals cause significant harm to the aquatic environment and humans [11]. Industrial pollution is a growing environmental issue in Bangladesh. The country’s limited industrial base accounts for 20% of GDP. Over half the contribution comes from manufacturing, which grew 5.04% between 1982 and 1992. Since the ready-made garments industry has risen significantly, so has the textile industry [12]. Coagulation, flocculation, quicksand, and progressive sand filtration purify water. Using slow sand filters. London uses SFFs, as did Western Europe until recently, and elsewhere. Slow sand filtering has declined in affluent countries due to rising land and labour costs, which elevate SSF-produced water costs. SSFs treat water cost-effectively when this is not the case (WHO n.y.). These conditions are common in developing nations, making it a promising method for water filtration and sustainable water systems. The process’s principle is straightforward. Sand physically and biologically filters contaminated freshwater. This eliminates sediments and pathogens. This approach relies on organisms’ infection-fighting abilities.

2. LITERATURE REVIEW

The number of chemical compounds used as raw materials in industry and infrastructure has expanded with the industry. Organic and inorganic material emissions into air, water, and soil rise. The problems are local, but their prevalence, scale, and potential implications are growing worldwide. Industrial wastes harm natural life through toxic activity or water quality changes [13]. A unsafe levels of industrial effluents and urban and agricultural waste in various Bangladeshi rivers and waterways. Dhaka, Bangladesh’s capital, is one of the world’s most populous cities with over 16 million, on the northern bank of the Buriganga River, the Turag, Dhaleshwari, Tongi Khal, Balu, and Sitalakhya rivers border it. Most businesses and manufacturing are around these rivers [14]. The Hazaribagh, Tejgaon, and Dhaka-Narayanganj-Demra dam sectors of Dhaka City have over 7000 industries along these rivers. Toxic waste from industrial areas and sewage lines, as well as petroleum from ships, launches, cargoes, boats, and so on, are polluting Dhaka City’s rivers [15]. River water is black like burned motor fuel in the dry season. Most physicochemical parameters meet WHO water standards. Some factors have changed during the past 40 years. Dissolve oxygen was 2 mg/L in 2000 [16]. It could be due to changes in sample collection procedure, time, and location. However, most research showed that extreme river contamination occurs in the Buriganga river basin. River water is black like burned motor fuel in the dry season. The vast majority of physicochemical fields [17]. Heavy metals like Pb, Cd, and Cr make river water dangerous. On Dhaka’s northern outskirts is the Turag River. Untreated industrial effluents, agricultural field wash, and slum sewage affect river water quality [18]. Most textile industries began here. Near the Turag River live farmers who employ inorganic fertilisers, pesticides, and herbicides. All waste lands in the river during the rainy season [19]. The Department of Environment labelled Turag River ecologically vulnerable. The upstream river water quality was poor due to the heavy industry in that area [20]. Farmers irrigate market crops using river water. People who eat vegetables, seafood, and rice from this area may have serious health issues. Research shows this area’s crops contain hazardous elements. The Turag River’s vegetation and animals bioaccumulated toxic metals, which could harm humans.  A Sitalakhya River tributary joins the river near Demra after crossing extensive wetlands in Beels and Belai. It joins the Turag River in northern Dhaka via Tongi Khal. Tongi, Norai, and Rampura khals and canals connected to the Balu River. Khals and canals carried toxic industrial effluent to the Balu River [21]. Effluents from the Tongi industrial zone, textile, pharmaceutical, food, soap and detergent, metal, dying, and other industries pollute river water. Municipal and agricultural waste enter the Balu River.Because to growing pollution, the Department of Environment declared the Balu River an environmentally critical state river in 2009 [22]. Former Brahmaputra River in Bangladesh is the source of all major rivers. Sitalakhya River crosses eastern Dhaka to join the Meghna at Kolagachi, Munsiganj. It draws water from the Balu and Dhaleshwari rivers [23]. Several factories were established on the riverbank through the canal, especially in Narayanganj, where industry is dense. The Sitalakhya River provides most cooking, drinking, bathing, washing, irrigation, and industrial water. Textile, cement, fertiliser, pulp and paper, sugar mill, jute, and other riverbank enterprises affect Sitalakhya River water quality. Pretreatment involves “roughing” treatment methods like sedimentation, storage, and roughing filtration to remove bigger, settleable particles before water enters the main treatment units. Pretreatment during high turbidity times can reduce the load on subsequent treatment units and save operating costs, especially for chemicals [24]. Rapid mix devices at the plant’s head end cause severe turbulence in raw water entry. Simple to build, run, and maintain with local resources and labour, hydraulic fast mixers including hydraulic jumps, flumes, and weirs can generate enough turbulence without mechanical equipment. The coagulant enters the raw water through an above-water perforated trough or pipe diffuser upstream of the peak turbulence [25]. Particle accumulation increases bed pressure loss for a given flow rate. In a gravity-fed bed, flow rate falls with constant pressure. Back-washing the bed removes particles when pressure loss or flow is unacceptable and the filter is no longer functioning. A fast pressurised sand bed filter occurs at 0.5 bar pressure drop. Pour backwash fluid through the bed to fluidize and expand by 30%. Sand grains combine and rub together, removing particle solids. Backwash fluid removes smaller particles to a settling tank. It takes a few minutes to fluidize the bed, but it requires 3 to 10 m3/m2/hr. Restocking the bed may be necessary after backwashing loses some sand [26].

