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.