The results speak for themselves - almost no complaints from the public. The effective use of the scrubbing tower is the key in my opinion - with out the chemical additive we now use, the complaints were many. In one particular factory, with only minor modifications to the existing equipment to accommodate the use of this additive, the complaints from the community have all but ceased. Ensure that as far as possible, all odours are collected at point of generation.
Final treatment using an oxidizing agent - again be careful of the air volumes involved.
I hope this might spark some ideas and be of some help.