The food industry:
new energy possibilities

The biological purification strategy is based on the natural metabolism of a number of bacterial species that digest organic pollutant compounds to grow in turn. Nature has developed an enormous variety of bacteria suitable for the most different environmental conditions. In biological purification plants, are applied techniques that intensify the growth of the desired bacterial species, replying the conditions best suited to them.

ACTIVATED SLUDGE TECHNIQUE

The most widespread biological technique, known as the activated sludge technique, uses bacterial species whose metabolism (similar to that of higher living beings) is based on the carbon oxidation and, for this reason, they breathe oxygen taking the name of aerobic species, which efficiently metabolize carbon over a wide range of temperatures. With them, have been developed techniques that break down also nitrogen.

The intensification of this technique involves high energy consumption, since it is necessary to supply oxygen to the bacteria. Experience, now almost one hundred years old, shows that no less than 1 kWh must be used to treat the carbon correspondent to 1 kg of COD; the metabolic efficiency means that from this treatment, no less than 200 grams of bacteria (sludge) to dispose are obtained.

ANAEROBIC TECHNIQUE

Less common, especially because efficient in a narrower temperature range (30-55 °C), are the families of bacterial species called anaerobic, whose metabolism is based on carbon reduction and which, for this reason, do not need to breathe oxygen. Their metabolism is much less efficient, so much that with the same amount of carbon they grow up less than one tenth of it in comparison to the aerobic ones; from their metabolism results, however, an interesting quantity of methane.

The application of the anaerobic technique is less widespread, because it requires temperatures higher than 30°C and a sufficient concentration of carbon, but above all because in the past the low cost of energy, the low sensitivity for its efficient use together with the low cost of sludge disposal, has favoured the less expensive technique in terms of the initial investment.

Today, however, the rising operating costs make it increasingly necessary to minimize the use of aerobic techniques for carbon abatement. Today it is fundamental, in biological purification, to use all the plant strategies, which make it possible to apply anaerobic technology to lowering carbon.
In anaerobiosis, the abatement of carbon corresponding to 1 kg of COD (which requires at least 1 kWh) involves irrelevant electricity consumption, while it produces a quantity of methane corresponding to almost 3.5 kWh of chemical energy.

The energy balance is also extremely profitable for the production of biomethane: net of heat requirements, energy consumption is less than one fifth of the energy produced.

In the food and beverage sector, biogas and biomethane plants are used very well: thanks to the IES FoodIndustry division, by-products and waste from food processes are enhanced and transformed into energy, offering a new source of income.

Our anaerobic fermentation technologies perfectly fit to the food industry, because:

1) they produce by-products, which use can be enhanced form an economic and environmental point of view;

2) they consume heat and electricity: the waste, through the production of biogas, allows to create energy and so provides new income in the perspective of a circular economy;

3) the use of by-products finds a great opportunity in the promotion of biomethane.

We have the best anaerobic solutions for:

• Beverage industry
• Potato and tuber industry
• Confectionery industry
• Brewing industry
• Biodiesel production
• Meat and fish industry
• Dairy industry

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