Sludge treatment success shows green solutions work for SMEs

An energy-saving sludge handling solution for small-to-medium food and beverage waste producers throughout Australasia and the Asia-Pacific has been shown in service to cut sludge volumes and waste transport and disposal costs to less than a seventh of previous levels.

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 typical of SME food and beverage processing operations and 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. They ideally complement and attach readily to typical dissolved air flotation (DAF) technology widely used in the 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, who has decades of Australasian and international experience in engineering cleaner and greener waste disposal plants, including in environmentally sensitive areas.

“But obstacles to wider adaptation of such technology by SMEs may include costly large dewatering systems when SMEs typically need more compact and profitable ways to make sludge dryer, lighter, easier to handle, and safer to dispose of,” he said.

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 $US40,300 previously to $US5,352 based on the extended trial period. (Approx $A60,000 to $A8500)
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 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 obstacles to 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 to 4,092 gal/hr (approximately 1,000 to 15,490 litres) with a 2 per cent input solids content.

Dried sludge handling benefits

Handling 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 an increasingly and necessarily strict regulatory environment 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 easily handles oily and fibrous material.

The optional skid-mounted version of KDS technology offers potential users a highly effective plug-and-play solution to waste processing needs,” said Bambridge.

Measuring only 3.8 by 2m, 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.

“As environmentally aware and quality-focussed 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,” said Bambridge, whose company has decades of experience as a premier provider of innovative wastewater treatment solutions throughout Australasia and Asia, as well as an equipment supplier around the world.