Changes of microbial characteristics of retained sludge during low-temperature operation of an EGSB reactor for low-strength wastewater treatment

In this study, a lab scale EGSB reactor was operated for 400 days to investigate the influence of temperature-decrease on the microbial characteristic of retained sludge. The EGSB reactor was started-up at 15°C seeding with 20°C-grown granular sludge. The influent COD of synthetic wastewater was set at 0.6–0.8 gCOD/L. The process-temperature was stepwise reduced from 15°C to 5°C during 400 days operation. Decrease of temperature of the reactor from 15°C to 10°C caused the decline of COD removal efficiency. However, continuous operation of the EGSB reactor led the efficient treatment of wastewater (70% of COD removal, 50% of methane recovery) at 10°C. We confirmed that the both acetate-fed and hydrogen-fed methanogenic activities of retained sludge clearly increased under 15 to 20°C. Changes of microbial profiles of methanogenic bacteria were analyzed by 16S rDNA-targeted DGGE analysis and cloning. It shows that genus Methanospirillum as hydrogen-utilizing methanogen proliferated due to low temperature operation of the reactor. On the other hand, genus Methanosaeta presented in abundance as acetoclastic-methanogen throughout the experiment.

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Treatment of Sugar Containing-Low Strength Wastewater at 20°C by Anaerobic Granular Sludge Bed Reactor

Water Practice & Technology ◽

10.2166/wpt.2010.055 ◽

2010 ◽

Vol 5 (3) ◽

Author(s):

W. Yoochatchaval ◽

K. Kubota ◽

T. Kawai ◽

T. Yamaguchi ◽

K. Syutsubo

Keyword(s):

Stable Process ◽

Growth Yield ◽

High Growth ◽

Granular Sludge ◽

Post Treatment ◽

Cod Removal ◽

Synthetic Wastewater ◽

Anaerobic Granular Sludge ◽

Treatment Technology ◽

Low Strength

To investigate the feasibility of anaerobic wastewater treatment technology for low strength sugar refinery wastewater (0.4 - 0.5 g COD/L), an 8.8 L volume of anaerobic granular sludge bed reactor was operated at 20°C for 400 days. The operation mode was combination of one pass flow (UASB, 50 min) and effluent-recirculation (EGSB, 10 min) mode. The aerobic down-flow hanging sponge (DHS) reactor was installed as a post-treatment. During the started-up period, reactors were fed with synthetic wastewater at overall HRT of 3 hours (anaerobic 2 hours, aerobic 1 hour). After day 85, feed was changed to real wastewater together with supplement of nutrients, trace elements and NaHCO3. The sufficient COD removal efficiency (85% SD±6.2) and stable process performance were elicited from the granular sludge bed reactor.Also, post-treatment (DHS reactor) offered good quality of effluent (45 mg COD/L, 7 mg BOD/L) and it achieved the discharge standard. Increasing of sulfate concentration of wastewater caused higher contribution of sulfate reducing bacteria for COD removal. The sludge concentration and settleability were well maintained thoroughly. However, floatation of large size granule was observed in the later part of experiment. This phenomenon may attribute to the high growth yield of retained sludge at 20°C.

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Removal of COD from Piggery Wastewater Using a Lab-Scale UASB Reactor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.534.221 ◽

2012 ◽

Vol 534 ◽

pp. 221-224

Author(s):

Fei Yan ◽

Jin Long Zuo ◽

Tian Lei Qiu ◽

Xu Ming Wang

Keyword(s):

Granular Sludge ◽

Cod Removal ◽

Upflow Anaerobic Sludge Blanket ◽

Synthetic Wastewater ◽

Uasb Reactor ◽

Anaerobic Sludge ◽

Volume Loading ◽

Piggery Wastewater ◽

Start Up ◽

Anaerobic Sludge Blanket

It took 55 days to start up a lab-scale upflow anaerobic sludge blanket (UASB) reactor at ambient temperature 27-28 oC by using the synthetic wastewater, and piggery wastewater was used as the influent after the reactor start-up. From day 120 onwards, COD removal efficiency maintained in the range of 85% to 95% with 6.79-9.66 kg COD/ (m3•d) of volume loading, and the effluent COD concentration ranged between 400 mg/L and 600 mg/L. Granular sludge formation was observed in the reactor after 40-day operation, and the sludge diameter reached 2-4 mm in the 120 day-old reactor. The pH changes in the influent had little influence on COD removal from piggery wastewater using the UASB reactor.

