Comparison between multi-stage and single stage microalgae dewatering processes

Abstract

The present work shows a quick, simple and accurate method for algae harvesting with a potential to relate the required polymer dose with in-situ hydrodynamics properties of alga solution. The method also reduces the lag time between the change in influent quality and chemical dosing adjustment during dewatering process. The tests were carried out using single and multi stage conditioning steps. Spectrophotometric measurements can potentially be used to select the best performing polymer and determine the optimum polymer dose for any type of Algae; optimum polymer dose calculated by use of CST and volume of filtrate match with optimum polymer dose achieved with absorbance measurements. Multi-stage conditioning process using ferric chloride and polymer resulted in better settling and algae dewatering when compared to the single stage conditioning using polymer or ferric chloride alone. The amount of conditioner used in multi-stage conditioning processes was less than the doses required for single stage process. The presented method could be useful in monitoring and optimize the polymer concentration and minimize the excessive use of polymers. Copyright (2018) by AIChE. All Rights Reserved.