Environmental Microbiology of Aquatic and Waste Systems

10.3 Systems for the Treatment of Sewage 263

then passes into a High Rate Pond (HRP) for rapid
growth of algae and concomitant production of oxy-
gen; in this pond, organic materials are oxidized. In
some systems, paddlewheels which revolve slowly
help to increase aeration in the HRP. Small ponds
immediately down stream remove algae. The water
next passes into Maturation Pond where it is held for a
period before being discharged. Maturation tanks pro-

vide opportunities for pathogen reduction, and when

the aim is to reduce pathogens the water may be passed

through a series of maturation tponds.

Effluent from AIPS is typically suitable for aqua-

culture because the fish feed on the algae in it. Under

such conditions, the algal settling and maturation

ponds may be eliminated or the water may held for

shorter periods in them.

Raw waste water Effluent

Anaerobic tank Aerobic tank

TOP VIEW

SIDE VIEW

30-50 m deep 10-20 m deep

Fig. 10.14 Setup in a two-pond oxidation pond system (Not drawn to scale) (Modified from Gerhardt and Oswald 1990 )

Advanced

facultative

pond

High rate pond settlingAlgal

ponds

Maturation

pond

Fermentation

pit

Effluent

Raw waste

water

TOP VIEW

Raw waste

water

Fermentation pit

Effluent

Advanced

facultative

pond

3-6 m deep

High rate pond

0.3 - 0.8 m deep

Maturation

pond

2 m deep

Algal

settling

ponds

2 m deep

SIDE VIEW

Paddlewheel

36 rpm

Paddlewheel

3 - 6 rpm

Fig. 10.15 Setup in a multiple pond system (Advanced Integrated pond System, AIPS; not drawn to scale) (Modified from Gerhardt
and Oswald 1990 )