微藻固定化条件优化及其污水氨氮去除潜力分析
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摘要
微藻污水处理被视为新概念引领下极具潜力的一项绿色技术,然而,微藻分离与采收一直是限制其大规模应用的瓶颈.本研究立足于固定化技术,以斜生栅藻(Scenedesmus obliquus)为研究对象,采用响应曲面法(RSM)耦合Box-Behnken设计,以固定剂浓度、交联剂浓度和交联时间为自变量,以藻球的机械强度、传质速率和生长速率为响应值,对固定化的过程参数进行优化,制备性能最优的固定化藻球;并探索和分析藻球对氨氮(NH4+-N)去除的最佳条件及其潜力.结果表明,固定剂浓度、交联剂浓度和交联时间分别为5%、2%和16 h为制备固定化藻球的最优条件,且包埋密度为1×106cells·m L~(-1),有机物(COD)浓度为300 mg·L~(-1)时,藻球混合培养去除NH4+-N的能力最强;此外,固定藻对高浓度NH4+-N的去除潜力显著优于自由藻,当初始浓度约为50和70 mg·L~(-1)时,固定藻混合培养5 d后NH4+-N去除率分别为(96. 6±0. 1)%和(65. 2±4. 5)%,而初始浓度约为30 mg·L~(-1)时,自由藻优势明显,3 d后NH4+-N去除率高达(97. 8±0. 6)%;但异养条件下固定藻对NH4+-N的去除率整体偏低且随浓度增加而降低,当初始浓度约为30 mg·L~(-1)时,去除率仅为(49. 0±3. 1)%.本研究为污水可持续处理提供了新思路,为资源回收提供了新途径,更为该技术推广应用奠定了较好的理论基础.
Application of microalgae in wastewater treatment is regarded as a potential green technology. However,its engineering application has been largely hindered because of the difficulty of biomass separation and harvesting. This study aimed to identify the key parameters influencing the process of microalgae immobilization. To do this,the study focused on immobilization technology and Scenedesmus obliquus,and employed the response surface methodology( RSM) and the Box-Behnken design( BBD). In an evaluation of the performance of microalgae beads,the fixing agent concentration,the cross-linking agent concentration,and the cross-linking time were selected as the independent variables,and the mechanical strength,the mass transfer rate,and the growth rate of immobilized microalgae beads were the response values. The optimal conditions and the uptake potential of the microalgae beads with respect to ammonia nitrogen( NH4+-N) were further explored and analyzed. The results showed that the optimal parameters for the preparation of immobilized microalgae beads were 5%,2%,and 16 h,and the maximum removal capacity was obtained using mixotrophic cultivation with an embedding density of 1 × 106 cells·m L~(-1) and an organic matter concentration of 300 mg·L~(-1). In addition,the removal capacity of immobilized microalgae with respect to high concentrations of NH4+-N was significantly higher than for free-living microalgae. When the initial concentrations of NH4+-N were approximately 50 and 70 mg·L~(-1),NH4+-N was removed by the immobilized microalgae( after a 5-day mixotrophic cultivation) at a rate of( 96. 6 ± 0. 1) % and( 65. 2 ± 4. 5) %,respectively. With an initial NH4+-N concentration of 30 mg·L~(-1),the dominance of free-living microalgae was clear,with a removal rate of( 97. 8 ±0. 6) % after a 3-day cultivation. However,under heterotrophic cultivation,the removal rate of NH4+-N by immobilized microalgae was generally low and gradually decreased with increasing concentrations. When the initial concentration was approximately 30 mg·L~(-1),the removal rate was only( 49. 0 ± 3. 1) %. This study provides new prospects for sustainable urban wastewater treatment,a new approach for resource recycling,and a strong theoretical foundation for the popularization and application of microalgae in wastewater treatment.