3. MATERIALS AND METHODS

The locations of the study areas along the Turag River. Samples were taken in Turag close to the Abdullahpur Bridge, Bishwa Ijtema Field and Tongi Railway Bridge. The location of the Bishwa Ijtema in Tongi is near the Turag River. The initial location for sampling, which accepts a variety of industrial and residential effluents, was Turag’s Tongi Railway Bridge. One factor contributing to the Bishwa Ijtema’s pollution is the presence of pilgrims who camp by the riverside for three to seven days without access to a decent sanitary system. Heavy contamination ensued from the discharge of trash in the river. The Abdullahpur point located at the place of abnormally high level of pollution and encroachment. Ijtema Field, Abdullahpur Bridge, and Turag River Tongi Railway Bridge were the three main locations from which three water samples were taken. 500 ml plastic bottles were utilised to gather samples. Before being collected, a detergent solution was used to clean the bottles. Grab sampling was used to collect each sample. The bottles were sealed and appropriately labelled for identification following the sample process.  Collected water for testing from three points. Point three is Ijtema Ground, Abdullahpur Bridge, and Tongi Railway Bridge. Collected water from these points in six seasons. The water is infiltrated slow sand filter. Before and after infiltrating the water, do five tests for pH, TSS, TDS, turbidity, and COD. After doing the tests like Ph, TDS, TSS, COD and Turbidity.Can see that the performance of filter number 3 was good between other two filter. Number 3 filter making process used Sylhet sand, nuripathor, gravel and coal. Observe some differences between the tested values before and after infiltration by the filter. For the sieve analysis, 1020 grammes of dry Sylhet sand were used, and it was weighed using a digital scale. Then, using the US standard sieve, arrange it in ascending order. Shake well for several minutes while keeping the sample in the upper sieve. After that, measurements were made using the preserved sample.  A pH meter is used to measure the acidity or alkalinity of hydrogen ion activity in a solution. Similarly, TDS meter is a small hand-held device used to indicate the total dissolved solids in a solution, usually water. Generally, a TDS level of between 50 and 150 is considered the most suitable and acceptable. If the TDS level is about 1000 PPM, it is unsafe and unfit for human consumption. Bring the samples to the laboratory for TDS testing. Then prepare the samples in different beakers for testing. Total sample size is eight. Bring reagent for COD. Use COD medium range of the Sample is 0-1500 mg/L to determine high-range reagent vials. Pick a fresh reagent vial for sample preparation level the vial with sample number/ID.  To test the turbidity, took 10 mL of the water sample and measured the turbidity using the 10 mL of water turbidity machine.

