南京大学学报(自然科学), 2024, 60(1): 151-157 doi: 10.13232/j.cnki.jnju.2024.01.015

藻⁃菌颗粒污泥粒径与除污效能的研究

胡国胜, 季斌,

武汉科技大学城市建设学院,武汉,430065

Study on the granular size and treatment performance of microalgae⁃bacterial granular sludge

Hu Guosheng, Ji Bin,

School of Urban Construction,Wuhan University of Science and Technology,Wuhan, 430065,China

通讯作者: E⁃mail:binji@wust.edu.cn

收稿日期: 2023-11-05  

基金资助: 国家自然科学基金.  52270048

Received: 2023-11-05  

摘要

作为一种光驱动的新兴污水处理工艺,藻⁃菌颗粒污泥(Microalgae⁃Bacterial Granular Sludge,MBGS)因其高除污效能、低能耗、零温室气体排放等优点而被广泛研究.MBGS粒径可以影响MBGS的藻⁃菌质量比与生态位,从而影响其传质及光利用效率,进而影响其污染物去除效能.鉴于此,考察了不同粒径MBGS (1.08,2.20,3.17和4.08 mm)的除污效能,发现1.08 mm的MBGS系统对有机物、氨氮及磷酸盐的去除效能最高,同时其出水溶解氧浓度最高.进一步结合文献调研和分析表明:当光强为100~500 μmol·m-2·s-1时,MBGS最优粒径范围为0.80~1.60 mm;MBGS粒径对于有机物及氨氮的去除影响较磷酸盐更大;通过提供剪切力(如水力或机械搅拌)能够维持MBGS的最优粒径.研究结果可为MBGS工艺应用于实际污水处理提供理论基础.

关键词: 藻⁃菌颗粒污泥 ; 污水生物处理 ; 颗粒粒径 ; 搅拌 ; 碳中和

Abstract

As an emerging photo⁃driven wastewater treatment process,microalgae⁃bacterial granular sludge (MBGS) has been widely studied for its efficient pollutant removal,low energy consumption,and zero greenhouse gas emission. Granular size could affect the algal⁃bacterial mass ratio and ecological niche of MBGS,which in turn affects its mass transfer and light utilization efficacy,and consequently its pollutant removal efficacy. In view of this,the pollutant removal efficiency of MBGS with different granular sizes (1.08,2.20,3.17 and 4.08 mm) were investigated,and it was found that the MBGS system at 1.08 mm showed the most effective removal of organics,ammonia⁃nitrogen and phosphate,as well as the highest effluent dissolved oxygen concentration. Further literature research and analyses show that the optimal MBGS granular size range should be 0.80~1.60 mm when the light intensity is 100~500 μmol·m-2·s-1; the MBGS granular size has a greater effect on the removal of organics and ammonia⁃nitrogen compared to phosphate; and the optimal range of granular size of MBGS can be maintained through the supply of shear force (e.g.,hydraulic or mechanical stirring). The results provide a theoretical basis for the application of the MBGS process for real wastewater treatment.

Keywords: microalgal⁃bacterial granular sludge ; biological wastewater treatment ; granular size ; stirring ; carbon neutrality

PDF (919KB) 元数据 多维度评价 相关文章 导出 EndNote| Ris| Bibtex  收藏本文

本文引用格式

胡国胜, 季斌. 藻⁃菌颗粒污泥粒径与除污效能的研究. 南京大学学报(自然科学)[J], 2024, 60(1): 151-157 doi:10.13232/j.cnki.jnju.2024.01.015

Hu Guosheng, Ji Bin. Study on the granular size and treatment performance of microalgae⁃bacterial granular sludge. Journal of nanjing University[J], 2024, 60(1): 151-157 doi:10.13232/j.cnki.jnju.2024.01.015

近年来,随着全球气候变化与能源危机的出现,藻⁃菌颗粒污泥(Microalgal⁃Bacterial Granular Sludge,MBGS)工艺因其高除污效能、低能耗、零温室气体排放等优点受到广泛关注1-3.相比于传统的活性污泥法,MBGS工艺无需曝气,微藻可协同细菌降解污水中的有机物4.在MBGS中,微藻利用细菌产生的二氧化碳进行光合作用,实现固碳并产生氧气,细菌则利用这些氧气降解污水中的有机物并产生二氧化碳5-6.基于此,MBGS工艺无需外部曝气,几乎无温室气体排放,对环境友好,可助力达成“碳中和”7-8.有研究发现,即使在处理低碳⁃氮比的污水时,MBGS也保持了较低的温室气体排放量9.此外,MBGS工艺能够通过微生物的同化作用富集污水中的有机物和污染物10,产生的生物质可用来生产生物肥料、生物油和高附加值产品,从而实现能源与资源的回收利用11-13.

