Li-Juan Feng

Zhejiang Ocean University, Чжоушань, Zhejiang Sheng, China

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Publications (11)34.75 Total impact

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    ABSTRACT: An enhanced lab-scale biofilm pretreatment process treating raw water obtained from eutrophicated water bodies was established and started up with a novel strategy of low-level nutrients addition and effluent recirculation. Results showed that the startup strategy was useful for biofilm formation and pollutants removal, but it had the risks of increasing substrate affinity constant (Ks) and biofilm decay in treating raw water. Fortunately, the increased Ks value did not affected the NH4(+)-N removal performance via keeping the NH4(+)-N loading rate larger than 6.29mgL(-1)d(-1). In addition, lower hydraulic retention time (HRT) favored the removal of organic matters, and the maximum TOC removal rate of 76.5mgL(-1)d(-1) were achieved at HRT of 2h. After long-term acclimatization at oligotrophic niche, the decrease of Ks value and increase of biomass, extracellular polymeric substances, bioactivity were achieved. Finally, the stable operation of biofilm pretreatment process was realized in treating polluted raw water.
    No preview · Article · Sep 2015 · Bioresource Technology
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    ABSTRACT: A lab-scale novel bio-diatomite biofilm process (BDBP) was established for the polluted raw water pretreatment in this study. Results showed that a shorter startup period of BDBP system was achieved under the completely circulated operation mode, and the removal efficiencies of nitrogen and disinfection by-product precursor were effective at low hydraulic retention time of 2-4h due to high biomass attached to the carrier and diatomite. A maximum NH4(+)-N oxidation potential predicted by modified Stover-Kincannon model was 333.3mgL(-1)d(-1) in the BDBP system, which was 4.7 times of that in the control reactor. Results demonstrated that the present of bio-diatomite favors the accumulation of functional microbes in the oligotrophic niche, and the pollutants removal performance of this novel process was enhanced for polluted raw water pretreatment. Copyright © 2015 Elsevier Ltd. All rights reserved.
    No preview · Article · May 2015 · Bioresource Technology
  • Guang-Feng Yang · Li-Juan Feng · Qi Yang · Liang Zhu · Jian Xu · Xiang-Yang Xu
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    ABSTRACT: The quality of raw water is getting worse in developing countries because of the inadequate treatment of municipal sewage, industrial wastewater and agricultural runoff. Aiming at the biofilm enrichment and pollutant removal, two pilot-scale biofilm reactors were built with different biological carriers. Results showed that compared with the blank carrier, the biofilm was easily enriched on the biofilm precoated carrier and less nitrite accumulation occurred. The removal efficiencies of NH4(+)-N, DOC and UV254 increased under the aeration condition, and a optimum DO level for the adequate nitrification was 1.0-2.6mgL(-1) with the suitable temperature range of 21-22°C. Study on the trihalomethane prediction model indicated that the presentence of algae increased the risk of disinfection by-products production, which could be effectively controlled via manual algae removing and light shading. In this study, the performance of biofilm pretreatment process could be enhanced under the optimized condition of DO level and biofilm carrier.
    No preview · Article · Sep 2014 · Bioresource Technology
  • Li-Juan Feng · Guang-Feng Yang · Liang Zhu · Xiang-Yang Xu
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    ABSTRACT: The removal performances of nitrogen and trace levels of endocrine-disrupting pesticides (cypermethrin and chlorpyrifos) were studied in the enhanced biofilm pretreatment system at various substrates concentrations and dissolve oxygen (DO) niches. No significant change of EDPs removal occurred with the increased feed of ammonia nitrogen in aerobic batch tests or nitrate in anaerobic batch reactors, but significantly enhanced via reed addition both in aerobic and anaerobic conditions. Simultaneously enhanced denitrification and EDPs removal were achieved in the anoxic niche with reed addition. The results of denaturing gradient gel electrophoresis (DGGE) indicated that new bands appeared, and some bands became more intense with the reed addition. Sequences analysis showed that the dominant species belonged to Methylophilaceae, Hyphomicrobium, Bacillus and Thauera, which were related to the nitrogen or EDPs removals. In addition, the growth of functional heterotrophic microbes may be promoted via reed addition.
