Water is a byproduct of the reaction between ammonia and acetaldehyde, so Le Chatelier's principle would likely disfavor the reaction in aqueous media. You might be able to use an acidic solution in the scrubber to hydrate the aldehyde to the geminal diol which would be a lot less volatile than the parent compound.
However, I'm still not totally sure what you are you trying to here. Do you want to recover the acetaldehyde for reuse, or remove it completely? As long as you are not recirculating the waste gas from the scrubber back into the fermentation vessel the acetaldehyde should be carried away completely.