Application of microalgae in wastewater treatment is regarded as a potential green technology. However,its engineering application has been largely hindered because of the difficulty of biomass separation and harvesting. This study aimed to identify the key parameters influencing the process of microalgae immobilization. To do this,the study focused on immobilization technology and Scenedesmus obliquus,and employed the response surface methodology( RSM) and the Box-Behnken design( BBD). In an evaluation of the performance of microalgae beads,the fixing agent concentration,the cross-linking agent concentration,and the cross-linking time were selected as the independent variables,and the mechanical strength,the mass transfer rate,and the growth rate of immobilized microalgae beads were the response values. The optimal conditions and the uptake potential of the microalgae beads with respect to ammonia nitrogen( NH4+-N) were further explored and analyzed. The results showed that the optimal parameters for the preparation of immobilized microalgae beads were 5%,2%,and 16 h,and the maximum removal capacity was obtained using mixotrophic cultivation with an embedding density of 1 × 106 cells·m L~(-1) and an organic matter concentration of 300 mg·L~(-1). In addition,the removal capacity of immobilized microalgae with respect to high concentrations of NH4+-N was significantly higher than for free-living microalgae. When the initial concentrations of NH4+-N were approximately 50 and 70 mg·L~(-1),NH4+-N was removed by the immobilized microalgae( after a 5-day mixotrophic cultivation) at a rate of( 96. 6 ± 0. 1) % and( 65. 2 ± 4. 5) %,respectively. With an initial NH4+-N concentration of 30 mg·L~(-1),the dominance of free-living microalgae was clear,with a removal rate of( 97. 8 ±0. 6) % after a 3-day cultivation. However,under heterotrophic cultivation,the removal rate of NH4+-N by immobilized microalgae was generally low and gradually decreased with increasing concentrations. When the initial concentration was approximately 30 mg·L~(-1),the removal rate was only( 49. 0 ± 3. 1) %. This study provides new prospects for sustainable urban wastewater treatment,a new approach for resource recycling,and a strong theoretical foundation for the popularization and application of microalgae in wastewater treatment.
引文
[1]冯玉杰,张照韩,于艳玲,等.基于资源和能源回收的城市污水可持续处理技术研究进展[J].化学工业与工程,2015,32(5):20-28.Feng Y J,Zhang Z H,Yu Y L,et al. Review of sustainable wastewater treatment technologies based on resource recovery and energy utilization[J]. Chemical Industry and Engineering,2015,32(5):20-28.
[2] Gong H,Jin Z Y,Wang Q B,et al. Effects of adsorbent cake layer on membrane fouling during hybrid coagulation/adsorption microfiltration for sewage organic recovery[J]. Chemical Engineering Journal,2017,317:751-757.
[3] Oswald W J,Gotaas H B,Golueke C G,et al. Algae in waste treatment[J]. Sewage and Industrial Wastes,1957,29(4):437-457.
[4] Ye J F,Liang J Y,Wang L,et al. The mechanism of enhanced wastewater nitrogen removal by photo-sequencing batch reactors based on comprehensive analysis of system dynamics within a cycle[J]. Bioresource Technology,2018,260:256-263.
[5] Chen Y M,Xu C G,Vaidyanathan S. Microalgae:a robust“green bio-bridge”between energy and environment[J]. Critical Reviews in Biotechnology,2018,38(3):351-368.
[6] Cabanelas I T D,Arbib Z,Chinalia F A,et al. From waste to energy:microalgae production in wastewater and glycerol[J].Applied Energy,2013,109:283-290.
[7]韩松芳,金文标,涂仁杰,等.基于城市污水资源化的微藻筛选与污水预处理[J].环境科学,2017,38(8):3347-3353.Han S F,Jin W B,Tu R J,et al. Selection of microalgae for biofuel using municipal wastewater as a resource[J].Environmental Science,2017,38(8):3347-3353.
[8]王秀锦,李兆胜,邢冠岚,等.蛋白核小球藻Chlorella pyrenoidosa-15的异养培养条件优化及污水养殖[J].环境科学,2012,33(8):2735-2740.Wang X J,Li Z S,Xing G L,et al. Optimization of Chlorella pyrenoidosa-15 photoheterotrophic culture and its use in wastewater treatment[J]. Environmental Science,2012,33(8):2735-2740.
