Yang Ming, Chen Jiabin, Peng Boyu, Yu Zhenjiang, Chu Huaqiang, Zhou Xuefei
State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University Shanghai 200092 China
RSC Adv. 2019 May 15;9(27):15277-15287. doi: 10.1039/c8ra10094b. eCollection 2019 May 14.
Coking nanofiltration (NF) concentrates, as typical wastewater with high salinity and refractory organics, have become one of the greatest challenges for "near-zero emission" processes. In our study, an advanced oxidation technology based on ferrous iron/persulfate (Fe(ii)/PS) and polyferric sulfate (PFS) coagulation coupled with ultrafiltration (UF) was used to treat NF concentrates and mitigate membrane fouling. Based on batch experiments, the optimal parameters of Fe(ii)/PS were obtained, during which we discovered that the slow reaction stage of total organic carbon (TOC) removal followed first-order degradation kinetics. Under the optimal reaction conditions, Fe(ii)/PS could efficiently mineralize 69% of organics in coking NF concentrates. In order to eliminate the iron floc generated in the Fe(ii)/PS step, a small amount of PFS (0.05 mM) was added to coagulate the iron floc, which could further improve the effluent quality so that the turbidity, iron content and TOC were significantly reduced by 79.18%, 98% and 21.79% respectively. Gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) and fluorescence excitation-emission matrix spectrometry (EEM) were performed to characterize the removal of phenols, PAHs, quinolines and humic acids in NF concentrates which were responsible for UF membrane fouling. Moreover, scanning electronic microscopy (SEM) and atomic force microscopy (AFM) were conducted to study the surface of the UF membrane after treatment of NF concentrates. The result exhibited that the organic pollutants deposited on the UF membrane surface were reduced by Fe(ii)/PS-PFS pretreatment, and UF membrane flux was thus enhanced. Our results show the potential of the approach of applying Fe(ii)/PS-PFS-UF in NF concentrate treatment.
焦化纳滤（NF）浓缩液作为典型的高盐度和难降解有机物废水，已成为“近零排放”工艺面临的最大挑战之一。在我们的研究中，采用基于亚铁/过硫酸盐（Fe（II）/PS）和聚合硫酸铁（PFS）混凝并结合超滤（UF）的高级氧化技术来处理NF浓缩液并减轻膜污染。基于批次实验，获得了Fe（II）/PS的最佳参数，在此过程中我们发现总有机碳（TOC）去除的慢反应阶段遵循一级降解动力学。在最佳反应条件下，Fe（II）/PS可有效地将焦化NF浓缩液中69%的有机物矿化。为了去除Fe（II）/PS步骤中产生的铁絮体，添加少量PFS（0.05 mM）来混凝铁絮体，这可以进一步提高出水水质，使浊度、铁含量和TOC分别显著降低79.18%、98%和21.79%。采用气相色谱-飞行时间质谱联用（GC×GC-TOFMS）和荧光激发-发射矩阵光谱法（EEM）来表征NF浓缩液中导致超滤膜污染的酚类、多环芳烃、喹啉和腐殖酸的去除情况。此外，进行扫描电子显微镜（SEM）和原子力显微镜（AFM）研究NF浓缩液处理后超滤膜的表面。结果表明，Fe（II）/PS-PFS预处理减少了沉积在超滤膜表面的有机污染物，从而提高了超滤膜通量。我们的结果显示了应用Fe（II）/PS-PFS-UF方法处理NF浓缩液的潜力。
