高温消化条件下污泥内碳源释放进程及特性
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摘要
为适应低C/N废水生物脱氮除磷的需求,利用剩余污泥开发内碳源备受重视。本文研究了不同温度条件下污泥消化过程内碳源释放进程的变化特征,探讨了污泥消化过程对上清液中有机物分子量分布的影响。研究表明:消化温度由40℃升至60℃时,污泥挥发性固体物(VS)减量化效果及消化液中化学需氧量(SCOD)浓度明显增加,高温条件有利于污泥内碳源的释放。60℃消化处理120h时,污泥消化体系短链脂肪酸(SCFAs)总量为8797mg/L,C/N(以SCOD/TN表示)、C/P(以SCOD/TP表示)分别达到11.7与38.2;消化温度对污泥上清液中有机物分子量分布影响显著,并使微生物副产物、有机质大分子物质更容易转化为其他代谢中间组分和小分子中间产物。若消化时间超过120h,污泥上清液中Mw>100000的大分子物质呈下降趋势,Mw<10000的小分子物质所占比例逐步增加,但SCFAs总量也呈降低趋势,不利于污泥内碳源的累积。
Aimed to meet the requirements of biological nitrogen and phosphorus removal for those wastewaters with low C/N ratio, more and more attention has been paid to the development of internal carbon source via excess sludge. In this study, the characteristics of carbon source releasing under different digestion temperature were investigated, and the effects of sludge digestion on the molecular weight distribution of organic compounds was also studied. As the temperature was raised from 40 to60℃, the reduction of volatile solids(VS) improved significantly, and the concentration of soluble chemical oxygen demand(SCOD) in digestion supernatant presented a significant increase. Raising the temperature can facilitate the release of internal carbon source from the sludge. For the reactor with digestion temperature of 60℃, the short chain fatty acids(SCFAs) at 120 h was 8797 mg/L, and the ratio of C/N(presented by SCOD/TN) and C/P(presented by SCOD/TP) were 11.7与 38.2, respectively. Thus, the digestion supernatant can meet the requirement of carbon source in the process of biological nutrient removal. Digestion temperature significantly affects the molecular weight distribution of organic compounds during sludge digestion process, and those soluble microbial by-products can be transformed into other metabolic intermediate components under thermophilic digestion condition, and the macromolecules may be smoothly converted to small molecular intermediates. As digestion time exceeded120 h, the macromolecules with Mw>100000 in the digestion substrate presented a downward trend, and the small molecules with Mw<10000 gradually increased, but the total amount of SCFAs in the supernatant declined, which was not conducive to the accumulation of internal carbon sources.
Aimed to meet the requirements of biological nitrogen and phosphorus removal for those wastewaters with low C/N ratio, more and more attention has been paid to the development of internal carbon source via excess sludge. In this study, the characteristics of carbon source releasing under different digestion temperature were investigated, and the effects of sludge digestion on the molecular weight distribution of organic compounds was also studied. As the temperature was raised from 40 to60℃, the reduction of volatile solids(VS) improved significantly, and the concentration of soluble chemical oxygen demand(SCOD) in digestion supernatant presented a significant increase. Raising the temperature can facilitate the release of internal carbon source from the sludge. For the reactor with digestion temperature of 60℃, the short chain fatty acids(SCFAs) at 120 h was 8797 mg/L, and the ratio of C/N(presented by SCOD/TN) and C/P(presented by SCOD/TP) were 11.7与 38.2, respectively. Thus, the digestion supernatant can meet the requirement of carbon source in the process of biological nutrient removal. Digestion temperature significantly affects the molecular weight distribution of organic compounds during sludge digestion process, and those soluble microbial by-products can be transformed into other metabolic intermediate components under thermophilic digestion condition, and the macromolecules may be smoothly converted to small molecular intermediates. As digestion time exceeded120 h, the macromolecules with Mw>100000 in the digestion substrate presented a downward trend, and the small molecules with Mw<10000 gradually increased, but the total amount of SCFAs in the supernatant declined, which was not conducive to the accumulation of internal carbon sources.
引文
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[16] WANG Z C, GAO M C, WANG Z, et al. Effect of salinity on extracellular polymeric substances of activated sludge from an anoxicaerobic sequencing batch reactor[J]. Chemosphere, 2013, 93(11):2789-2795.
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[20] WILSON C A, NOVAK J T. Hydrolysis of macromolecular components of primary and secondary wastewater sludge by thermal hydrolytic pretreatment[J]. Water Research, 2009, 43(18):4489-4498.