4. RESULT & DISCUSSION

The result obtained on some physicochemical parameters of the Turag River water samples is presented in table below.

Table 01: Parameters of Turag River Raw and Filter water samples in the summer, Rainy, autumn, Late Autumn, winter, and spring seasons.

Name of Parameters	Season		Station												Mean ± SD					Bangladesh Standard		WHO
			Ijtema Ground (South West Corner)					Abdullahpur Bridge				Tongi Railway Bridge
			Raw		Filter			Raw		Filter		Raw	Filter		Raw			Filtrated
pH	Summer		7.8		7.6			8		7.9		8.1	7.8		7.9 ± 0.15			7.7 ± 0.15		6.5-8.5		6.5-8.5
	Rainy		7.9		7.8			8		7.6		8	7.8		7.9 ± 0.05			7.7 ± 0.12
	Autumn		8		7.7			8.1		8		7.9	7.7		8 ± 0.1			7.8 ± 0.17
	Late Autumn		7.9		7.7			8.3		7.8		8	7.8		8.06 ± 0.20			7.7 ± 0.08
	Winter		9.1		8.5			8.4		8		8.3	7.9		8.6 ± 0.43			8.1 ± 0.32
	Spring		7.8		7.8			8		7.8		8	7.9		7.9 ± 0.11			7.8 ± 0.05
TDS (mg/L)	Summer		330		311.66			350		337.6		300	284		326.66 ± 25.1			311.1 ± 26.8		1000		–
	Rainy		270		259.83			310		299		280	273.3		286.66 ± 20.8			277.38 ± 19.8
	Autumn		590		577.66			560		540.6		470	461.1		540 ± 62.45			526.28 ± 59.56
	Late Autumn		580		569.67			595		583.66		500	486		558.3 ± 51.07			546.4 ± 52.81
	Winter		600		584			630		607.67		600	585		610 ± 17.32			592.2 ± 13.38
	Spring		575		568.66			600		585.66		490	478.6		555 ± 57.66			544.33 ± 57.49
TSS (mg/L)	Summer		43.78		40.90			44.7		41.93		46.2	41.59		44.9 ± 1.23			41.49 ± 0.49		75		–
	Rainy		41.45		39.53			41.25		38.44		43.5	41.43		42.06 ± 1.24			39.80 ± 1.51
	Autumn		45.66		43.19			52.47		49.65		51.3	46.94		49.81 ± 3.6			46.59 ± 3.2
	Late Autumn		52.72		49.33			51.29		48.08		54.2	50.83		52.73 ± 1.45			49.49 ± 1.37
	Winter		56.29		52.55			54.66		51.62		55.8	52.28		55.58 ± 0.83			52.15 ± 0.47
	Spring		53.30		49.59			48.5		44.51		49.6	47.82		50.46 ± 2.51			47.31 ± 2.57
Name of Parameters		Season		Station												Mean ± SD			Bangladesh Standard		WHO
				Ijtema Ground (South West Corner)			Abdullahpur Bridge				Tongi Railway Bridge
				Raw		Filter	Raw		Filter		Raw			Filter		Raw	Filtrated
COD (mg/L)		Summer		50		47	46		44		53			50		49.66 ± 3.5	47± 3		4.00		5-20
		Rainy		38		34.33	39		36.33		45			43		40.66 ± 3.7	37.88± 4.5
		Autumn		42		38.66	47		44.33		55			52.33		48 ± 6.55	45.11± 6.8
		Late Autumn		52		49.34	56		53		60			54.66		56 ± 4	52.33± 2.7
		Winter		58		54.66	61		57.66		66			61		61.66 ± 4.04	57.77± 3.1
		Spring		51		48.33	50		47.33		57			53.3		52.66 ± 3.78	49.66± 3.2
Turbidity (NTU)		Summer		38.3		35.37	42.22		38.79		45.6			42.28		42.04 ± 3.65	38.81± 3.4		10		–
		Rainy		35.58		31.78	36.4		32.84		38.33			34.29		36.77 ± 1.41	32.97± 1.2
		Autumn		55		50.66	50		45.33		47.5			43.80		50.83 ± 3.81	46.60± 3.6
		Late Autumn		61		56.33	57		52.33		55			50.67		57.66 ± 3.05	53.11± 2.9
		Winter		70		63.33	65		59.3		65			59.66		66.66 ± 2.88	60.77± 2.2
		Spring		65		58.66	61		54.66		62.66			56.67		62.66 ± 2.08	56.66± 2

