Introduction to tycho-filtration-A biotechnology for lacustrine detrophication

Excess of nitrogen (N) and phosphorus (P) increases the eutrophy level and can produce severe algal blooms in lakes and ponds. We introduce tycho-filtration based on self-settling algae aggregates, a biotechnology to extract excess of N and P from hypertrophic waters. This technical note has the following four scopes: (i) explaining the operating principle of tycho-reactors, (ii) drawing attention to parameters that may influence performance, (iii) identifying strategies for containing nuisance organisms in tycho-reactors, and (iv) discussing potential applications of this technology. A proof of concept 3 m² tycho-reactor with 880 liters per hour daily-peak flow-through rate yielded ≤120.4 g dry weight (DW) algae biomass m^-2 day^-1. This biomass consisted of 55% desmid Chlorophyceae and 44.8% diatoms vol:vol, carrying ≈4.16% N and ≈0.43% P per DW. Biological interferences requiring specific management include surface-attached filamentous algae, toxin-producing cyanobacteria, and the algae-eating bladder snail (Physella acuta). Advantages of tycho-filtration are predicted to come from photosynthesis being reliant on solar light, low cost of algae harvesting, potential for automation, and suitability for solar-based water flow. Potential applications of this technology include preventing severe algal blooms in small lakes, control of N in recirculated aquaculture, and detrophication of liquid effluents from aquafarms that threaten downstream ecosystems.