scholarly journals Operation of Submerged Anaerobic Membrane Bioreactors at 20 °C: Effect of Solids Retention Time on Flux, Mixed Liquor Characteristics and Performance

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1525
Author(s):  
Santiago Pacheco-Ruiz ◽  
Sonia Heaven ◽  
Charles J. Banks
Keyword(s):  
Retention Time ◽  
Membrane Fouling ◽  
Extracellular Polymeric Substances ◽  
Oxygen Demand ◽  
Membrane Bioreactors ◽  
Transmembrane Pressure ◽  
Capillary Suction ◽  
Solids Retention Time ◽  
Anaerobic Membrane Bioreactors ◽  
Solids Retention

Four flat-sheet submerged anaerobic membrane bioreactors ran for 242 days on a simulated domestic wastewater with low Chemical Oxygen Demand (COD) and high suspended solids. Organic loading was maintained around 1.0 g COD L−1 day−1, while solids retention time (SRT) was varied from 20–90 days. This was achieved at a constant membrane flux, maintained by adjusting transmembrane pressure (TMP) in the range 1.8-9.8 kPa. Membrane fouling was assessed based on the required TMP, with mixed liquors characterised using capillary suction time, frozen image centrifugation and quantification of extracellular polymeric substances (EPS). SRT had a significant effect on these parameters: fouling was least at an SRT of 30 days and highest at 60 days, with some reduction as this extended to 90 days. Operation at SRT <30 days showed no further benefits. Although operation at a short SRT was optimal for membrane performance it led to lower specific methane productivity, higher biomass yields and higher effluent COD. Short SRT may also have accelerated the loss of essential trace elements, leading to reduced performance under these conditions. A COD-based mass balance was conducted, including both biomass and methane dissolved in the effluent.

Membrane fouling and performance evaluation of conventional membrane bioreactor (MBR), moving biofilm MBR and oxic/anoxic MBR

2014 ◽  
Vol 69 (7) ◽  
pp. 1403-1409 ◽  
Author(s):  
Sher Jamal Khan ◽  
Aman Ahmad ◽  
Muhammad Saqib Nawaz ◽  
Nicholas P. Hankins
Keyword(s):  
Membrane Fouling ◽  
Extracellular Polymeric Substances ◽  
Water Flux ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Membrane Bioreactors ◽  
Nitrogen And Phosphorus ◽  
Biofilm Carrier ◽  
Cake Layer ◽  
And Performance

In this study, three laboratory scale submerged membrane bioreactors (MBRs) comprising a conventional MBR (C-MBR), moving bed MBR (MB-MBR) and anoxic-oxic MBR (A/O-MBR) were continuously operated with synthesized domestic wastewater (chemical oxygen demand, COD = 500 mg/L) for 150 days under similar operational and environmental conditions. Kaldnes® plastic media with 20% dry volume was used as a biofilm carrier in the MB-MBR and A/O-MBR. The treatment performance and fouling propensity of the MBRs were evaluated. The effect of cake layer formation in all three MBRs was almost the same. However, pore blocking caused a major difference in the resultant water flux. The A/O-MBR showed the highest total nitrogen and phosphorus (PO4-P) removal efficiencies of 83.2 and 69.7%, respectively. Due to the high removal of nitrogen, fewer protein contents were found in the soluble and bound extracellular polymeric substances (EPS) of the A/O-MBR. Fouling trends of the MBRs showed 12, 14 and 20 days filtration cycles for C-MBR, MB-MBR and A/O-MBR, respectively. A 25% reduction of the soluble EPS and a 37% reduction of the bound EPS concentrations in A/O-MBR compared with C-MBR was a major contributing factor for fouling retardation and the enhanced filtration capacity of the A/O-MBR.

scholarly journals The potential of ultrasonic membrane anaerobic systems in treating slaughterhouse wastewater

2015 ◽  
Vol 5 (3) ◽  
pp. 293-300 ◽  
Author(s):  
N. H. Abdurahman ◽  
Y. M. Rosli ◽  
N. H. Azhari ◽  
Hayder A. Bari
Keyword(s):  
Steady State ◽  
Removal Efficiency ◽  
Retention Time ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Yield Coefficient ◽  
Slaughterhouse Wastewater ◽  
Mixed Liquor ◽  
Solids Retention Time ◽  
Solids Retention

Direct discharge of slaughterhouse wastewater causes serious environmental pollution due to its high chemical oxygen demand (COD), total suspended solids (TSS) and biochemical oxygen demand. In this study, an ultrasonic-assisted membrane anaerobic system was used as a novel method for treating slaughterhouse wastewater. Six steady states were achieved, using concentrations of 7,800–13,620 mg/l for mixed liquor suspended solids and 5,359–11,424 mg/l for mixed liquor volatile suspended solids (MLVSS). Kinetic equations were used to describe the kinetics of treatment at organic loading rates of 3–11 kg COD/m3/d. The removal efficiency of COD was 94.8–96.5% with hydraulic retention times of 308.6–8.7 days. The growth yield coefficient was found to be 0.52 g VSS/g. COD was 0.21 d−1 and methane gas production rate was 0.24–0.56 l/g COD/d. Steady-state influent COD concentrations increased from 8,000 mg/l in the first steady state to 25,400 mg/l in the sixth steady state. The minimum solids retention time, θcmin obtained from the three kinetic models was 6–14.4 days. The k values were 0.35–0.519 g COD/g VSS.d and μmax values were between 0.26 and 0.379 d−1. The solids retention time decreased from 600 to 14.3 days. The complete treatment reduced the COD content and its removal efficiency reached 94.8%.

Treatment of Domestic Strength Wastewater with Anaerobic Hybrid Reactors

1987 ◽  
Vol 22 (3) ◽  
pp. 474-490 ◽  
Author(s):  
R.L. Droste ◽  
S.R. Guiot ◽  
S.S. Gorur ◽  
K.J. Kennedy
Keyword(s):  
Retention Time ◽  
Suspended Solids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Synthetic Wastewater ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Removal Efficiencies ◽  
Hybrid Reactors

Abstract Anaerobic treatment of dilute synthetic wastewater (300-1,000 mg chemical oxygen demand/L using laboratory upflow sludge blanket filter reactors with and without effluent recycle is described. Treatment of dilute synthetic wastewater at hydraulic retention times less than 1 and 2 h in reactors without and with recycle, respectively, resulted in biomass washout as the solids retention time decreased to less than 12 d. Reseeding would be required to operate at these critical hydraulic retention times for extended periods. Treatment of dilute synthetic wastewater at hydraulic retention times between 3-12 h resulted in soluble COD removal efficiencies between 84-95% treating 300 mg COD/L. At a 3 h hydraulic retention time, solids retention time of 80 d and stable reactor biomass concentrations of 25 g volatile suspended solids/L were maintained.

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