Zmniejszenie uciążliwości zapachowych oczyszczalni ścieków w Tychowie

The most important aim of the study was to find the optimum conditions of the process of dewatering of sewage sludge using decanter centrifuge, and also reduce noxiousness of the centrifuge service, by applying orange essential oil as a partial substitute of flocculants. The tests were performed at sewage treatment plant in Tychowo where dewatering process of sewage sludge is carried using decanter centrifuge ALFA LAVAL, type ALDEC with application of different proportions of orange essential oil mixed with ZETAG® 9048FS flocculant for dose C = 76.3 dm3/m3. Water content in the sediment, dry matter content in effluent and concentration of orange essential oil odour in dewatered sediments were assessed. Conducted tests proved that orange essentials oil is a efficient, good flocculant, which may be used as an addition do centrifugal sedimentation process. Addition of orange essential oil has a substantial advantage: it causes the decrease of odorous noxiousness of dewatered sediments. The experiments were conducted on-site in the sewage treatment plant in the centrifuge station. Analysis of odorous noxiousness was conducted in the laboratory using samples collected on-site. Odorous noxiousness was assessed by determination of oudour concentration. Measurements were made using method of dynamic olfactometry according to standard PN-EN 13725:2007 [14] on four station olfactometer T08 (figure 1) equipped with all necessary apparatus. One measurement consisted of four series. Computer software colleted all the measurements results and calculated result of the measurement team (Zite, pan) –geometric mean of all individual measurements. This value is at the same time the concentration of odour in the sample (cod), expressed in european odorous units per cubic meter (ouE/m3) in accordance with PN-EN 13725:2007 [14]. As a result of conducted tests, taking into account good quality of dewatering of sludge with simultaneous, partial, but clear and noticeable reduction of noxious odours emitted from the sediments, both reagents are recommended for dosage that is ZETAG® 9048FS flocculant and orange essential oil, both 50% of the dose volume. It is advisable to conduct further research on the use of essential oils from other plants as flocculants in the broadly defined processes of water and sludge technology, as well as conducting works on the economic production of essential oils form waste materials, also including the logistics of their separation at the selection of waste stage, or their acquisition from fruit processing plants.