[9] Lam M K,Lee K T. Immobilization as a feasible method to simplify the separation of microalgae from water for biodiesel production[J]. Chemical Engineering Journal,2012,191:263-268.
[10] Cheirsilp B,Thawechai T,Prasertsan P. Immobilized oleaginous microalgae for production of lipid and phytoremediation of secondary effluent from palm oil mill in fluidized bed photobioreactor[J]. Bioresource Technology,2017,241:787-794.
[11]张玉琳,王应军,李伟雨,等.固定化斜生栅藻净化畜禽废水中氨氮和磷的影响因素[J].环境工程学报,2015,9(5):2253-2258.Zhang Y L,Wang Y J,Li W Y,et al. Controlling factors on ammonia-nitrogen and phosphorus removal from livestock wastewater by immobilized Scenedesmus obliquus[J]. Chinese Journal of Environmental Engineering,2015,9(5):2253-2258.
[12]毛书端,张小平,牛曼. 2种藻菌固定化改进方法的比较及优化研究[J].中国环境科学,2012,32(5):869-874.Mao S D,Zhang X P,Niu M. Optimization and comparison of two improved methods of algae-bacteria immobilized[J]. China Environmental Science,2012,32(5):869-874.
[13] Liu K,Li J,Qiao H J,et al. Immobilization of Chlorella sorokiniana GXNN 01 in alginate for removal of N and P from synthetic wastewater[J]. Bioresource Technology,2012,114:26-32.
[14] Zhang T Y,Wu Y H,Zhu S F,et al. Isolation and heterotrophic cultivation of mixotrophic microalgae strains for domestic wastewater treatment and lipid production under dark condition[J]. Bioresource Technology,2013,149:586-589.
[15] Chen G H,Li J,Tabassum S,et al. Anaerobic ammonium oxidation(ANAMMOX)sludge immobilized by waterborne polyurethane and its nitrogen removal performance-a lab scale study[J]. RSC Advances,2015,5(32):25372-25381.
[16]宋伟龙,戴友芝,唐彬,等. Box-Behnken响应曲面法优化高聚复配絮凝剂制备条件[J].环境工程学报,2014,8(7):2753-2759.Song W L,Dai Y Z,Tang B,et al. Optimization on preparation technique of polymer composite flocculants using Box-Behnken response surface methodology[J]. Chinese Journal of Environmental Engineering,2014,8(7):2753-2759.
[17]韩丽君,范晓,郑乃余.用于固定化载体的褐藻酸钙凝胶条件的研究[J].海洋科学,1992,(3):56-59.Han L J,Fan X,Zheng N Y. Study on the Ca-alginate gelling condition as stablization garrier[J]. Marine Sciences,1992,(3):56-59.
[18] Soo C L,Chen C A,Bojo O,et al. Feasibility of marine microalgae immobilization in alginate bead for marine water treatment:bead stability, cell growth, and ammonia removal[J]. International Journal of Polymer Science,2017,2017:6951212.
[19]蒋宇红,黄霞,俞毓罄.几种固定化细胞载体的比较[J].环境科学,1993,14(2):11-15.
[20] Syiem M B,Bhattacharjee A. Structural and functional stability of regenerated cyanobacteria following immobilization[J]. Journal of Applied Phycology,2015,27(2):743-753.
[21] Mujtaba G,Rizwan M,Kim G,et al. Removal of nutrients and COD through co-culturing activated sludge and immobilized Chlorella vulgaris[J]. Chemical Engineering Journal,2018,343:155-162.
[22]梁晶晶,蒋霞敏,江茂旺,等.固定化微绿球藻去除NH4+-N、PO34--P效果的研究[J].水生生物学报,2016,40(5):1033-1040.Liang J J,Jiang X M,Jiang M W,et al. Study on removal rate of NH4+-N and PO34--P by immobilized Nannochloropsis oculata[J]. Acta Hydrobiologica Sinica,2016,40(5):1033-1040.
[23] Singhasuwan S,Choorit W,Sirisansaneeyakul S,et al. Carbonto-nitrogen ratio affects the biomass composition and the fatty acid profile of heterotrophically grown Chlorella sp. TISTR 8990 for biodiesel production[J]. Journal of Biotechnology,2015,216:169-177.