影响MBGS处理污水效能的因素有很多,比如污泥浓度、温度、光照强度、水力停留时间等14.但是到目前为止,关于MBGS的颗粒粒径对污水处理效能影响的研究较少.MBGS在处理污水的过程中会不断生长,其粒径也随之增大.较大粒径的MBGS会由于颗粒的光衰减而面临光能利用效率低的问题,进而导致产氧量低10.同时,过大粒径的MBGS中藻⁃菌的质量比偏小,藻⁃菌之间传质效率降低1015,进而影响除污效能.因此,研究MBGS粒径与除污效能之间的关系是非常有必要的.之前报道过平均粒径分别为0.356,0.760,0.951和1.444 mm的MBGS处理污水的效能,认为粒径较大有利于有机物的去除,而对氨氮和磷酸盐的去除无明显影响5.但是,因其研究的颗粒粒径范围较小,对于粒径大于1.5 mm的MBGS未涉及.

本文系统研究了不同粒径MBGS的处理效能,通过文献调研以及研究数据对比,总结得到MBGS处理生活污水的最优粒径范围,探讨粒径对有机物、氮及磷酸盐去除的影响机制,并提出控制MBGS最优粒径的方案.本研究结果有望为MBGS工艺高效处理实际污水提供理论依据.

1 材料与方法

1.1 人工合成污水

实验采用人工合成污水,配方根据之前的研究调整而来8.主要成分:300 mg·L-1 COD (Chemical Oxygen Demand) (NaAc),40 mg·L-1NH4+⁃N (NH₄Cl),10 mg·L-1PO43-⁃P (KH₂PO₄),50 mg·L-1 MgSO₄⋅7H₂O,10 mg·L-1 CaCl₂,10 mg·L-1 FeSO₄⋅7H₂O,20 mg·L-1 NaHCO₃以及1 mL微量元素浓缩液.

1.2 实验设置

MBGS是将成熟的好氧颗粒污泥(Aerobic Granular Sludge,AGS)置于约200 μmol·m-2·s-1光强的全光谱LED灯下,用人工合成污水培养得来的16.采用不同孔径的标准筛将成熟的MBGS分为平均粒径分别为1.08,2.20,3.17和4.08 mm的实验组.然后用一批50 mL玻璃反应器进行实验,每组设置两个平行对照组.实验开始时的挥发性悬浮固体浓度(Volatile Suspended Solids,VSS)为(3.23±0.17) g·L-1.实验运行周期为12 h,整个实验进行了21 d.采用全光谱的LED灯提供~200 μmol·m-2·s-1强度的光照.每个周期开始与结束收集的样品通过0.45 μm滤膜过滤并进行水质分析.

1.3 分析方法

按照标准方法17测定COD,NH4+⁃N,PO43-⁃P和VSS,分别采用YSI5100溶解氧仪(Yellow Springs,OH,USA)和STARTER3100 pH计(Ohaus,New Jersey,USA)测量溶解氧(Dissolved Oxygen,DO)浓度和pH.用ImageJ分析MBGS的颗粒大小18.

1.4 数据分析

实验结果的差异通过IBM SPSS 26.0的独立样本t分析、Mann⁃Whitney U分析和单因素方差分析(Analysis of Variance,ANOVA)进行比较.“p<0.01”表示有显著差异,“p>0.01”表示没有显著差异.使用Origin 2023进行图像绘制.

