Flow conditions influence nutrient removal at an artificial lake and a drinking water reservoir with an algal floway

To optimize flow condition of algal turf scrubber (ATS) system for nutrient (nitrogen and phosphorus) removal at eutrophic waterbodies, we constructed two experimental scale (2.5 m(2)) algal floways to test nutrient removal rates under various flow conditions via regulating flow rate and intermittent frequency of pump on/off. Results showed that the largest algal productivity and nutrient removal rate were generally obtained under the hydraulic loadings of 120 L min(-1) m(-1). Nutrient removal rate was high with an intermittent inflow 4 h(-1), followed by 12 h(-1) and 60 h(-1). We estimated that a hectare-scale floway system under a flow rate of 120 L min(-1) m(-1) and intermittent flow 4 h(-1) which would have satisfactory performance with affordable investment. This option has the greatest potential for the application of such technology in nutrient pollution abatement while producing bioresources from harvested microalgae.