Since this month November 2022, GRAL dispersion model presents a new website: https://gral.tugraz.at/ The Graz Lagrangian Model - GRAL - was initially developed in 1999 at the Institute of Thermodynamics and Sustainable Propulsion Systems at Graz University of Technology.

   In addition, new features and bugfixes have been implemented in the new GRAL Version 22.09, which is now available on the GRAL homepage.

   Wastewater treatment plants (WWTPs) are fundamental for water ecosystems conservation but when they are located in the proximity of residential areas may produce odour nuisance. One of the most common odours pollutants emitted in WWTPs is hydrogen sulphide (H₂S) and release to the atmosphere (in waste-waterfalls, manholes), producing a strong unpleasant smell. In this work, field olfactometry and H₂S measurement enabled to identify the main odour source, located in the inlet of the WWTP.

   The maximum H₂S concentration in this emission point measured was 15 ppm and odour concentration was D/T 60, enough high to produce odour nuisance despite they were produced in open atmosphere. By means of a thorough data analysis of the essential variables involved, such as wind speed, wind direction and the H₂S concentrations in its role as the central pollutant, it could be shown via contrasting annual, monthly and daily patterns, that the probability to be affected for these residential areas is the highest in summer from 19:00 hours.