Effluent use in an automotive industrial complex

ABSTRACT

In this work, some changes in the productive system and in the effluent treatment plant of an automotive industrial complex have been performed in order to enable the treated effluent use in the cooling towers of the industry. Initially, a hydric balance in the industrial processes was performed, allowing the determination of water consumption. After, the effluent quality was analysed through its physico-chemical parameters at two sites of the effluent treatment plant: in the secondary settling tank (P1) of the physico-chemical treatment and in the exit of the polishing pond (P2). These analyses showed that the effluent from the settle tank does not have the ability to contemplate the specifications for water used in the cooling towers without much change in effluent treatment so that the effluent from polishing pond was used for testing in the cooling towers after some changes. These changes have included: phosphoric acid and nitric acid concentration changes in the cleaning solution of phosphating tanks, 50% increase in the aeration capacity of the aerated lagoon and replacement of aluminum sulfate coagulant by ferric chloride in physico-chemical treatment. With these modifications, the effluent from polishing pond approached the parameters specified for water cooling towers. The use of this treated effluent as 40% of water volume of the cooling tower resulted in hardness cycle increase and reduction in silica cycle. The use of a softener filter after the polishing pond decreased the effluent quality parameters to similar values to those for water cooling towers.

Keywords:
effluent; reuse; automobile industry; cooling towers