Selected river pollution in Bangladesh based on industrial growth and economic perspective: a review

The main goal of sustainable development is to engage the public in setting the groundwork for developing profiles based on carrying capacity assessments. Since industrial projects are located in traditional, non-industrial zones, the broad human resource development program includes environmental research, education, and training to build technical and practical skills in the country-based and scientific statistics system data gathering. It is noteworthy that the examinations were conducted sporadically and that the research did not correspond to the pollution level in Bangladesh’s waterways. Therefore, it is essential to conduct a methodical examination that may offer a complete picture of river pollution so that appropriate preventative actions can be adopted to safeguard against pollution threats. Bangladesh has many environmental issues, including dirty air from various vehicles, unhealthy water, accumulating urban waste, untreated sewage, interior air pollution from wood smoke, and usage of fad-driven contemporary materials in homes. Each of them contributes more to the destruction of the environment. With the current trend of population growth followed by the construction of companies to suit their wants, such a situation may worsen. Hazardous gases, dust particles, or liquid effluents are the waste products emitted from industrial sources. These discharges are full of harmful chemicals that pollute aquatic ecosystems, disrupt the local biota, and eventually harm living things and associated flora and animals. As a result, studies were conducted, including the physicochemical characterization of sugar refineries, distilleries, and other rivers that receive such effluents. These characteristics of subsurface water were also taken into consideration throughout the inquiry. This research will be anticipated to offer proper preventive methods for preserving the purity of the Bangladeshi rivers.


Introduction
Globally, people are becoming increasingly aware of the need to safeguard the environment. Environmental concerns were brought to international attention during the Stockholm Conference on the Human Environment (Najam, 2005). But since then, despite considerable advancements in many areas of the fight against environmental problems, the state of Abstract The main goal of sustainable development is to engage the public in setting the groundwork for developing profiles based on carrying capacity assessments. Since industrial projects are located in traditional, non-industrial zones, the broad human resource development program includes environmental research, education, and training to build technical and practical skills in the country-based and scientific statistics system data gathering. It is noteworthy that the examinations were conducted sporadically and that the research did not correspond to the pollution level in Bangladesh's waterways. Therefore, it is essential to conduct a methodical examination that may offer a complete picture of river pollution so that appropriate preventative actions can be adopted to safeguard against pollution threats. Bangladesh has many environmental issues, including dirty air from various vehicles, unhealthy water, accumulating urban waste, untreated sewage, interior air pollution from wood smoke, and usage of fad-driven contemporary materials in homes. Each of 1 3 Vol:. (1234567890) the planet's ecosystem has worsened, and the world's hazards have worsened. These environmental, environmentally sustainable, and socially just development issues were covered during the Rio Conference. At the Rio Conference, the four major topics were climate change, ozone layer protection, industrial pollution, and habitat loss (Eneh, 2011).
Millions of people's living situations are hazardous to their health and might have disastrous societal ills (Briggs, 2003). In contrast to what would be predicted given the current changes in the natural environment, such as the global climate change, ozone layer depletion, loss of rain and forests, pollution of the seas, lakes, and rivers, acid rain, and the extinction of plant and animal species, the urban environment crisis is having a more significant immediate impact on health (Singh & Singh, 2017). The capacity of local governments to handle garbage collection and disposal and air pollution from roads, industries, and other sources has been outpaced by urban expansion. As a result of using biomass fuels for cooking and heating, individuals are exposed to both outside and interior air pollution. Extreme exposure and housing occur in a dangerous, unhealthy social setting where fear, insecurity, and violence are prevalent.

