Abbattimento degli odori

   Transporting liquid waste is a continuously growing activity in several industries. This transportation is made in trucks and sea containers. Often, the liquid transported contains Volatile Organic Compounds (VOC) and odours. The process of washing and cleaning the truck tanks usually involves the emission of odours and VOCs. The aim of this study was to evaluate the odour abatement efficiency of a multistage hybrid approach consisting of alkaline scrubbing, condenser, adsorption with impregnated Al₂O₃ + active carbon (AC), and the injection of a deodorizing product to abate odour and VOC emission. In addition, the second aim of this study was to show that the use of these sequential technologies reduce VOC emissions below the limit of 100 mg/m³ set in the environmental authorisation.

   Before the abatement system was installed, VOC concentration was measured over a week averaging 200 mg/Nm³. After the installation of the abatement system, the results showed that the average VOC concentration was always well below the legal limit. In addition, when washing activities took place, the odour concentration measured at the inlet, and outlet of the abatement system was 5000 ou_E/m³ and 150 ou_E/m³, respectively. This was a 97% odour abatement efficiency.

   Odour impact is generally low around Waste Water Treatment Plants (WWTP) when conventional Odour Control Unit (OCU) such as chemical scrubbers or biofilters are implemented. However, for some specific WWTP processes such as sludge thermal drying releasing odorous Volatile Organic Compounds (VOC) in particular aldehydes and ketones, these conventional OCU are not effective enough to avoid odour nuisances in the environment.

   To fix this issue, we have proposed a simple and relevant two stages treatment line to treat odorous VOCs from WWTP. The first step of the treatment line consists of an enhanced water scrubber (absorption) and the second one, an Activated Carbon (AC) filter (adsorption). The enhanced water scrubber, patented by Suez and named Azurair^TM Cool, uses a chiller to cool the inlet scrubber water in order to increase VOCs removal in scrubber and dehumidifie air before the second stage of AC filtration.