As landfills become scarcer and more expensive, engineers act for a cleaner, greener future


Piling food and beverage waste into landfill poses many hazards and high environmental and business costs that may become unsustainable.

CST Wastewater Solutions

Piling food and beverage waste into landfill poses many hazards and high environmental and business costs that may become unsustainable.

Excessive dumping releases toxins into the environment, leachate into water tables, as well as high volumes of greenhouse gases into the air – including methane, which is 25 times more potent than carbon dioxide.

Further, a lot of costly fossil fuel energy is expended in getting sloppy, hazardous, and unhealthy heavy waste from processing facilities to landfill facilities – with some of it ending up on public roads in the process – arousing public and statutory concern and creating sizeable clean-up costs.

So the costs of landfill to waste producers are inevitably going to rise further as there are fewer off them, and as Australia fully implements its greenhouse gas reductions targets and the Federal Government’s National Waste Policy, which outlines the five key principles for waste management that will enable Australia to transition to a circular economy. These include:

  • Avoid waste
  • Improve resource recovery
  • Increase use of recycled material and build demand and markets for recycled products
  • Better manage material flows to benefit human health, the environment and the economy
  • Improve information to support innovation, guide investment and enable informed consumer decisions

“Landfills themselves will become scarcer and more expensive, with increasing community and government concerns over damage created to water tables and atmospheric emissions,” says Michael Bambridge, an environmental engineer and wastewater treatment specialist with more than 40 years’ experience in food, beverage and municipal wastewater treatment and waste recycling.

“In practical terms, this means the future is arriving very quickly for food and beverage producers. Leading food processors – managing their risks years and decades ahead – can see that prevention will rapidly become far less expensive than cure,” says Bambridge, whose company, CST Wastewater Solutions, bases his observations on the scores of waste processing and wastewater treatment plants his company has installed in Australasia, including for big names such as McCain, Simplot, Golden Circle, plus major NZ fruit and vegetable processors and multiple breweries meat processors, dairy organisations, and municipal WWTPs in Australia and New Zealand.

He says the front-line components of such WWTPs – including more efficient screening and dewatering – are fundamental to efficiently extracting waste and ensuring solids output is delivered in a cleaner and drier state, making it more suitable for composting.

“Obviously from both an environmental and cost-efficiency perspective, food and beverage leaders are already focussing on minimising landfill and reducing waste by their own initiatives on-site, where we have been involved in the process throughout Australasia.”

Technologies employed by leading processors range from better screening and waste extraction and dewatering technology – to produce drier and cleaner was most suitable for composting and recycling – through to anaerobic digestion of organic streams in wastewater to produce biogas to replace fossil fuels.

“It just makes sense in both an environmental and businesses sense – sodden, hazardous waste can cost $150 a tonne (more more) to transport to landfills – and landfills themselves are an increasingly expensive and scarce resource. Some Australasian councils are already warning that their landfill facilities will be full before the end of this decade, and there is strong community opposition to opening new ones.

One company’s response

Putting its money where its mouth is, CST Wastewater Solutions has invested in local production of its range of rotary drum screens which, with high performance dewatering, reduce, by up to half, the volumes of solids to be transported and placed in landfill.

The rotary drum screens are now being manufactured in Sydney, rather than being imported from overseas in a time of stretched supply lines. The move to local manufacture and high engineering standards increases quality and supply to Australasia and South Asia.

Locally engineered screens, built for widely varying local conditions, withstand shock loads and larger solids that most other screens using lighter mesh construction cannot – and which may cause them to fail prematurely in peak load conditions, such as floods or spills often encountered in Australasia.

More efficient drum screening technology – featuring a 0.5mm rotary screen, complete with compactor – was used by a subsidiary of Kraft Heinz to replace the previous plant. In service, this installation has allowed improved and greater removal of solids from the wastewater, with considerably better solids capture. The compact system also permitted removal of a tall existing structure and hoppers, making solids handling more accessible for the plant operator, improving operational efficiency and enhancing OH&S benefits by reducing solids handling.

“Well-designed rotary drum screens are also engineered for far greater whole-of-life performance, and unlike cheaper alternatives, they require minimal ongoing maintenance.”

“It is important to remember that a lot of food and beverage companies (and councils) just don’t have the engineering and technical staff on the payroll to provide the standards of maintenance that a manufacturer can.”

“So if disruptions such as floods and high flows cause breakdowns and leaks into the environment, the can be looking at environmental spills and groundwater damage that can incur statutory, reputational and financial damage. Saving small sums on cheaper and more damage-prone technology, with lesser service backup, can suddenly look like a terribly bad decision.”

Examples of engineering features contributing to maximum reliable service life (and minimised maintenance and operational risk) include all-stainless construction, including being fully enclosed for OH&S odour and aerosol control.

