Figure 2 : Proportion of sewage disposal directly to the rivers
in different states of India (Source: Kumar, 2021)
From the data obtained from the Central Pollution Control Board, India,
it can be concluded that there is still lacking in the implementation of
the laws or regulations in the Indian context. The disposition of sewage
is associated with heavy metal contamination as we have apprehended from
the above sections. Thus, in the next part, we will mostly cover the
effects of heavy metals found in sewage and the pollution caused by
them. Heavy metal pollution has been a serious environmental concern in
river basins for the last 40 years, and extensive research has been
conducted to demonstrate the sources, diffusion, and destiny of the
pollutants, as well as the accompanying interactions with civilization.
The worldwide number of heavy metals discharged into the environment in
the final half of the twentieth century was 22,000 tonnes of Cd, 939,000
tonnes of Cu, 783,000 tonnes of Pb, and 1,350,000 tonnes of Zn (Sharma
2011). Heavy metals, due to their solubility, may be spread by water
and, as a result, harm aquatic habitats. (Masindi & Muedi 2018). In
2006, the dissolved metal content in the Buriganga River (Bangladesh)
was 126 ppm of Cd, 805 ppm of Pb, 5,274 ppm of Cr, and 595 ppm of As
(Bhuiyan et al. 2015). Such high amounts of heavy metals in surface
water are a direct hazard to human health and necessitate immediate
action as well as more investigation (Siddiqui & Pandey, 2019). In the
case of Indian rivers, the Ganga river contains the majority of heavy
metal pollution. The next part will go through the present state of the
situation.