Lagoon de-sludging works completed

In late December 2012, Coliban Water began lagoon de-sludging works at the Kyneton Water Reclamation Plant to assist treatment processes and manage odour generation on-site. The last time such works were carried out at the lagoon was 2007.

General Manager Operations Neville Pearce said sludge removal is part of normal plant operations and was needed to restore the plant to full treatment capacity.

“This lagoon is the only treatment lagoon on-site collecting trade waste from businesses in the area,” said Pearce.

“It is currently at capacity and needs the sludge removed to allow more room in the lagoon for the full biological treatment time to take place, ensuring ongoing treatment.

“Less room in the lagoon compromises treatment and creates potential for odour on-site.”

As the plant is the only treatment lagoon on-site, the works needed to be done simultaneously while the lagoon continued to operate.

The de-sludging process involved dredging the sludge from the bottom of the lagoon and pumping it through three centrifuges to remove excess liquid. Around 20,000 m³ of wet sludge was removed and produced 1600 dry tonnes of sludge after the centrifuge process.

A polymer was added at this stage to bind the sludge and achieve the desired 20% solid mass. It was then transported to drying beds and air dried until 60% solid mass was reached.

After testing the sludge to ensure it met Environmental Protection Authority (EPA) guidelines for re-use as biosolids, it was put to use as fertiliser for local agriculture as part of an Environmental Improvement Plan.

This process makes an important contribution to sustainable environmental management by returning organic material, trace elements, moisture and nutrients to soil and completing the natural nutrient cycle.

The works took six weeks to complete and were carried out by Transpacific Industrial Solutions, which finished a few weeks earlier than expected and on budget.