Biological nutrient removal in a small-scale MBR treating household wastewater.
The biological nutrient-removal potential of an on-site Membrane bioreactor (MBR) located in the basement of a four-person house treating domestic wastewater was investigated. The reactor consists of two tanks in series. This treatment plant differs from other conventional MBRs by a highly fluctuating influent water flow and a lack of pretreatment. During the first period, the first reactor was operated as a primary clarifier, resulting in nitrogen and phosphorus removals of 50% and 25%, respectively. Primary sludge production and bad odors in the basement were further disadvantages. When using the first reactor as an anaerobic/anoxic reactor by recycling activated sludge and mixing the first reactor, nitrogen and phosphorus removals of over 90% and 70% were achieved, respectively. By applying a dynamic model of the plant, the return sludge ratio was identified as the most important parameter. With a return sludge ratio of about 1.2, optimal PAO growth and phosphorous removal up to 90% was reached. Since only activated sludge is produced with this operational mode, on-site sludge dewatering is possible. During vacation periods without loading, the Bio-P activity is kept constant if the aeration is reduced to 5-20 min d(-1).
Abegglen
Christian
C
Eawag, Swiss Federal Institute of Aquatic Sciences and Technology, CH-8600 Dubendorf, Switzerland. christian.abegglen@eawag.ch
Ospelt
Mario
M
Siegrist
Hansruedi
H
D019149:Bioreactors; D006798:Housing; D009584:Nitrogen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D012722:Sewage; D013557:Switzerland; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism
D012722:Sewage; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen