Utilização de biopolímero extraído da pinha de Pinus Elliotti como auxiliar de floculação para a aplicação no processo de tratamento de água

Abstract

Currently, the most widespread water treatment process for human consumption is conventional treatment, where it goes through the stages of clarification, filtration, disinfection, fluoridation and acidity correction. In the clarification step, the coagulation process occurs, which occurs through the addition of chemical or natural coagulants, where the destabilization of the particles occurs. The use of natural coagulants as a coagulation/flocculation aid can help to reduce the formation of toxic by-products and reduce the addition of synthetic elements in the treatment of supply water. Therefore, the use of natural coagulation aids can be of great benefit, as they have as raw material natural elements found in abundance in nature. In Brazil, pine is cultivated to extract its wood and the pine cones end up being discarded. Thus, this work aims to use the biopolymer extracted from Pinus Elliotti pinecone as a flocculation aid in water treatment. The water was collected from the Ijuí River in the municipality of Cerro Largo. For the tests, the two factors of interest were defined: dosage of the coagulant aluminum sulfate (mg·L-1), and dosage of the biopolymer extracted from the pinecone which is intended to be evaluated as a flocculation aid (mg·L-1). The parameters (dosages) were combined at random levels for the purpose of building clotting diagrams and determining the best regions of color removal efficiency, turbidity and absorbance at 254 nm. From the CCD, the experimental tests were performed where these tests were calculated by the Minitab®18 software. Thus, the 13 coagulation, flocculation and sedimentation tests were performed using the jar-test, where the coagulant was added in the rapid mixing stage and the flocculation aid in the slow mixing. Subsequently, samples were collected at settling times of 2, 4, 6 and 10 min and analyzes were performed on the parameters of turbidity, apparent color and absorbance at 254 nm. From the results, it can be seen that in the settling time of 6 min, removal percentages for apparent color between 0 and 18,18% were obtained. For turbidity, the removal percentages ranged from 65,12 to 99,42%. For the 254nm absorbance, the removal percentages ranged from 54,07 to 99,75%. The volume of sludge generated after the sedimentation process was also evaluated and through this experiment and the percentages of removal obtained, it is assumed that experiment 2 is the most appropriate experiment, since little coagulant and flocculation aid was used and generated 2 mL·L-1.