[21] MAVINIC D S, MAHENDRAKER V, SHARMA A, et al. Effect of microaerophilic conditions on autothermal thermophilic aerobic digestion process[J]. Journal of Environmental Engineering, 2001, 127(4):311-316.
[22] FANG M, WONG M H, WONG J W C. Digestion activity of thermophilic bacteria isolated from ash-amended sewage sludge compost[J]. Water Air and Soil Pollution, 2001, 126(1/2):1-12.
[23] WANG D B, YANG G J, LI X M, et al. Inducing mechanism of biological phosphorus removal driven by the aerobic/extended-idle regime[J]. Biotechnology and Bioengineering, 2012, 109(11):2798-2807.
[24] WEI D, SHI L, YAN T, et al. Aerobic granules formation and simultaneous nitrogen and phosphorus removal treating high strength ammonia wastewater in sequencing batch reactor[J]. Bioresource Technology, 2014, 171:211-216.
[25] SHANABLEH A, JOMA S. Production and transformation of volatile fatty acids from sludge subjected to hydrothermal treatment[J]. Water Science and Technology, 2001, 44(10):129-135.
[26] LIPCZYNSKA-KOCHANY E. Humic substances, their microbial interactions and effects on biological transformations of organic pollutants in water and soil:a review[J]. Chemosphere, 2018, 202:420-437.
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[29] HUANG P M, HARDIE A G. Formation mechanisms of humic substances in the environment, in biophysico-chemical processes involving natural nonliving organic matter[M]//SENESI N, XING B,HUANG P M, eds. Environmental Systems. Hoboken, NJ, USA:John Wiley&Sons, Inc., 2009:41-111.
[2] BARNARD J L. Biological nutrient removal:where we have been,where we are going[J]. Proceedings of the Water Environment Federation, 2006, 13:1-25.
[3] HU J Y, ONG S L, NG W J, et al. A new method for characterizing denitrifying phosphorus removal bacteria by using three different types of electron acceptors[J]. Water Research, 2003, 37(14):3463-3471.
[4] KULIKOWSKA D, BERNAT K. Nitritation-denitritation in landfill leachate with glycerine as a carbon source[J]. Bioresource Technology,2013, 142:297-303.
[5] SANTOS C E D, MOURA R B, DAMIANOVIC M H R Z, et al.Influence of COD/N ratio and carbon source on nitrogen removal in a structured-bed reactor subjected to recirculation and intermittent aeration(SBRRIA)[J]. Journal of Environmental Management, 2016,166:519-524.
[6] THOMAS M, WRIGHT P, BLACKALL L, et al. Optimization of Noosa BNR plant to improve performance and reduce operating costs[J].Water Science&Technology, 2003, 47(12):141-148.
[7] TAHERZADEH M J, KARIMI K. Pretreatment of lignocellulosic wastes to improve ethanol and biogas production:a review[J].Internatioal Journal of Molecular Sciences, 2008, 9(9):1621-1651.
[8] SURENDRA K C, TAKARA D, HASHIMOTO A G, et al. Biogas as a sustainable energy source for developing countries:opportunities and challenges[J]. Renewable and Sustainable Energy Reviews, 2014, 31:846-859.
[9] CZECHOWSKI F, MARCINKOWSKI T. Primary sludge stabilization with calcium hydroxide[J]. Environmental Chemistry Letters, 2006, 4(1):11-14.
[10]贾舒婷,张栋,赵建夫,等.不同预处理方法促进初沉/剩余污泥厌氧发酵产沼气研究进展[J].化工进展, 2013, 32(1):193-197.JIA S T, ZHANG D, ZHAO J F, et al. Research on different pretreatment methods for improving anaerobic digestion of primary/excess sludge of biogas production[J]. Chemical Industry and Engineering Progress, 2013, 32(1):193-197.
[11] LIU S G, ZHU N W, LI L Y. The one-stage autothermal thermophilic aerobic digestion for sewage sludge treatment:stabilization process and mechanism[J]. Bioresource Technology, 2011, 104:266-273.
[12] LIU S G, ZHU N W, NING P, et al. The one-stage autothermal thermophilic aerobic digestion for sewage sludge treatment:effects of temperature on stabilization process and sludge properties[J].Chemical Engineering Journal, 2012(197):225-230.
