Acta Sci. Pol. Formatio Circumiectus 17 (4) 2018, 85–95 DOI: www.formatiocircumiectus.actapol.net/pl/ ISSN 1644-0765 ORIGINAL PAPER Accepted:  e-mail: mmak@up.poznan.pl © Copyright by Wydawnictwo Uniwersytetu Rolniczego w Krakowie, Kraków 2018 ENVIRONMENTAL PROCESSES HYDRAULIC CHARACTERISTICS OF THE AIRLIFT PUMP Sebastian Kujawiak, Małgorzata Makowska  , Radosław Matz Department of Hydraulic and Sanitary Engineering, Poznan University of Life Sciences, ul. Piatkowska 94A, 60-649 Poznań ABSTRACT Airlift pumps are the simplest devices used for lifting and transporting of liquid in water and wastewater systems. They constitute the subject of interest in numerous studies, focusing on their two-phase fow. The knowledge of two-phase fow parameters is necessary for the correct design of an airlift pump. In the avail- able literature on the subject, one will fnd numerous models describing the two-phase gas-liquid fow. One of the most popular is the Zuber – Findlay model, also called the slip model. The subject of the present research consisted in a vertical bubble column, with the diameters of 50 and 75 mm, used to transport the water-air mixture. Based on the results obtained, hydraulic characteristics were developed: liquid fow depending on the depth H s and the air fow Q p . For the mathematical description, second-degree polynomial model was applied, as well as and assessment of the determination coeffcient was performed. Effciency factors of the airlift pump and other parameters for two-phase mixture during the airlift pump’s operation were determined using the slip model. Based on the experiment, it has been found for both of the analysed diameters that the effciency of the airlift pump increased along with the depth H s and the air fow Q p . The airlift pump achieves maximum liquid effciency within a specifed range of the immersion depth. In a small diameter airlift pump (50 mm), slug and plug fow regimes are predominant. Keywords: airlift pumps, two-phase fow, airlift pumps effciency INTRODUCTION Airlift pumps are the simplest devices, in terms of structure, that perform similar functions to classic pumps. They can lift and transport liquid over short distances. Literature is rich in examples of the use of airlift pumps in various branches of industry and bio- technology (Grzywacz, 2012). In water and wastewa- ter technology, lifts are used for transport in water and sewage systems. In Poland, they are used for the trans- port of sewage and sludge in sewage treatment plants as well as for transporting the bed in self-regulating flters and for the renovation of drilled wells (Heidrich et al., 2008; Kalenik, 2015; Merchuk and Gluz, 2002; Solecki, 2010). Airlift pumps are perfectly suitable for water conditioning for aquaculture and reclamation of reservoirs and lakes (Fan et al., 2013; Parker, 1983). Due to their construction, they ideally mix and aerate water, removing carbon dioxide therefrom in industri- al fsh farming (Barrut et al., 2012). Numerous advan- tages, including simple structure and lack of mechan- ical elements make them highly reliable. In chemical engineering, they are used to transport corrosive and radioactive liquids, and in the petrochemical industry, they are used for transporting fuels (Cachard and Del- haye, 1996; Hanafzadeh et al., 2011; Kassab et al., 2007; Khalil et al., 1999). An important area in which airlift pumps are ap- plied is the transport of solids, including sand. Kalenik (2017) built a research unit for transporting a mixture of sand and water, and he provided formulas for cal- culating the size of the stream of transported media. Sawicki (2004) analysed this issue with regard to the design of aerated sand traps.