B3-KH-8-A c to orderrelated documentation Without oil fill Bevel-helical gear Reduction Box B3

Flender/Flender Gear Units/Bevel-helical gear Reduction Box B3

rocess Unit sizes for JP Marais WWTP Treatment Unit Units Details Bioreactor Total volume m3 1,8 Water depth 4.5 Anaerobic zone 3 1,3 Anoxic zone m3 8 Aerobic total m3 8,6 Size of surface aerators kW 5 No. of aerators No. 1 Secondary and Tertiary Clarifiers No. of secondary clarifiers No. 2 No. of tertiary clarifiers No. 1 Diameter 3 Area (each) 2 7 Volume (each) m3 Maximum RAS rate (per clarifier) / 1 Maximum RAS rate wrt. ADWF ~1:1 The anaerobic and anoxic mass fractions are 0.1 and 0.0 respectively. The anoxic mass fraction can be increased by turning off upstream aerators. If the fir st two aerators are turned off, the anoxic volume increases to 2,6 m3 giving an anoxic mass fraction of 0.2. Turning off the first four aerators increases the anoxic volume and mass fraction to 4,3 m3 and 0.4 respectively. 5.2.4 Activated Sludge Aeration System The aeration system consists of 1 5 kW low sing le speed surface aerators arranged in rows of 2 along the aerobic zone. The design did not allow fo tapered aeration configuration to cater for . . located in the last aerobic cell; one approximately in the centre and the other ne ar the bioreactor outlet. The DO meters were out of service for the whole du ration of the project in 2. portable DO meter was used to monitor DO concentrations. The plant was designed to operate using fixed DO ae ration control strategy hence the aeration system is controlled to primarily maintain set DO in the aerobic zone stipulated in the design to be maintained between 1 and 2 mgO/. Aeration control was designed to be achieved as follows: fixed DO setpoint is selected by the operator. immersion depth of the surface ae rators is varied using an adjustable weir at the bioreactor outlet. PLC, using the signal from the DO meters (average of the two meters) is used to automatically control the height of th