Harvesting Colonial Microcystis flos-aquae using two-stage filtration: Influence of pre-filtration on harvesting performance

•Pre-filtration with a 20 μm screen improved harvesting rate by 25%.•Pre-filtration changed size distribution and concentration of colonial Microcystis.•Larger colony size or narrower size distribution resulted higher harvesting rate.•Harvesting rate increased with cellular concentration initially and then decreased.•Influences of size distribution and concentration were predicted by a MLR model.