Environmental problem status in Bangladesh
Three categories may be used to classify Bangladesh's environmental issues: • Type I: Issues resulting from a lack of development include deforestation caused by the exploitation of fuel wood, unsanitary slums, soil erosion, a lack of sanitation, and a threatened water supply (Baten & Titumir, 2016). • Type II: Problems such as air and water pollution, hazardous waste disposal, water logging in irrigation projects, pesticide contamination, and fertilizer runoff into streams are brought on by the lack of environmental protection in development projects (Kraham, 2017). • Type III: Issues include ozone depletion, marine pollution, loss of genetic diversity, and global warming. These are influenced by the current development patterns, way of life, and energy (Martens, 2013).
All three environmental problem types exist in Bangladesh but lack the resources to manage or control them. Type I environmental problems are those that result from a lack of development, whereas type II problems are those that are caused by development efforts. If people do not advance quickly, type III issues will engulf us. People won't care about the environment, and type II will take control. As a result, Bangladesh's economic development and environmental conservation alternatives must be considered.
The past few decades have seen dramatic environmental changes due to the trends of population growth, urbanization, technological advancement, industrialization, new agricultural practices, etc. These changes have led to several environmental pollution issues involving the air, noise, water, and land. The lack of resources is becoming more acute as growth progresses on all fronts (Yu et al., 2010).
In the 1980s and 1990s, there was a more significant expansion of companies that release effluents that include contaminants. Between 1990Between -2000Between and 2001Between -2015, the output of several consumer goods categories, including paper and leather products, as well as items like petroleum products, fertilizer, caustic soda, iron and steel, and sulphuric acid, have more than doubled (Yang & Mlachila, 2007). Due to inadequate investment in environmental protection, the industrial transformation is impacting the environment. Petroleum refineries, thermal power generation, chemicals, food processing, sugar factories, paper, and fertilizer are the significant components of rising industries.

Research methodology
An ample amount of research is performed regarding environmental/river pollution. That is why a review is needed to identify the factor affecting environmental/river pollution due to industrial growth. The element includes pH, total solids, biochemical oxygen demand, chemical oxygen demand, and total nitrogen, which are mostly causes of environmental pollution. This research mainly focuses on previous research employed for industrial growth, such as sugar, distillery, paper, and textile industries. Finally, a decision is made based on a different literature review focused on other countries to solve environmental pollution.

Sugar factory
One of Bangladeshi's most polluting businesses is the cane sugar industry. The distribution of industrial sugar units by districts is shown in Fig. 1. Table 1 lists the different attributes of waste in the sugar business. The current investigation has discovered that sugar mills release a significant volume of wastewater with a low pH and high concentrations of suspended particles, dissolved solids, BOD, and COD. There is a significant quantity of dissolved organic matter in the effluent from the sugar mills (Saleh-e-In et al., 2012). Because this organic stuff is easily broken down by biological processes, dumping these alcoholic beverages into surface waters seriously harms the aquatic life in river water.
The barometric condenser in sugar businesses needs a lot of water because it has several effects that evaporate and vacuum pans. After passing through a spray pond to cool, the water is often either totally or partially recirculated. This cooling water becomes contaminated when it absorbs organic materials from the boiling syrup vapor in evaporators and vacuum pans. The water from the spray pond overflows forms part of the affluent and typically has a low BOD. However, a significant amount of sugar may entrain the condenser water due to inadequate maintenance and unfavorable operating circumstances. Instead of being cycled, this contaminated water is discharged as surplus condenser water. In many sugar mills, these discharges have a sizable impact on the waste volume and a minimal impact on BOD. Wastewater is also produced by leaking and spilling juice syrup and molasses in various areas and routine floor cleaning. Despite having a modest volume, these wastes contain a relatively high BOD (Hoque & Clarke, 2013).
Through correct operation and maintenance, effective evaporator separation, lowering entrainment in separators, acceptable water consumption, and proper handling and storage of molasses, the pollution consequences of sugar mills may be significantly decreased (Haque & Sharif, 2021).
The pollution produced by the industrial sugar plants is measured by basin. Because there are not many businesses concentrated in rural regions, it is essential to note that the sugar industry is concentrated there, where pollution loads are significantly lower. The tube well water is typically unavailable when winter crops are at their optimum due to an energy shortage. Under these conditions, there is little choice except to use the sugar industry's wastewater for irrigation. It causes the production of sludge in the soil, which ultimately has an impact on soil fertility (Mojid et al., 2010).
It has been observed that the sugar mill waste fluids are susceptible to treatment by anaerobic digestion followed by stabilization in an aerobic oxidation pond due to pollution generated by sugar plant effluents. It has been argued that lagoons and stabilization by organisms in a multiphasic system are essential in addition to process improvements for lowering the wastewater volume and excellent housekeeping. Others have reported on the anaerobic digestion of cane sugar wastewater; wastewater parameters have also been employed to enhance the removal of organic materials by coagulation. For wastewater treatment from sugar mills, procedures for up-flow anaerobic sludge blanket reactors have been devised. The production of volatile fatty acids by the acid-genesis of sugar has also been studied, but this time in a continuous flow reactor with a specific gas and sludge separator mechanism. About 95% of BOD reductions have been seen in acidification lagoons. About 90% less COD has been produced by another procedure. While extensive research has been done on treating wastewater from sugar mills using various biological techniques, little is known about the treatment of wastewater from sugar mills in an up-flow anaerobic filter (Haque & Sharif, 2021).
In contrast to sugar beet, sugarcane is cultivated in tropical and subtropical regions where several illnesses and pathological states are prevalent, including alcoholism, trachoma, and malaria. Poverty, as well as the surrounding environment and employment circumstances exacerbates this. The upshot is that the employees need to consume a lot of fluids. They have no other option than to use alcohol because the water is frequently of low quality and does not match the standards for drinking water (Hasan et al., 2019).
Additionally, during different phases of the refining process, fumes and gases such as carbon dioxide, sulphur dioxide, carbon monoxide, and fumes from hydrochloric acid may be released. The procedure emits problematic and occasionally dangerous gases and steam due to the high temperatures. Bagassosis can be brought on by inhaling dust that contains oven residue. It has been discovered that noise levels in some facility areas may be higher than acceptable.
The sugar business experiences little difference comparing workplace accidents in the agricultural and industrial sectors. The most frequent illnesses and injuries include heat exhaustion, dermatitis, conjunctivitis, burns, and falls. Dental decay is a relatively common occurrence. In comparison to other industries, morbidity is typically 50% greater. Sugar factories are known for having tuberculosis, alcoholism, chronic weariness, and illnesses specific to the location. The poor standards of life may be blamed for all of these (Das & Hoque, 2014).