[24] Gao F,Li C,Yang Z H,et al. Continuous microalgae cultivation in aquaculture wastewater by a membrane photobioreactor for biomass production and nutrients removal[J]. Ecological Engineering,2016,92:55-61.
[25] Chen H,Zheng Y L,Zhan J,et al. Comparative metabolic profiling of the lipid-producing green microalga Chlorella reveals that nitrogen and carbon metabolic pathways contribute to lipid metabolism[J]. Biotechnology for Biofuels,2017,10:153.
[26] Thawechai T,Cheirsilp B,Louhasakul Y,et al. Mitigation of carbon dioxide by oleaginous microalgae for lipids and pigments production:Effect of light illumination and carbon dioxide feeding strategies[J]. Bioresource Technology,2016,219:139-149.
[27] Sutherland D L,Howard-Williams C,Turnbull M H,et al. The effects of CO2addition along a pH gradient on wastewater microalgal photo-physiology, biomass production and nutrient removal[J]. Water Research,2015,70:9-26.
[2] Gong H,Jin Z Y,Wang Q B,et al. Effects of adsorbent cake layer on membrane fouling during hybrid coagulation/adsorption microfiltration for sewage organic recovery[J]. Chemical Engineering Journal,2017,317:751-757.
[3] Oswald W J,Gotaas H B,Golueke C G,et al. Algae in waste treatment[J]. Sewage and Industrial Wastes,1957,29(4):437-457.
[4] Ye J F,Liang J Y,Wang L,et al. The mechanism of enhanced wastewater nitrogen removal by photo-sequencing batch reactors based on comprehensive analysis of system dynamics within a cycle[J]. Bioresource Technology,2018,260:256-263.
[5] Chen Y M,Xu C G,Vaidyanathan S. Microalgae:a robust“green bio-bridge”between energy and environment[J]. Critical Reviews in Biotechnology,2018,38(3):351-368.
[6] Cabanelas I T D,Arbib Z,Chinalia F A,et al. From waste to energy:microalgae production in wastewater and glycerol[J].Applied Energy,2013,109:283-290.
[7]韩松芳,金文标,涂仁杰,等.基于城市污水资源化的微藻筛选与污水预处理[J].环境科学,2017,38(8):3347-3353.Han S F,Jin W B,Tu R J,et al. Selection of microalgae for biofuel using municipal wastewater as a resource[J].Environmental Science,2017,38(8):3347-3353.
[8]王秀锦,李兆胜,邢冠岚,等.蛋白核小球藻Chlorella pyrenoidosa-15的异养培养条件优化及污水养殖[J].环境科学,2012,33(8):2735-2740.Wang X J,Li Z S,Xing G L,et al. Optimization of Chlorella pyrenoidosa-15 photoheterotrophic culture and its use in wastewater treatment[J]. Environmental Science,2012,33(8):2735-2740.
[9] Lam M K,Lee K T. Immobilization as a feasible method to simplify the separation of microalgae from water for biodiesel production[J]. Chemical Engineering Journal,2012,191:263-268.
[10] Cheirsilp B,Thawechai T,Prasertsan P. Immobilized oleaginous microalgae for production of lipid and phytoremediation of secondary effluent from palm oil mill in fluidized bed photobioreactor[J]. Bioresource Technology,2017,241:787-794.
[11]张玉琳,王应军,李伟雨,等.固定化斜生栅藻净化畜禽废水中氨氮和磷的影响因素[J].环境工程学报,2015,9(5):2253-2258.Zhang Y L,Wang Y J,Li W Y,et al. Controlling factors on ammonia-nitrogen and phosphorus removal from livestock wastewater by immobilized Scenedesmus obliquus[J]. Chinese Journal of Environmental Engineering,2015,9(5):2253-2258.
[12]毛书端,张小平,牛曼. 2种藻菌固定化改进方法的比较及优化研究[J].中国环境科学,2012,32(5):869-874.Mao S D,Zhang X P,Niu M. Optimization and comparison of two improved methods of algae-bacteria immobilized[J]. China Environmental Science,2012,32(5):869-874.
