Comparison of sonocrystallization and seeding as pretreatment approaches for scale control to improve heat transfer in thermal brine concentrator

• Published in: Desalination 2022-02, Vol.523, p.115444, Article 115444
• Main Authors: Banakar, V.V., Sabnis, S.S., Gogate, P.R., Raha, A., Saurabh, Adak, A.K.
• Format: Article
• Language: English
• Subjects: Calcium sulphate dihydrate; Fouling; Operating parameters; Seeding; Supersaturation; Ultrasound
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2021.115444

As a fouling mitigation approach, precipitation of scalable salt using pretreatment by seeding, ultrasound and combining ultrasound with seeding was studied with quantification of fouling resistances. It was demonstrated that 1.16 g/l, 1.48 g/l and 1.5 g/l of calcium sulphate precipitated out for the approaches of seeding, ultrasound and seeding + ultrasound approaches respectively. It was also confirmed that the lowest fouling resistance of 1.12m2K/W was obtained for a combination of seeding and US whereas for only ultrasound treatment and only seeding, it was 1.51 m2K/W and 1.76 m2K/W respectively, which were still lower compared to untreated system (3.287 m2K/W after 24 h operation). Particle size analysis revealed that the seeding + ultrasound pretreatment resulted in the lowest mean particle size of 10.32 μm followed by 14.84 μm for only US pretreatment whereas only seeding pretreatment resulted in mean particle size of 46.84 μm. XRD was used to check the morphology of formed crystals after pretreatment while SEM analysis was performed to establish the morphology of formed scale which is found to be dominated by platelet type of crystals. Overall an effective pretreatment approach based on ultrasound in combination with seeding has been proposed to improve the heat transfer based on effective removal of scale-forming components. •Evaluation of seeding and ultrasound based approaches for fouling mitigation.•Insight into the effect of various process parameters on the fouling resistance.•Optimization of US pretreatment parameters for combined approach•Evaluation of various process parameters on bulk and particulate crystallization.