In the third system, the active biomass in the pond
is increased by using attached growth on floating
media. Shin and Polprasert (1987) reported that an
attached media volume comprising 10% of total
pond volume was optimal and achieved 80% COD
removal in 5 days at a loading of 100 kg COD/
ha.day. Nutrient removal was increased due to
uptake into the attached films, but faecal coliform
die-off was similar to normal ponds.
Constructed wetlands
The advantages of constructed wetlands systems
include low operational cost, their 'green appeal',