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Overview

Aeration is intermittent during the day. At system controlled intervals, the turbine aerator is run at low speed mixing only to create anoxic conditions for de-nitrification. Turbine shutdown to allow clarification and solids settlement is timed to coincide with daily low inflow periods. The exclusion of an isolated non-mechanical primary settlement stage removes the possibility of the production of foul odors emanating from unstable putrid sludge and permits construction in close proximity to habitable dwellings.

1. FILLING
   
   Screened or macerated effluent is transferred from collection sump and pumping lift station into the treatment tank(s). Pump operation and liquid inflow is regulated (forward feed/batch volume controlled) by level sensors and the main process control system. For below ground systems, gravity inflow may be considered without the requirement for pumping equipment.
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3. AERATION
   
   The organic materials are oxidized and digested as long as normal sewage input to the SBR continues with constant aeration. Oxygen input is varied and controlled to facilitate thorough nitrification and de-nitrification of the effluent. The consistent biological action keeps the environment regular and stabilized (non-haphazard) thereby preventing odourous off-gas production.
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5. SETTLEMENT
   
   The turbine aerator stops and is set into standby when there is little system flow. The process of gravity settlement begins and the reactor becomes a sedimentation tank. Settlement is complete when the liquid medium has stratified and clarified effluent occupies the top portion of the basin.
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7. DECANT
   
   Clarified effluent is discharged from the reactor basin via an automated siphon - type decanting system or by duty - standby decant pumps. Following decantation additional tertiary disinfection and filtration may follow (dependent on treatment objectives and environmental control regulations).
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9. BUFFER
   
   Rest interval prior to SBR recharge and new cycle start. The concentrated sludge remains biologically activated in a state of endogenous respiration. The biomass profile is molecularly simpler and more inert from bacterial decomposition with little remaining caloric value.