Comparison of membrane fouling during short-term filtration of aerobic granular sludge and activated sludge

Aerobic granular sludge was cultivated adopting internal-circulate sequencing batch airlift reactor. The contradistinctive experiment about short-term membrane fouling between aerobic granular sludge system and activated sludge system were investigated. The membrane foulants was also characterized by Fourier transform infrared （FTIR） spectroscopy technique. The results showed that the aerobic granular sludge had excellent denitrification ability; the removal efficiency of TN could reach 90%. The aerobic granular sludge could alleviate membrane fouling effectively. The steady membrane flux of aerobic granular sludge was twice as much as that of activated sludge system. In addition, it was found that the aerobic granular sludge could result in severe membrane pore-blocking, however, the activated sludge could cause severe cake fouling. The major components of the foulants were identified as comprising of proteins and polysaccharide materials.

Community analysis of ammonia and nitrite oxidizers in start-up of aerobic granular sludge reactor

A lab-scale sequencing batch reactor （SBR） was set-up and the aerobic granular sludge was successfully incubated using anaerobic granular sludge as seed sludge. Nitrogen was partially removed by simultaneous nitrification and denitrification （SND） via nitrite with free ammonia （FA） of about 10 mg/L. The denaturing gradient gel electrophoresis （DGGE） method was used to investigate community structure of α-Proteobacteria, β-Proteobacteria, ammonia oxidizing bacteria （AOB）, and Nitrospira populations during start-up. The population sizes of bacteria, AOB and Nitrospira were examined using real-time PCR method. The analysis of community structure and Shannon index showed that stable structure of AOB population was obtained at day 35, while the communities of α- Proteobacteria, β-Proteobacteria, and Nitrospira became stable after day 45. At stable stage, the average cell densities were 1.1× 10^12, 2.2×10^10 and 1.0×10^10 cells/L for bacteria, AOB and Nitrospira, respectively. The relationship between characteristics of nitrifying bacteria community and nitrogenous substrate utilization constant was discussed by calculating Pearson correlation. Certain correlation seemed to exist between population size, biodiversity, and degradation constant. And the influence of population size might be greater than that of biodiversity.

Re-activation characteristics of preserved aerobic granular sludge

In some industrial plants, wastewater was intermittently or seasonally generated. There may be periods during which wastewater treatment facilities have to be set into an idle phase over several weeks. When wastewater was generated again, the activated sludge flocs may have disintegrated. In this experiment, re-activation characteristics of aerobic granular sludge starved for 2 months were investigated. Specific oxygen utilization rate(SOUR) was used as an indicator to evaluate the metabolic activity of the sludge. The results revealed that aerobic granular sludge could be stored up to two months without running the risk of losing the integrity of the granules and metabolic potentials. The apparent color of aerobic granules stored at room temperature gradually turned from brownish-yellowish to gray brown. They appeared brownish-yellowish again 2 weeks after re-activation. The velocity and strength of granules after 2-month idle period could be fully restored about 3 weeks after re-activation. Metabolic activity, however, dropped to 15 8 mg O_2/(g MLVSS·h), i.e. 74 % reduction after 2 months of storage. After restarting the reactor, it took 2 weeks that SOUR of up to 48 5 mg O_2 /(g MLVSS·h) was achieved. A stable effluent COD concentration of less than 150 mg/L was achieved during the re-activation process.

Molecular characterization of bacterial community in aerobic granular sludge stressed by pentachlorophenol

To characterize the effects of pentachlorophenol (PCP) on the performance and microbial community of aerobic granular sludge in sequencing batch reactor (SBR), the web-based terminal restriction fragment length polymorphism (T-RFLP) and real-time PCR (RT- PCR) techniques were used to explore the bacterial community structure. When PCP increased from 0 to 50 mg/L, the COD removal rate changed little, while the ammonia removal rate dropped from 100% to 64.9%. The results of molecular characterization showed t...