Distillery
The issue of how to dispose of the effluents from various types of wastewater has been a significant source of worry. It has been discovered that some wastes with large concentrations of biodegradable organics may be processed anaerobically to create biogas. It lessens the environmental pollution burden. The distillery industry is one of the worst pollutants to the aquatic environment in general. The distilleries produce a lot of highly organic trash. Table 2 provides a summary of the general features of distillery effluents (Islam et al., 2015a).
The current study showed that distillery effluent is significantly more acidic than effluent from the sugar industry. Due to its high BOD, COD, color, and odor levels, wastewater discharged by distilleries that make industrial alcohol from sugarcane molasses presents challenges for disposal to acceptable standards. As a result, it is anticipated that the river's water quality will be compromised, negatively impacting the river's flora and fauna (Saha et al., 2018).
The distillery effluent is one of the most damaging industrial effluents while not being harmful. The effluent's BOD value has a very high indication of the polluting nature. It is a severe challenge to manage such a vast amount of wastewater with such high levels of pollution potential. The BOD and COD must be reduced to the necessary level.
For every liter of alcohol produced, the distillery effluent generates around 15 gallons. High organic contents cause the dissolved oxygen concentration to steadily drop until it eventually falls below the threshold beyond which plants and animals cannot live. Due to the wasted wash's high putrescible organic content, the water is no longer safe to drink. Anywhere it is stagnant, the wastewater dumped in the Moran stream has an unpleasant odor. Hydrogen sulphide is the source of the distinctive odor. All of this almost certainly makes life difficult for both humans and animals (Tonner et al., 2019).
The disposal of distillery effluent is a topic that is getting a lot of attention. The wastes produced by a distillery include wasted wash, condenser, water, carbon dioxide, gas plant wastewater, and yeast sludge. Condenser, carbon dioxide, and gas plant wastewater are reasonably clean and do not contain a lot of pollution, so they do not present any treatment issues. The dried yeast sludge removed from fermentation vats is used to make chicken feed or as a possible source of manure. However, occasionally, the wasted wash is also drained together with the yeast sludge, increasing the organic strength of the wastewater significantly (Hafizur et al., 2017).
Generally speaking, distilleries need between 120 and 130 L of process water for every liter of alcohol produced. Along with the manufacture of alcohol, wasted wash production also fluctuates. Acidic, heated waste is also colored. Distilleries often release the final effluent as wasted wash and condensate water. The standard procedure used to dispose of distillery waste that has not been without or partial treated. Due to the distance between the distillery issue and the river location, it is crucial to treat the distillery effluents. It has been proposed that the following processes are crucial in this direction (Turinayo, 2017). • Direct use after neutralization and dilution for irrigation purposes • Evaporation and incineration of spent wash for the recovery of potassium salt • Ammonification process • Manufacture of Torula Yeast from the spent wash • Anaerobic treatment such as anaerobic lagoons and anaerobic digestion Anaerobic procedures have been used for a very long time to treat distillery waste wash. It has been claimed that this procedure removed 85% of COD and reduced BOD by 95%. Even with a short retention duration of around 15 days, up-flow anaerobic filters have been proven to significantly reduce the pollutant load and increase efficiency. The electrooxidation approach for treating distillery effluent could reduce the BOD level to zero while anodic oxidation simultaneously decolorizing the wastewater. Additionally, electro-oxidation had a notable impact on several other parameters, including pH, COD dissolved solids, and suspended particles (Rahman et al., 2021).
It is a common knowledge that wasted wash mainly consists of carbs and a little protein, in addition to salt, potassium, calcium, sulphates, and a few chlorides. Nitrates and the substance in which nitrogen is found are both presents. Additionally, sulphides have been discovered in the used wash. During the anaerobic or aerobic oxidation process, the pyruvic acid cycle oxidizes the proteins and carbohydrates. The oxidizable species are changed during the electrooxidation process into carbon dioxide and nitrogen, which are safely released into the atmosphere (Islam et al., 2015b).
During anodic, an aerobic environment with abundant oxygen released by water electrolysis is present. Both nascent and gaseous oxygen may be obtained, and some may be accessible as hydroxyl ions for reaction. Both aerobic and anaerobic conditions cause the oxidation of sugars and amino acids. Anaerobic oxidation of carbohydrates produces pyruvic acid, which can then undergo aerobic oxidation to produce water and carbon dioxide. Similar to this, amino acid oxidation results in gaseous by-products. Additionally, carbon dioxide, nitrogen, and water are produced due to the anodic treatment of the used wash.