2 结果与讨论

2.1 不同粒径MBGS的处理效能

图1展示了本研究所选取的平均粒径分别为1.08,2.20,3.17和4.08 mm的MBGS形态.从图2中可以很明显地看出平均粒径为1.08 mm的MBGS对COD、氨氮、磷酸盐的去除率最高,而且在COD去除方面的优势最为显著.在COD的去除实验中,COD去除率与粒径呈反相关,四组实验的COD去除率随着粒径的增大而降低.平均粒径为1.08 mm的MBGS与其他组数据相比,去除率都具有显著的差异性(p<0.01);平均粒径为2.20 mm的MBGS的去除率与平均粒径为4.08 mm的MBGS具有差异性(p<0.01).平均粒径为4.08 mm的MBGS去除COD效能最差,仅为57.86%±7.27%.对于氨氮的去除,四组实验的平均去除率在60%~75%波动,但平均去除率仍然是粒径为1.08 mm的MBGS最优,随着粒径的增大氨氮去除呈下降趋势.对于磷酸盐的去除,平均粒径为1.08和2.20 mm的MBGS非常相似且平均去除率最高,而且都与平均粒径为4.08 mm的MBGS有非常显著的差异(p<0.01),平均粒径为4.08 mm的MBGS在整个实验中去除率波动很大,极不稳定.

图1

图1   不同粒径藻⁃菌颗粒污泥的形态

Fig.1   Morphology of microalgal⁃bacterial granular sludge in different granular size


图2

图2   不同粒径藻⁃菌颗粒污泥的处理效能(n=20)

Fig.2   Treatment performance of MBGS in different granular sizes (n=20)


不同粒径MBGS的出水pH和DO如图3所示.可以明显地看出,MBGS粒径越大,其出水pH和DO浓度越低.平均粒径为1.08 mm的MBGS的出水pH与平均粒径为3.17和4.08 mm的实验组都表现出显著的差异(p<0.01).DO也表现出与pH类似的差异性,平均粒径为1.08 mm的MBGS在一个实验周期中产氧最多,这是因其拥有较高的藻⁃菌质量比10,且与其他实验组的出水DO都表现出显著差异(p<0.01).而较高的产氧量会对COD的去除性带来积极影响15.这说明在一定范围内,MBGS的粒径越小,其藻⁃菌比越大,产氧效果越好,处理效能越优越.

图3

图3   不同粒径藻⁃菌颗粒污泥的出水pH和DO (n=20)

Fig.3   Effluent pH and DO of MBGS with different granular sizes (n=20)


2.2 MBGS的最优粒径

为了探究不同粒径MBGS的除污效能,本文收集了研究不同粒径MBGS的文献并将其中COD,NH4+⁃N以及PO43-⁃P去除数据整理成比去除速率(Specific Pollutants Removal Rates,SPRR).如图4所示,MBGS的COD比去除速率可以根据其粒径分为两组,粒径为0.8~1.8 mm的MBGS是高COD去除效能组;粒径小于0.8 mm和大于1.8 mm的MBGS是其他组,它们对于COD的去除效能相对较低.而且平均粒径为0.8~1.8 mm的MBGS在COD去除方面与其他组有显著差异(p<0.01).对于氨氮的去除,平均粒径为0.8~1.6 mm的MBGS优于其他粒径,且其SPRR与其他粒径组有显著差异(p<0.01).但是,对于磷酸盐的去除,MBGS的粒径似乎对去除率影响不大,其SPRR基本稳定在0.02~0.10 (mg P)·(g VSS)-1·h-1;数值较高且集中的SPRR所对应的粒径范围与其他粒径组没有显著差异(p>0.01).在之前的研究中19,丝状藻类因光驱动占据着MBGS的外层,是MBGS系统中聚磷酸盐的主要累积者.而粒径不会改变藻类在颗粒外层的分布,即使在大粒径的MBGS的外层也有约1.25 mm厚的蓝藻层15.此外,磷酸盐的去除与pH因素相关,因此粒径的大小对磷酸盐的去除效果影响较小.

图4

图4   不同粒径藻⁃菌颗粒污泥的COD,NH4+⁃N以及PO43-⁃P的比去除速率

Fig.4   COD,NH4+⁃N and PO43-⁃P specific removal rates of MBGS in different granular sizes


通过对比不同文献中不同粒径的MBGS除污效能,可以得出0.8~1.6 mm是MBGS除污效能最优的粒径范围.在此粒径范围内的MBGS,对COD,NH4+⁃N的去除效能最高,且明显区别于其他粒径.而MBGS粒径的变化对于磷酸盐去除的影响似乎不大.

