This paper describes the study conducted by People's Science Institute that aimed at determining the threshold level of toxicity of a paper mill effluent, and the level of toxicity that it created in the receiving water body and at identifying the physico chemical parameters of the effluent that may be causing the observed toxicity. The study was conducted in Star Paper Mill in Saharanpur in Uttar Pradesh, which is one of the oldest and the largest paper mills in the country.
Evidence indicates that wastewaters generated from the processes in the paper mills contain a range of toxic chemicals such as mercury, chlorinated lignins and their derivatives, chlorides and suspended solids, which can be extremely harmful to living organisms in the water bodies. Many a times, the wastewaters are not recycled and are directly released as effluents into the water bodies.
A soda recovery plant within the Star Paper Mill in Saharanpur processes about 1700 m3/ day of black liquor from the pulping process. All wastewater from the mill is channeled through a single drain to the effluent treatment plant, where it is treated by activated sludge. The effluent is then released into the River Hindon, which is a seasonal river and has very low flows for much of the year.
Fish and Rice bioessays were performed to look at the impact of the effluents on the aquatic animals and plants. The study found that: