Rotating biological contactor treatment system in the factory
The RBC was selected and installed by the factory as it has the advantage of low operating and maintenance costs. The RBC was fed continuously with the effluent from the pretreatment unit. It consists of a four stages RBC. Each stage was filled with plastic packed materials in the form of rings which provide a total surface
area of 4000 m2 (Fig. 11). The discs were rotated at 3-5 rpm with approximately 45% of the surface area submerged in the wastewater. The total liquid volume of
the system was 6 m3 .The hydraulic load applied to the RBC was 0.02 m3 /m2 .d. The water is dosed to the RBC by rotating cups mounted on a large disc attached to the main shaft. The factory RBC performance was monitored. Table 2 shows the characteristics of the treated effluent. Residual values of COD and BOD ranged
from 127 to 543 and 25 to 385 mgO2/l with average values of 362 and 139 mgO2/l, respectively. Corresponding average removal values were 86% and 88%.
The average percentage removal of total suspended solids was 73%. The corresponding residual concentration was 95 mg/l. The average residual value of oil
and grease was 27 mg/l with 77% corresponding removal value. The characteristics of the treated effluent are comparable with the results obtained by using the
lab unit RBC.
Conclusion
The obtained results using the activated sludge, rotating biological contactor and UASB technology proved to be efficient for the treatment of wastewater dis-
charged from a flavor production factory. The wastewater characteristics of each treatment process are in compliance with the Egyptian law which regulates the
discharge of industrial wastewater to the sewerage system. The factory installed RBC proved to be efficient and reliable on account of the characteristics of the
treated effluent as compared to the results obtained from the lab unit.