All wastewater is gravity fed into a Primary Sewage Tank where the waste undergoes settlement and digestion during a retention period of approximately 24 hours. The settled wastewater then flows into the Turbojet unit. This unit is divided into two distinct chambers - submerged contact aeration (S.C.A.) tank and humus tank.
Effluent from the Primary Sewage Tank then flows into the S.C.A. chamber. During regular time clock intervals, water and air are pumped into the S.C.A. tank by means of strategically placed jets. The jets are positioned so as to cause a vigorous overturning and turbulence of the tank contents. Effluent entering the S.C. A. chamber is forced into a spiralling flow pattern. A biomass develops within the sludge particles tumbling through the tank. This biomass assimilates nutrients and oxygen from the water leading to gradual reduction of impurities as the effluent passes through the tank. The effluent and sludge particles then flow into the humus tank where the sludge particles settle to the floor of the tank and the effluent flows upward through a contact media box. This box contains plastic contact media on which a biomass acts as a tertiary interception and removal centre for remaining B.O.D. and suspended solids, thus further polishing the effluent before flowing into the contact sampling pit where it is further clarified and chlorinated (if and when required by Health Inspector) before being discharged into the stormwater drain or other means of disposal.
Settled humus tank sludge is automatically returned to the inlet of the S.C.A. tank by means of a vortex lift pump, which in turn is driven by the main S.C.A. delivery pump. Effluent and sludge particles are also re-circulated through the primary sewage tank by means of a 12mm dia. by-pass feed line from the main S.C.A.delivery pump.
(a) Excess sludge is returned to the primary sewage tank for storage and digestion.
(b) Clean effluent is recycled through the plant which tends to suppress
the activities of
micro-organisms which emit odours
(c) By regularly recycling effluent, the circulating and fixed biomass
in the S.C.A. tank is being fed
with stored organics from the primary sewage tank. This keeps the micro-organisms at
maximum population levels and reduces the problems of treatment plants not being used for
extended periods e.g. vacations. Consequently, untreated effluent is prevented from being
discharged from the unit when persons return suddenly from extended periods of non-use.