ABSTRACT
The use of geothermal energy is of significant importance in the context of the goals and provisions of Directive 2009/28/EC of the European Parliament and of the Council on the promotion of the use of energy from renewable sources (OJ L 140/16 of 5.6.2009), Poland’s National Energy Strategy until 2030 and the National Action Plan on support for developing the utilization of renewable energy sources (RES) (Kępińska & Tomaszewska 2010, Tomaszewska & Hołojuch, 2012). Therefore, the interest of Polish municipal local government bodies and businesses in the utilisation of geothermal waters for heating, and also for balneological and leisure purposes, has been growing in recent years (Bujakowski et al., 2008, Bujakowski 2010, Bujakowski et al., 2010, Tomaszewska et al., 2010, Kasztelewicz & Pajak 2010). Elevated salinity levels and the presence of microelements such as boron, fluoride, barium, strontium, bromides and heavy metals often lead to difficulties related to the disposal of spent (cooled) water. Spent (cooled) geothermal water may be discharged, e.g., into surface waters, or reinjected into the reservoir. In both cases, it is treated as a waste product of the energy extraction process. Water reinjection prevents its excessive extraction, which could result in a decrease of the formation pressure. However, the injection process poses numerous technical challenges and requires
additional consumption of energy to drive the pumps. A partial solution to this problem may lie in the deployment of water treatment technologies, which will enable its further use (Bujakowski et al., 2012, Tomaszewska, 2011). Among the technological enhancements related to the desalination of seawater and saline underground waters which are continuously being developed and implemented, separation processes using pressure-driven membrane processes and hybrid methods that combine the advantages of various technologies play a significant role (Bodzek & Konieczny 2011a, 2011b, Mezher et al., 2011, Sauvet-Goichon 2007). Membrane-based water desalination processes and hybrid technologies that combine membrane processes are widely used to produce drinking water in many regions of the world. They are also considered a technologically and economically viable alternative for desalinating water (mainly seawater), often with the use of renewable (solar, wind, geothermal, photovoltaic) energy (Bodzek et al., 2011, Bodzek & Konieczny 2005). In these processes, the membrane can be viewed as a barrier between contaminated and purified water streams. The separation of these two streams often allows for operation with no or minimal chemical water pre-treatment, which otherwise can form deleterious by-products (Bodzek & Konieczny 2011b).
