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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 13, No. 8, 2016, pp. 1917-1932
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Bioline Code: st16177
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 13, No. 8, 2016, pp. 1917-1932
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Treatment of septic tank effluent using moving-bed biological reactor: kinetic and biofilm morphology
Almomani, F. A. & Khraisheh, M. A. M.
Abstract
Septic tanks are very commonly used wastewater collection systems throughout the world, and especially
in rural areas. In this study, the use of moving-bed biological reactors (MBBR) for the treatment of septic tank
effluent (STE) was examined. The study was conducted in
two phases. In Phase I, the performance of septic tanks
from four projects working under different operational
conditions and with different service lives was followed to
determine the parameters that required further treatment. In
Phase II, four specially designed continuous flow pilotplant MBBRs and one laboratory-scale batch reactor were
tested for their efficiency in treating STE. Experiments
were carried out at various temperatures (8–25 °C) and
with different hydraulic retention times (HRTs). MBBR
effectively reduced STE’s nutrients and chemical oxygen
demand by 90 and 85 %, respectively, over 180 days of
operation. The average ammonia removal rate at 25 °C
increased from 0.279 to 0.540 kg N/m3 when the reactor
HRT changed from 5.7 to 13.3 h. Under these conditions,
the ammonia removal kinetics were successfully correlated
with a theta model with an average θ value of 1.054. The
biofilm morphology showed a stable and global biomass
coverage (>70 %) and a high percentage of live cells. A
thinner biofilm was observed when the MBBR operated at
high temperatures. The results of this study showed that
MBBR is a promising technology for post-treatment of
septic tank effluent.
Keywords
Wastewater treatment; Moving biological reactors; Nitrification; Morphology
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