    No preview · Article · Aug 2014 · Bioresource Technology
  • Li-Juan Feng · Liang Zhu · Qi Yang · Guang-Feng Yang · Jian Xu · Xiang-Yang Xu
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    ABSTRACT: A novel drinking water biofilm pretreatment process with reed addition was established for enhancement of simultaneously organics and nitrogen removal. Results showed that nitrate removal efficiency was positively related with the influent C/N ratio, reaching to 87.8±2.8% at the C/N ratio of 4.7. However, the predicted trichloromethane (THM) levels based on total organic carbon (TOC) and UV(254) were high with the increase of influent C/N ratio. Combined with the pollutants removal performance and microbial community variation, an appropriate C/N ratio via reed addition was determined at 2.2 for the continuous biofilm reactor. With adjustment of hydraulic retention time (HRT), the highest of nitrate removal efficiency (74.2±1.4%) and organics utilization efficiency (0.63mg NO(3)(-)-Nmg(-1)TOC) were achieved at an optimum HRT of 18h, with both low effluent NO(3)(-)-N (0.88±0.03mgl(-1)) and TOC (2.86±0.67mgl(-1)).
    No preview · Article · Nov 2012 · Bioresource Technology
  • Li-Juan Feng · Jian Xu · Xiang-Yang Xu · Liang Zhu · Jing Xu · Wei Ding · Jing Luan
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    ABSTRACT: In recent years, nitrogen pollution has been increasingly serious in natural waters including drinking source water. A simulated river biofilm reactor fed with contaminated drinking source water was established to evaluate the effects of dissolved oxygen (DO) partitioning and step feeding on the nitrogen removal performance and biofilm microbial community. Results showed that after the hydraulic retention time of anoxic zone extending and step feeding, the effluent concentration of ammonia was below 0.2 mg L−1, and the removal efficiency of total nitrogen increased from 12.02% ± 4.59% to 34.98% ± 2.65%, which indicated the occurrence of simultaneous nitrification and denitrification. The results of denaturing gradient gel electrophoresis showed that the microbial community of biofilm obviously shifted via DO controlling and step feeding. Low DO concentration favored the enrichment of denitrifying bacteria and coexistence of algae and bacteria, and the pattern of step feeding could increase the community abundance. The dominant heterotrophic bacteria species of biofilm in oligotrophic niche belonged to Hyphomicrobium sp., Pseudomonas sp., Chloroflexi sp., Enterobacter sp., Pantoea sp., and Synechococcus sp., which were mostly associated with denitrification and refractory organics utilization. It was worth noting that the ammonia-oxidizing bacteria (AOB) community of biofilm was stable throughout the whole experiment, and Nitrosomonas sp. was the predominant AOB in the oligotrophic niche.
    No preview · Article · Jul 2012 · International Biodeterioration & Biodegradation
  • Liang Zhu · Wei Ding · Li-Juan Feng · Xin Dai · Xiang-Yang Xu
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    ABSTRACT: An aerobic denitrifier was isolated from the Hua-Jia-Chi pond in China and identified as Pseudomonas mendocina 3-7 (Genbank No. HQ285879). This isolated strain could express periplasmic nitrate reductase which is essential for aerobic denitrification occurred when the dissolved oxygen (DO) level maintains at 3-10 mg L(-1). To determine whether the ability of isolated strain is exhibited in the bioremediation of polluted drinking source water, the heterotrophic nitrification and aerobic denitrification characteristics of P. mendocina 3-7 under different cultural conditions such as oxygen level, nitrate and organic concentrations were studied from the nitrogenous balance in the paper. By measuring the nitrogen balance in all experiments under different culture conditions, the removal of total organic carbon and ammonium was positively correlated with total nitrogen removal, especially under high substrate level. With substrate concentration decreasing, ammonium and nitrate removal occurred separately, and ammonium was completely utilized first under low substrate concentration. Compared to that under high substrate level, the specific growth rate of P. mendocina 3-7 was not low under the low substrate level and the pollutant removal efficiencies remained high, which implies the stronger nitrogen removal and acclimatization capacities of the strain in oligotrophic niches.
    No preview · Article · Mar 2012 · Environmental Science and Pollution Research
  • Liang Zhu · Wei Ding · Li-juan Feng · Yun Kong · Jing Xu · Xiang-yang Xu
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    ABSTRACT: In recent years, nitrogen pollution has been increasingly serious in environmental waters in China, especially in drinking source. Seven predominant aerobic denitrifiers were isolated and characterized from the oligotrophic ecosystems. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Pseudomonas, Achromobacter and Acinetobacter, and all isolates could express periplasmic nitrate reductase which was essential for the aerobic denitrification. The growth rates of the isolates were at 0.30-0.83 h(-1), and obvious denitrification occurred when the dissolved oxygen (DO) level maintained at 3-10 mg L(-1). The isolates were able to conduct heterotrophic nitrification for realizing completely nitrogen removal in aerobic oligotrophic niche. Furthermore, three strains especially Pseudomonas sp.3-7 showed outstanding capacities of extracellular polymeric substances (EPS) secretion and aggregation. Results demonstrated that the isolation of aerobic denitrifiers favored the bioremediation of oligotrophic ecosystems.