A comparable study of microbial community in aerobic granular sludge and activated sludge for wastewater treatment

Effect of ammonia at different concentrations on aerobic granular sludge and activated sludge was investigated in this study. Meanwhile, bacterial diversity variation and ammonia oxidizing bacterium （AOB） quantification within both kinds of sludge were monitored by terminal restriction fragment length polymorphism （T-RFLP） and real-time PCR （RT-PCR） technique, respectively. The results showed that the COD removal of both kinds of sludge changed slightly when the ammonia removal efficiency decreased gradually with the ammonia concentration increased from 100 mg L^-1 to 500 mg L^-1 Furthermore, activated sludge demonstrated higher ammonia removal ability than that of aerobic granular sludge （10%- 16%）. As revealed by T-RFLP, activated sludge was of higher ammonia removal ability and more abounding bacterial diversity than that of aerobic granular sludge, suggesting that the bacterial diversity was probably relevant to the ammonia removal. The RT-PCR results indicated that the AOB population size of activated sludge and aerobic granular sludge were 2.80× 10^4-3.44× 10^4cells （g dried sludge）^-1 and 7.83×10^4-1.18×10^5cells （g dried sludge）^-1, respectively. There is no obvious positive correlation between the ammonia removal ability and number of AOB in both kinds of sludge.

Resistance to salt stresses by aerobic granular sludge:sludge property and microbial community

Saline wastewater is regarded as a challenge for wastewater treatment plants because high-salinity conditions negatively affect on traditional biological technologies.Aerobic granular sludge(AGS)has gained attention as a promising technology for saline wastewater treatment because of its compact structure and the ability to withstand toxic loadings.Therefore,this study investigated the saltresistance performance,sludge properties and microbial community of AGS under low-salinity and high-salinity conditions,with the saline concentrations ranging from 0 to 50 g/L.The results showed that AGS could withstand long-term saline stresses,and the maximum salinity reached 50 g/L within 113 d.Under salinities of 10,30,and 50 g/L,the chemical oxygen demand(COD)removal efficiencies were 90.3%,88.0%and 78.0%,respectively.AGS also its maintained strength and aggregation at salinities of 10 and 30 g/L.Overproduction of extracellular polymeric substances(EPS)by non-halophilic bacteria that enhanced sludge aggregation.The compact structure that ensured the microorganisms bioactivity helped to remove organic matters under salinities of 10 and 30 g/L.At a salinity of 50 g/L,moderately halophilic bacteria,including Salinicola,Thioclava,Idiomarina and Albirhodobacter,prevailed in the reactor.The dominant microbial communities shifted to moderately halophilic bacteria,which could maintain aerobic granular stabilization and remove organic matters under 50 g/L salinity.These results in this study provide a further explanation for the long-term operation of AGS for treating saline wastewater at different salinities.It is hoped that this work could bring some clues for the mystery of salt-resistance mechanisms.

Screening and identification of functional bacterial attachment genes in aerobic granular sludge

The screening and identification of attachment genes is important to exploring the formation mechanism of biofilms at the gene level.It is helpful to the development of key culture technologies for aerobic granular sludge(AGS).In this study,genome-wide sequencing and gene editing were employed for the first time to investigate the effects and functions of attachment genes in AGS.With the help of whole-genome analysis,ten attachment genes were screened from thirteen genes,and the efficiency of gene screening was greatly improved.Then,two attachment genes were selected as examples to further confirm the gene functions by constructing gene-knockout recombinant mutants of Stenotrophomonas maltophilia;when the two attachment genes were knocked out,the attachment potential was reduced by 50.67%and 43.93%,respectively.The results provide a new theoretical principle and efficient method for the development of AGS from the perspective of attachment genes.

Hierarchically porous biochar derived from aerobic granular sludge for high-performance membrane capacitive deionization

Membrane capacitive deionization(MCDI)is a cost-effective desalination technique known for its low energy consumption.The performance of MCDI cells relies on the properties of electrode materials.Activated carbon is the most widely used electrode material.However,the capacitive carbon available on the market is often expensive.Here,we developed hierarchically porous biochar by combining carbonization and activation processes,using easily acquired aerobic granular sludge(AGS)from biological sewage treatment plants as a precursor.The biochar had a specific surface area of 1822.07 m^(2)g^(-1),with a micropore area ratio of 58.65%and a micropore volume of 0.576 cm3 g^(-1).The MCDI cell employing the biochar as electrodes demonstrated a specific adsorption capacity of 34.35 mg g^(-1),comparable to commercially available activated carbon electrodes.Our study presents a green and sustainable approach for preparing highly efficient,hierarchically porous biochar from AGS,offering great potential for enhanced performance in MCDI applications.