Figure 01: Before Filtration and After Filtration Value of pH

Figure 02: Before Filtration and After Filtration Value of TDS

Figure 03: Before Filtration and After Filtration Value of TSS

Figure 04: Before Filtration and After Filtration Value of COD

Figure 05: Before Filtration and After Filtration Value of Turbidity

Figure 06: Average Efficiency of Before Filtration and After Filtration Value

Figure 07: Percentage of Before Filtration and After Filtration pH Value

Figure 08: Percentage of Before Filtration and After Filtration TDS Value

Figure 09: Percentage of Before Filtration and After Filtration TSS Value

Figure 10: Percentage of Before Filtration and After Filtration COD Value

Figure 11: Percentage of Before Filtration and After Filtration Turbidity Value

Tests showed good water quality: 3.22% pH, 2.73% TDS, 6.33% TSS, 6.1% COD, and 8.8% Turbidity. Bangladeshi and WHO requirements for drinkable water pH are 6.5-8.5. In between: 8.5. In winter, Ijtema field has a pH of 9.1, far higher than drinkable. In five of six seasons, water pH is acceptable for agriculture, but winter pH is too high. Water with TDS per litre less than 300 is good, according to WHO recommendations. 300–600 mg/L is preferable. The ideal range is 600–900 mg/L. 900 to 1200 mg/L is harmful; higher is inappropriate. Bangladeshi TDS is 1000 mg/L. Agriculture tolerates 200–500 mg/l TDS. In summer, rainy season, and spring, TDS is 200–500. Water TDS is over 200–500 in the remaining 3 seasons. So agriculture may use summer, rainy, and spring water. Autumn, late autumn, and winter are all unsuitable for farming. Season 3 has a TDS value over 200-500. TSS testing of the water from the three places shows that Summer Rainy and Spring water can be used for agriculture at 50 mg per litre. Northern water is inappropriate for agriculture since its TSS value is over 50 in late autumn and winter. Tests show that summer, monsoon, and spring Turag River water is good. Monsoons and strong rains occur throughout summer. Spring river levels are high due to monsoon rains and fall to the bed. Due to river water rising, the water is clearer than in other seasons. Bangladesh specifies 10 NTU turbidity and WHO 5 NTU. Out of six seasons, it did not meet Bangladesh or WHO standards. The seasonal mean pH values for Summer, Rainy, Autumn, Late Autumn, Winter, and Spring were 7.9, 7.9, 8, 8.06, 8.6, and 7.9. Table shows the DoE standard pH 6–9 value for irrigation, home, and recreational purposes. The pH Ijtema Ground (South West Corner) Winter is over 9, making it unfit for irrigation or residential usage. Normal pH for surface water systems is 6.5–8.5 and groundwater is 6–8.5 (Gob, Environment Conservation Rules, 1997). Biological activity is highly affected by pH. It impacts water body features like organism activity and poisonous substance efficacy. Corrosiveness of water requires alkalinity and pH measurements. Except for the Railway Bridge station, all testing samples met the FAO drinking water criterion (1000 μs/cm). Total dissolved solids (TDS) indicate the presence of colloidal and dissolved minerals such ammonia, nitrite, nitrate, phosphate, alkalis, certain acids, sulphates, metallic ions, etc. Also a key water chemistry characteristic. Summer, Rainy, Autumn, Late Autumn, Winter, and Spring mean. According to WHO principles per litre of drinking water, the TDS value of the sample water was good because it varied little with TDS. Surface water COD is usually 20 milligrammes per litre or less for clean water. River and running water had COD levels over 200 mg/L. COD can range from 100 to 60,000 mg/L in industrial water. WHO limits COD in water to 10 ppm. Railway Bridge has greater COD since most industries are near its bank. Their organic/inorganic garbage enters this waterway. Concentrations were higher in the dry season and lower in the wet. Autumn had the highest value. The Railway Bridge had the highest COD in autumn and the lowest in spring. Water should not exceed 4 mg/L (DoE/BEMP, 2003). The three points’ water samples had a mean turbidity of 52.77 NTU.  The present investigation found higher Turag River water turbidity than the highest mean of 66.66 NTU. The seasonal mean turbidity values for Summer, Rainy, Autumn, Late Autumn, Winter, and Spring were 42.04, 36.77, 50.83, 57.66, 66.66, and 62.66 NTU. All levels surpass DoE (1997), DPHE (2019), and USEPA (2012) drinking and irrigation limits. Only the two contrasts—winter against rainy season and winter compared pre-winter—showed a substantial difference in turbidity. The three water samples had a mean TSS content of 49 mg/L. At 55 mg/L, Turag River water had more TSS.  Industrial effluent entered the river through pipelines, canals, open drains, etc., polluting it and perhaps raising TSS levels. The seasonal mean TSS values for Summer, Rainy, Autumn, Late Autumn, Winter, and Spring were 44.49, 42.06, 49.81, 52.73, 55.58, and 50.46 mg/L. The assessed TSS values exceeded the drinking threshold, according to DPHE (2019). TSS values vary greatly by season, except for winter extremely summer and pre-winter versus wet season.

