How to handle wastewater with low environmental impact

CST Wastewater Solutions is assembling a wastewater treatment system for installation on the World Heritage-listed Lord Howe Island — one of Australia’s most remote local authorities. The system is designed to replace the existing waste management facility, cutting maintenance, energy demands and OH&S issues in the process.

The island’s waste management facility sorts various waste streams including food waste, paper and cardboard, green waste, recyclable materials, re-usable materials and general waste. Septic waste from the residential and commercial system is also treated at the facility, drawn from about 220 wastewater systems on the island, 25 of which are commercial operations. Pump-outs are delivered to the facility via an 1800 L wastewater tanker.

CST was tasked by the Lord Howe Island Board to review a ‘best fit’ sludge dewatering system for the septic waste, as the current infrastructure is becoming outdated and the existing drying beds are to be decommissioned. Working with the board’s project manager, the company developed a solution that combined impressive environmental performance with strong OHS performance — and which has a smaller footprint than the drying rack system used currently.

The first component of the two-stage system is a CST Screen Extractor with coarse screening at 6 mm upfront to remove plastic, rags and other disposals typically found in community, commercial and industrial wastewater treatment plants. The second stage employs separator technology from KDS — for which CST is the exclusive distributor — for fine screening and dewatering of the fines. This technology combination produces a hygienic and compact output that is easy to handle and transport.

The hygienic and easily handled output obtained in the Lord Howe Island application.

The compact KDS multidisc roller separator features a self-cleaning dewatering and conveying system with oval plate separation and transfer structure that prevents clogging and permits automatic continuous operation that handles oily and fibrous material with ease. Designed for efficiency, sustainability and conservation of resources in small to medium applications, the energy-efficient separator consumes as little as 0.06 kWh of electricity and uses no wash water.

“This simple-to-maintain separator offers a high throughput within a small body, with the smallest model being just under 350 mm wide and weighing 50 kg,” said CST Managing Director Michael Bambridge. “It is ideal for applications such as Lord Howe Island and other smaller communities and industrial applications throughout the Asia–Pacific, including coastal, remote and ecologically sensitive areas.”

Top image: The view from the beach at Lord Howe Island.