Optimization of Coagulation/Flocculation Treatment of Brewery Wastewater Employing Organic Flocculant Based of Vegetable Tannin

Abstract

The brewing industry is an important sector in the world economy, and its production process generates a large amount of wastewater. It is essential the proper treatment of this wastewater and a significant amount of biomass may be recovered by coagulation/flocculation process. When using vegetable tannin as an organic flocculant, biomass can be used in the preparation of organic fertilizer, unlike what would occur if a metal base flocculant was used, some of which are considered to be toxic. This work presents a study on the use of vegetable tannin as flocculant agent (Tanfloc SL) for the treatment of brewery wastewater, which also contains microalgae originated from an aerated pond of a local brewery industry. Experiments of coagulation/flocculation and sedimentation were carried out using jar test equipment. A sequential 22 factorial design and two-factor Doehlert design were used to determine the optimum levels of pH and tannin concentration for turbidity and apparent color removals from the wastewater. The higher efficiency results in the biomass separation were obtained by employing 0.23 mL L−1 of vegetable tannin at pH = 4.9, resulting in the substantial removal of approximately 99% of turbidity and apparent color. The removals of biomass and nutrient components were also evaluated: N-NH4+ (80.8%), N-NO2- (83.6%), N-NO3 (56.9%), total phosphorus (82.3%), orthophosphate (76.2%), COD (96.5%), BOD (69.4%), and total solids (40.8%). The Tanfloc SL showed to be efficient in flocculation of the brewery effluent, allowing the reuse of water in industry and the recovered biomass material containing nutrients in agriculture.