Whether the wastewater treated in plants smells bad or not is dependent on many factors. Wastewater’s constituents determine its potential to generate odors. These constituents vary greatly depending on whether the source of the wastewater is industrial plants or private households. Many wastewater treatment plants perform a mechanical pretreatment and then biological clarification using microorganisms such as bacteria and fungi.
In the case of low to moderately contaminated wastewater, organic matter and pollutants can be degraded under the influence of oxygen. This aerobic process results in relatively low odor generation. Anaerobic wastewater treatment, which is less expensive and suited to heavily polluted wastewater, excludes oxygen and therefore produces odorous gases such as hydrogen sulfide and ammonia.
The contaminant gases produced in such processes can have serious health consequences for both the employees on site and the local population. Hydrogen sulfides irritate the mucous membranes, cause headaches, and can lead to symptoms of poisoning. Permanent odors can lower concentration, impair well-being, and constitute a psychological burden. Effective gas phase filtration can minimize health risks and intense smells by removing harmful and odorous gases from the exhaust air of wastewater treatment plants.
Special pellets can be used to separate acidic and alkaline contaminant gases such as hydrogen sulfide and ammonia. Other pellets can be integrated into the systems to suit the constituents of the wastewater. Activated carbon-based pellets can effectively adsorb odors caused by volatile organic compounds (VOCs). Exhaust air filtration is an absolute must for occupational safety.
Source:
https://www.alicat.com/de/unterstuetzung/wissensbank/aerobe-vs-anaerobe-abwasserbehandlung/
https://www.veoliawatertechnologies.de/verfahren/aerobe-abwasserreinigung
https://centriair.de/systemloesungen/abluftbehandlung-fuer-klaeranlagen/
https://www.lfu.bayern.de/buerger/doc/uw_23_geruchsbelaestigungen.pdf