Department of Construction Environment Engineering, KICT School, University of Science & Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon, 34113, Republic of Korea.
Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology, 283, Goyang-Daero, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do, 10223, Republic of Korea.
Chemosphere. 2019 Dec;236:124288. doi: 10.1016/j.chemosphere.2019.07.019. Epub 2019 Jul 5.
Several defluoridation techniques for reducing high initial fluoride concentration (IFC) in wastewater have been tested, but only a few of them have achieved the permissible standards. This study examined the hybrid crystallization-reverse osmosis technique (HRO) in light of flux, fluoride removal efficiency, fouling tendency, mineral recovery, complying zero liquid discharge (ZLD), and effluent discharge standard (EDS). Simulated wastewater with an IFC of 6600 mg/L was utilized and the final HRO performance was compared with those of the low-pressure (30 bar) standalone reverse osmosis (SRO), nanofiltration (SNF), and membrane distillation (SMD) processes. Accordingly, the study on SRO and SNF revealed that pressure, feed pH, membrane type, and IFC were the major factors affecting performance, and SRO was unable to sufficiently defluoridate wastewater with IFC >614 mg/L, needing pretreatment. Subsequently, the HRO process was selected and it was seen that the optimum calcium dose and respective final effluent pH for attaining EDS and ZLD were 16.5 g/L & 7.1 and 19.8 g/L & 5.7 respectively. The best operating pH for all conditions in HRO was approximately 9. Additionally, HRO showed good mineral recovery tendency and less organic fouling. The overall comparisons of flux and residual fluoride for HRO, SRO, SNF, and SMD were 49.3 LMH & 1.21 mg/L; 34.9 LMH & 62 mg/L, 44.05 LMH & 301 mg/L, and 38 LMH & 0.9 mg/L respectively. Therefore, low-pressure HRO can be applied to treat wastewater with high IFC; good tendency of mineral recovery, as good as that of SMD.
已经测试了几种脱氟技术来降低废水中的初始高氟浓度 (IFC)，但只有少数几种达到了允许的标准。本研究考察了混合结晶反渗透技术 (HRO) 的通量、氟去除效率、结垢倾向、矿物回收、零液体排放 (ZLD) 和排放标准 (EDS)。使用初始氟浓度为 6600mg/L 的模拟废水，将最终 HRO 性能与低压 (30bar) 独立反渗透 (SRO)、纳滤 (SNF) 和膜蒸馏 (SMD) 过程进行比较。相应地，对 SRO 和 SNF 的研究表明，压力、进料 pH 值、膜类型和 IFC 是影响性能的主要因素，而 SRO 无法充分脱除 IFC>614mg/L 的废水，需要预处理。随后选择了 HRO 工艺，发现达到 EDS 和 ZLD 的最佳钙剂量和相应最终出水 pH 值分别为 16.5g/L 和 7.1 以及 19.8g/L 和 5.7。对于 HRO 所有条件下的最佳操作 pH 值约为 9。此外，HRO 表现出良好的矿物回收倾向和较少的有机结垢。HRO、SRO、SNF 和 SMD 的通量和残留氟的综合比较分别为 49.3LMH 和 1.21mg/L；34.9LMH 和 62mg/L、44.05LMH 和 301mg/L 和 38LMH 和 0.9mg/L。因此，低压 HRO 可用于处理高 IFC 的废水；矿物回收趋势良好，与 SMD 相当。
