Application of a Hybrid Uf-Ro Process to Geothermal Water Desalination. Concentrate Disposal and Cost Analysis

Abstract

M embrane-based water desalination processes and hybrid technologies are often considered as a technologically and economically viable alternative for desalination of geothermal waters. This has been confi rmed by the results of pilot studies concerning the UF-RO desalination of geothermal waters extracted from various geological structures in Poland. The assessment of the feasibility of implementing the water desalination process analysed on an industrial scale is largely dependent on the method and possibility of disposing or utilising the concentrate. The analyses conducted in this respect have demonstrated that it is possible to use the solution obtained as a balneological product owing to its elevated metasilicic acid, fl uorides and iodides ions content. Due to environmental considerations, injecting the concentrate back into the formation is the preferable solution. The energy effi ciency and economic analysis conducted demonstrated that the cost effectiveness of implementing the UF-RO process in a geothermal system on an industrial scale largely depends on the factors related to its operation, including without limitation the amount of geothermal water extracted, water salinity, the absorption parameters of the wells used to inject water back into the formation, the scale of problems related to the disposal of cooled water, local demand for drinking and household water, etc. The decrease in the pressure required to inject water into the formation as well as the reduction in the stream of the water injected are among the key cost-effectiveness factors. Ensuring favourable desalinated water sale terms (price/quantity) is also a very important consideration owing to the electrical power required to conduct the UF-RO process.

Zero-waste initiatives – waste geothermal water as a source of medicinal raw material and drinking water

“…Therefore, apart from the factors related to the efficiency of producing desalinated water that meets the requirements for water intended for human consumption, the operation of the water treatment plant must be optimised in order to produce just a small stream of concentrate that could be re-injected into the rock formation oreven betterutilised for industrial purposes. Earlier work by the authors, which concerned geothermal waters obtained from carbonate formations within the framework of the Podhale geothermal system [32][33][34][35] threw light on the possible commercial use of concentrate ingredients. The physical and chemical properties of the concentrates obtained during the desalination of water from the GT-1 and GT-2 wells were also evaluated in terms of the requirements applicable to balneological products.…”

Selected problems with boron determination in water treatment processes. Part I: comparison of the reference methods for ICP-MS and ICP-OES determinations

“…In seawater, the boron concentration ranges from 0.5 to 9.6 mg/L, an average value is found between 4.5 ppm and 4.6 mg/L (Woods 1994 ; Farhat et al 2013 ; Kabay et al 2010 ). A high boron concentration is also a common feature of geothermal water sources (Dill 2010 ; Bundschuh et al 2013 ; Tomaszewska and Szczepański 2014 ; Tomaszewska et al 2014 ), especially when TDS is greater than 1 g/L (Tomaszewska and Bodzek 2013a ).…”

Nanofiltration renovation of mineral water

“…In the concentrate, which is the liquid created by the separation of ions in the nanofi ltration process, a signifi cant increase was noted in the content of most of the ingredients (Tomaszewska et al 2014). Water of a sulphate-chloride- …”