Performance monitoring of systems for airpuricationAuthor:Anders

Abstract: Wastewater treatment plants (WWTP) are often the cause of malodor. The compounds which are the main causes of the odor is hydrogen sulfide (H2S), ammonia(NH3), mercaptans (RSH) and volatile organic compounds (V OC) [1]. The odorous air can be analyzed to determine the concentration of the odorants. The odorous can also be analyzed by measuring the odor. The odor is measured, a test panel of people smells the odorous air and determines how many times greater the concentration of the odorants is compared to the odor threshold which is the concentration at which a compound or a mixture is detectable by smell [3]. Measurements were done at three systems for air purication at three different locations, the Vimmerby WWTP, the Alvim WWTP and Renova's biological waste treatment facility in Gothenburg. The odor was measured at the inlet and the outlet and the concentration of H2S and ozone (O3) were measured at all the sampling points of the systems. The system at Vimmerby consisted of three CIFs followed by an UV-reactor and an AC-reactor. In Alvim there were two system which used UV and AC. The system at Renova consisted of a barrier filter followed by UV and AC. The system at the Vimmerby WWTP had a conversion rate between 87-97% of H2.S The CIFs had conversions between 50-64% of the H2S. H2S was not detected at any of the other systems. O3 was only detected at Renova where ground level O3 was present at the inlet, 0.16 ppm. The concentration increased to 0.20 ppm after the UV-reactor. The activated carbon could adsorb all the incoming O3. The odor at the Vimmerby WWTP was determined to 27500 Ou/m3 at the inlet and 19071 Ou/m3 at the outlet. The odor conversion over the system was 31%. The odor conversion at the Alvim WWTP was 99.8%. With an odor of 5490 Ou/m3 atthe inlet and 11 Ou/m3 at the outlet. The ingoing air at the system at Renova had an odor of 434 Ou/m3 and was reduced to 36 Ou/m3 at outlet. The odor conversion at Renova was 92%. To increase the accuracy of the measurements the time between the sampling and measurements should have been minimized. The test panels should also have been larger and the panelists should have been screened in advance, so results from panelists which were over and under sensitive to odors were not included in the final results.