Odours in sewer networks: nuisance assessment.

As odour nuisance can affect the quality of life, the population is more and more demanding and in many cities sewers are a critical source of odours. Both factors can lead to increasing numbers of complaints due to the odour nuisance perceived by the residents, affecting also the public image of the sewer management companies. Odours associated with sewer networks are very heterogeneous, in as much as the different 'types of odours' encountered are sewer site specific. The state of the art indicates that there are three parameters that play an important role with the nuisance generated by an odour: hedonic odour tone, odour concentration and odour intensity. This paper presents the results of the study on odour nuisance carried out in different points of the sewer network, with the aim to assess the nuisance generated and identify which points of the sewer should be targeted to implement corrective actions. Considering the different parameters assessed, pumping stations have been identified as critical points of odour nuisance in the sewers, being recommended to implement an odour treatment system in order to guarantee the odour comfort of residents.

Assessment of odour and H(2)S impact in WWTPs by cryo-condensation.

Stability of gaseous samples is a major concern when dealing with odours and airborne pollutants sampling. In terms of odours, the representativeness of the sample can be very seriously compromised, despite the rigorous application of the maximum storage time established by EN-13725. The present paper is focused on the use of the cryo-condensation technique (Cryocore) for time-weighted-average (TWA) sampling in waste water treatment plants (WWTPs), with the aim of comparing the values of TWA odour and H(2)S concentration when using the Cryocore system and other well established sampling methods, such as those described in EN-13725 and passive sampling. The study showed comparable results when comparing all the methodologies tested.