Healesville Sewage Treatment Plant by hjkuiw354


									Healesville Sewage Treatment Plant
Introduction                                                    circulation and oxygen transfer promoting the growth of
Around 93% of the sewage that Yarra Valley Water collects       micro-organisms that consume organic matter to
                                                                breakdown and release nitrogen. Alum is dosed to the
is transferred to Melbourne Water for treatment at either
                                                                sewage at the inlet to the oxidation ditch to aid phosphorus
the Western or Eastern Treatment Plants.
However, the remaining 7% of wastewater is treated in
small treatment plants, which we own and operate, located       Capacity
in suburban and semi-rural areas, such as the Healesville       The current design and licensed capacity of the Healesville
STP. The water from these treatment plants is released          treatment plant are shown below:
into rivers and streams, or reused and must therefore
undergo a high standard of treatment.
                                                                 Parameter                            Value
                                                                 Organic Capacity                     720 kg/d BOD
The Healesville STP was initially commissioned as a small
                                                                 Equivalent Population                10,000
neighbourhood plant in 1987 however; it was replaced in
1990 by the larger current plant. Over the following years, a    Average Dry Weather Flow             1.5 ML/d
chemical dosing facility was installed and once the plant        Licensed Mean Daily Flow Rate        1.4 ML/d
came close to reaching capacity, the decommissioned
aeration tanks from the Whittlesea STP were relocated to
the Healesville STP.                                                       Healesville Sewage Treatment Plant

The plant is located on the outskirts of Healesville on
Argoon Road; it is EPA licensed and treats sewage from
the Healesville Township and surrounding areas; with the
treated effluent being discharged into the Yarra River in
accordance with EPA standards.

The Treatment Process
The treatment process includes an influent pump station,
an inlet screen, biological treatment utilising an oxidation
ditch and two treatment reactors, secondary clarification,
upward flow clarification and UV disinfection.

The oxidation ditch is a horseshoe-shaped basin where
incoming effluent is mixed with return sludge from a
secondary clarifier. The ditch provides a mechanism for
Healesville STP Treatment Process                                                                                 Sewage is pumped into the treatment plant
Fig 1 (right): Briefly describes the main treatment processes that occur at the plant
Fig 2 (below): A schematic diagram of the plant’s treatment process
                                                                                                                             Preliminary Treatment
          Influent from Healesville                                                                             The flow of sewage passes through screens so that
                Branch Sewer
                                                                                                                rubbish and other large objects can be removed
                                         Station                                                                Alum is dosed to the sewage at the inlet to the
                                                                                                                oxidation ditch to aid phosphorus removal
                                                                                                                Caustic soda is dosed into the oxidation ditch to
                                                                                                                maintain a neutral pH
         Screenings to
                                       Inlet Screens
                                                                                                                              Secondary Treatment
                                                                                                                Secondary treatment involves the use of an oxidation
                                                                                                                ditch and two sidestream reactors. The mixed liquor is
                                                                                                                then piped back to the oxidation ditch from the
                                                                                         Educt off-site to
       Caustic Soda                                                                                             reactors.
                                                                                        Brushy Creek STP
                                                          WAS        Sludge                                     Removal of soluble organic matter; nitrogen and some
                                      Oxidation Ditch               Thickening
                                                                       Tank                                     phosphorus occurs.
                                                                                                                The effluent then flows into the secondary clarifier,
                                                                                                                where settling occurs to remove suspended solids
           Tanks                                                                                                Waste sludge is thickened and then transported to

                                                                                                                Brushy Creek for disposal into Melbourne Water’s
                                                                                                                sewage system
                                                                                                                                Tertiary Treatment
                                                                                                                The effluent then flows through the upward flow
                                                                                                                clarifiers, for further removal of suspended solids
                                                                                                                Following clarification, the effluent undergoes UV
                                       Upward Flow                                                              disinfection to inactivate and destroy any disease
                                         Clarifier                                                              causing pathogens that are still present

                                                                                                               Now the effluent is of an acceptable standard to be
                                                                                                             discharged into the Yarra River, without causing harm
                                      UV Disinfection
                                         System                                                                                to the environment
                                                                        Yarra River

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