4.1 Discussion

Samples were taken from eight different points along the river to monitor the water quality: Mirpur Bridge (M B), Hazaribag (H B), Kamrangir Char (KC), Chandni Ghat (C G), Sadar Ghat (S G), Dholaikhal (DL), Bangladesh China Friendship Bridge (BCFB), and Pagla (Pa). pH ranged from 6.58 to 7.98 in 2015, while the normal pH range for inland surface water for fishing is 6.5 to 8.5. The pH ranged from 6.66 to 7.79 in 2014. In 2015, the dissolved oxygen (DO) level of the Buriganga river water was exceedingly low (0.0 mg/l). The DO of the Buriganga river was more than EQS (>5 mg/l) in 2015. The highest DO (5.70 mg/l) was measured at Mirpur Bridge in July, and the lowest (0.0 mg/l) was reported at all locations between January and April. The proximate reasons of DO depletion in the dry season are reduced water flow, direct discharge of untreated effluent from industries, residential wastes, and tannery wastes into the river, and during the wet season (June to October), the DO level in all river locations increased modestly.  The Shitalakhya River is a tributary of the Brahmaputra. It is navigable throughout the year. Water samples were obtained from three separate places for monitoring water quality: Demra Ghat, Ghorasal Fertilizer Factory (GFF), and near the ACI factory in Narayanganj. Shitalakhya river water’s pH in 2015 was within the EQS (6.5-8.5) range for inland surface water. At Ghorasal Fertilizer Factory (G.F.F), the greatest pH was 7.97 in March and the lowest PH was 6.66 in May. pH ranged from 6.8 to 7.8 in 2014. In 2015, the highest DO (5.5 mg/l) was discovered at G.F.F in August, while the lowest (0.0 mg/l) was discovered near the ACI facility in November and December. DO levels ranged from 0.0 to 5.6 mg/l in 2014. During a dry time in 2015, BOD levels at Damra Ghat were extremely high. BOD levels near the Ghorasal Fertilizer Factory were within the EQS (6 mg/l) for fisheries in May and June. As the industry has grown, so has the number of chemical compounds utilized as raw materials in the industry and industrial facilities. As a result, there is an increase in organic and inorganic material emissions into the air, water, and soil [27]. Although the problems occur in specific locales and regions, they are global in the sense that their incidence, scale, and possible consequences are quickly increasing [28]. Industrial wastes are recognized to have a negative impact on natural life, either directly through toxic action or indirectly through qualitative changes in the water’s nature [29]. Pollution from industrial effluents and urban and agricultural garbage has reached dangerous levels in several rivers and water bodies in Bangladesh [30]. Dhaka City, Bangladesh’s capital, is one of the world’s most populous cities, with a population of more than 16 million people. It is situated on the northern bank of the Buriganga River, bordered by the Turag, Dhaleshwari, Tongi Khal, Balu, and Sitalakhya rivers. The majority of enterprises and factories are located on or near the banks of these rivers [31]. Because the amount of organic matter in the raw water limits the microorganisms, the stationary phase of bacterial populations occurs when the flow is stopped (where cell growth and cell death are at equilibrium). Organic matter is liberated and made accessible to microorganisms deeper inside the filter during this phase. This method achieves steady-state biological growth and organic matter biodegradation [32]. When the filter flow is interrupted, the pore and ponded water may become depleted of substrates, dissolved oxygen, and nutrients, endangering the filter’s microorganisms. It has discovered a significant drop in DO within 2 hours of ceasing flow in a bacteriologically active filter. The generation of near-anaerobic conditions decreased the total fixed bacteria density in the filter. However, at lower water temperatures, when bacteria are already less active, the effect was less noticeable. Despite the reported loss in biomass, it has found minimal influence on the quality of generated water.

