Reedbeds and Sewage

The Eco cabins at CAT have their own reed bed systems which are used to treat sewage. Reed bed  sewage systems use a series of natural filtration systems to treat waste water. Discharging of raw wastewater has a negative impact on the environment such as eutrophication of receiving water bodies, pollution of groundwater and odor. What is more, wastewater contains pathogenic organisms which transmit disease to animals and human. For these reasons it is crucial to have an effective sewage management system and operate it in proper way. This is what our biology department does.


There are different technologies of wastewater treatment. I am going to focus on reedbeds system which are used here in CAT. The reedbeds are a  type of constructed wetland which treats municipal or industrial high strength effluents. Reedbeds effectively remove from the sewage organic matter, phosphate, oxidize ammonia, and reduce nitrite. The mechanism of nutrients removal is complex and involves microorganisms’ oxidations, sedimentation, filtration and chemical precipitation. Reedbeds can be designed for 30 people like the Eco cabins one or for a 25,000 people like the largest reedbeds in the UK in Redgate Mill.

The Eco-cabins’ reedbeds were constructed in 1990 and are one of the oldest in UK. At that time reedbeds were treated as experimental and new technology. Performance of the system has been occasionally monitored over twenty one years and recently we have decided to evaluate its operation again. To do so we are collecting the sewage samples from different stages of the system and analyzing them in terms of ammonia, phosphate, nitrate and microorganisms concentration. Another aim of the reedbeds project is to compare charcoal, sawdust, sand and woodchip in terms of sewage purification. So far results show that charcoal is the best filtration media for all monitored nutrients. For ammonia removal the most ineffcient is sand,  forphosphate removal sawdust and  for nitrate removal it is woodchip. We think that charcoal used for sewage treatment might significantly improve the health and productivity of the soil when mixed together. However, this will be the next experiment for future volunteers. Additionally, we have decided to calculate the operational and embodied carbon footprint for Eco cabins reedbeds system as most of the wastewater treatment plants are obliged to do so. To calculate it the UKWIR methodology will be used as it is the newest and especially designed method for carbon accounting in the water sector.

The exciting research about the wonderful wild world of reedbeds is still going on so please stay with us and follow the newest results!!