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Evaluation of UASB Reactor Performance During Start-Up Operation Using Glucose Bearing Synthetic Wastewater

International Journal of Environment ◽

10.3126/ije.v9i1.27432 ◽

2020 ◽

Vol 9 (1) ◽

pp. 32-51

Author(s):

Revanuru Subramanyam

Keyword(s):

Removal Efficiency ◽

Loading Rate ◽

Granular Sludge ◽

Cod Removal ◽

Synthetic Wastewater ◽

Organic Loading Rate ◽

Anaerobic Sludge ◽

Cod Removal Efficiency ◽

Start Up ◽

Seed Sludge

This research article describes start-up performance of an UASB (Upflow Anaerobic Sludge Blanket) reactor in terms of chemical oxygen demand (COD) removal efficiency, biogas production, sludge loading rate (SLR), volatile fatty acids (VFA), pH, alkalinity, total solids (TS) and volatile suspended solids (VSS), fed with synthetic wastewater with increased concentrations of glucose. The reactor was loaded up to an OLR (Organic Loading Rate) of 15 kg COD m-3 d-1 and achieved a COD removal efficiency of 82 ±3%. The results showed that digested seed sludge was successfully acclimatized and transformed finally into granular sludge within a period of 120 days. An increase in the accumulation of VFA at high OLRs showed that methanogenesis could be the rate-limiting step in the reactor operation. The SLR and VSS/TS ratio were increased with an increase in OLR. During the initial stages, uniform distribution of VSS concentration and later on maximum VSS concentration were found at port number two at a height of 350 mm. The carbon balance depicts that the maximum percentage of influent COD converted to methane COD. An increase in specific methanogenic activity values with the age of sludge confirmed the transformation of the seed sludge in to a granular sludge.

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Treatment of domestic sewage at low temperature in a two-anaerobic step system followed by a trickling filter

Water Science & Technology ◽

10.2166/wst.2004.0840 ◽

2004 ◽

Vol 48 (11-12) ◽

pp. 199-206 ◽

Cited By ~ 5

Author(s):

T.A. Elmitwalli ◽

J. van Lier ◽

G. Zeeman ◽

G. Lettinga

Keyword(s):

Low Temperature ◽

Low Cost ◽

Granular Sludge ◽

Domestic Sewage ◽

Cod Removal ◽

Nitrification Rate ◽

Trickling Filter ◽

E Coli ◽

Loading Rates ◽

Significant Difference

The treatment of domestic sewage at low temperature was studied in a two-anaerobic-step system followed by an aerobic step, consisting of an anaerobic filter (AF) + an anaerobic hybrid (AH) + polyurethane-foam trickling filter (PTF). The AF+AH system was operated at a hydraulic retention time (HRT) of 3+6 h at a controlled temperature of 13°C, while the PTF was operated without wastewater recirculation at different hydraulic loading rates (HLR) of 41, 15.4 and 2.6 m3/m2/d at ambient temperature (ca. 15–18°C). The AF reactor removed the major part of the total and suspended COD, viz. 46 and 58% respectively. The AH reactor with granular sludge was efficient in the removal and conversion of the anaerobically biodegradable COD. The AF+AH system removed 63% of total COD and converted 46% of the influent total COD to methane. At a HLR of 41 m3/m2/d, the COD removal was limited in the PTF, while at HLR of 15.4 and 2.6 m3/m2/d, a high total COD removal of 54-57% was achieved without a significant difference between the two HLRs. The PTF was mainly efficient in the removal of particles (suspended and colloidal COD removal were 75–90% and 75–83% respectively), which were not removed in the anaerobic two-step. The overall total COD removal in the AF+AH+PTF system was 85%. Decreasing the HLR from 15.4 to 2.6 m3/m2/d, only increased the nitrification rate efficiency in the PTF from 22% to 60%. Also, at HLR of 15.4 and 2.6 m3/m2/d, PTF showed a similar removal for E. coli by about 2 log. Therefore, the effluent of AF+AH+PTF system can be utilised for restricted irrigation in order to close water and nutrients cycles. Moreover, such a system represents a high-load and a low-cost technology, which is a suitable solution for developing countries.