Paper factory
Pulp and paper production is one of the leading businesses in Bangladesh that contributes to water pollution. Wood, sugars, cellulose, fiber, lignin, and other ingested compounds that impart high BOD, COD, color, etc. (as shown in Table 3) are pollutants that often result from the industry. Black liquor, brown stock wash water, green liquor, white liquor, equipment wastewater, and sanitary wastes are examples of the industry's effluents. Wood sugars, which make up 70% of BOD, and lignin, which make up 30% of the initial weight of the raw material, are essential components of wastewater. The presence of lignin, which is not readily biodegradable and contributes to a high ratio of COD and BOD, gives the waste its color. The scale of the plant's production process determines the effluent volume and composition (Haque, 2017).
The river's water quality suffers due to the paper and chemical industries' improperly treated effluent being released directly into the waterway, creating severe risks to the public's health. Examining the river, affluent, and subsurface water has been done both quantitatively and qualitatively. The findings indicate that majority of the metrics' values have dramatically risen. According to studies, the effluent flow through the drain caused long-distance river water quality degradation, rendering the water unusable for irrigation, drinking, bathing, fish habitats, and other recreational uses. Thousands of people in the central city depend on the river for survival. Therefore, analysis of the water assures that it should not be dumped into the river without sufficient effluent treatment (Easir Arafat Khan et al., 2017).
As old as the paper mill business, wastewater treatment and disposal is a common practice. Hundreds of  Islam et al., 2015c). The most feasible and cost-effective method for treating vast amounts of wastewater from home, commercial, industrial, and agricultural sources has been anaerobic bacterial processes. Because they need less time and money to build than other anaerobic biological processes, up-flow anaerobic filters are becoming increasingly important. Studies on the toxicity of paper mill effluent have been conducted on fish. After extended exposure to both a deadly and sub-lethal dosage of paper mill effluent, the histopathological damage in the gill and liver tissues was studied. There are procedures for evaluating the acute toxicity of pulp, paper mill, and other liquid effluents (Hasan et al., 2019).

