There are many companies producing biowaste and by-products, particularly in the agri-food sector. Among them, dairies and cheese factories have unavoidable biowaste in their manufacturing processes. These can be of different natures and methanogenic potentials and therefore require variable treatments and logistics.

Whey, also called serum or lactoserum, is the liquid residue that remains after milk has been curdled and the fat and proteins have been extracted to make cheese. It is rich in lactose and proteins and is an interesting product for a methanizer although its methanogenic power is not systematically high (it can vary between 35 and 100 nm3 of CH4 per tonne of raw material, depending on the production methods).

Curd pomace is the solid part that remains after the whey is extracted. It is generally used as animal feed or can be processed into other products, such as dietary supplements or cosmetics.

Wash water, or white water, is water used to rinse equipment after production. It can be reused in methanization only if it has not been mixed with cleaning products that would be harmful to the biology of a methanizer. Its methanogenic potential is often low because the organic matter is very diluted (around 18 nm3 of CH4 per tonne of raw material) but it happens that the volumes of dry matter are more present and therefore the methanogenic power more interesting.

Buttermilk is a liquid resulting from the manufacture of butter by churning: it is also called churned milk or beaten milk. It has a methanogenic potential generally around 37 nm3 of CH4 per tonne of raw material.

Finally, it may happen that finished products are downgraded, for commercial reasons or expiry dates. In this case, the methanogenic potential can be interesting since the organic matter is optimized. Milk can have a methanogenic potential of around 70 nm3 of CH4 per tonne of raw material, white cheese around 100 nm3, or even cheese much higher depending on the cheese in question.

All these products come from animals and therefore fall into the category of SPAN 'Animal By-Products'. This origin leads to very specific regulations around their treatment. For methanizers, this implies having health approval (except for exemptions in certain cases), and ensuring that the product is sanitized (heated to 70° for a few hours) before entering the biology of the methanizer.

Methappro references dairy and cheese partners who have regular volumes of biowaste that they need to dispose of. For any request, contact us! contact@methappro.fr