Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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  • Article
    Citation - WoS: 40
    Citation - Scopus: 47
    Boron in Geothermal Energy: Sources, Environmental Impacts, and Management in Geothermal Fluid
    (Elsevier, 2022) Mott, A.; Baba, Alper; Hadi Mosleh, Mojgan; Ökten, Hatice Eser; Babaei, Masoud; Gören, Ayşegül Yağmur; Feng, C.; Recepoğlu, Yaşar Kemal; Uzelli, Taygun; Uytun, Hüseyin; Morata, Diego; Yüksel Özşen, Aslı
    The problem of hazardous chemicals in geothermal fluid is a critical environmental concern in geothermal energy developments. Boron is among the hazardous contaminants reported to be present at high concentrations in geothermal fluids in various countries. Poor management and inadequate treatment of geothermal fluids can release excessive boron to the environment that has toxic effects on plants, humans, and animals. Despite the importance of boron management in geothermal fluid, limited and fragmented resources exist that provide a comprehensive understanding of its sources, transport and fate, and the treatment strategies in geothermal energy context. This paper presents the first critical review from a systematic and comprehensive review on different aspects of boron in geothermal fluid including its generation, sources, toxicity, ranges and the management approaches and treatment technologies. Our research highlights the origin of boron in geothermal water to be mainly from historical water-rock interactions and magmatic intrusion. Excessive concentrations of boron in geothermal fluids have been reported (over 500 mg/L in some case studies). Our review indicated that possible boron contamination in geothermal sites are mostly due to flawed construction of production/re-injection wells and uncontrolled discharge of geothermal water to surface water. The dominancy of non-ionic H3BO3 species makes the selection of the suitable treatment method for geothermal waters limited. Combining boron selective resins and membrane technologies, hybrid systems have provided effluents suitable for irrigation. However, their high energy consumption and course structure of boron selective resins encourage further research to develop cost-effective and environmentally friendly alternatives.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 11
    Brine Minimization in Desalination of the Geothermal Reinjection Fluid by Pressure-Driven Membrane Separation Processes
    (Elsevier, 2022) Jarma, Yakubu A.; Karaoğlu, Aslı; Senan, Islam Rashad Ahmed; Baba, Alper; Kabay, Nalan
    Brine obtained during water treatment by pressure driven membrane processes remains the major drawback. Therefore, it is of paramount important to find a lasting solution in order to minimize its production by both nanofiltration (NF) and reverse osmosis (RO) membranes. In this study, an experimental study with the aim of brine minimization during membrane desalination of the geothermal reinjection fluid using a mini-pilot scale membrane test system having spiral wound NF and RO membranes was conducted. The membranes employed for this task were TR-NF and BW30-RO membranes. First, studies with different brine to feed ratios of 1:4, 1:3, 1:2 and 2:3 represented as NF-F2, NF-F3, NF-F4 and NF-F5, respectively were investigated using TR-NF membrane. A control study with no brine recirculation was conducted as well in order to check the effect of brine recirculation on the membrane performance. Secondly, studies with BW30-RO membrane using same brine to feed ratios as in the case of NF membrane studies were carried out. An applied pressure of 15 bar, initial water recovery of 60% and 4 h of experimental time were employed as operational conditions for both NF and RO membrane studies. Based on the results obtained, it was found that the brine recirculation (with a brine to fresh feed ratio of 2:3) has a significant impact on the permeate flux. The product water can be utilized for the agricultural irrigation purposes. Nevertheless, the boron concentration in the product water was still high for the sensitive crops.