Performance of Anammox granular sludge bed reactor started up with nitrifying granular sludge

The anaerobic ammonia oxidation(Anammox) granular sludge bed reactor was started up successfully with nitrifying granular sludge. During the operation, the nitrifying granular sludge was gradually converted into Anammox granular sludge with good settling property and high conversion activity. The Anammox reactor worked well with the shortest HRT of 2 43 h. Under the condition that HRT w as 6 39 h and influent concentration of ammonia and nitrite was 10 mmol/L, the removal of ammonia and nitrite was 97 17% and 100 00%, respectively. Corresponding volumetric total nitrogen loading rate and volumetric total nitrogen conversion rate were 100 83 mmol/(L·d) and 98 95 mmol/(L·d). The performance of Anammox reactor was efficient and stable.

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.

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.

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.

Influence of Chemical Oxygen Demand Concentrations on Anaerobic Ammonium Oxidation by Granular Sludge From EGSB Reactor

Objective To investigate the effect of chemical oxygen demand （COD） concentrations on the anaerobic ammonium oxidation （ANAMMOX）. Methods An Expanded Granular Sludge Bed （EGSB） reactor was used to cultivate the granular sludge and to perform the ANAMMOX reaction in the bench scale experiment. NH4^＋-N and NO2^--N were measured by using colorimetric method. NO3^＋-N was analyzed by using the UV spectrophotometric method. COD measurement was based on digestion with potassium dichromate in concentrated sulphuric acid. Results When the COD concentrations in the reactors were 0 mg/L, 200 mg/L, 350 mg/L, and 550 mg/L, respectively, the NH4^＋-N removal efficiency was 12.5%, 14.2%, 14.3%, and 23.7%; the removal amount of NO2-N was almost the same; the nitrate removal efficiency was 16.8%, 94.5%, 86.6%, and 84.2% and TN removal efficiency was 16.3%, 50.7%, 46.9%, and 50.4%, moreover, the COD removal efficiency was 85%, 65.7%, and 60%; the COD removal rate was 27.42, 61.88, and 97.8 mg COD/（h·L）. Conclusion COD concentrations have a significant influence on anaerobic ammonium oxidation by granular sludge.

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.

Eubacteria and Archaea community of simultaneous methanogenesis and denitrification granular sludge

Based on the successful performance of a lab-scale upflow anaerobic sludge blanket （UASB） reactor with the capacity of simultaneous methanogenesis and denitrification （SMD）, the specific phylogenetic groups and community structure of microbes in the SMD granule in the UASB reactor were investigated by the construction of the Eubacteria and Archaea 16S rDNA clone libraries, fragment length polymorphism, and sequence blast. Real time quantitative-polymerase chain reaction （RTQ-PCR） technique was used to quantify the contents of Eubacteria and Archaea in the SMD granule. The contents of some special predominant methanogens were also investigated. The results indicated that the Methanosaeta and Methanobacteria were the predominant methanogens in all Archaea in the SMD granule, with contents of 71.59% and 22.73% in all 88 random Archaea clones, respectively. The diversity of Eubacteria was much more complex than that of Archaea. The low GC positive gram bacteria and ε-Protebacteria were the main predominant Eubacteria species in SMD granule, their contents were 49.62% and 12.03% in all 133 random Eubacteria clones respectively. The results of RTQ-PCR indicated that the content of Archaea was less than Eubacteria, the Archaea content in total microorganisms in SMD granule was about 27.6%.

Stability of expanded granular sludge bed process for terylene artificial silk printing and dyeing wastewater treatment

Terylene artificial silk printing and dyeing wastewater(TPD wastewater), containing averaged 710 mg/L terephthalic acid(TA) as the main carbon source and the character pollutant, was subjected to expanded granular sludge bed(EGSB) process. The stability of the EGSB process was firstly conducted by laboratory experiment. TA ionization was the predominated factor influencing the acid-base balance of the system. High concentration of TA in wastewater resulted in sufficient buffering capacity to neutralize the volatile fatty acids(VFA) generated from substrate degradation and provided strong base for anaerobic system to resist the pH decrease below 6.5. VFA and UFA caused almost no inhibition on the anaerobic process and biogas production except that pH was below 6.35 and VFA was at its maximum value. Along with the granulating of the activated sludge, the efficiency of organic removal and production rate of biogas increased gradually and became more stable. After start-up, the efficiency of COD removal increased to 57%—64%, pH stabilized in a range of 7.99—8.04, and production rate of biogas was relatively high and stable. Sludge granulating, suitable influent of pH and loading were responsible for the EGSB stability. The variation of VFA concentration only resulted in neglectable rebound of pH, and the inhibition from VFA could be ignored in EGSB. The EGSB reactor was stable for TPD wastewater treatment.

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...