5. CONCLUSION

The study collected water samples from three points of Abdullahpur Bridge, Tongi Railway Bridge and South West Corner of Bishwa Ijtema Maidan in six seasons. The raw water parameters observed were not acceptable for drinking water purposes and also not acceptable for irrigation purposes because all parameters do not follow the irrigation range. For this research, make three filter, which is slow sand filter. After filtering number 3 filter performance is good between other two filter. The performance of these three filters is good in that it removes some impurities. The water quality of Turag River varies from time to time. Maximum pollution is found in late autumn and winter. After filtration, it is observed that Turag river water is not suitable for drinking water purpose but mostly suitable for irrigation purpose as per water quality range of Bangladesh. Depending on the results, it can be said that the water of Turag River is polluted.

6. RECOMMENDATION

Some recommendation for de-pollution of Turag River are following.

• Necessary initiatives should be taken to realize the importance of water among the citizens, the navigability of the river should be increased by dredging, various chemical and fertilizers are mixed in the arable land along the river, these fertilizer and chemicals get mixed in the river water with rain.
• The use of fertilizers and chemicals should be stopped. The construction of factories on the banks of the river should be stopped, as well as the treatment of chemical and tannery wastes from factories in major industrial areas of the country should be made mandatory and their safe disposal should be ensured.
• So it is mandatory to set up a treatment plant or Effluent Treatment Plant (ETP) with every industrial plant. Mixing of oily effluents from factories should be prevented.
• Necessary measures should be taken to prevent encroachment, filling and pollution of rivers, proper enforcement of environmental laws and legal punishment of water polluters should be ensured.
• Public awareness is also needed in this regard.