表1   文献中不同粒径藻⁃菌颗粒污泥的实验条件

Table 1  Experimental conditions for MBGS in different granular sizes in the literature

粒径(mm)

光强

(μmol·m-2·s-1)

COD SPRR

((mg COD)·(g VSS)-1·h-1)

氨氮SPRR

((mg N)·(g VSS)-1·h-1)

磷酸盐SPRR

((mg P)·(g VSS)-1·h-1)

数据来源
0.52003.990.21300.0523[20]
0.52222003.760.19990.0449[21]
0.751504.230.40990.0159[3]
0.881806.790.48500.0908[22]
0.95008.220.64230.0678[23]
1.03007.38-0.0692[24]
1.082005.900.42800.0855本研究
1.1562006.060.55880.0982[25]
1.32006.480.63140.0675[1]
1.552005.580.7222-[26]
1.71007.230.33070.0248[3]
2.02005.180.46700.0512[27]
2.202004.700.40580.0852本研究
2.62004.360.18330.0411[28]
3.172004.600.39060.0789本研究
4.082004.190.35430.0708本研究

新窗口打开| 下载CSV


2.3 MBGS粒径的影响机制

已有研究发现MBGS的藻⁃菌质量比与其粒径大小相关10.(1)小粒径的MBGS藻⁃菌质量比更高,藻类占主导地位;光能更好地透过小粒径的颗粒层,颗粒的光利用效率高,颗粒产氧量更高;颗粒内层产生的气体能使颗粒更加疏松多孔,使颗粒内外层的微生物能更好地进行传质5.但是,过小的粒径会导致更低的细菌占比,富余的氧气反过来会抑制藻类的新陈代谢29,而且光合氧可能会抑制藻⁃菌系统中反硝化细菌的活性30,从而影响MBGS除污效能.藻⁃菌比的偏高可能会导致由细菌分泌的胞外聚合物减少,藻类的生物絮凝和颗粒化受到影响30,使小颗粒的MBGS的沉降性能变差.(2)大粒径的MBGS的藻⁃菌比较低,藻类因光驱动大多会占据颗粒的表层,细菌则主要在颗粒内部形成缺氧层和厌氧层,藻⁃菌协同处理污染物1530.但过大的粒径带来的藻⁃菌分层以及光透过率的下降,会导致整个颗粒的光利用率不高以及藻⁃菌传质效率下降510,从而影响MBGS系统的除污效能.大粒径的MBGS可能更适合进行同步硝化反硝化脱氮15.因此,MBGS的粒径在0.8~1.6 mm最适宜,过大或过小的粒径会影响MBGS的藻⁃菌质量比与生态位,从而影响其传质和光利用效率,进而影响其除污效能.

2.4 调控MBGS粒径的策略

MBGS去除污染物的主要机理是其微生物的同化作用10,因此MBGS在处理污水的过程中必然会有生物量的增长.而MBGS生物量的增长主要体现为其粒径和污泥浓度的增大15,污泥浓度可以通过排泥和调整污泥停留时间进行控制,而粒径的控制须依靠其他策略.

目前已有研究表明,水力剪切力是MBGS造粒过程中的重要因素31,因此给予MBGS剪切力的操作能够将其粒径稳定维持在一定范围内.这是因为在较高的水力剪切力下往往难以形成大颗粒,而小颗粒的丰度会增加;其次,剪切力会影响细菌的表面疏水性和EPS分泌32-33.搅拌和曝气往往是MBGS造粒中的常用手段.根据文献报道,对于间歇式反应器,保证无曝气MBGS工艺粒径稳定的搅拌速率在120~300 r·min-1[2.当搅拌速率为250 r·min-1时(剪切力为0.140 N·m-2),颗粒粒径可被保持在1.7 mm以下34.可能因为曝气会促进微生物的生长,所以曝气目前仅被研究用于MBGS的造粒33,曝气强度与粒径维持相关的研究鲜有开展.