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Granular biofilm-based anaerobic digestion: molecular biomonitoring and high-rate psychrophilic treatment of phenolic wastewater

Water Science & Technology ◽

10.2166/wst.2007.027 ◽

2007 ◽

Vol 55 (1-2) ◽

pp. 43-49 ◽

Cited By ~ 4

Author(s):

C. Scully ◽

G. Collins ◽

V. O'Flaherty

Keyword(s):

Community Dynamics ◽

Phenol Degradation ◽

Granular Sludge ◽

Cod Removal ◽

High Rate ◽

Synthetic Wastewater ◽

Polymorphism Analysis ◽

Applied Loading ◽

Microbial Community Dynamics ◽

Start Up

Two pairs of expanded granular sludge bed (EGSB) bioreactors, R1/R2 and R3/R4, were designed. R1/R2 were used for mesophilic (37 °C) treatment of synthetic wastewater over a 100-day trial. A successful start-up was achieved by R1 and R2, with COD removal over 90%. Both reactors were operated under identical parameters; however, increased organic loading induced a reduction in COD removal by R1, while R2 maintained satisfactory performance throughout the experiment. R3/R4 were operated at 15 °C throughout a 422-day trial and were used for the stabilisation of volatile fatty acid-based wastewater. Phenol was introduced to R4 at an applied loading rate of 1 kg phenol m−3 d−1, which was increased to 2 kg phenol m−3 d−1. No phenol was supplied to R3. Efficient COD conversion was recorded in both R3 and R4, thus demonstrating the feasibility of high-rate phenol degradation under psychrophilic conditions. Terminal restriction fragment length polymorphism analysis was applied to the characterisation of microbial community dynamics within each of the reactors. The results indicated a microbiological basis for the deviation, in terms of operational performance, of R1 and R2. TRFLP analyses indicated stable microbial communities in R3 and R4, but detected changes in the abundance of specific ribotypes in response to phenol mineralisation.

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Process Characteristics Study of Anaerobic Baffled Reactor (ABR)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.160-162.1551 ◽

2010 ◽

Vol 160-162 ◽

pp. 1551-1557

Author(s):

Lu Ning ◽

Jin Liu

Keyword(s):

Removal Efficiency ◽

Ph Value ◽

Granular Sludge ◽

Cod Removal ◽

Synthetic Wastewater ◽

Anaerobic Baffled Reactor ◽

Process Characteristics ◽

Cod Removal Efficiency ◽

Start Up ◽

The Matrix

In this paper, Anaerobic Baffled Reactor (ABR) was applied to treat the synthetic wastewater in the matrix of starch and glucose. the reactor was started using low loading start-up , VLR controlled at 0.59~11.05kgCOD/m3•d, there are some granular sludge appeared after running 18 days. The figure and size of granular sludge in each compartment revealed different characteristics due to the changing of OLRs and shear force between gas and liquid in each compartment. The COD removal efficiency was higher than 90% and steady when the reactor’s start-up finished.When the anaerobic granular sludge appeared in the reactor, the VLR was 1.29kgCOD/(m3•d)、COD removal efficiency was 83％、hydraulic surface loading was 0.078m3/m2.h and an HRT was 30h. The VLR had remarkable influence on COD removal efficiency、VFA、pH and ALK. When VLR was 5.57kgCOD/(m3•d), COD removal efficiency and ALK were the minimum, VFA in the outflow exceeded 1000mg/L, reactor’s efficiency decreased .The reactor recovered after adjusting VLR and ALK value. Compared with the third and fourth compartments, the first and second compartments were less sensitive to changing of VFA. When pH deviated from adapt range, the COD removal efficiency was decreased obviously, so pH value was kept in the range of 6.2 to 6.5 for the later stage of experiments.

