The removal of indicator microorganisms from primary treated wastewater in subsurface reed beds using different...

Subsurface, horizontal flow, experimental reed beds, were designed and built based on a combination of two design methodologies, that of the WRc and Severn Trent Water Plc and that of the USA, EPA. Four different growing media were used with a combination of top soil, gravel, river sand and mature sewage sludge compost, aiming to determine the best substrate for enteric pathogen removal. Eight units were constructed, two for each material. One bed for each pair was planted with Typha latifolia plants commonly known as cattails. Primary treated domestic wastewater, was continuously fed in to the bed for more than six months. All beds achieved a high reduction of Escherichia coli and faecal coliforms with the best results recorded in the gravel reed beds with an average removal above 3.3 log for E. coli and 3.0 for faecal coliforms. There was no significance difference in the performance of planted and unplanted reed beds.