Air | Biotrickling filter

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• Biofilter
• Bioscrubber

Biological air treatment: biotrickling filter

Purpose

• Removal of odour
• Removal of biological degradable volatile compounds with a rather high Henry-constant, like alcohols, aldehydes and ketones
• Removal of nitrogen compounds: NH₃, amines, ...
• Removal of sulfur compounds: H₂S, mercaptans, ...
• Organochlorines: chloromethane, methylene chloride, ...

Principle

In a biotrickling filter the micro-organisms that take care of the degradation are immobilized on an inert carrier material (plastic gaskets, lava stones, ...). Around the biofilm layer on the inert particles there is a thin layer of water due to the wash water that is flowing continuously or discontinuously over the support material. The components to be removed get absorbed in this water layer and then diffuse into the biofilm where they are broken down.

Potentially also nutrients (nitrogen, phosphorus, ...) and an acid or alkaline for pH-adjustment are added to the wash water. The surplus of biofilm (waste sludge) must be removed in order to prevent clogging of the filter. Therefore the design of the filter must be based on a relative low load and establishing a slow biofilm formation.

In some cases, after the biotricklingfilter an additional biofilter is installed as a downstream polishing technique.
 

Scheme

Scheme biotrickling filter

Applications

This type of filter is often applied for the abatement of acid generating components in gas flows, like H₂S, NH₃, chlorinated organic compounds, …

• Removal of odours:
  • water treatment
  • tobacco industry
  • textile industry
  • stable odour
  • manure treatment
  • fermentation plant
  • …
• Solvents (VOC):
  • chemical industry
  • …

The most common ways of implementing biotricklingfilter are:

• Plastic scrubbertank
• Concrete with appropriate lining

Realisations

Concrete biotrickling filter

Plastic lava filter