**3.3 Anionic surfactant level in the Gomti River water**

Detergents make our cloth brighter or whiter by emitting blue light after absorbing UV light. In this study, the anionic surfactant is measured between 0.1005 and 0.2758 mg/L whereas the highest concentration was analyzed at Pakka Pul and lowest concentration at Khatu Shyam station. The average value (0.1832 mg/L) was found within the prescribed standard of Indian standard, while the value were exceed in Pakka Pul, Daliganj Bridge and Dilkusha sampling station, at this location the activity of washer man is higher to washing the cloths that can creating the emerging level of anionic detergent (**Figure 2**). Different type of detergent are using for cleaning of cloth such as Surf Excel, Active Wheel, Ariel, Tide Nirma, Saheli, Ghari, Rin Supreme and Fena in the powder form and many others in liquid form. This washing substance made up with many different chemical components such as surfactants, enzyme, bleaches, optical brightness, perfume, color and builders, and anti-redeposition agent and filter. They are dissolved in water and react with dirt and remove from cloth and other materials. The discharging of that wastewater into the river water without proper treatment created serious issue such as foaming, decreasing light penetration into different depth of the river making aerobic zone, eutrophication and several eco-toxic effects on aquatic animals. The concentration of anionic surfactant from 1 to 20 mg/L showed LC50 in fish [49, 50]. Koç and Güven [51] studied the single and progressive dose of 12.5 to 35.0 mg/L in *Oncorhynchus mykiss*. Many researchers have shown that activated carbon is an effective adsorbent for treating water with high concentrations of organic compounds [44]. Various biotechnological techniques have recently described an important group of bio surfactants using lipases or enzymes that can reduce environmental load of detergent products as the chemicals used in conventional methods; they are biodegradable and non-toxic, and also leave no harmful residues [52].

## **3.4 Heavy metals in the Gomti River water**

The Gomti River receives industrial as well as domestic waste from various drains in the city. The analyzed concentration of Mn, Pb, Ni, Cd, Cr, Fe, Co, Cu and Zn were represented in **Figure 3** and the average value were found to be 0.045, 0.057, 0.134, 0.007, 0.036, 0.792, 0.250, 0.303, and 0.110 mg/L respectively.

The results were found that Cd and Pb in higher amount which is very toxic for environment as well as aquatic ecosystem. The level of Mn, Fe, Co, Cu and Zn were higher in Khatu Shyam. Higher concentration of metal in water and sediment could be due to the industrial/agricultural/domestic runoff coming into the river. The maximum concentration of Pb, Ni, Cd and Cr were observed at Gomti Barraj. Intake of excessive concentration of heavy metals can pose carcinogenic effect on human and water quality assessment is necessary where the water using as a drinking purpose because of human actives creating huge quantities of wastes that can cause environmental pollution. The concretions of As, Cu, Fe and Cd in the Gomti River water were 0.029 to 0.079, 0.0145 to 0.061, 0.077 to 1.685 and 0.0144 to 0.0244 mg/L respectively. Kumar et al. [53] also found the similar result in the Gomti River. Industrialization and urbanization is growing rapidly with population and untreated waste disposal also increased due to mismanagement and overload wastes discharges from household into aquatic system [54]. That untreated wastewater and sewage loaded with heavy metals and organic compound into the water stream.