Textile industry
The enormous textile mill has a wildly fluctuating water usage. Water is necessary for many textile industry processes and other utilities, including steam generation, cooling, and sanitary functions. The number of processing sequences determines how much water is used overall in the mill (Karn & Harada, 2001).
The printing processes of designing, scanning, bleaching, rinsing, drying, and printing are the primary sources of effluent from a textile mill. Additionally, waste streams are produced from several sources, including floor cleaning, equipment, and water treatment facilities for boiler houses. Colored, high in BOD, COD, and suspended particles, extremely alkaline, and at a moderately high temperature, textile industry wastewater is also a variety of other characteristics. Extreme variation and hazardous chemicals and metals are present in the effluent. The following Table 4 provides information on the makeup of process wastes (Halder & Islam, 2015).
The production, water use, quality and type of textiles produced, and the raw materials utilized all contribute to the many textile mill's pollution burdens. The stream's water quality is impacted in many ways by wastewater that textile factories discharge. Temperature, pH, color, odor, turbidity, organic compounds, hazardous chemicals, and metals are some factors that affect these changes (M. S. . The processing unit's hot waste stream raised water temperature and reduced the DO burden. The water's pH rises due to the high pH and alkalinity waste. The stream's biological activity was impacted by the pH rise over 9.0. The waste's colors prevent sunlight from penetrating, which is thought necessary for photosynthesis. The water's turbidity increased due to the colloidal organic debris in the effluent. The colors of the dye and the waste scum gave off an unpleasant look (Dey & Islam, 2015).
The loss of dissolved oxygen was the most severe consequence of textile wastes in the receiving stream. Dextrin and starch, two organic waste components, increase the stream's oxygen requirement (BOD). Additionally, inorganic compounds like sulphate, sulphite, and sulfurizes hasten the loss of oxygen (Sakamoto et al., 2019).
The fish life in this stream was impacted by hazardous compounds such as sulphides, chlorine, aniline, and sulphur dyes, as well as heavy metals like chromium. The usage of textile wastes on agricultural land was discovered to have negative effects in various ways, such as the following: • The suspended and colloidal metal closed the soil's pores and reduced its permeability. • The high alkalinity and salinity unpaired the plant growth. • The wastewater's high salt concentration hardened the soil's texture and reduced its ability to hold water. Additionally, the sodium served as a deflocculating agent and displaced the divalent cations like "calcium" and "magnesium," which reduced the productivity of the soil. According to the findings, pollution levels are highest in the summer and winter compared to the monsoon season. The rising water table during monsoon season is probably to blame.

Industry and environment
Through the complete cycle of raw materials, exploration and extraction, transformation into products, energy consumption, waste creation, and use and disposal by consumers, industry and its products influence the natural resources basis of civilization (Islam et al., 2020).
Initial perceptions of the damaging environmental effects of industrial activities focused on small-scale issues with air, water, and land contamination. New industrial techniques and technologies have been created to lessen pollution and other harmful environmental effects. It is becoming increasingly evident that there are many more diverse, intricate, and interconnected sources and pollution causes. Once local, pollution issues are now regional or even global in scope. Agrochemical contamination of soils, groundwater, and humans is growing, and chemical pollution has reached every region of the world. Significant chemically harmful accident occurrence has increased (Ayatullah et al., 2017).
Naturally, costs and advantages have differed among industries. Comparing the costs of new plants and equipment that contain pollution control systems is one way to calculate the cost of pollution abatement in industry. Businesses engaged in producing food, iron and steel, non-ferrous metals, autos, pulp and paper, distilleries, chemicals, and electric power, all of which contribute significantly to pollution, have borne a sizable share of the industry's overall expenditure in pollution management. Recycling and reusing water is now considered standard practice in many industrial areas (Hossain et al., 2016).
Untreated effluents, inefficient waste management, and a lack of environmental awareness are problems in Bangladesh that affect both industry and the environment. Naturally, costs and advantages have differed among industries. Comparing expenditures on new plants and equipment with pollution control facilities is one way to calculate the industry's pollution reduction cost. The majority of industry's total investment in pollution control has been borne by companies that produce significant amounts of pollution, including those in the food processing, iron and steel, non-ferrous metals, automotive, pulp and paper, distilleries, chemical, and electric power generation industries. Reusing and recycling water is already commonplace in many industrial areas. Untreated effluents, inefficient waste management, and a lack of environmental awareness are problems in the Bangladeshi industry and the environment. Massive amounts of untreated industrial effluents are dumped daily into rivers, lakes, and the ocean. The emissions from a rising number of enterprises are contaminating the air. The increase in pollutants has also exacerbated the decline in living quality (Mottaleb & Sonobe, 2011).

