Project: Constructed wetlands for waste water treatment
Gumbricht, T., . Tertiary wastewater treatment using the root-zone method in temperate climates. Ecological Engineering, 1 (3) , 199-212. closed
Abstract
Between September 1988 and June 1991 a full-scale experiment with a 1100 m2 root-zone bed treating secondary wastewater was conducted in southern Sweden. The species used were Phragmites australis and Typha latifolia. The average hydraulic load in the studied root-zone was 16 cm day−1 per surface unit. Loads of nitrogen, phosphorus and BOD were 1.7, 0.6 and 1.0 g m−2 day−1, respectively. Mean weekly reductions were 46% of nitrogen, 61% of phosphorus and 71% of BOD, equivalent to specific removals of 0.8, 0.4 and 0.7 g m−2 day−1, respectively. In comparison with other root-zones studied under similar conditions, the efficiency of the presented root-zone is high. Possible explanations for the relative success include; favourable soil media containing peat (i.e. organic source for denitrification and buffering pH), depth (greater than other root-zones), high iron-content and slightly acid pH (enhancing phosphorus adsorption and precipitation and application of pretreated wastewater (nitrification not limiting).