Treatment of anaerobically treated domestic wastewater using rotating biological contactor.
A small-scale pilot plant consisting of a three-stage RBC has been investigated for the removal of E. coli, COD fractions and ammonia from the effluent of an UASB reactor treating domestic wastewater. The results obtained reveal that a three-stage system operated at a HRT of 3.0 h represents an effective posttreatment process. The remaining COD in the final effluent was only 51 (+/- 7) mgl(-1). Ammonia concentration was reduced by 67 (+/- 7.6) %. The overall E. coli reduction was 1.39 log10 at an influent count of 6.5 log10 corresponding to an overall removal efficiency of 95.8 (+/- 4.7) %. However, according to prevailing standards, residual E. coli counts are still high for unrestricted reuse for irrigation purposes. When the system was operated at a HRT of 10 h, overall E. coli removal and ammonia reduction were 99.9 (+/- 0.05)% and 92 (+/- 6.5) % respectively. At a HRT of 10 h, recirculation of the 3rd stage effluent to the 1st stage reduced the residual of E. coli in the final effluent from 2 x 10(3) to 9.8 x 10(2)/100ml. Moreover, the recirculation of nitrified effluent from the 3rd stage to the 1st stage increased ammonia removal in the stage 1 from 23 to 43%. This relatively high ammonia removal likely can be attributed to the supply of nitrifiers from 3rd stage to the 1st one.
National Research Centre, Water Pollution Control Department, Cairo, Egypt. tawfik8@hotmail.com
A
A
Tawfik
B
B
Klapwijk
F
F
El-Gohary
G
G
Lettinga
D000641:Ammonia / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000502:physiology*; D019149:Bioreactors; D004926:Escherichia coli / Q000302:isolation & purification; D010100:Oxygen; D010865:Pilot Projects; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*
D012722:Sewage; D000641:Ammonia; D010100:Oxygen