Treatment of domestic wastewater in an up-flow anaerobic sludge blanket reactor followed by moving bed biofilm reactor.
The performance of a laboratory-scale sewage treatment system composed of an up-flow anaerobic sludge blanket (UASB) reactor and a moving bed biofilm reactor (MBBR) at a temperature of (22-35 degrees C) was evaluated. The entire treatment system was operated at different hydraulic retention times (HRT's) of 13.3, 10 and 5.0 h. An overall reduction of 80-86% for COD(total); 51-73% for COD(colloidal) and 20-55% for COD(soluble) was found at a total HRT of 5-10 h, respectively. By prolonging the HRT to 13.3 h, the removal efficiencies of COD(total), COD(colloidal) and COD(soluble) increased up to 92, 89 and 80%, respectively. However, the removal efficiency of COD(suspended) in the combined system remained unaffected when increasing the total HRT from 5 to 10 h and from 10 to 13.3 h. This indicates that, the removal of COD(suspended) was independent on the imposed HRT. Ammonia-nitrogen removal in MBBR treating UASB reactor effluent was significantly influenced by organic loading rate (OLR). 62% of ammonia was eliminated at OLR of 4.6 g COD m(-2) day(-1). The removal efficiency was decreased by a value of 34 and 43% at a higher OLR's of 7.4 and 17.8 g COD m(-2) day(-1), respectively. The mean overall residual counts of faecal coliform in the final effluent were 8.9 x 10(4) MPN per 100 ml at a HRT of 13.3 h, 4.9 x 10(5) MPN per 100 ml at a HRT of 10 h and 9.4 x 10(5) MPN per 100 ml at a HRT of 5.0 h, corresponding to overall log(10) reduction of 2.3, 1.4 and 0.7, respectively. The discharged sludge from UASB-MBBR exerts an excellent settling property. Moreover, the mean value of the net sludge yield was only 6% in UASB reactor and 7% in the MBBR of the total influent COD at a total HRT of 13.3 h. Accordingly, the use of the combined UASB-MBBR system for sewage treatment is recommended at a total HRT of 13.3 h.
Tawfik
A
A
Water Pollution Research Department, National Research Center, El-Behouth St., Dokki, Cairo, Egypt. tawfik8@yahoo.com
El-Gohary
F
F
Temmink
H
H
D000693:Anaerobiosis; D018441:Biofilms; D019149:Bioreactors; D004867:Equipment Design; D006868:Hydrolysis; D009068:Movement; D009584:Nitrogen / Q000737:chemistry; D012722:Sewage; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water / Q000737:chemistry; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D012722:Sewage; D014874:Water Pollutants, Chemical; D014867:Water; D009584:Nitrogen