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Upgrading Wastewater Treatment by Water Hyacinth in Developing Countries

Water Science & Technology ◽

10.2166/wst.1990.0241 ◽

1990 ◽

Vol 22 (7-8) ◽

pp. 153-160 ◽

Cited By ~ 3

Author(s):

Pradeep Kumar ◽

R. J. Garde

Keyword(s):

Wastewater Treatment ◽

Water Hyacinth ◽

Treatment Plant ◽

Cod Removal ◽

Treatment System ◽

Synthetic Wastewater ◽

Second Phase ◽

Treatment Unit ◽

Batch Studies ◽

New Treatment

With increasing stress on existing wastewater treatment systems, it is necessary either to upgrade the treatment unit(s) or install an entirely new treatment plant. Obviously, the upgrading is preferred over the alternative of having a new system. Keeping this in view, in the present project, an attempt has been made to explore the possibility of upgrading existing facultative ponds using water hyacinth. Bench-scale batch studies were designed to compare the performance of hyacinth treatment system with facultative ponds. Investigations were carried out with synthetic wastewater having COD in the range of 32.5-1090 mg/l. The efficiency of COD removal in water hyacinth ponds was 15-20 percent more than the facultative ponds. Based on the results, an empirical model has been proposed for COD removal kinetics. In the second phase of the project a hyacinth pond was continuously operated. BOD, COD, TS, TN, TP, pH, and DO were regularly monitored. However, the DO of the effluent from hyacinth treatment system was considerably reduced. Effluent should be aerated before it is discharged. The results indicate that the existing facultative ponds can be stalked with water hyacinth to improve their performance as well as hyacinth treatment systems can be installed to support the conventional treatment.

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The bacterial numeration and an observation of a new syntrophic association for granular sludge

Water Science & Technology ◽

10.2166/wst.1997.0584 ◽

1997 ◽

Vol 36 (6-7) ◽

pp. 133-140 ◽

Cited By ~ 3

Author(s):

Zhu Jianrong ◽

Hu Jicui ◽

Gu Xiasheng

Keyword(s):

Anaerobic Bacteria ◽

Granular Sludge ◽

Methanogenic Bacteria ◽

Uasb Reactor ◽

Two Phase ◽

Methanogenic Activity ◽

Syntrophic Association ◽

Group I ◽

Acetogenic Bacteria ◽

Fermentative Bacteria

The bacterial numeration and microbial observation were made on granular sludge from laboratory single and two-phase UASB reactors. It was shown that the fermentative bacteria (group I), H2-producing acetogenic bacteria (group II) and methanogenic bacteria (group III) of granular sludge in single UASB reactor were 9.3 × 108−4.3 × 109, 4.3 × 107−4.3 × 108, 2.0−4.3 × 108, respectively, during the granulation process. The sludge of methanogenic reactor exhibited the similar results. That indicates there is no big difference between suspended and granular sludge, and bacterial population for three groups of anaerobic bacteria are similar. The formation of granular sludge depends mainly on the organization and arrangement of bacteria. An observation of granular sludge using electron microscope revealed that the fermentative bacteria and hydrogenotrophic methanogens existed on outer surface of granules, and aceticlastic methanogens and H2-producing acetogenic bacteria occupied the inner layer. A new syntrophic association between Methanosaeta sp. and Syntrophomonas sp. (even plus Methanobrevibacter sp.) was observed. Because Methanosaeta can effectively convert the acetate (the end product of propionate and butyrate) to methane, such a new syntrophic association is supposed to support the degradation of short fatty acids and high methanogenic activity of granular sludge. Based on structural pattern, a hypothesis on mechanism of granulation called “crystallized nuclei formation” is proposed.

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