Sir,

Toxicity of wastewater / industrial effluents treated or untreated according to standards prescribed shall be carried out using fish and any other aquatic organisms as recommended by regulatory authority. Toxicity evaluation is carried out on treated effluent for disposal to environmental media.

Rats are not used for evaluating the toxicity of industrial wastewater.

Raw wastewater at JETL is subjected to physico-chemical and aerobic biological treatment in a Combined Wastewater Treatment Plant (CWWTP) and the treated effluent has been meeting the discharge standards for disposal to sewer since 1998 onwards. It is meaning less as well as surprising to conduct studies on the toxicity of the untreated wastewater using rats as the test animal. It is still surprising to state that the wastewater requires treatment.

Data on characterization of wastewater used in the study (Table-1) do not represent the characteristics of raw wastewater received and stored before biological treatment. The values reported for TDS is 36.898 ppm. On the other hand chlorides as 1799.4ppm, sulphate 6982.867 ppm and phosphate as 6125 ppm. The anions along with cations eg. Na, K, Ca & Mg will be present in TDS and hundreds of times higher than TDS value reported. Hence the sample used for the study does not represent the wastewater received at JETL for treatment.

Hence the authenticity of the study is questionable. The publisher may look into these aspects and call for explanation from the authors of the publication and inform us.

Thank you,