Plants processing food of animal origin like dairy, meat or fish products need usually large quantities of clean water in production. More than 90% of clean water is converted into wastewater demonstrating very high potential risk of environmental pollution. The present study was undertaken to compare, under the same analytical conditions, the efficiency of ferric sulfate used as coagulant (dose: 450 g/m³) in chemical treatment of raw technological wastewater collected from three various food industry plants (dairy processing, meat processing and fish processing). Results of visual and physicochemical evaluation of chemically treated wastewater indicated significant improvement of their selected characteristics, however different response to the coagulant treatment was observed within the tested samples. Removal efficiencies for individual parameters varied in the wide range between 20.9 and 97.2%. Since bacterial bioluminescence inhibition used as biotoxicity indicator of effluents collected after treatment with ferric sulfate was less than 20%, they should be considered as non-toxic samples.

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