Such drum screening technology is proven in the toughest environments, including meat, dairy, poultry, fishery, and livestock plants. Typical industries to use the Rotary Drum Screen include general food processing (vegetables, fruit, starch processing), beverages (beer, wine, juice, soft drinks), slaughterhouses and abattoirs, tanneries, pulp and paper mills, textile plants, plastic manufacturers and many more industries. Municipal treatment plants also use the screens for fine screening of raw sewage, pre-MBR (membrane bioreactor) screening, and sludge thickening for easier handling, transport, and disposal.

In many industrial plants, these screens allow the important product recovery of fat and proteinaceous material, which is all worth money to companies seeking to sustainably maximise their use of resources,” says Bambridge.

The screen and compactor technology – which are a first line of defence in preventing downstream process issues, overflows, and bypassing to the natural environment – are integral not only to processing operations, but also to the sustainability of livestock industries sharing valuable water resources with nearby communities, and wishing to maintain their social license to operate.

Sludge dewatering for small-to-medium operations

Another clean, green waste management technology introduced to the Australasian  market is the KDS sludge dewatering technology that reduces waste volume by up to 90%.

The multi-roller system, already in use in Australasia, eliminates processing spillages by producing a drier, waste that is more easily transported and recycled The more compact, drier product radically cutting landfill needs while reducing transport costs and helping prevent any potential spillages onto public roads during transport.

The compact and efficient technology is engineered to overcome the limitations of technologies such as screw presses, belt presses and centrifuges typically employed by small-to-medium applications to treat the sludge produced by their operations. It uses very little power and no water for washing.

KDS applications also include thickening and dewatering of Dissolved Air Flotation (DAF) sludge – a very common wastewater application – the KDS achieves solids capture of 95-99% sludge at a dryness of 15-20%. Waste activated sludges are typically 15-18% dryness.

Benefits proven in service

Used on fruit such as apples and pears (and suitable for a wide variety of other fruit) the technology dewaters wet, sloppy screened waste from processing, reducing waste volumes by up to 90 per cent, improving OHS and cleanliness outcomes and radically reducing the cost and spillage issues of disposing of waste.

 “It transforms wet waste to a much drier product that is easier to handle resulting in a more hygienic and cleaner product to transport for recycling to stockfeed and composting,” says Bambridge.

In one particular application, The KDS typically handles 6m3 (approx. 100-150kg) per hour of watery waste containing leaves, twigs, and unsuitable fruit. The output is transformed into waste for disposal or stock food, that is much cleaner, neater, and healthier to handle.

“Reducing waste volume by up to 90% radically reduces transport costs and helps prevent any potential spillages onto public roads during transport. Both issues are very important, with rising specialised waste disposal transport costs and with local communities and councils very mindful of how companies treat waste.

The fruit processor uses the KDS technology to handle a highly variable quality and volume. “This adopter of the KDS technology had previously tried alternative technologies, but none handled the variable volume involved or dewatered the fruit waste enough to prevent excess water and product from creating an unhygienic site and causing leakage.”

A different engineering philosophy

Mike Bambridge is the first to admit that his solutions are built up to a technical standard, not down to a price.

“Our engineering approach is not one-size-fits-all, because one size (or type) does not. Our horizontal in-channel rotary drum screening technology, for example, is built from the outset to be both robust and adaptable, not to be cheaper up front (which is false economy where it just transfers cost and problems down the line).

This whole-of-lifespan value, as distinct from a race to the bottom on sticker price, is a mature engineering approach in meeting and continuing to meet users’ tasks that vary from place to place, day-to-day and week-to-week as loads on the system change, he says.

“We have plenty of screens installed in the industrial space which have been going for more than 25 years  with minimal operational costs.”

It also builds in greater protection for the environment, which is a price all food and beverage producers have to account for and engineer properly for as Australasia moves to protect its reputation as a clean-green producer.

“Some non-technical people, who don’t have to live with the results of their decisions, might say “So what?”. “Our philosophy does not address such people.”

“We believe informed people on the front line of engineering for environmental change – the operators, the engineers, the regulators and the science-based community – will have a different view. That’s why we present our engineering and operational principles here to the technically proficient and socially responsible, for a mature and timely discussion.”

Providing a Full Range of Quality, Cost-Effective Solutions for 25 Years. Nearly a quarter-century ago, CST Wastewater Solutions P/L (CST) was founded as Contra Shear Technology: a supplier of specialised, patented wastewater screens for the industrial and municipal wastewater markets.  Since then, our company has flourished to become a premier provider of innovative wastewater treatment solutions throughout Australia and equipment supplier around the world.

CST offers the latest in specialised mechanical and process equipment, built from our ‘hands-on’ experience in the industry and a clear understanding of our clients’ needs. Beyond equipment supply, we have the ability to design, install, maintain, and in specific cases, operate premium wastewater treatment systems. For clients who require a more comprehensive solution, CST constructs complete wastewater treatment plants in partnership with major specialist companies.

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