Formaldehyde toxicity in anaerobic systems

2000 ◽  
Vol 42 (5-6) ◽  
pp. 223-229 ◽  
Author(s):  
G. Gonzalez-Gil ◽  
R. Kleerebezem ◽  
G. Lettinga
Keyword(s):  
Granular Sludge ◽  
Anaerobic Granular Sludge ◽  
Formaldehyde Concentration ◽  
Trophic Groups ◽  
Toxicity Studies ◽  
Acetoclastic Methanogenesis ◽  
Dual Character ◽  
Formaldehyde Toxicity ◽  
Sludge Concentration

Formaldehyde toxicity during acetoclastic methanogenesis exerted a dual character: It was in part reversible and in part irreversible. Toxicity was only reversible at very low formaldehyde concentration. The degree of irreversible toxicity was proportionally related to the initial sludge concentration, but was independent of the initial specific acetoclastic activity. Formaldehyde conversion seemed to be dependent on the concentration of the various trophic groups present in the anaerobic granular sludge used. Hence biomass diversity may play an important role in the outcome of toxicity studies and may furthermore contribute to the explanation of the controversies with respect to toxicity values reported in literature.

Rheological behaviors of anaerobic granular sludge in a spiral symmetry stream anaerobic bioreactor

2015 ◽  
Vol 72 (4) ◽  
pp. 658-664 ◽  
Author(s):  
Xiaoguang Chen ◽  
Ruobin Dai ◽  
Xinyi Xiang ◽  
Chengyu Ma ◽  
Gang Li ◽  
...  
Keyword(s):  
Apparent Viscosity ◽  
Granular Sludge ◽  
Shear Thinning ◽  
Anaerobic Granular Sludge ◽  
Anaerobic Bioreactor ◽  
Rheological Behaviors ◽  
Viscosity Behavior ◽  
Thixotropic Behavior ◽  
The Relationship ◽  
Sludge Concentration

The rheological behaviors of the anaerobic granular sludge (AGS) in a spiral symmetry stream anaerobic bioreactor (SSSAB) were investigated. Shear-thinning behavior, thixotropic behavior, concentration–viscosity behavior and temperature–viscosity behavior were evaluated based on the constitutive equation of the AGS. The results indicated that the Herschel–Bulkley model was able to adequately describe the constitutive relation of AGS in the SSSAB. The AGS also showed shear-thinning behavior as well as thixotropic behavior. The critical shear rate and network strength of the AGS were 61.8 s−1 and 497.0 W m−3, respectively. The relationship between the apparent viscosity and the sludge concentration was illustrated and explained by the Woodcock formula. The relationship between apparent viscosity of the AGS and temperature could be modeled using the Arrhenius equation. The AGS was significantly thermo-sensitive and its mean energy of activation was 14.640 kJ mol−1. Notably, it was necessary to consider such behaviors in the hydrodynamic modeling of SSSAB in which shear condition, sludge concentration and temperature were in non-uniform distribution.

Toxicity of Sulfite and Cadmium to Anaerobic Granular Sludge

1994 ◽  
Vol 29 (4) ◽  
pp. 581-598
Author(s):  
C.F. Shew ◽  
N. Kosaric
Keyword(s):  
Granular Sludge ◽  
Upflow Anaerobic Sludge Blanket ◽  
Shock Load ◽  
Anaerobic Sludge ◽  
Anaerobic Granular Sludge ◽  
Scanning Electron Micrographs ◽  
Bacterial Growth Rate ◽  
Digestion Rate ◽  
Sulfate Reducing ◽  
Load Conditions

Abstract Toxicity of sulfite (Na2SO3) and cadmium (CdCl2) ions to anaerobic granular sludge was investigated in 1.2 litre bench-scale upflow anaerobic sludge blanket (UASB) reactors during process acclimation and shock load conditions. Minimal sulfite toxicity was observed under gradual and shock load conditions at sulfite concentrations of up to 1000 mg S/L if proper acclimation was allowed to occur. No long-term toxic effects were observed although the COD digestion rate was temporarily inhibited by shock load of sulfite. Scanning electron micrographs indicated that more sulfate-reducing bacteria were present in the granules developed in the reactors with sulfite supplement although rod-shaped Methanosaeta-like bacteria were still dominant. High bacterial growth rate was observed in the reactors which were supplied with the feed containing sulfite. The COD digestion rate was inhibited at a cadmium loading rate of 2.4 g Cd per day under both acclimation and shock load conditions. Acclimation did not seem to improve the bacteria to tolerate the toxicity of cadmium. The concentration of free cadmium was very low in the reactors under normal conditions, but increased rapidly when the COD digestion in the reactors ceased. The bacteria could not be reactivated after inhibited by cadmium. When reactors were operated at low specific COD loading rates, more inorganic precipitates were formed inside the granules which consequently settled faster.

scholarly journals Screening for electrical conductivity in anaerobic granular sludge from full-scale wastewater treatment reactors

2020 ◽  
Vol 159 ◽  
pp. 107575
Author(s):  
Leire Caizán-Juanarena ◽  
Annemiek ter Heijne ◽  
Jan Weijma ◽  
Doekle Yntema ◽  
Diego A. Suárez-Zuluaga ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Wastewater Treatment ◽  
Granular Sludge ◽  
Full Scale ◽  
Anaerobic Granular Sludge

Bioremediation of wastewaters with decabromodiphenyl ether by anaerobic granular sludge

2015 ◽  
Vol 128 ◽  
pp. 522-527 ◽  
Author(s):  
Shou-Qing Ni ◽  
Zhibin Wang ◽  
Lu Lv ◽  
Xueyou Liang ◽  
Longfei Ren ◽  
...  
Keyword(s):  
Granular Sludge ◽  
Anaerobic Granular Sludge ◽  
Decabromodiphenyl Ether

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

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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