Pré-tratamento de efluente de microcervejaria por adsorção empregando adsorventes alternativos

Abstract

The organic matter present on craft brewery wastewater goes from 2000 mg.L-1 to 200.000 mg.L-1 of chemical oxigen demand (COD). The main goal of this study was to evaluate the use of pottery residues (clay ceramic) (CE) and recycled building construction wastes as alternative adsorbents in the pretreatment of craft beer wastewater based in Curitiba. Activated charcoal (CA) was used as reference for evaluating the potential of alternative adsorbents. In order to reduce the total number of experiments to achieve the best conditions of the batch adsorption and to figure out which factors and their interactions influence on adsorption process, a full 24 factorial design with two central point was carried out, considering as independent factors mass of adsorbent (m), time of contact (t), the initial COD concentration (Co) and pH. The levels analyzed were 5g and 10g to m, 1h and 3h to t, 1100 mg.L-1 and 3500 mg.L-1 to Co and 3 and 7 to pH. The response considered was the amount of organic matter adsorbed in terms of COD per unit of adsorbent. The results indicated that the factor that has more interference on the adsorption process for the three adsorbents was Co, presenting an average effect of 21.0375 on the response applying CA; 16.5563 applying CE and 10.956 applying RCCR. The second most important factor was m, which had an effect of -8.1250 applying CA, -7.7188 applying CE and 4,919 applying RCCR. The third most important factor was the interaction of the factors Co and m, presenting an average effect of -9.9125, -7.2187 and -3.644 on average using CA, CE and RCCR respectively. Adsorption of organic matter was favored at high levels (+) of Co, and low levels (-) of m. The pH and t factors have not shown great porpotion effects. The R² values found were 100%, 99.99% and 88.49% respectively for CA, CE and RCCR, indicating that the aquared models are good representatives of the relation between the factors and the response. The CE behavior as an adsorbent on the craft beer wastewater pretreatment was very similar to the CA, showing up to 63% of COD removal on the studied operacional conditions, while the RCCR reached 40%. The conclusion is that both alternative adsorbents analyzed are able to be used on the craft beer wastewater pretreatment process.