Waste and environment
Chemical usage has increased significantly due to industrial expansion, agricultural product modernization, and higher living standards. Around ten million compounds are created every year worldwide. As a result, many different types of wastes, including hazardous, solid, liquid, and gaseous wastes, are produced. Everywhere in the world, garbage is precisely the same level of harmful. The hazards are more consequential in Bangladesh due to a lack of management plans and information (Masud et al., 2018).
All societal activity generates wastes, including those from the home and other consumer products, agriculture, industrial activities, demolition and building projects, extractive industries, sewage sludge, alcohol, and energy generation.

Ground water
It is essential to determine if the water used for human consumption is potable due to rising environmental degradation. It is crucial to carefully evaluate water's physicochemical and bacterial quality since it is a significant carrier of many illnesses with both chemical and bacterial origins. Water's physical, chemical, and microbiological aspects are typically used to characterize its quality. As a result, during the past several years, there has been much interest in examining water samples to identify abiotic and biotic components (Huq et al., 2020).
In general, groundwater is pure and unpolluted. There are noticeable differences in their quality due to ecological variables. As groundwater quality is becoming more of a concern, efforts are being undertaken to avoid, mitigate, and eradicate groundwater contamination because it degrades natural water quality. The movement of groundwater through the diverse geological environment causes various chemical compounds to dissolve during its flow, resulting in groundwater enrichment. Water from aquatic bodies is mixed with effluent released by industries. The wastewater's inorganic components will swiftly reach the groundwater source as they move through the soil. Health risks might be caused by pollution (Ahmad et al., 2018).
The findings showed that groundwater in the vicinity of industry had been significantly contaminated. This filthy water may have impacted the population's state of health. It occurred due to the neighborhood's residents' complaints about various health issues. Only the seepage of effluents into the underground water may account for the high concentration of several parameters in the water.

Trace element
Trace elements refer to a collective group of chemical elements present at low concentrations. Some of these elements perform an essential function obtained from the environment in adequate amounts to optimize cellular metabolism. Because of their relatively low concentrations, trace elements often function as catalysts in the metabolic process. There are 15 trace elements known to be essential to human health. While deficiency of these elements will cause ill-health and even death, an excess may be dangerous. For every element, there is a window of safe intake. Antagonistic effects between trace elements are also common, and an excess of one element may severely inhibit the uptake of another (Rakib et al., 2021).
Because it might impact people, animals, and plants, the rising amount of trace elements in effluents and rivers is a serious problem. The majority of transition metals are known to be free radicals and capable of changing the valency of one electron, making them suitable redox catalysts. These transition metals operate as catalysts in the active centers of specific oxidases to speed up the slow reactions of molecular oxygen (Sharif et al., 1993).
The free radicals and activated oxygen species which have been implicated in biological systems are as follows: Lipid peroxidation is one of the essential oxygenand carbon-centered free radical-mediated biological processes. A biological membrane's polyunsaturated fatty acid molecule is attacked during lipid peroxidation, which reduces the membrane's fluidity, increases non-specific membrane permeability, and inactivates several membrane-bound enzymes (Amin et al., 2011).
It has been found that catalysis by iron allows the Haber-Weiss reaction to occur much faster. The Haber-Weiss reaction is Because of the facts mentioned above, it is evident that the association between age-related diseases such as cancer, senile dementias, cardiovascular diseases, and arthritis and free radical formation induced by trace elements is of great concern. Evidence is accumulating that most diseases that affect humans have their origin in harmful free radical reactions. The utilization of oxygen in living organisms produces superoxide ( O − 2 ) and hydroxyl ( * OH ) radicals and the activated oxygen species singlet oxygen ( O 2 ) and hydrogen peroxide ( H 2 O 2 ). These electrophilic species can damage genetic material and oxidize unsaturated fatty acids in cell membranes.
The development and detection of free radicals in people, the presence of biological systems that include elements like free iron and copper that can catalyze the synthesis of hydroxyl radicals, and the function of natural, free radical scavengers are all areas that require more study. Extensive epidemiological research on disease and antioxidants should be launched to prove the function of dietary free radical scavengers and define the optimal intake for preventing degenerative illnesses (Borrell et al., 2016).

