Breweries biological waste and wastewater – Full of usable free energy
In breweries many kinds of biological waste are formed during the process. Some of them are utilised well but not all.
Production of beer starts by mashing milled malt and other solid adjuncts in water at a set temperature. During the mashing process malt and hop particles swell, starches gelatinize, soluble materials dissolve, and enzymes actively convert the starches to fermentable sugars. After mashing all solid compounds are separated from the almost completed wort.
The separated compound is called mash and at least in Finland it is used as cattle feed.
After the worts separation clear wort must be boiled. Boiling denatures worts enzymes and ends mashing. After boiling the last of the hops and trub are removed from the now completed wort. Trub consist mainly of denatured proteins.
Trub is used in the following wort boiling.
When wort boiling and cooling is over it is ready for the addition of yeast. When yeast is added the beer´s fermentation can start. During fermentation yeast is taken out of fermentation tanks many times before the end. Some of the viable yeast can be used again.
In Finland most of the waste yeast that can´t be used in the following brewing process is concentrated and used as pig and cattle feed.
After fermentation beer is ready for filtration and after that bottling, canning and kegging. During the filtration of the beer water and other adjuncts such as colorants and hop oils are added. After filtration and the beers packaging all the now unclean tanks, pipelines and filters have to be cleaned and disinfected. Cleaning processes generates large amounts of wastewater which is full of sugars, yeast, beer, soluble starch, ethanol, volatile fatty acids and other biological components.
Breweries wastewaters are full of biological energy and heat. The incoming raw water temperature is approximately 10 ̊C and the outgoing wastewaters 20-30̊ C. This usable heat is totally wasted and is a significant area for research and development. How can we take out all those benefits this wasted heat can offer?
And what about this biological energy? All sugars, starch and other biological material works as feed for bacteria which produces methane. Methane is used as biogas but it isn’t taken into store from brewery wastewaters.
The biggest problem is unstable produce of these two wasted energy sources and it creates also one challenge for the future.
Research question: How can we take out all those benefits this wasted heat can offer? And what about biological energy?