An upgrade by Richmond Valley Council of its Casino Sewage Treatment plant has paid immediate dividends by withstanding the fury of June’s storms and flooding without any polluting spills or odours.
The turnkey upgrade – which included retrofitting of fine screening technology by CST Wastewater solutions – was completed just days before the bad weather along Australia's East Coast dumped more than 160mm of water on the council region within 48 hours.
"The Council couldn't have timed the upgrade any better. Their foresight and technology upgrade was perfect," said CST Wastewater Solutions Managing Director Michael Bambridge. "The Northern Rivers District of NSW is one of the most flood-prone areas outside of the tropics, where events like this are likely to occur and reoccur, so the investment in new technologies has already paid off."
The retrofit project - of a type that is applicable to councils and industrial uses throughout Australia and New Zealand – replaces the previous coarse raked screen design with current fine screening technology. This captures more solids to reduce potential blockages in tanks and downstream equipment, while reducing odours by sealing the inlet works and by the installation of new odour control units.
The project's high-efficiency fine screening SFC technology (Screen Press For Channel Installation) is engineered to deliver low-maintenance performance with reduced WHS hazards for municipal and industrial waste water operators.
The SFC allows for a much finer level of screening – 5mm compared with typical old systems at 60mm or more – which has led to a significant reduction in solids in the tanks, while producing more efficient treatment with less maintenance.
The retrofit also involved the installation of an SDS 20 compactor with two inlets - one for each screen - to dewater screenings to 25-30% dry solids. Each screen has an enhanced design capacity of 250L/s flow, providing a total capacity of 500L/s.
The original inlet works at Casino STP were designed with a coarse manual raked bar screen system. The functional components of the treatment process downstream of the bar screen receive a high amount of debris, which formerly impacted the efficiency of the treatment process. The original inlet area also received a high amount of odorous gases, which previously contributed significantly to odours emanating from the treatment plant.
In addition to minimizing these issues, the upgrade project involved fitting new technology into an existing layout, including tailoring the screens to fit into the existing formed channel.
The SFC technology involved in the retrofit – designed to lower investment, operational and maintenance costs in screening of municipal and industrial waste water with compacting of extracted solids – has also cut the amount of maintenance and waste that has to be handled by plant operators, reducing operational health hazards and improving OHS performance.
The same benefits are widely applicable to other industry and municipal applications, says Bambridge.
The technology is also suitable for applications such as food and beverage, manufacturing and processing, mining, energy and resources camps where its low maintenance /high hygiene qualities are appreciated, agribusiness, and remote installations where low maintenance and high efficiency is a priority for users who don't need to have specialist staff constantly available.
"Not only are the tanks clearer and more efficient now, but the screen extractor also operates on level control and is fully automated, eliminating the previous labour-intensive operator handling of screenings," he said.
The robust and proven extractor is constructed from AISI 304 or 316 stainless steel without the need for hanger, intermediate or bottom bearings. Featuring a space-efficient design suited to small sewage plants, the standard unit can handle up to 1000m3 an hour with custom engineering also available for particular installations. A vertical version is also available to easily retrofit into existing pump stations with depths up to 8m, the screen allows removal of material before pumping, says Bambridge.
The versatile SFC Screen Extractor can be installed in a channel or supplied with self-supporting tank, complete with inlet and outlet flange and optional bypass screen.