REFERENCES

1. Rahman, A., Jahanara, I., & Jolly, Y. N. (2021). Assessment of physicochemical properties of water and their seasonal variation in an urban river in Bangladesh. Water Science and Engineering, 14(2), 139-148.
2. Rahman, M. O., & Alam, M. Z. (2021). Seasonal Variation of Water Quality Constituents in the Turag River. International Journal of Research and Innovation in Applied Science, 6(9), 118-125.
3. Islam, M. J. (2024). A Study on Seasonal Variations in Water Quality Parameters of Dhaka Rivers. Iranica Journal of Energy & Environment, 15(1), 91-99.
4. Khatun, M., & Rashidul Alam, A. K. M. (2020). Phytoplankton assemblage with relation to water quality in Turag River of Bangladesh. Caspian Journal of Environmental Sciences, 18(1), 31-45.
5. KHAN, S. A., KAROBI, S. N., AHAMMED, S. S., RABBANI, K. A., & ISLAM, M. E. (2020). Assessment of selected water quality parameters of Turag River in Dhaka, Bangladesh. Pollution Research, 39, 39-42.
6. Jesson Tejano Rivera (2024). Assessment of Household Hazardous Waste (HHW) in Quezon City towards a Better Management System. Dinkum Journal of Natural & Scientific Innovations, 3(01):38-57.
7. Hossain, M. N., Rahaman, A., Hasan, M. J., Uddin, M. M., Khatun, N., & Shamsuddin, S. M. (2021). Comparative seasonal assessment of pollution and health risks associated with heavy metals in water, sediment and Fish of Buriganga and Turag River in Dhaka City, Bangladesh. SN Applied Sciences, 3, 1-16.
8. Tania, A. H., Gazi, M. Y., & Mia, M. B. (2021). Evaluation of water quantity–quality, floodplain landuse, and land surface temperature (LST) of Turag River in Bangladesh: an integrated approach of geospatial, field, and laboratory analyses. SN Applied Sciences, 3, 1-18.
9. Kabir, M. H., Tusher, T. R., Hossain, M. S., Islam, M. S., Shammi, R. S., Kormoker, T., … & Islam, M. (2020). Evaluation of spatio-temporal variations in water quality and suitability of an ecologically critical urban river employing water quality index and multivariate statistical approaches: a study on Shitalakhya river, Bangladesh. Human and ecological risk assessment: an international journal, 27(5), 1388-1415.
10. Alam, M. K., Uddin, M. A., Satter, M. F., & Majed, N. (2020). Seasonal variation of water quality and waste loads in Buriganga river with GIS visualization. Bangl J Sci Indus Res, 55, 113-30.
11. Chowdhury, N. J., Shammi, M., Rahman, M. M., Akbor, M. A., & Uddin, M. K. (2022). Seasonal distributions and risk assessment of polychlorinated biphenyls (PCBs) in the surficial sediments from the Turag River, Dhaka, Bangladesh. Environmental Science and Pollution Research, 29(30), 45848-45859.
12. Chowdhury, N. J., Shammi, M., Rahman, M. M., Akbor, M. A., & Uddin, M. K. (2022). Seasonal distributions and risk assessment of polychlorinated biphenyls (PCBs) in the surficial sediments from the Turag River, Dhaka, Bangladesh. Environmental Science and Pollution Research, 29(30), 45848-45859.
13. Karobi, S. N., Khan, S. A., Ahammed, S. S., & RABBANI, K. A. SEASONAL VARIATION IN TURAG RIVER WATER ALKALINITY.
14. Mukarram, M. M. T., Rukiya, Q. U., Mukarram, T., & Das, A. (2022). Spatial Assessment of Post COVID Water Quality Status of Turag River for Sustainable Water Resource Management in Bangladesh.
15. Mukarram, M. M. T., Rukiya, Q. U., Mukarram, M. M. T., & Das, A. (2023). GIS-based Spatial Assessment of Post COVID Water Quality Status of Turag River for Water Resource Conservation in Bangladesh. Journal of Environmental Issues and Climate Change, 2(1), 51-69.
