Wastewater-fed Aquaculture Otelfingen, Switzerland: Influence of system design and operation parameters on the efficiency of nutrient incorporation into plant biomass

; (). Wastewater-fed Aquaculture Otelfingen, Switzerland: Influence of system design and operation parameters on the efficiency of nutrient incorporation into plant biomass. Wastewater Treatment, Plant Dynamics and Management in Constructed and Natural Wetlands. Dordrecht, NL: Springer Science + Business Media B.V..

A wastewater-fed, partly indoor aquaculture plant consisting of 36 basins
with a total area of 360 m2, charged with effluent from a methanization plant
processing organic household waste (Kompogas System), started operation in
spring 1998 in Otelfingen, Switzerland. Due to high effluent concentrations on one
hand (total organic carbon, total nitrogen, and total phosphorus concentrations
being 670, 255, and 52 mg l−1, respectively) and stringent wastewater regulations on the other hand, the aquaculture was split into modules and stocked with organisms of different environmental requirements. The modular structure, as opposed to traditional one-pond polyculture, allowed manipulation and better nutrient budgeting of the system. Research focused on nutrient-recycling efficiency of a wide array of modules, producing biomass such as algae, fish, zooplankton, and aquatic macrophytes as ornamental plants (Eichhornia, Pistia, Ipomoea, Lemna, Azolla) which were suitable for sale on the Swiss market. Different arrangements of modules, of water and wastewater flows and of nutrient concentrations were tested in 3 years, 1998-2000. Our research showed that aquaculture can be set up to either produce treated wastewater ready for discharge into surface waters or to maximize nutrient recycling through biomass production. In the first case, the recommended loadings are below 0.47 g N m−2 day−1 and 0.084 g P m−2 day−1, in the latter 4.3 g N m−2 day−1 and 0.31 g P m−2 day−1 still resulted in a 78% removal of nitrogen and 28% removal of phosphorus. Through weekly biomass harvest, up to 0.36 g N m−2 day−1 and 0.06 g P m−2 day−1 were converted into plants. With appropriate planning and
plant selection and management, it was possible to increase the fraction of  nutrients eliminated via primary production up to 40%, which is significantly higher than reported in the literature.