526
M.G. McGarry, CD. Lin and J.L. Merto
6AM
I2N
6PM
I2M
TIME OF
DAY
6AM
Fig. 4.
Diurnal variations of pond C effluent quality
settled sewage
pond effluent
Γ wet algae
( o ) ( o ) DRUM
^ - ^ 1 ^ - ^ DRIVERS
dry algae
Fig. 5.
The high rate pond process flow diagram incorporating alum recovery and recycle
studied; in fact, noon time BOD's remained well below 20 mg/1 throughout the test
period in all ponds.
ALUMINIUM RECOVERY AND REUSE
Alum flocculation and downflow flotation (Fig. 5) is used to clarify the pond
effluent and concentrate the algae (McGarry and Tongkasame, 1971). Removal of the