Odorous wastewater emissions
The objective of this article is to review odour problems of wastewater treatment facilities and air emission treatment methods. The malodorous wastewater emissions consist of a complex mixture of substances with different properties. A screening of volatile organic and reduced sulphur compounds revealed very low concentrations of individual compounds (< 50 ppb), and only dimethyl sulphide, hydrogen sulphide and methyl mercaptan were found at concentrations above threshold values. Indicating one single compound responsible for the foul odours was not possible.
Two case studies are presented and discussed. In the first, a compact biofilter was evaluated for the treatment of gas streams from a sewage pumping station. A rockwool filter media was inoculated with a mixed bacterial wastewater culture that established successfully. However, evaluating the biofilter’s performance proved analytically difficult and expensive due to the low concentrations of incoming gases. In the second case study the odour nuisance situation around a wastewater treatment plant was evaluated and a holistic approach to manage the odour problems was developed. An odour panel of local observers worked well, since they got involved in the process. However, using the panel’s reports on odour episodes to find the source of the odour was difficult.