Evaluation of the coagulating potential of the crude extract from the Barbatimão bark for the treatment of dairy effluents

Abstract

The coagulating potential of the crude extract from the barbatimao bark for the treatment of dairy effluent was assessed and compared with industrial coagulants such as aluminum sulfate (inorganic coagulant), the crude extract of black wattle bark (used in the manufacture of natural organic coagulants), and gallic acid (the main constituent of condensed tannins). The aqueous extract of barbatimao was obtained by refluxing for 12 h, and the black wattle was provided by a producer of natural coagulants. The determinations of total phenolic compounds and tannins in the extracts were performed by the Folin-Ciocalteu method and precipitation with casein, respectively. The treatment of the effluent with coagulant was performed by the Jar-Test. After testing, the effluent was evaluated for turbidity, total solids, and biochemical oxygen demand (BOD). A higher content of phenolic compounds (19.81% mg of gallic acid/g extract) was observed in the barbatimao extract than in the black wattle extract (14.24% mg of gallic acid/g extract). However, the extracts contained the same amount of tannins, 13.95% for the barbatimao extract and 12.89% for the black wattle extract. A 63%, reduction in BOD was observed for the effluent treated with barbatimao extract, 35% for the black wattle extract, 58% for gallic acid and 60.59% for the treatment with aluminum sulfate. Treatment with gallic acid caused a 98% reduction in the turbidity of the effluent; with aluminum sulfate, a 97% reduction was obtained; with barbatimao extract, 96%, and with black wattle extract, 93%. The barbatimao extract was shown to be a potential coagulant for dairy effluents.