ABSTRACT
All odourants susceptible of being scrubbed and converted biologically can be treated with bioscrubbers. There are two different treatment techniques:
Scrubber water is onoculated with activated sludge, i.e. special microorganisms ;
on large-surface scrubbers the so-called “biological mat” develops.
In both techniques the mocroorganisms change the odour characteristics of the emitted waste air to such an extent that odour nuisance will no longer occour in the more or less distant vicinity. Bioscrubbers working on the principle of the activated sludge technique involve high input in design and control. Therefore it is only the more simple designed percolator scrubber that has been used for the cases of application referred to in this paper. Countercurrent or crosscurrent scrubbers the construction of which conforms exclusively to the case of application are shown by the aid of different examples.
The principle of scrubbing noxiuous or odour-intensive substances of the process waste air has been applied in industry for many years. It refers to relatively large devices in which the air is scrubbed. After that the scrubbed substances are generally neutralized by chemicals.
In the area of agriculture and food industry as well as the public sewage plants there are increasingly problems because of odour nuisance in the neighbourhood. The substances emitted from the different processes are seldom noxious. They are many individual components of very low concentration which together result in a specific odourous mixture. And this is felt to be penetrating and intolerable. This refers in particular to odours from
rendering plants
casings and glue boiling
slaughterhouses, particularly from blood storage tanks, bristles disposal
dung and calf stomach drying plants
public sewage plants
feed milling and mixing plants
starch drying plants
malt-houses and brewery
pig and chicken management.