    No preview · Article · Mar 2012 · Bioresource Technology
  • Xiang-Yang Xu · Li-Juan Feng · Liang Zhu · Jing Xu · Wei Ding · Han-Ying Qi
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    ABSTRACT: The start-up pattern of biofilm remediation system affects the biofilm characteristics and operating performances. The objective of this study was to evaluate the performances of the contaminated source water remediation systems with different start-up patterns in view of the pollutants removal performances and microbial community succession. The operating performances of four lab-scale simulated river biofilm reactors were examined which employed different start-up methods (natural enrichment and artificial enhancement via discharging sediment with influent velocity gradient increase) and different bio-fillers (Elastic filler and AquaMats® ecobase). At the same time, the microbial communities of the bioreactors in different phases were analyzed by polymerase chain reaction, denaturing gradient gel electrophoresis, and sequencing. The pollutants removal performances became stable in the four reactors after 2 months' operation, with ammonia nitrogen and permanganate index (COD(Mn)) removal efficiencies of 84.41-94.21% and 69.66-76.60%, respectively. The biomass of mature biofilm was higher in the bioreactors by artificial enhancement than that by natural enrichment. Microbial community analysis indicated that elastic filler could enrich mature biofilm faster than AquaMats®. The heterotrophic bacteria diversity of biofilm decreased by artificial enhancement, which favored the ammonia-oxidizing bacteria (AOB) developing on the bio-fillers. Furthermore, Nitrosomonas- and Nitrosospira-like AOB coexisted in the biofilm, and Pseudomonas sp., Sphaerotilus sp., Janthinobacterium sp., Corynebacterium aurimucosum were dominant in the oligotrophic niche. Artificial enhancement via the combination of sediment discharging and influent velocity gradient increasing could enhance the biofilm formation and autotrophic AOB enrichment in oligotrophic niche.
    No preview · Article · Nov 2011 · Environmental Science and Pollution Research
  • Jing Xu · Liang Zhu · Wei Ding · Li-juan Feng · Xiang-yang Xu
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    ABSTRACT: Aiming at the carbon source limitation of denitrification in oligotrophic habitat, this paper studied the effects of intermittent aeration on the nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water, and approached the feasibility and process mechanism of shortcut nitrification and denitrification in the system. Under the condition of 8 h-16 h anoxic-aerobic phase (I), the remediation system performed stably, and its average removal efficiency of ammonium (NH4+ -N), permanganate index (COD(Mn)), and total nitrogen (TN) was 93.0%, 78.1%, and 19.4%, respectively. Under the condition of 16 h-8 h anoxic-aerobic phase (II), the NH4+ -N and COD(Mn) removal efficiency still maintained at 81.2% and 76.4%, respectively, the accumulation of nitrite (NO2- -N) was significant, and the removal efficiency of TN reached more than 50%. The nitrogen transformation characteristics in the system during a cycle under condition II demonstrated that at the prerequisite of effluent NH4+ -N and DO concentrations reaching the standards, shortening aerobic phase length could maintain the DO concentration at 0. 5 -1.5 mg L(-1) in a long term, inhibit the growth and activity of nitrite-oxidizing bacteria, and thereby, NO2- -N had an obvious accumulation, and the nitrogen removal via shortcut nitrification-denitrification in the biological contact oxidation remediation system for micro-polluted source water was finally achieved.
    No preview · Article · Apr 2011 · Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban
  • Wei Ding · Liang Zhu · Jing Xu · Li-Juan Feng · Xiang-Yang Xu
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    ABSTRACT: Two simulated river bioreactors with elastic filler and AquaMats were applied to remediate micro-polluted source water. Under intermittent aeration and gradual increase of aeration intensity, the biofilm reactor with elastic filler was successful start-up within 50 days, and average removal efficiencies of permanganate index, NH4(+) -N were 78.2% and 93.5%, respectively, but the removal efficiencies of the reactor with AquaMats were more than 70% and 80% after two weeks. On the condition of aerobic to anoxic ratio of 3 h: 3 h and aeration intensity of 250 L x h(-1), elastic filler was more efficient for the removal of permanganate index, NH4(+) -N, TN and TP. The pollutant removal of AquaMats was strongly enhanced when the aerobic to anoxic ratio and aeration intensity changed to 2 h :4 h and 120 L x h(-1), which suggested its potential of energy saving. Microscopic observation revealed that the surface of elastic filler was fully surrounded with filamentous bacteria and more inorganic particulate matter after successful start-up of the reactor, and the biofilm attaching to AquaMats was of higher microbial population diversity. The results indicated that elastic filler with homogeneous biofilm had a strong retention capacity for its radial structure, and the AquaMats with microporous structure was more suitable for the enrichment of different functional microorganisms and enhanced the collaborative removal of multiple pollutants.
    No preview · Article · Nov 2010 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]