CIESC Journal ›› 2019, Vol. 70 ›› Issue (3): 1089-1098.DOI: 10.11949/j.issn.0438-1157.20180793

• Energy and environmental engineering • Previous Articles     Next Articles

Transformation of Fe3+ and its effect on anoxic sludge flocculation in A2O process

Lanhe ZHANG1,2(),Mingshuang ZHANG1,Jingbo GUO3,Yanping JIA1,Zheng LI1,Zicheng CHEN1   

  1. 1. School of Chemical Engineering, Northeast Electric Power University, Jilin 132012, Jilin, China
    2. Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, Jilin, China
    3. School of Civil and Architecture Engineering, Northeast Electric Power University, Jilin 132012, Jilin, China
  • Received:2018-07-13 Revised:2018-11-03 Online:2019-03-05 Published:2019-03-05
  • Contact: Lanhe ZHANG

Fe3+在A2O工艺缺氧区的转化规律及其对污泥絮凝性的影响

张兰河1,2(),张明爽1,郭静波3,贾艳萍1,李正1,陈子成1   

  1. 1. 东北电力大学化学工程学院, 吉林省 吉林市132012
    2. 吉林建筑大学松辽流域水环境教育部重点实验室,吉林 长春 130118
    3. 东北电力大学建筑工程学院, 吉林省 吉林市 132012
  • 通讯作者: 张兰河
  • 作者简介:张兰河(1971—),男,博士,教授,<email>zhanglanhe@163.com</email>
  • 基金资助:
    国家自然科学基金项目(51678119,51508073);吉林省科技发展计划项目(20180201016SF,20180101309JC,20170519013JH)

Abstract:

To study the effect of iron on the flocculation of A2O process sludge, the distribution and migration and tranformation of Fe3+ in sludge supernatant, extracellular polymeric substances (EPS) and sediment (Pellet) were investigated. A large amount of wastewater containing Fe3+ was generated in the rapidly developed industries such as metallurgy, electroplate and mineral separation. Fe3+ entered the sewage biological treatment system and could affect the sludge biological flocculation and the removal of COD, TN and TP. Information on the morphology, structure change, migration and conversion of iron ions in the anaerobic, anoxic and oxic sludge was scrace. The occurrence form and structural characteristics of iron ions were analyzed and the interaction mechanism between Fe3+ and microbial metabolites was revealed based on the analyses of three-dimensional excitation (3D-EEM), atom absorption and X-ray diffraction (XRD). The effect of Fe3+ on the denitrification and phosphorus removal was explored. The results showed that low concentration of Fe3+(<10 mg·L-1) could improve COD and TN removal, promote microbial activity and enhance the biological flocculation of sludge. When Fe3+ increased from 0 to 10 mg·L-1, the removal efficiency of COD and TN increased from 42% and 37% to 60% and 45%, respectively, while the dehydrogenase activity increased from 20.09 mg·(L·h)-1 to 31.91 mg·(L·h)-1. The flocculation ability (FA) increased from 30% to 53% and the maximum sludge particle size was 43.3 μm. High concentration of Fe3+ could inhibit microbial activity, increase EPS content and induce sludge deflocculation. When Fe3+ concentration increased from 10 mg·L-1 to 40 mg·L-1, the removal efficiency of COD and TN decreased by 28% and 34%, respectively. Protein (PN)/polysaccharide (PS) in loosely bound EPS(LB) and tightly bound EPS(TB) was the key factor affecting the flocculation of sludge. Fe3+ addition could enhance TP removal efficiency and it was 93% when Fe3+ was 40 mg·L-1. Fe3+ concentration distribution in the sludge was TB>supernatant>LB>soluble microbial products(SMP), and the main form of Fe element in the sludge was Fe3+. The iron content of different forms changed with the increase of Fe3+ concentration. In addition, Fe3+ could enrich and accumulate in the microorganism cells and could change the composition of EPS layers.

Key words: iron, wastewater, bioreactors, anoxic sludge, migration and transformation, morphology, biological flocculation

摘要:

为了研究铁元素对A2O工艺污泥絮凝性的影响,考察Fe3+在污泥上清液、胞外聚合物(extracellular polymeric substances,EPS)与底泥(Pellet)中的分布和迁移转化规律,结合三维荧光光谱(3D-EEM)、原子吸收和X射线衍射仪(XRD)分析Fe的存在形态和结构特征,揭示Fe3+与微生物代谢产物的作用机制,探索Fe3+对脱氮除磷效率的影响。结果表明:低浓度Fe3+(<10 mg·L-1)能够提高COD和TN去除率,促进微生物活性,增强污泥生物絮凝性;高浓度Fe3+(10~40 mg·L-1)则抑制微生物活性,使EPS总量升高,污泥絮体脱稳,LB、TB层PN/PS是影响污泥絮凝性的关键因素;Fe3+的投加强化生物除磷效率,当Fe3+浓度为40 mg·L-1时,TP去除率为93%。Fe3+在污泥混合液中的分布规律为TB>上清液>LB>SMP,Fe3+在生物体内富集累积,能够改变EPS各层的组分。

关键词: Fe, 废水, 生物反应器, 缺氧污泥, 迁移转化, 形态学, 生物絮凝性

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