An energy-saving sludge handling solution for small-to-medium food and beverage waste producers throughout the Asia-Pacific region has been shown in service to cut sludge volumes and waste transport and disposal costs to less than a seventh of previous levels. CST Wastewater Solutions director, Michael Bambridge, outlines what that means for Australian companies.
A US in-service performance assessment of KDS sludge dewatering technology – conducted over 250 days to demonstrate accuracy and reliability – involved a mixed food waste disposal challenge involving oily and starchy wastewater treatment issues of a type typical of SME food and beverage processing operations and of commercial kitchen waste, cleaning and grease trap processes.
Wastewater treatment authority, Michael Bambridge, said the technology assessment – which is equally applicable to KDS operations in Australasia and SE Asia – also produced waste that is safer for wastewater maintenance and cleaning staff by radically reducing the amount of sticky, hazardous waste they typically have to handle.
“The in-service trial of KDS technology – which cuts sludge volume before dewatering from 403 tons to 53.52 tons afterwards – disproves the common misconception that energy-efficient and environmentally harmonious sludge separation wastewater treatment is mainly for the largest applications,” said Bambridge, whose company, CST Wastewater Solutions, is installing the low maintenance, low energy stainless steel system in industrial and municipal applications.
KDS systems have already been installed in potato processing, fruit processing, and municipal mixed waste applications in Australasia, where they ideally complement, and attach readily to, typical dissolved air flotation (DAF) technology widely used in food, beverage, and primary product processing industries.
“Efficient sludge dewatering can reduce the volume of sticky sludge produced by typical DAF installations by 70-90 per cent, making it lighter, drier, safer to handle, transport and dispose of or recycle,” said Bambridge.
“But obstacles to wider adaptation of such technology by SMEs may include costly large dewatering systems, when SME’s typically need more compact and profitable ways to make sludge dryer, lighter, easier to handle, and safer to dispose of.”
Oversized systems often have built-in high operating costs to achieve results, including costly use of polymer, electricity, and wash water. They also may require the presence of skilled engineering staff to optimise their performance, dedicated skills that SMEs often do not have and cannot afford.
The KDS Multidisc Roller technology from CST Wastewater Solutions – which requires no wash water, while capturing 90-97 per cent of solids – is engineered for simple, reliable operation, with its self-cleaning multidisc functionality helping to overcome the limitations and maintenance needs of technologies such as screw presses, belt presses and centrifuges.
The US in-service trial of the technology demonstrated:
- Reductions of yearly sludge disposal costs from US$40,300 previously, to US$5352 based on the extended trial period (approx $60,000 and $8500).
- Zero water and extra polymer costs.
- Power usage of less than half a kilowatt over an eight-hour day (0.48 kW).
“Treating wastewater is an energy-intensive and costly process, and a large source of both direct and indirect greenhouse gas emissions through energy use and release of methane and other gases,” said Bambridge.
“In food processing waste treatment, energy typically accounts for a significant portion of the overall cost, often ranging between 15 per cent and 50 per cent, depending on the specific process and facility.”
The Japanese-engineered KDS system – built to meet some of the world’s strictest regulations for food safety and quality – is designed to overcome such obstacles for sludge dewatering by SMEs, including where they use simple DAF as a primary sludge handling process.
KDS separators – all featuring the unique multidisc self-cleaning action - are available in hydraulic capacities from 264-4,092 gal/hr (approx. 1,000-15,490 litres) with input solids content of 2 per cent.
Dried sludge handling benefits
Handling of sticky hazardous waste poses hazards to the wastewater treatment maintenance and cleaning staff, particularly in the event of a spill or preparing larger volumes of waste for transport.
“Just finding a facility prepared to take sludge waste is already an expensive process because there are fewer of them – and those that are left must charge more, because they are responsible for preventing groundwater leakage in increasingly strict regulatory environments driven by legislative and community pressure,” said Bambridge.
“KDS technology’s unique self-cleaning dewatering and conveying system – with oval plate separation and transfer structure – prevents clogging and permits automatic continuous operation that handles oily and fibrous material with ease.
“The optional skid-mounted version of KDS technology offers potential users a highly effective plug-and-play solution to waste processing needs,” he said.
Measuring only 3.8 by 2 metres, it offers the type of low-maintenance high efficiency that is so important where agribusiness, industrial and municipal operations don’t have the resources to place engineering staff on close standby.
SME applications for which the KDS separator is designed include:
- Food and beverage processing waste, including production plants, snack foods, kitchen and restaurant waste, brewery waste, raw wastewater (primary screening), and sludge.
- Intensive livestock and aquaculture operations, including abattoir, feedlots, fisheries, poultry and dairy farm wastewater and sludge. Cattle manure cake dryness of 25-35 per cent is typically achieved. Pig farm raw manure and sludge, with cake dryness of 20-30 per cent.
- Barrel polishing water. The food and beverage industry demands highly polished metal surfaces to ensure hygiene and cleaning ease.
- Water-based paint wastewater, grease trap waste (which cannot be released untreated to sewerage systems), dyeing wastewater, waste oil, and plastic recycling.
- Textile processing, with the KDS employed after the DAF processing stage.
- Sewage treatment, including raw wastewater (primary screening) and sludge to landfill.
“As environmentally aware and quality-focused wastewater treatment professionals, we don’t ever propose that just one solution is the total answer to all water quality issues – that would be absurd. There are many excellent technologies out there, of which KDS is an outstanding example in the SME separator category,” concluded Bambridge.
