Process Description

Rotating Disc plants are constructed to rely on gravity flow as much as possible as opposed to installing an array of pumps, compressors, blowers and level switches throughout the treatment process. This is a fundamental design implementation of ours.

The Rotating Disc wastewater treatment plants are based on the Rotating Biological Contactor (RBC) methodology.

The Rotating Disc plant operates as follows:

  1. Primary Settling Tanks (Holding Tanks)
    The incoming raw sewage is deposited in sealed primary settling tanks , where primary settlement and anaerobic digestion occurs. These tanks also act as balancing tanks for the incoming flow, and have a combined settling capacity to ensure at least 24 hour retention.

    The retention capacity created in the primary settling tanks ensure proper settling of bio-solids and anaerobic digestion. This digestion results in the primary tanks only requiring de-sludging (pump-out via vacuum tanker) once every 12 - 18 months.

    The settling tanks are equipped with a balancing weir, ensuring a constant flow through the plant and providing an additional storage at the plant in the event of an emergency or storm.
  2. Rotating Biological Contactor (RBC Rotor Unit)
    Primary settling tank effluent flows through to the Rotating Disc stage (RBC Rotor Unit); this is where aerobic treatment takes place. The treatment bacteria attach themselves to the discs to provide both Carbon Oxidation and Nitrification treatment. This bacteria cannot be washed out of the system with shock or fluctuating seasonal loads and is therefore consistent and reliable.

    The population of the Carbon Oxidation and Nitrification bacteria will automatically vary depending on the influent volume, which therefore accommodates the seasonal loadings.

    The turbulence created in the rotor basin ensures that the biomass receives oxygen and all matter treats the wastewater effectively. This design means the rotor unit never needs to be stopped for cleaning or maintenance tasks.
  3. Clarification (Humus Settling Tank)
    Effluent from the Rotating Disc stage then passes through the Clarifier (Humus Settling Tank). The humus sludge is returned to the primary settling tanks via a small submersible pump located in the tank. This forms part of the recirculation process and denitrification is achieved.
  4. Disinfection (Chlorine Contact Tank)
    Clarified effluent will then flow into the chlorine contact tank where adequate contact time for disinfection is provided.
    Two types of chlorine disinfection are offered, depending on the design and the client's preference:
     • Pill type Chlorine
     • Liquid Chlorine Dosing
     After the disinfection stage, the treated effluent can be irrigated or dispersed as per site instructions.
  5. Effluent Polishing
    Additional treatment and disinfection can be incorporated into the design of the Rotating Disc plant.
    This equipment can include:
    • Media Filtration
     • Phosphate Removal
    • UV Disinfection
     • Membrane Filtration
    Where Effluent Polishing is included in the design, this occurs after Clarification and before Chlorine Disinfection.

As outlined in the above process, the Rotating Disc plant is simple, self-compensating and the design is able to handle variations easily.

ABN: 33 124 536 161