[13] Liu K,Li J,Qiao H J,et al. Immobilization of Chlorella sorokiniana GXNN 01 in alginate for removal of N and P from synthetic wastewater[J]. Bioresource Technology,2012,114:26-32.
[14] Zhang T Y,Wu Y H,Zhu S F,et al. Isolation and heterotrophic cultivation of mixotrophic microalgae strains for domestic wastewater treatment and lipid production under dark condition[J]. Bioresource Technology,2013,149:586-589.
[15] Chen G H,Li J,Tabassum S,et al. Anaerobic ammonium oxidation(ANAMMOX)sludge immobilized by waterborne polyurethane and its nitrogen removal performance-a lab scale study[J]. RSC Advances,2015,5(32):25372-25381.
[16]宋伟龙,戴友芝,唐彬,等. Box-Behnken响应曲面法优化高聚复配絮凝剂制备条件[J].环境工程学报,2014,8(7):2753-2759.Song W L,Dai Y Z,Tang B,et al. Optimization on preparation technique of polymer composite flocculants using Box-Behnken response surface methodology[J]. Chinese Journal of Environmental Engineering,2014,8(7):2753-2759.
[17]韩丽君,范晓,郑乃余.用于固定化载体的褐藻酸钙凝胶条件的研究[J].海洋科学,1992,(3):56-59.Han L J,Fan X,Zheng N Y. Study on the Ca-alginate gelling condition as stablization garrier[J]. Marine Sciences,1992,(3):56-59.
[18] Soo C L,Chen C A,Bojo O,et al. Feasibility of marine microalgae immobilization in alginate bead for marine water treatment:bead stability, cell growth, and ammonia removal[J]. International Journal of Polymer Science,2017,2017:6951212.
[19]蒋宇红,黄霞,俞毓罄.几种固定化细胞载体的比较[J].环境科学,1993,14(2):11-15.
[20] Syiem M B,Bhattacharjee A. Structural and functional stability of regenerated cyanobacteria following immobilization[J]. Journal of Applied Phycology,2015,27(2):743-753.
[21] Mujtaba G,Rizwan M,Kim G,et al. Removal of nutrients and COD through co-culturing activated sludge and immobilized Chlorella vulgaris[J]. Chemical Engineering Journal,2018,343:155-162.
[22]梁晶晶,蒋霞敏,江茂旺,等.固定化微绿球藻去除NH4+-N、PO34--P效果的研究[J].水生生物学报,2016,40(5):1033-1040.Liang J J,Jiang X M,Jiang M W,et al. Study on removal rate of NH4+-N and PO34--P by immobilized Nannochloropsis oculata[J]. Acta Hydrobiologica Sinica,2016,40(5):1033-1040.
[23] Singhasuwan S,Choorit W,Sirisansaneeyakul S,et al. Carbonto-nitrogen ratio affects the biomass composition and the fatty acid profile of heterotrophically grown Chlorella sp. TISTR 8990 for biodiesel production[J]. Journal of Biotechnology,2015,216:169-177.
[24] Gao F,Li C,Yang Z H,et al. Continuous microalgae cultivation in aquaculture wastewater by a membrane photobioreactor for biomass production and nutrients removal[J]. Ecological Engineering,2016,92:55-61.
[25] Chen H,Zheng Y L,Zhan J,et al. Comparative metabolic profiling of the lipid-producing green microalga Chlorella reveals that nitrogen and carbon metabolic pathways contribute to lipid metabolism[J]. Biotechnology for Biofuels,2017,10:153.
[26] Thawechai T,Cheirsilp B,Louhasakul Y,et al. Mitigation of carbon dioxide by oleaginous microalgae for lipids and pigments production:Effect of light illumination and carbon dioxide feeding strategies[J]. Bioresource Technology,2016,219:139-149.
[27] Sutherland D L,Howard-Williams C,Turnbull M H,et al. The effects of CO2addition along a pH gradient on wastewater microalgal photo-physiology, biomass production and nutrient removal[J]. Water Research,2015,70:9-26.
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