At a bakery that manufactures ciabatta loaves and baguettes, any loaf that is outside of specification and any dough that is of an incorrect consistency cannot pass through the supply chain and is deemed as ‘waste’ (although it is in fact recycled as animal feed) in order to meet the demands of retailers and consumers.
In preparation for an upcoming expansion, the owners identified waste removal as an inefficient task. This non-compliant waste material was being handled manually – conveyor belts from two production lines would move the waste into one tonne bins, which were then taken outside by forklift trucks and loaded into a designated lorry provided by the animal feed company. Waste was picked every two days.
In a bid to find an alternative solution that could reduce manpower, improve hygiene standards and optimise the waste removal process, the owners of the bakery approached progressive cavity (PC) pump supplier Seepex UK. PC pumps are rotary positive-displacement pumps. The PC pump has two pumping elements: rotor and stator. The rotor is typically a single external screw that rotates inside an elastomeric stator, which has a double internal helix. The rotor rotates eccentrically within the stator, creating a cavity which is progressed through the pump, conveying a variety of thin to highly viscous products with minimum shear and low pulsation.
A two-to three-week project subsequently took place, which encompassed a pump being organised, delivered to site, set up and eventually trialled over a day in July 2018. Seepex provided the equipment and expertise without cost to the customer.
FRESH EYES
“One bakery can have totally different needs to another,” explains Joao Rodrigues, applications engineer at Seepex UK. “The challenge in this instance was not just that dough is a difficult substance to pump – it is prone to bridging in hoppers – but also, that the variety of materials being handled (dough, baked and waste bread) behave so differently.” Bridging occurs when the product forms a solid ‘blanket’ over the auger feed screw, preventing product from reaching the pumping elements. This can happen with sticky or non-flowable products.
Rodrigues continues: “Dough is a highly viscous product – it is dense, wet and sticky; fresh bread is light and compressible; and waste bread is hard and non-flowable. We needed to create a solution that could handle all three of these very different substances, and to do that we needed to understand how they would behave in a pump, both separately and together.”
Two Seepex engineers were assigned to the project and worked to understand each of the waste products, as well as the volumes being generated, and the manufacturing process.
“After collecting all the necessary information, our engineers analysed it and combined it with the experience we have gained over years of working on other food and beverage projects,” explains Rodrigues. “We then devised a preliminary solution that the client opted to trial on-site.”
A SEEPEX SOLUTION
Seepex proposed a solution that comprised a BTM open hopper pump. The BTM range pumps have an integrated macerating device in the compression zone that allows for easy processing in subsequent processes. Its conveying capacity is 0.25 m³/h – 130 m³/h (1.1 USGPM – 572 USGPM), while pressure is up to 24 bar (350 psi).
As the waste product contained a high volume of solid and viscous material, which can be difficult to feed into the pump, the BTM also has an auger that mixes the different products and prevents them from bridging in the hopper. The pump also contains integral three rotating knives and three static knives that help to reduce the particle size and produce a pumpable consistency. This then passes into the pumping elements of the stator and rotor, and is transferred through enclosed pipework into the removal lorries.
IMPROVEMENTS
As a fully automated, enclosed solution, this system has the potential to greatly improve hygiene standards at the factory, according to Seepex. This is because the existing manual system often resulted in waste product falling or being dropped on to the factory floor, creating an unhygienic and hazardous environment. Movement of waste from production areas to the outside of the bakery can also present further hygiene problems.
In contrast, the only open part of the new solution is the hopper, into which waste product is loaded. After that, every part of the system is enclosed, including delivery of the waste into the removal lorry. There is no need for anyone to enter and exit the factory, and the reduction of spillage means the factory floor can be kept clean. The combination of these factors improves hygiene as well as health and safety, says Seepex, by reducing product spillage, manual transfer of tote bins, and forklift traffic.
Crucially for a company that is expanding, a fully automated solution means that only one person is required to load product into the hopper, freeing resources for production. Furthermore, the level controls inside the hopper mean that the pump only starts running when there is product to handle, and stops the moment the hopper is empty, helping to reduce energy demand. OE asked Seepex about the energy savings produced, but it did not provide any data.
Rodrigues concludes: “During the trial, every possible combination of product mix was tested, at varying volumes. The system coped well with every variation and the client requested no changes from the preliminary solution we proposed. As the next phase of its expansion progresses, we expect this system to revolutionise how the company treats its waste in the future.
“Viscous, sticky dough products have been notoriously difficult to pump in the past, often causing blockages in the pump. Using an open hopper BTM pump with an integral auger and knives, this solution offers manufacturers of bakery products, such as pizza, cakes, bread and scones, an efficient, safe and hygienic way to dispose of their viscous, sticky and non-flowable waste.”