The control of odor emissions has become a major consideration in the design and operation of wastewater conveyance, treatment and residuals processing facilities. As public concern is generally increasing, effective odor control has become an essential part of successful wastewater and biosolids treatment processes.
Odor is released by nearly all steps of wastewater and sludge collection, treatment and disposal. Typically, these odors are considered to be objectionable. Depending on the treatment process they may even be hazardous. Odorants released are differing much in kind and conditions and require adapted treatment.
One of the most common and well known odor substances is hydrogen sulfide (H2S). The odor threshold of H2S is very low (0.5 ppb) which helps the human nose to identify rotten food easily. This warning signal turns into a nuisance, if the odor is associated with wastewater. In wastewater treatment plants however, H2S does not appear as a single substance. Many other chemical substances contribute to wastewater odours.
OSHA considers a H2S concentration of 20 ppm to be the acceptable ceiling concentration. In Germany, the “max. working place concentration“ for H2S is 7.1 mg/m³, which is equivalent to approx. 5 ppm.
Although H2S is commonly known as a wastewater odor, wastewater treatment plants seldom stink like rotten eggs. Wastewater odors are typically a mixture of many different odor substances like other reduced sulfur substances, ammonia, volatile organic carbons etc. are amongst them.
Neutralox Umwelttechnik GmbH has developed different processes into a widely accepted odor control technologies.