3 结论

本研究考察了不同粒径的MBGS (1.08,2.20,3.17和4.08 mm)的除污效能,发现1.08 mm的MBGS系统去除有机物、氨氮及磷酸盐的效能最高,同时其出水溶解氧浓度最高.通过文献分析数据进一步发现,当光强为100~500 μmol·m-2·s-1时,0.8~1.6 mm是MBGS最优粒径范围.过大或过小的粒径会影响MBGS的传质及光利用效能,从而影响藻⁃菌生态位及其除污效率.为保证MBGS在市政污水处理中的高除污效能,可以通过对MBGS系统提供剪切力(如水力或机械搅拌)来维持其最优粒径范围.

参考文献

Ji BZhang MGu Jet al.

A self⁃sustaining synergetic microalgal⁃bacterial granular sludge process towards energy⁃efficient and environmentally sustainable municipal wastewater treatment

Water Research,2020179115884.

[本文引用: 2]

Ji B.

Towards environment⁃sustainable wastewater treatment and reclamation by the non⁃aerated microalgal⁃bacterial granular sludge process:Recent advances and future directions

Science of the Total Environment,2022806150707.

[本文引用: 1]

Abouhend A SMcNair AKuo⁃Dahab W Cet al.

The oxygenic photogranule process for aeration⁃free wastewater treatment

Environmental Science & Technology,201852(6):3503-3511.

[本文引用: 3]

张宇饶志侯欢.

新一代污水生物处理技术:微藻⁃菌颗粒污泥

环境科学与技术,202144(6):201-210.

[本文引用: 1]

Zhang YRao ZHou Het al.

A new generation of wastewater treatment technology:Microalgae⁃bacterial granular sludge process

Environmental Science & Technology,202144(6):201-210.

[本文引用: 1]

Zhang MJi BWang S Let al.

Granule size informs the characteristics and performance of microalgal⁃bacterial granular sludge for wastewater treatment

Bioresource Technology,2022346126649.

[本文引用: 4]

Inuwa A BPervez ANazir R.

Microalgae⁃based wastewater treatment system:Current state,antibiotic resistant bacteria and antibiotic resistance genes reduction potentials

International Journal of Environmental Science and Technology,202320(12):14053-14072.

[本文引用: 1]

Gikas P.

Towards energy positive wastewater treatment plants

Journal of Environmental Management,2017203621-629.

[本文引用: 1]

Ji BLiu C.

CO2 improves the microalgal⁃bacterial granular sludge towards carbon⁃negative wastewater treatment

Water Research,2022208117865.

[本文引用: 2]

Zhao Z WYang X JCai Wet al.

Response of algal⁃bacterial granular system to low carbon wastewater:Focus on granular stability,nutrients removal and accumulation

Bioresource Technology,2018268221-229.

[本文引用: 1]

Ji BLiu Y.

Assessment of microalgal⁃bacterial granular sludge process for environmentally sustainable municipal wastewater treatment

ACS ES&T Water,20211(12):2459-2469.

[本文引用: 7]

Liu LHong Y LYe Xet al.

Biodiesel production from microbial granules in sequencing batch reactor

Bioresource Technology,2018249908-915.

[本文引用: 1]

Quijano GArcila J SBuitrón G.

Microalgal⁃bacterial aggregates:Applications and perspectives for wastewater treatment

Biotechnology Advances,201735(6):772-781.

季斌龚喜平.

藻⁃菌颗粒污泥中微生物胞外多糖特性研究

环境科学学报,202242(11):117-122.

[本文引用: 1]

Ji BGong X P.

Study on the characteristics of extracellular polysaccharides from the microalgal⁃bacterial granular sludge

Acta Scientiae Circumstantiae,202242(11):117-122.

[本文引用: 1]

Chen Z PXie YQiu Set al.

Granular indigenous microalgal⁃bacterial consortium for wastewater treatment:Establishment strategy,functional microorganism,nutrient removal,and influencing factor

Bioresource Technology,2022353127130.

[本文引用: 1]

Abouhend A SMilferstedt KHamelin Jet al.

Growth progression of oxygenic photogranules and its impact on bioactivity for aeration⁃free wastewater treatment

Environmental Science & Technology,202054(1):486-496.

[本文引用: 6]

Ji BZhang MWang Let al.

