No abstract

Water usage generates wastewater, which must be collected and treated properly before being returned into the hydrological cycle for reasons of sustainable development and water supply.The content and volume of waste water generated are determined by a range of elements, as most of them are the waste of households, industries and so on. It also dictates the necessary treatment methods. Waste water treatment facilities function at a crucial stage in the water cycle, assisting nature in protecting water from contamination. Treatment methods can be categorized into four segments: preliminary, primary, secondary and tertiary wastewater treatment. Screening and grit removal are ordinary parts of preliminary wastewater treatment. Basically, it prepares wastewater for further treatment. Although the primary purpose of wastewater treatment is to separate easily-removable suspended particles and BOD, wastewater components that occur as dissolved solids or settleable wastewater solids may also be eliminated here using a septic tank, the Imhoff tank. The conversion of organic materials to more oxidised or reduced forms occurs in treatment plants of secondary wastewater treatments and sometimes in tertiary treatment also. Disinfection and suspended particles removal are the most common techniques used to modify conventional wastewater treatment plant effluents for crop application. Advanced wastewater treatment, also known as tertiary treatment, is used in treatment technologies when a higher quality of water is desired but secondary treatment procedures cannot provide. Advanced or tertiary water treatment includes the removal of nitrogen, phosphorus, several organics and metals. Finally, the treated waters can be used for multiple purposes. Rainfall waters being less polluted, can be easily treated and fewer treatment methods will require here. However, to make them more efficient, several improvements are needed for commonly used systems like trickling filters, oxidising ponds, rotating bio contractors (RBCs), septic tanks, etc.

The present study focuses on the evaluation of the river (Ganga) water quality by estimating  various quality indicators (also termed the physicochemical parameters) such as pH, temperature, dissolved oxygen (DO), electrical conductivity (EC), chlorides, sulfates, phosphates, hardness, chemical oxygen demand (COD), biochemical oxygen demand (BOD5). Rise in the concentration of the pollution signifies an upsurge in a load of pollution due to the different sources namely, sewage arising from domestic sources, effluents arising from industrial discharge, and effluents arising due to various anthropogenic activities. For the purpose of the comparative evaluation of the river water quality, the water samples were collected from the three different banks of the Ganga River for a well-organized interpretation.Obtained results indicate thatthe discharge of the various effluents has a grave impact on the water quality of the river. Industrial effluents mixing with the river water were noted to have the most deleterious impact on the deterioration of the water quality parameter. The extended aim of the study was to collect the fish samples from the three above-mentioned sampling points and thereby detect the presence of the heavy metal concentration (determined through atomic absorption spectroscopy or AAS). Obtained results also indicates that the fish specimen collected from the sampling point where the industrial effluents are mixing have the highest levels of heavy metals in the tissues of the selected fish sample. Accordingly, the study indicated a novel approach toward the characterization of the river water and thereby indicating the impact of bioaccumulation of heavy metals into the fishtissues which indicates the novelty of this work. The authors strongly believe that this work will be beneficial to various stakeholders and will be definitely helpful to various competent national and international authorities for decision-making and strategies formulation.