Pretreatment WWTP

Inlet Works, Screening and Grit equipment

The plant receives sewage from a drainage area of over 9,200 hectares and is designed for annual average flows of 60 megalitres per day and serves an equivalent population in excess of 200,000 people.

All wastewater from the network is pumped into the Inlet Works. Removal of larger solid inorganic material such as paper, plastic, grit and silt, which are abrasive and damage plant equipment, also occur at these preliminary stages. 

SPIRAC Products Used:

  1. Four Traveling Fine Screens
  2. SPIRAC Grit Vortex
  3. Launder System
  4. Three SPIROWASH® MW-Q280
  5. Three screenings SPIROTAINER® 10m3
  6. Two SANDWASH® SGW30
  7. Two grit SPIROTAINER® 10m3


The Solution

SPIRAC was asked to update the pretreatment area. To handle up to 2100 L/sec four traveling fine screens were installed. The screens work in an on and off-line configuration to prevent grit settlement upstream of the screens.

The screenings get transferred from the screens via launder system to three SPIROWASH® units our screenings treatment units. The SPIROWASH® units wash out the organic material, reduce the volume and weight of the screenings and compacts them. SPIROWASH® pushes the screenings through a press tube and drops the material into SPIROTAINERs®. The screenings handling system is able to continue to handle the maximum screenings loading should a SPIROWASH® be out of service.

SPIROTAINER® units are capable of containment and road transport and therefore are a durable and efficient solution for wastewater treatment and materials handling. Retractable chutes between the press tubes and the SPIROTAINER® units reduce the chances of spills and leaks.

Given the proximity of the metropolitan areas, the entire system was designed to contain foul air. SANDWASHTM our grit washer and SPIROTAINER® our disposal unit was combined to treat and store the grit provided by a vortex grit cyclone. Two SANDWASHTM units make sure that the grit is cleaned prior to being deposited into SPIROTAINERs®. The washed and classified grit is directed to SPIROTAINERs® for disposal off site. SPIROTAINERs® have a nominal capacity of 10 m3 and two bins have been provided with weight cells for the grit treatment area.


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