Study of 4-t-octylphenol degradation and microbial community in granular sludge

In this study, the authors have investigated the effects of various factors on both aerobic and anaerobic degradation of 4-t-octylphenol （4-t-OP） in granular sludge. In comparison, the aerobic degradation rate was much higher than that of anaerobic degradation. The optimal pH values for 4-t-OP degradation in granular sludge were 9 and 7 under aerobic and anaerobic conditions, respectively. And the degradation rate decreased with an increase in the initial 4-t-OP concentration. Addition of yeast extract or homologous compounds such as phenol also enhanced the 4-t-OP degradation, especially under the aerobic condition. To investigate the bacterial community in this study, the denaturing gradient gel electrophoresis （DGGE） method was applied, based on the primers, for the 16S rDNA V3 region of bacteria, γ-proteobacteria and bacillus were identified as the major species of sludge.

Cultivation and characters of aerobic granules for pentachlorophenol(PCP) degradation under microaerobic condition

Cultivation of aerobic granular sludge for pentachlorophenol(PCP) degradation under microaerobic condition(DO concentration was controlled at 0.2—0.7 mg/L) was studied in this paper. Anaerobic granules were selected as inoculum. The changes of appearance were observed and the variations of SVI, VSS/TSS, PN/PS and the size of sludge were measured during cultivating. The capabilities for degradation of PCP, AOX and COD_ Cr were also studied. Observations on mature granules were carried out by scanning electron microscope, and the results indicated bacillus was dominant on the surface of granules while in the inner of granules both bacillus and coccus were the dominant microorganisms. K, Na, Fe, Ca, Mg, Ni, Co, Mn, Cu and Zn were detected in the granules by element analysis.

Performance Characteristics for Nitrogen Removal in SBR by Aerobic Granules

The sequencing batch reactor (SBR) was started up by seeding the anaerobic granular sludge and the aerobic granular sludge was successfully cultivated. The performance characteristic of the aerobic granules for nitrogen removal was investigated in detail. The experimental results demonstrated the relationship between operational parameters [dissolved oxygen (DO) and pH] and variation of chemical oxygen demand (COD), ammonium (NH4+-N)and total nitrogen (TN). In continuous flow pattern, COD was too low in the reactor at the later stage of a cycle,which restrained denitrification and decreased the removal of nitrogen, while in discontinuous flow pattern, the carbon source could be supplemented in time, which improved denitrification and increased the removal of TN from 66% to 81%.

好氧颗粒污泥的解体机制及修复策略研究进展

好氧颗粒污泥(AGS)技术被誉为有望替代活性污泥法的下一代污水生物法处理技术,但其存在长期运行下颗粒易解体而造成系统失稳的瓶颈问题,未能大规模化工程应用.通过文献分析和整理,系统归纳了造成AGS解体的各类不利因素及其危害阈值与作用机制,梳理了解体AGS的现有修复策略,成效及其再颗粒化机理,并基于现有研究的局限性对未来的研究方向进行展望,以期实现AGS系统a解体-再颗粒化”的动态稳定运行,推动污水厂采纳AGS技术而低碳化转型.

同步硝化内源反硝化除磷好氧颗粒污泥的储存与恢复

针对好氧颗粒污泥颗粒化时间慢等问题,进行了同步硝化内源反硝化除磷好氧颗粒污泥常温储存及活性恢复实验研究.结果表明,好氧颗粒污泥经过60d的常温储存后,颗粒的结构基本能保持稳定,但是颗粒污泥的活性大幅度降低,污染物去除率仅有储存前的30%~40%.将常温储存的颗粒污泥接种到反应器中,经过一定的调控手段,可以在60d内恢复好氧颗粒污泥的功能及活性.此外,经过储存与恢复,好氧颗粒污泥的群落结构也发生了明显变化.大部分的微生物的相对丰度变化可逆,经过储存和恢复可以恢复至储存前的状态(包括Defluviicoccus(GAOs)和Flavobacterium(PAOs)),重构同步脱氮除磷的微生物群落结构.