[13] JOWITT Z L, MAVINIC D S, KELLY H G. Batch and continuous feeding of thermophilic aerobically digested sludge supernatant as a carbon source for biological nutrient removal[J]. Journal of Environmental Engineering and Science, 2002, 1(1):213-224.
[14]国家环境保护总局.水和废水监测分析方法[M]. 4版.北京:中国环境科学出版社, 2002.State Environmental Protection Administration of China. Methods for monitoring and analyzing water and wastewater[M]. 4th ed. Beijing:China Environmental Science Press, 2002.
[15] LIU S G, YANG X, YAO X F. Effects of pH on the biodegradation characteristics of thermophilic micro-aerobic digestion for sludge stabilization[J]. RSC Adv., 2019, 9:8379-8388.
[16] WANG Z C, GAO M C, WANG Z, et al. Effect of salinity on extracellular polymeric substances of activated sludge from an anoxicaerobic sequencing batch reactor[J]. Chemosphere, 2013, 93(11):2789-2795.
[17]徐昌文,朱南文,寿宗奇,等.污泥返混对自热高温好氧消化效果的影响研究[J].环境污染与防治, 2013, 35(8):23-27.XU C W, ZHU N W, SHOU Z Q, et al. Effect of sludge backflow on autothermal thermophilic aerobic digestion process[J]. Environmental Pollution&Prevention, 2013, 35(8):23-27.
[18]冯磊,寇宏丽,张旭东,等.餐余垃圾中高温高固体厌氧消化过程中的pH和氨氮抑制[J].环境工程学报, 2016, 10(9):5100-5105.FENG L, KOU H L, ZHANG X D, et al. pH and free ammonia inhibition during mesophilic and thermophilic high-solid naerobic digestion of kitchen waste[J]. Chinese Journal of Environmental Engineering, 2016, 10(9):5100-5105.
[19]王慧勇,冯泽,陈翔,等.微波协同低碱预处理剩余污泥效果分析[J].化工进展, 2015, 34(9):3456-3461.WANG H Y, FENG Z, CHNG X, et al. Pretreatment effects of waste activated sludge by combined microwave and low-alkali[J]. Chemical Industry and Engineering Progress, 2015, 34(9):3456-3461.
[20] WILSON C A, NOVAK J T. Hydrolysis of macromolecular components of primary and secondary wastewater sludge by thermal hydrolytic pretreatment[J]. Water Research, 2009, 43(18):4489-4498.
[21] MAVINIC D S, MAHENDRAKER V, SHARMA A, et al. Effect of microaerophilic conditions on autothermal thermophilic aerobic digestion process[J]. Journal of Environmental Engineering, 2001, 127(4):311-316.
[22] FANG M, WONG M H, WONG J W C. Digestion activity of thermophilic bacteria isolated from ash-amended sewage sludge compost[J]. Water Air and Soil Pollution, 2001, 126(1/2):1-12.
[23] WANG D B, YANG G J, LI X M, et al. Inducing mechanism of biological phosphorus removal driven by the aerobic/extended-idle regime[J]. Biotechnology and Bioengineering, 2012, 109(11):2798-2807.
[24] WEI D, SHI L, YAN T, et al. Aerobic granules formation and simultaneous nitrogen and phosphorus removal treating high strength ammonia wastewater in sequencing batch reactor[J]. Bioresource Technology, 2014, 171:211-216.
[25] SHANABLEH A, JOMA S. Production and transformation of volatile fatty acids from sludge subjected to hydrothermal treatment[J]. Water Science and Technology, 2001, 44(10):129-135.
[26] LIPCZYNSKA-KOCHANY E. Humic substances, their microbial interactions and effects on biological transformations of organic pollutants in water and soil:a review[J]. Chemosphere, 2018, 202:420-437.
[27]成绍鑫.腐殖酸类物质概论[M].北京:化学工业出版社, 2007.CHENG S X. Introduction of humic substances[M]. Beijing:Chemical Industrial Press, 2007.
[28] CLAPP C E, HAYES M H B, SIMPSON A J, KINGERY W L.Chemistry of organic matter[M]//TABATABAI M A, SPARKS D L,eds. Chemical Processes in Soils, SSSA Book Series 8. Madison, WI:Soil Science Society of America, 2005:1-150.
[29] HUANG P M, HARDIE A G. Formation mechanisms of humic substances in the environment, in biophysico-chemical processes involving natural nonliving organic matter[M]//SENESI N, XING B,HUANG P M, eds. Environmental Systems. Hoboken, NJ, USA:John Wiley&Sons, Inc., 2009:41-111.