Soil characteristics
The capacity of soils to absorb and decompose wastes and pollutants of various types is relatively high. Human activity, which produces home sewage, rubbish, landfills, agricultural runoff, and industrial effluents, may be a source of metals in soils. It is widely known how industrial effluents affect soil and how municipal and industrial wastewater may be used to irrigate crops. It has also been investigated how dirt functions as a filtering medium. It has been noted how soil pH affects how well plants absorb nutrients. However, it is recognized that specific soil characteristics, including pH, organic matter content, cation exchange capacity, and base status, might impact the number of heavy metals plants can absorb (Barua & Haque, 2013). It is thus possible that such a change in the soil characteristics may affect the crop productivity as well as a change in the nature and properties of their biochemical profile.
The impact of pollutants on the soil presents a more serious problem than their impact on the drinking water resources of the affected area. Almost every activity, natural and anthropogenic, has contributed to heavy metals and other pollutants in the soil. In soil, there is an intimate interplay between the soluble available and unavailable fraction of trace elements. In the area, the soil is victimized by intense industrial, domestic, and agricultural activities through improper waste disposal. Currently, soil contamination of heavy nature is confirmed in site-specific locations around the distillery. It would mean intensification of existing heavy metal toxicity hazards to the soil with the potential of more metal influx in store. Ultimately, this may result in potential danger of toxicity to surface water, groundwater, and crop plants since soil forms the standard matrix through which metal mobility's can be initiated, accelerated, and maintained with time (Hafiz et al., 2016).
In a recent study, it has been reported that land disposal of distillery effluents would not only save the water bodies from pollution by the effluents but also improve the crop productivity, as it contains valuable nutrients. However, fear is expressed regarding the effect of effluent on soil health. Irrigation with effluent increased the organic matter content, available potassium, and electrical conductivity of soils. However, the pH of the soils decreased, and applying effluent at different levels increased the biomass yield of crops such as wheat.

Discussion
The Buriganga, Shitalakshya, and Karnaphuli river water quality is deteriorating rapidly due to intense human activities and the infusion of pollutants from the surroundings. These materials mainly comprise decomposable organic matters of plant and animal origin, land surface washing, industrial, domestic, and agricultural and other wastes. The addition of such waste into the water makes it unfit for drinking and indigenous aquatic organisms. It is estimated that about 70% of the total pollution generated by the industries and township is dumped through outfalls into the Buriganga, Shitalakshya, and Karnaphuli rivers. The water temperature of river water was minimum in winter, and the highest temperature was recorded in summer.
The highest values of hardness were recorded during the summer months. It may be due to reduced flow rate and water level. Highest values of hardness recorded at confluence point of Buriganga River. It may be due to the confluence of industrial effluents and domestic sewage. Similar observations were also obtained in a study on rivers Buriganga, Shitalakshya, and Karnaphuli.
Dissolved oxygen plays a vital role in supporting aquatic life in the running water. At the confluence point site, DO values were much lower than those prescribed (6.5 to 8.5 mg/l) for bathing and drinking by the Bangladeshi standard institution (ISI). Its leading cause is the addition of millions of liters of industrial effluents. The effluents are rich in organic matter.
The low DO value is probably due to high water temperature and greater oxygen consumption by secondary producers and decomposers. The dissolved oxygen content of water indicates the health of the aquatic ecosystem. The levels of DO. decline substantially during rains due to high loads of suspended particles, soil particles, discharged effluents, and decomposed organic matter reaching the water and reducing the penetration of light, lowering the photosynthesis.
Seasonal variations in BOD values appear to be an indicator of changing dilution and availability of water in the system. In the present observation, higher values of BOD were recorded at all the stations during the summer seasons. It may be due to the reduced quantity of water and due to industrial effluents and domestic sewage outfall near the sampling point. At the confluence point, a higher BOD value is also due to higher microbial activity of the domestic sewage and continuous discharge of industrial effluents. Due to the dilution factor, all sites decreased the value of BOD in the rainy season.
Vol.: (0123456789) A comparison of BOD values at different sites with its standard limits (3 mg/l) showed that the Buriganga, Shitalakshya, and Karnaphuli river water in this stretch is not even fit for drinking or bathing purposes. COD concentrations were higher at the confluence site, indicating organic pollution due to industrial effluent. The concentration of free Coz during monsoon indicates its influx through rain waters in the form of carbonic acid. At the same time, it was lower during early summer and winter due to deoxygenation and increased photosynthetic activity of bottom vegetation, respectively.
The high value of sulphate concentration at the confluence point site might be due to industrial effluents. Higher concentrations of heavy metals were recorded at both highly polluted sites due to the continuous discharge of a large amount of domestic sewage and industrial effluents. The presence of heavy metals like iron, manganese, cadmium, and zinc is a further cause of concern.
The commonly used pesticides DDT and HCH were determined in river water. Although pesticide residues are minimal, the concentrations are sufficient to harm the aquatic flora and fauna.
The impact of industrial effluent and domestic sewage on rivers' water quality has been made by physical-chemical and biological analysis. Based on the present investigation, it has been found that the values of CO2, pH, chloride, total hardness, total dissolved solids, total nitrogen, sulphate, phosphate, BOD, COD, oil and grease, the concentration of pesticide residues, and heavy metals increased with increased in pollution load by industrial effluents and domestic sewage. The pollution load of these rivers is Buriganga, Shitalakshya, and Karnaphuli.
Therefore, using such water for drinking or bathing is not advisable without prior treatment. The industrial effluent and domestic sewage should be discharged after proper pre-treatment to prevent deterioration of the quality of Buriganga, Shitalakshya, and Karnaphuli.