AOA后置短时低氧曝气实现短程硝化反硝化除磷

为培养亚硝酸盐型反硝化聚磷菌实现好氧颗粒污泥(AGS)短程硝化内源反硝化除磷,设置3组同规格以厌氧/好氧/缺氧后置短时曝气(AO_(1)A-O_(2))模式运行的SBR,各反应器好氧段/后置好氧段(O_(1)/O_(2))的曝气强度和曝气时间均不同,通过对比3组反应器60 d的运行情况,探究各系统污染物处理性能和功能菌活性。结果表明,后置短时低氧曝气10 min且O_(1)、O_(2)的曝气强度分别为5、2.5 L/(h·L)的R2脱氮除磷效果最佳,其COD、TP、NH^(+)_(4)-N、TN去除率达95.49%、95.57%、100%、95.52%。通过短时好氧饥饿和低溶解氧可以创造出短程硝化内源反硝化除磷的最适环境,R2中约60%的除磷菌为DPAOs,且亚硝酸盐型聚磷菌最多,可达38.76%,其反应器好氧段的亚硝酸盐积累率(R_(NA))为74.19%,实现了较高的NO^(-)_(2)-N积累,游离亚硝酸(FNA)为1.03μg/L,可抑制PAOs和NOB,同时富集出更多的AOB和DPAOs。

好氧颗粒污泥资源化中类藻酸盐胞外多糖研究进展

好氧颗粒污泥(AGS)资源化研究已成为AGS技术的重点研究方向之一,从AGS中提取所得的类藻酸盐胞外多糖(ALE)被认为是好氧颗粒污泥中最具价值的可回收资源之一。在污水处理厂技术变革聚焦于高附加值产物回收的背景下,AGS中ALE的回收应用已经形成一条较清晰的通路。首先基于AGS的形成机理及其组分,分析了AGS胞外聚合物(EPS)中所含有的ALE的独特结构和性质,总结了国内外回收和评价ALE的方法,并阐述了废水有机负荷率、碳氮比、盐度、污泥颗粒粒径、污泥停留时间等因素对ALE产量的影响,之后对同步回收ALE和其他附加值产物的研究进行了总结,最后通过对ALE广泛应用范围和实际经济价值的讨论,提出了ALE在AGS资源化方面的潜在研究方向。

氧化锌纳米颗粒和四环素复合胁迫对好氧颗粒污泥处理低碳源废水的影响

为明确新污染物氧化锌纳米颗粒(ZnO NP)和四环素抗生素(TCA)复合胁迫对好氧颗粒物污泥处理低C/N废水的影响,构建了小试规模的颗粒污泥反应器,探究了ZnO NP和TCA复合影响对AGS处理低C/N废水的影响,分析了出水水质、污泥特征及微生物群落特征的变化,揭示了ZnO NP和TCA复合胁迫对AGS的影响机制。结果表明,ZnO NP和TCA复合胁迫对AGS处理低C/N废水具有拮抗作用。ZnO NP和TCA复合暴露组别内,出水COD和溶解性磷酸盐(SOP)浓度分别为42.8~53.4 mg/L和1.95~2.36 mg/L,对应去除效率分别下降至75.1%~78.5%和70.3%~75.6%,远低于ZnO NP和TCA单一暴露组别。ZnO NP和TCA复合胁迫降低了AGS污泥浓度总固体(TS)至5.5~5.8 g/L,挥发性固体/TS至0.61~0.64,但刺激胞外聚合物(EPS)含量至91.6~93.4 mg/g。此外,ZnO NP和TCA复合胁迫提高了EPS内蛋白质(PN)和多糖(PS)含量,并提高PN/PS。酶活性分析表明ZnO NP和TCA复合胁迫降低了与污染物和营养盐去除相关的关键酶活性。微生物群落结构分析ZnO NP和TCA复合胁迫降低了属水平上与反硝化相关的Tsukamurella、unclassified f_Comamonadaceae、Micropruina和Microbacterium的相对丰度。ZnO NP和TCA复合胁迫产生的生态毒性对AGS具有严重影响。研究结果为理解新污染物ZnO NP和TCA复合胁迫的环境风险具有一定的理论意义。

