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Tackling the cost of food production residues with biotech

20 May 2019

Chris Hughes talks about the costs of food production waste disposal and the experiences of food producers who have made use of onsite exothermic technology which can deliver between 60% and 90% reduction in mass from mixed organic waste streams. 

Managing food production waste in an increasingly costly issue for food producers. Both solid and liquid biological production residues, that are rich in nutrients and organic content, need to be dealt with. For an industry that has to balance customer expectation for low-cost food, with rising prices for raw ingredients, this is an increasingly costly overhead requiring on-site treatment before safe discharge to sewers, or disposal off-site. 

Disposal of waste by-products from food manufacturing is heavily-regulated. Biological Oxygen Demand (BOD) needs to be reduced to meet trade discharge consents and there is growing pressure from the UK Government to reduce the biological load in wastewater discharged from production processes and for zero organic waste to be sent to landfill.  

There are similar environmental pressures in the USA and Europe. Legislation and taxation are also pushing hard to limit dumping, and all the while volumes are increasing.  Naturally a high-water content makes solid and liquid waste costly to transport, as well as being inefficient to incinerate.  As a result, most production facilities require an on-site effluent treatment plant.

Current treatments
Conventional processes to treat biological production waste range from settlement tanks and bioreactors to activated sludge processes and dissolved air flotation (DAF) systems. These are designed to filter out and remove suspended solids, BOD, plus oils and greases – to leave clean water and reduce the biological load to meet discharge consents. Some are more environmentally friendly than others, but the processes tend to be slow and they can take up valuable site space. Meanwhile the resulting solid residues still need to be hauled away for disposal to incineration or landfill.  

A novel approach is to use exothermal technologies and thermophilic bacteria to consume a much higher percentage  of the organic material than is possible with conventional solutions – leaving clean water and a small inert residue for use as refuse derived fuel (RDF) or as a soil improver. These systems have a small footprint, taking up little space and processing is fast.

Bacteria-based and natural bio-stimulant digestion systems offers benefits simply by reducing the organic fraction, while at the same time shrinking the haulage and potentially the disposal costs of the residual waste. These residues can still be ‘mined’ for valuable materials such as metals, but the ‘digestion’ approach avoids the need for inefficient, time-consuming and increasingly costly manual sorting at source.

When one a confectionery company identified a need to significantly reduce the mass and volume of its chocolate residues and eliminate noxious odours and airborne pollutants, Advetec proposed its exothermic technology. The company wanted a fast and efficient system that could also reduce the water content of residual material to below 10% humidity and have a clean output. Therefore a safe, environmentally friendly, biological solution that did not use hazardous chemicals was chosen to ensure the process complied with agreed environmental sustainability directives. 

Advetec started a site survey by collecting samples and analysing them to assess expected digestion rates. It then installed a trial unit in the factory ground, weighed and loaded containers full of confectionery waste and packaging into the machine for a pilot trial. The results showed that 2350kg of influent waste was digested to 186kg of output. This level of waste reduction is equivalent to a 92% reduction of the original mass. Following a trial period, the Advetec XO reactor proved it could effectively reduce the sludge waste, achieving volume reduction rates greater than 90% within 72 hours. 

Chris Hughes is sales manager at Advetec.

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