Removal mechanisms of phosphorus in non⁃aerated microalgal⁃bacterial granular sludge process

Bioresource Technology,2020312123531.

[本文引用: 1]

国家环境保护总局. 水和废水监测分析方法. 第4版. 北京中国环境科学出版社2002.

[本文引用: 1]

Igathinathane CPordesimo L OColumbus E Pet al.

Shape identification and particles size distribution from basic shape parameters using ImageJ

Computers and Electronics in Agriculture,200863(2):168-182.

[本文引用: 1]

Ji BFan S QLiu Y.

A continuous⁃flow non⁃aerated microalgal⁃bacterial granular sludge process for aquaculture wastewater treatment under natural day⁃night conditions

Bioresource Technology,2022350126914.

[本文引用: 1]

Fan S QJi BAbu Hasan Het al.

Microalgal–bacterial granular sludge process for non⁃aerated aquaculture wastewater treatment

Bioprocess and Biosystems Engineering,202144(8):1733-1739.

[本文引用: 1]

Wang S LJi BZhang Met al.

Tetracycline⁃induced decoupling of symbiosis in microalgal⁃bacterial granular sludge

Environmental Research,2021197111095.

[本文引用: 1]

Ji BZhu LWang S Let al.

Temperature⁃effect on the performance of non⁃aerated microalgal⁃bacterial granular sludge process in municipal wastewater treatment

Journal of Environmental Management,2021282111955.

[本文引用: 1]

Ji BShi Y TYılmaz M.

Microalgal⁃bacterial granular sludge process for sustainable municipal wastewater treatment:Simple organics versus complex organics

Journal of Water Process Engineering,202246102613.

[本文引用: 1]

Sun P HLiu CLi A Jet al.

Using carbon dioxide⁃added microalgal⁃bacterial granular sludge for carbon⁃neutral municipal wastewater treatment under outdoor conditions:Performance,granule characteristics and environmental sustainability

Science of the Total Environment,2022848157657.

[本文引用: 1]

Xiao M XXin J YFan Jet al.

Response mechanisms of microalgal⁃bacterial granular sludge to zinc oxide nanoparticles

Bioresource Technology,2022361127713.

[本文引用: 1]

Wang S LJi BCui B Het al.

Cadmium⁃effect on performance and symbiotic relationship of microalgal⁃bacterial granules

Journal of Cleaner Production,2021282125383.

[本文引用: 1]

Hou HWang S LJi Bet al.

Adaptation responses of microalgal⁃bacterial granular sludge to polystyrene microplastic particles in municipal wastewater

Environmental Science and Pollution Research,202229(40):59965-59973.

[本文引用: 1]

Hu G SFan S QWang H Yet al.

Adaptation responses of microalgal⁃bacterial granular sludge to sulfamethoxazole

Bioresource Technology,2022364128090.

[本文引用: 1]

Fard M BWu D.

Potential interactive effect on biomass and bio⁃polymeric substances of microalgal⁃bacterial aerobic granular sludge as a valuable resource for sustainable development

Bioresource Technology,2023376128929.

[本文引用: 1]

Fallahi ARezvani FAsgharnejad Het al.

Interactions of microalgae⁃bacteria consortia for nutrient removal from wastewater:A review

Chemosphere,2021272129878.

[本文引用: 3]

Hann M. Factors impacting the cultivation,structure,and oxygen profiles of oxygenic photogranules for aeration⁃free wastewater treatment. Master Dissertation. Amherst,MAUniversity of Massachsetts Amhers2018.

[本文引用: 1]

Jiang Q RChen H LFu Z Det al.

Current progress,challenges and perspectives in the microalgal⁃bacterial aerobic granular sludge process:A review

International Journal of Environmental Research and Public Health,202219(21):13950.

[本文引用: 1]

Liu LFan H YLiu Y Het al.

Development of algae⁃bacteria granular consortia in photo⁃sequencing batch reactor

Bioresource Technology,201723264-71.

[本文引用: 2]

Abouhend A SGikonyo J GPatton Met al.

Role of hydrodynamic shear in the Oxygenic Photogranule (OPG) wastewater treatment process

ACS ES&T Water,20233(3):659-668.

[本文引用: 1]

/