进水底物对好氧颗粒污泥特性及微生物群落的影响

为了研究进水底物对好氧颗粒污泥(AGS)特性的影响,通过接种絮状污泥于序批式反应器(SBR)中以生活污水和模拟生活污水作为进水底物,对AGS形成过程中的污泥特性和微生物群落展开研究。研究表明:以模拟生活污水为进水底物,发现颗粒污泥内部以丝状菌为框架,通过对污泥的截留逐渐形成AGS,污泥沉降性能良好。随着AGS的形成胞外聚合物(EPS)组分中蛋白质(PN)含量增加显著,PN/PS由1.77上升至5.80,促进了AGS的形成和稳定性,且EPS含量与Zeta电位、污泥沉降指数呈负相关。连续投加Fe(OH)_(3)胶体抑制了NOB菌的活性,导致生活污水阶段污染物的去除效果较差;AGS形成后污染物的去除效果明显上升,特别是氮、磷污染物。生活污水阶段Candidatus_Microthrix菌属引起了系统内丝状菌膨胀,同时微生物群落丰富度、多样性逐渐降低。模拟生活污水阶段具有疏水性和分泌EPS功能的菌属丰度占比持续上升,例如:unclassified_o__Saccharimonadale(33.%→22.0%)、Zoogloea(3.0%→6.0%)、unclassified_f__Sphingomonadaceae(0.87%→3.1%)菌属等;促进了污泥颗粒化;同时随着污泥颗粒化程度提高,具有反硝化和除磷功能的菌属丰度占比持续上升,保证了AGS系统高效的脱氮除磷性能。

定向调控电子受体强化好氧颗粒污泥内源反硝化脱氮除磷

为强化内源反硝化作用,加强对有限碳源的高效利用,设置了1组厌氧/好氧/缺氧(A/O/A)和3组不同好氧时间分配的厌氧-两级短时好氧/缺氧(A/(O/A)_(2))序批式反应器,探究定向调控电子受体下污泥的颗粒化及反硝化聚糖菌(DGAOs)的富集情况.结果表明,采用两级短时好氧/缺氧的反应器好氧颗粒污泥结构更加致密、沉淀性能更好,缺氧段及好氧段电子受体更充足,DGAOs储存内碳源的能力得以强化,系统中反硝化聚糖菌和DGAOs对碳源的竞争达到平衡状态,系统有更高的内源反硝化脱氮率,实现了深度脱氮除磷.其中,两级短时好氧时间分配时间为前段60min/后段30min的R2的脱氮除磷效果最好,DGAOs含量最高,且颗粒沉降性能最佳.第45d,R2的COD、TN、TP去除率分别达到90.52%、85.71%、92.73%,内源反硝化效率达到58.59%,具有良好的污染物去除效果.

好氧颗粒污泥结构稳定强化策略研究评述

好氧颗粒污泥由于其强大的抗冲击能力和出色的除污效果,在常规活性污泥性能升级改造中得到热点关注,而其形成时间较长和稳定性较弱的问题限制了在污水处理厂的商业化应用。为了能尽快将好氧颗粒污泥技术广泛投入到污水处理领域中,有必要重新深入认知形成机制和结构稳定性的关键影响因素,从而达到精准调控其形成过程和实现长期稳定有效使用目的。该文通过系统地收集和分析相关研究文献,梳理了好氧颗粒污泥形成机制,形成机制主要集中在七大类假说,即晶核理论、自凝聚原理、胞外聚合物假说、丝状菌假说、细胞疏水性假说、选择压驱动假说和阶段假说等。从宏观和微观两个角度分析了其稳定性的关键影响因素。宏观上,反应器的高径比、水力剪切力、有机负荷率等因素都会对好氧颗粒污泥的形成和稳定性产生影响;微观上,微生物的群体感应及其分泌的胞外聚合物等因素也发挥着重要作用。详细阐述了好氧颗粒污泥微生物群落组成和功能,进一步整理了好氧颗粒污泥微生物群落与颗粒结构稳定性能的内在关联。依据以上研究进展并结合工程应用的实际情况和需求,总结概况了好氧颗粒污泥结构稳定强化策略,即控制污泥粒径、改善进料与曝气方式、调控胞外聚合物分泌、调控群体感应等。初步构想了基于生物强化、崩解和再造粒的技术路径,具有生化、物化和化学理论融合的特点,在一定程度上可能代表了群体感应-晶核凝聚共诱导造粒的研究方向。