Conclusion
The problem of pollution due to increased industrialization is now a well-known phenomenon. Contamination of water bodies occurs due to the discharge of effluents from industries, domestic sewage, agricultural runoff, and dead bodies thrown into it. The significant sources of river pollution have been linked to industrial and domestic waste. Industrial effluents contain pollutants that cause harmful effects on receiving water bodies and adversely impact human health and aquatic biota.
Accordingly, the rivers and aquatic bodies which receive the effluent will be affected to such an extent that the survival of their flora and fauna will be questionable since river water is used for drinking, bathing, agriculture and a variety of other purposes.
• The study results reveal that the sugar factories discharge a large amount of waste with low pH, with a high concentration of suspended solids, dissolved solids, BOD, and COD The effluent from the sugar factory contains a large quantity of organic matter which readily decompose by the biological reaction. Thus, the discharge of their liqueurs to the surface causes severe damage to aquatic life in rivers. • The distillery industries are amongst the major polluters of the aquatic environment. The problem of effluent disposal of the distillery has been more significant, attracting global attention. The primary course of pollution by distillery effluent is high BOD. Due to the presence of organic matter, both have suspended solids and dissolved solids. • Dissolved oxygen (DO) is vital in supporting aquatic life in running water. At the confluence point site, DO's values were much lower than those prescribed (6.5 to 8.5 mg/l) for bathing and drinking by Bangladeshi Standard Institution. Its leading cause is the addition of millions of liters of industrial effluents. Industrial effluents are rich in organic matter. The DO contents of water indicate the health of the aquatic ecosystem. The levels of DO decline substantially during rains due to the high load of suspended particles. • Chemical oxygen demand (COD) concentration was higher at the confluence site, indicating organic pollution due to industrial effluents. The concentration of free CO during Monsoon indicates its reflux through rain waters in the form of carbolic acid. It was lower during early summer and winter due to deoxygenation and increased photosynthetic activity of bottom vegetation. • The higher values of sulphate concentration at the confluence point site might be due to industrial effluents.
• Higher concentrations of heavy metals were recorded at highly polluted sites due to the continuous discharge of a large amount of domestic sewage and industrial effluents. The presence of heavy metals like iron, manganese, cadmium, and zinc is a further cause of concern. • The commonly used pesticides DDT and HCH were determined in river water. However, the concentrations are sufficient to harm the aquatic flora and fauna. • The assessment of the impact of industrial effluents and domestic sewage on rivers' water quality has been made by both physico-chemical and biological analysis. Based on the present investigation, it has been found that the values of FCO2, PH, chloride, total hardness, total dissolved solids, total nitrogen, sulphate, phosphate, BOD, COD, oil and grease, heavy metals, and concentration of pesticide residues increased with increase in pollution load by industrial effluents and domestic sewage. • Therefore, using such river water for drinking or bathing is not suitable without prior treatment for prevention and control of pollution and requirement of the technologies in view to attain the quality of the product as well as the effluents to the requisite standard because of the current water pollution policy of the Government of Bangladesh.