Production and application of anaerobic granular sludge produced by landfill

Sludge granulation is considered to be the most critical parameter governing successful operation of an upflow anaerobic sludge blanket and expanded granular sludge bed （EGSB） reactors. Pre-granulated seeding sludge could greatly reduce the required startup time. Two lab-scale and a pilot-scale EGSB reactors were operated to treat Shaoxing Wastewater Treatment Plant （SWWTP） containing wastewater from real engineering printing and dyeing with high pH and sulfate concentration. The microbiological structure and the particle size distribution in aerobic excess sludge, sanitary landfill sludge digested for one year, and the granular sludge of EGSB reactor after 400 d of operation were analyzed through scanning electron microscopy （SEM） and sieves. The lab-scale EGSB reactor seeded with anaerobic sludge after digestion for one year in landfill showed obviously better total chemical oxygen demand （TCOD） removal efficiency than one seeded with aerobic excess sludge after cation polyacrylamide flocculation-concentration and dehydration. The TCOD removed was 470.8 mg/L in pilot scale EGSB reactor at short hydraulic retention time of 15 h. SEM of sludge granules showed that the microbiological structure of the sludge from different sources showed some differences. SEM demonstrated that Methanobacterium sp. was present in the granules of pilot-scale EGSB and the granular sludge produced by landfill contained a mixture of anaerobic/anoxic organisms in abundance. The particle size distribution in EGSB demonstrated that using anaerobic granular sludge produced by sanitary landfill as the seeding granular sludge was feasible.

Niche Differentiation of Phenol-Degrading Microorganisms in UASB Granular Sludge as Revealed by Fluorescence in situ Hybridization

A microbial community structure of granules harvested from an anaerobic sludge blanket reactor treating phenolic wastewater was investigated using fluorescence in situ hybridization(FISH)and clone library construction.Clones of Syntrophorhabdaceae and Cryptanaerobacter were observed to be responsible for phenol degradation.For accurate taxonomic assignment of Cryptanaerobacter clones,phylogenetic analysis using nearly full-length 16S ribosomal RNA(rRNA)gene sequences was necessary.Three oligonucleotide probes were designed to detect the following three taxonomic groups:Syntrophorhabdaceae,Cryptanaerobacter,and Syntrophus.FISH analysis of thin sections of anaerobic granules showed a random distribution of bacteria and archaea.However,a well-defined distribution of Syntrophorhabdaceae,Cryptanaerobacter,and Syntrophus was observed.Cryptanaerobacter and Syntrophus were found on the outer layer of the granules and were closely associated with each other,while Syntrophorhabdaceae was located in the deeper part of the granules.Such specific distribution of the bacteria is most likely due to their metabolic association and affinity for the substrate.Phenol degradation in the granular sludge was observed to be carried out in the following way.First,Cryptanaerobacter converts phenol to benzoate,which is then degraded by Syntrophus into acetate.This syntrophic degradation of phenol occurs near the surface of the granule,where the phenol concen-tration is high.In the deeper part of the granule,where the phenol concentration is lower,Syntrophorhabdaceae degrades phenol into acetate.We observed that Syntrophorhabdaceae is less likely to produce benzoate as an intermediate to feed the neighboring organisms,which contradicts the theo-ries presented by previous studies.

Inhibitory effect of ammonia nitrogen on specific methanogenic activity of anaerobic granular sludge

A series of batch experiments were conducted in 125mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed(UASB) and expanded granular sludge bed(EGSB) reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50% inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia nitrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7d.

Several Characteristics of Granular Sludge Blanket and Granular Sludge in Interior Diversion-EGSB Reactor

The influence of up-flow velocity on the working state and characteristics of the granular sludge blanket in Interior Diversion Expanded Granular Sludge Blanket（ID-EGSB）reactor for treating brewery wastewater were studied in this paper.The results show that the proper up-flow velocity（Vup）should be 2.1-3.3 m/h with the COD concentration of 18215-18304 mg/L,while the sludge bed reactor is inflated with expansion rate of 43.7%.When the organic loading rate reaches to 18.22-18.30 kgCOD/(m3·d-1),COD removal rate remains stabilized above 85.3%and the reactor ran without plug

Experimental Study on Granular Sludge Cultivation Based on IC Reactor

[Objective]We aimed to discuss the optimal conditions of sludge granulation on the basis of IC reactor.[Method]By using the formulated glucose wastewater,we studied the rapid cultivation of granular sludge as well as its influencing factors,so as to discuss the optimal conditions of sludge granulation.[Result]Through the static culture outside of IC reactor and dynamic culture in IC reactor,granular sludge appeared within a training cycle,with particle size of 1.0-1.5 mm.In IC reactor,when COD concentration of influent water was 5 000 mg /L,rising velocity was 0.9 m /h,pH was around 7,and auxiliary materials (like flocculant and active carbon) and mature granular sludge were added to the actor during the training process,the granulation process of sludge was accelerated.[Conclusion]The research could provide references for the rapid start-up of IC reactor.

Microbiological Characteristics of Anaerobic Granular Sludge in Hybrid Anaerobic Baffled Reactor

Anaerobic granular sludge is of key importance for highly effective operation of hybrid anaerobic baffled reactor(HABR).An observation and analysis on the composition of anaerobic granular sludge in each separation compartment of HABR was conducted by using scanning electron microscope(SEM)and molecular biotechnology,and specific methanogenic activity(SMA)and coenzyme F420 content were determined.It was indicated that the disparity of microbial composition was significant among these separation compartments of HABR,and the HABR encouraged phase separation.The results show the understanding of microbiological characteristics of anaerobic granular sludge in HABR is helpful for cultivating granular sludge,which ensures the effective operation of the reactor.

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.