Estratégias biológicas para tratabilidade de água em processo de fabricação de papel reciclado

Abstract

The pulp and paper industries are responsible for about 1% of the entire Brazilian GDP, and are considered economic indicators for reflecting the variations in the commercial market. Among these industrial plants, we can distinguish the recycled paper mills, which operate in the production of paper from trimmings derived from the recycling of cardboard previously sold. As a result of the physical- chemical characteristics of the chips and the use of other inputs, by-products are generated that alter the color, turbidity, electrical conductivity and other parameters, which influence the performance of the production process. These aspects can be accentuated when considered plants with no effluent disposal. In closed systems, as a consequence of water reuse in the production process, an increase in the percentage of contaminants is identified, which also interferes in final product characteristics. Fungal cultures have been used in order to minimize these effects in a sustainable way in pulp and paper, textile, and galvanic industries, among others. In the present work, cultivations of Pleurotus albidus and Lentinus crinitus were carried out aiming to improve the water quality of a recycled paper industry in a closed system. The cultivations were performed in media composed by different percentages of recycling water (30 to 90% v/v) and glucose (0 to 20 g/L), at 28oC, in flasks under agitation. Among the conditions evaluated for P. albidus, mean values of reduction of color and electrical conductivity of the medium of 88 and 30% were attained, respectively, in medium formulated with 90% (v/v) of recycling water and glucose, in 9 days of process. In L. crinitus cultivation less cell growth was quantified, but the constitutive production of lacases using 90% (v/v) of recycling water was about 10 times higher than that obtained with P. albidus. Considering the reduction of color and electrical conductivity, the results were similar to those achieved in P. albidus cultures. With 90% (v/v) of recycle water and glucose supplementation, an average reduction of 30% of electrical conductivity was obtained by L. crinitus on the 3rd day of cultivation and 70% of color in 9 days of process. The results presented clean and sustainable alternatives for improving water quality in paper industries with the closure of the water and effluent circuit and with recycled raw materials. [resumo fornecido pelo autor]