Municipal wastewater treatment by modified tannin flocculant agent

A new tannin-based coagulant and flocculant agent (TANFLOC) has been tested in order to treat urban wastewater. TANFLOC has showed a high effectiveness in turbidity removal (almost 100%, depending on the dosage) and around 50% of BOD5 and COD removal, which makes TANFLOC an appropriate coagulant agent with an efficiency that is comparable to alum's. Coagulant and flocculant process does not depend on temperature, and optimum agitation speed and time have been found to be 40 rpm for 30 min. Polyphenol content does not increase drastically, and 30% of anionic surfactants are removed. Sedimentation process seems to be a flocculent separation so Sludge Volumetric Index and its evolution with flocculant dosage have been determined. TANFLOC has been revealed as a quite effective coagulant and flocculant agent in wastewater treatment.