Investigação da utilização dos polímeros reciclados quimicamente poliestireno sulfonado, de copos plásticos, e hemicelulose catiônica, de palha de milho, como auxiliares de coagulação no tratamento do esgoto industrial

Abstract

This work approaches the investigation of the use of sulfonated polystyrene from plastic cups and cationic hemicellulose from corn husk as coagulation auxiliary in the treatment of residential and industrial effluents. The cationic hemicellulose was also investigated as coagulant. Measurements of turbidity, color and pH were performed to evaluate the efficiency of the polymers in jar-tests. The results obtained were compared with commercial polyacrylamide (Acripol C10 ®). The interference of pH variation and the presence of total sulfides in the use of polymers and coagulant in wastewater were evaluated. The results of the use of sulfonated polystyrene as coagulation auxiliary did not demonstrate efficiency on the removal of turbidity and color because of the negative charge of the polymer stabilize the colloids present in wastewater, impairing the coagulation process. Nevertheless, it may be viable to use in other types of effluent where they are favorable physico-chemical characteristics. The cationic hemicellulose used as coagulation auxiliary showed better results than the commercial polyacrylamide at a dose of 40 mg/L. The percentages of reduction of color and turbidity of the hemicellulose were respectively 79.9% and 71.8% and 10% better than the results of polyacrylamide. The investigation of polymers by varying the pH of the effluent found that a pH of about 5 the coagulation process is favored because of decreased interference from total sulfides. The best results for removing color and turbidity at pH 5 were found for the cationic polymers at a dosage of 10 mg/L. In the application test cationic hemicellulose as coagulant is observed that in the initial dosage of 200 mg/L was a significant reduction in turbidity and color of the wastewater (48.4% and 18.3% turbidity and color reduction), however with increasing polymer dosage was increased turbidity and color because of the increase of the flakes which, being fragile and brittle, dissolved in the effluent. The cationic polymer hemicellulose derived from corn husk may be used in the treatment of residential and industrial wastewater by replacing polyacrylamide, which has been generally used, as coagulation auxiliary or as a coagulant.