Nitrogen and Phosphorus Removal by Periphyton from Agricultural Wastes in Artificial Streams

Dissolved nutrient concentrations were rapidly reduced in slow moving waters by the periphyton growing in shallow experimental streams. Nutrients added after an initial decrease were removed at a faster rate by the well developed periphyton community. Biomass of 36.2 g DW.m−2, 23.7 g AFDW.M−2 and 100 mg Chl.m−2 grew in a high phosphorous loaded stream, while 31.7 g DW.m−2, 16.6 g AFDW.m−2 and 42 mg Chl.m−2 were determined in a low loaded stream. The two different nutrient concentrations also generated quite different qualitatively biotic communities from identical origin. Stigeoclonium tenue dominated in both systems, but Cyclotella spp., Epithemia spp., and Synedra spp. occurred in different proportions. Nutrient uptakes of 83 mg P.m−2 .d−1 and 203 mg N.m−2 .d−1 were calculated based on concentration reduction. Light, temperature, and pH levels in the semi-natural greenhouse environment suggested little effect upon the periphyton community uptake of nutrients.