16. Al Mamun, S. (2020). Seasonal Variations of Major Anions in Water at Baro Haor of Kishoreganj, Bangladesh and Revealing The Suitability for Aquatic Resource Management. Jurnal Akta Kimia Indonesia (Indonesia Chimica Acta).
17. Sadiqa, H., Al-Amin, M., & Sarker, M. M. H. (2021). Impact of Urban Wastes on Water Quality of Turag River. Post Graduate Dissertation, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.
18. BHUIYAN, M. A. H., ISLAM, M. R., ISLAM, S. S., KOWSER, A., KAKOLY, S. A., MOHID, M., … & KHONDKER, M. (2022). Water quality and potamoplankton periodicity of Sitalakhsya river, Narayanganj, Bangladesh. dynamics, 2, 5.
19. Niloy, N. M., Haque, M. M., & Tareq, S. M. (2022). Temporal changes in hydrochemistry and DOM characteristics of the Brahmaputra River: implication to the seasonality of water quality. Environmental Science and Pollution Research, 29(23), 35165-35178.
20. Kabir, A., Sraboni, H. J., Hasan, M. M., & Sorker, R. (2022). Eco-environmental assessment of the Turag River in the megacity of Bangladesh. Environmental Challenges, 6, 100423.
21. Yasmin, F., Hossain, T., Shahrukh, S., Hossain, M. E., & Sultana, G. N. N. (2023). Evaluation of seasonal changes in physicochemical and bacteriological parameters of Gomti River in Bangladesh. Environmental and Sustainability Indicators, 17, 100224.
22. Hasan, M. M., Ahmed, M. S., Adnan, R., & Shafiquzzaman, M. (2020). Water quality indices to assess the spatiotemporal variations of Dhaleshwari river in central Bangladesh. Environmental and Sustainability Indicators, 8, 100068.
23. Haque, M. M., Niloy, N. M., Nayna, O. K., Fatema, K. J., Quraishi, S. B., Park, J. H., … & Tareq, S. M. (2020). Variability of water quality and metal pollution index in the Ganges River, Bangladesh. Environmental Science and Pollution Research, 27, 42582-42599.
24. Sultana, M. S., & Dewan, A. (2021). A reflectance-based water quality index and its application to examine degradation of river water quality in a rapidly urbanising megacity. Environmental Advances, 5, 100097.
25. Prativa Shrestha, Bikash Shrestha, Jitendra Shrestha, Surendra karki & Jasmine adhikari (2024). AMR Active surveillance of E.coli spps. Isolates in poultry of different area of Surkhet at Veterinary Laboratory, Surkhet. Dinkum Journal of Natural & Scientific Innovations, 3(01):109-116.
26. Barman, S., Sultana, S., Yesmin, F., & Hasanuzzaman, M. (2022). Assessment of water quality parameters of the Bangshi River during dry and wet season in Bangladesh.
27. Shultana, S., Maraz, K. M., Islam, F., Haque, K. M., Hossain, M. M., Haque, M. M., … & Khan, R. A. (2022). Investigation of the water samples of six central rivers of Banglades. GSC Advanced Research and Reviews, 10(3), 062-070.
28. Afrad, M. S. I., Monir, M. B., Haque, M. E., Barau, A. A., & Haque, M. M. (2020). Impact of industrial effluent on water, soil and Rice production in Bangladesh: a case of Turag River Bank. Journal of Environmental Health Science and Engineering, 18, 825-834.
29. Jesmin Akther & Md. Jahangir Sarker (2023). The Status & Assessment of Natural Food Abundance For Hilsha Shad (Tenualosa Ilisha) During Breeding Season In The Meghna River Estuary, Bangladesh. Dinkum Journal of Natural & Scientific Innovations, 2(12):882-903.
30. Islam, M. S., Chakma, N. B., Chakma, P., Kabir, M. H., Shammi, R. S., Hoque, M. M. M., & Iqubal, K. F. (2022). Seasonal Variation of Water Qualities in River, Lake and Waterfall in Rangamati and Khagrachhari Hill Tracts, Bangladesh.
31. Nyantakyi, J. A., Fei-Baffoe, B., & Akoto, O. (2020). Seasonal variations in physicochemical and nutrient water quality of River Tano in Ghana.
32. Das, P., & Ali, M. (2020). Water Quality Assessment of Tongi Khal (Canal) During Dry Season.