Impact of sludge flocs on membrane fouling in membrane bioreactors

Publikation: Konferencebidrag uden forlag/tidsskriftKonferenceabstrakt til konferenceForskningpeer review

Resumé

Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control.
Large variation in filtration properties measured as flux decline was observed for the different types of sludges. Further, the flux could partly be reestablished after the relaxation period depending on the sludge composition. The results underline that sludge properties are important for membrane fouling and that control of floc properties, as determined by the composition of the microbial communities and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR.
High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration of divalent ions such as calcium and iron. Furthermore, it was shown that the ratio between cations and EPS was important for the fouling potential of the sludge. A high ratio between divalent ions and EPS reduced membrane fouling as soluble EPS were adsorbed and bound within the sludge flocs. Strong compact flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high.

Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant showed that the flux decline was most pronounced for the supernatant indicating that sludge flocs had a positive effect on permeate flux. Mixing sludge flocs and supernatant in different ratios shows that the permeate flux increase with sludge floc concentration. This could be due to the scouring effect of the flocs or the formation of more loose fouling layers on the membranes.
The study showed that sludge with strong compact sludge flocs and low concentration of suspended EPS and colloidal particles gave lower fouling propensity. It is known that the composition of the microbial community to some extent determines floc structure, which was not further determined here. However, presence of strong flocs are usually also supported when the concentration of divalent ions is high, the ionic strength is low and the reactor is well-aerated.
OriginalsprogEngelsk
Publikationsdato2016
StatusUdgivet - 2016
BegivenhedNordic Filtration Symposium - Lappeenranta University of Technology, Lappeenranta, Finland
Varighed: 24 aug. 201626 aug. 2016
Konferencens nummer: 16

Konference

KonferenceNordic Filtration Symposium
Nummer16
LokationLappeenranta University of Technology
LandFinland
ByLappeenranta
Periode24/08/201626/08/2016

Citer dette

Christensen, M. L., Niessen, W., & Jørgensen, M. K. (2016). Impact of sludge flocs on membrane fouling in membrane bioreactors. Abstract fra Nordic Filtration Symposium, Lappeenranta, Finland.
Christensen, Morten Lykkegaard ; Niessen, Wolfgang ; Jørgensen, Mads Koustrup. / Impact of sludge flocs on membrane fouling in membrane bioreactors. Abstract fra Nordic Filtration Symposium, Lappeenranta, Finland.
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title = "Impact of sludge flocs on membrane fouling in membrane bioreactors",
abstract = "Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges. Further, the flux could partly be reestablished after the relaxation period depending on the sludge composition. The results underline that sludge properties are important for membrane fouling and that control of floc properties, as determined by the composition of the microbial communities and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration of divalent ions such as calcium and iron. Furthermore, it was shown that the ratio between cations and EPS was important for the fouling potential of the sludge. A high ratio between divalent ions and EPS reduced membrane fouling as soluble EPS were adsorbed and bound within the sludge flocs. Strong compact flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high. Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant showed that the flux decline was most pronounced for the supernatant indicating that sludge flocs had a positive effect on permeate flux. Mixing sludge flocs and supernatant in different ratios shows that the permeate flux increase with sludge floc concentration. This could be due to the scouring effect of the flocs or the formation of more loose fouling layers on the membranes.The study showed that sludge with strong compact sludge flocs and low concentration of suspended EPS and colloidal particles gave lower fouling propensity. It is known that the composition of the microbial community to some extent determines floc structure, which was not further determined here. However, presence of strong flocs are usually also supported when the concentration of divalent ions is high, the ionic strength is low and the reactor is well-aerated.",
author = "Christensen, {Morten Lykkegaard} and Wolfgang Niessen and J{\o}rgensen, {Mads Koustrup}",
year = "2016",
language = "English",
note = "null ; Conference date: 24-08-2016 Through 26-08-2016",

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Christensen, ML, Niessen, W & Jørgensen, MK 2016, 'Impact of sludge flocs on membrane fouling in membrane bioreactors' Nordic Filtration Symposium, Lappeenranta, Finland, 24/08/2016 - 26/08/2016, .

Impact of sludge flocs on membrane fouling in membrane bioreactors. / Christensen, Morten Lykkegaard; Niessen, Wolfgang; Jørgensen, Mads Koustrup.

2016. Abstract fra Nordic Filtration Symposium, Lappeenranta, Finland.

Publikation: Konferencebidrag uden forlag/tidsskriftKonferenceabstrakt til konferenceForskningpeer review

TY - ABST

T1 - Impact of sludge flocs on membrane fouling in membrane bioreactors

AU - Christensen, Morten Lykkegaard

AU - Niessen, Wolfgang

AU - Jørgensen, Mads Koustrup

PY - 2016

Y1 - 2016

N2 - Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges. Further, the flux could partly be reestablished after the relaxation period depending on the sludge composition. The results underline that sludge properties are important for membrane fouling and that control of floc properties, as determined by the composition of the microbial communities and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration of divalent ions such as calcium and iron. Furthermore, it was shown that the ratio between cations and EPS was important for the fouling potential of the sludge. A high ratio between divalent ions and EPS reduced membrane fouling as soluble EPS were adsorbed and bound within the sludge flocs. Strong compact flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high. Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant showed that the flux decline was most pronounced for the supernatant indicating that sludge flocs had a positive effect on permeate flux. Mixing sludge flocs and supernatant in different ratios shows that the permeate flux increase with sludge floc concentration. This could be due to the scouring effect of the flocs or the formation of more loose fouling layers on the membranes.The study showed that sludge with strong compact sludge flocs and low concentration of suspended EPS and colloidal particles gave lower fouling propensity. It is known that the composition of the microbial community to some extent determines floc structure, which was not further determined here. However, presence of strong flocs are usually also supported when the concentration of divalent ions is high, the ionic strength is low and the reactor is well-aerated.

AB - Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges. Further, the flux could partly be reestablished after the relaxation period depending on the sludge composition. The results underline that sludge properties are important for membrane fouling and that control of floc properties, as determined by the composition of the microbial communities and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration of divalent ions such as calcium and iron. Furthermore, it was shown that the ratio between cations and EPS was important for the fouling potential of the sludge. A high ratio between divalent ions and EPS reduced membrane fouling as soluble EPS were adsorbed and bound within the sludge flocs. Strong compact flocs reduced membrane fouling, and more compact and strong flocs were formed if the concentration of divalent ions were high. Sludge was fractionated by centrifugation providing supernatant with soluble EPS and colloidal particles but without flocs. Filtration test on untreated sludge and supernatant showed that the flux decline was most pronounced for the supernatant indicating that sludge flocs had a positive effect on permeate flux. Mixing sludge flocs and supernatant in different ratios shows that the permeate flux increase with sludge floc concentration. This could be due to the scouring effect of the flocs or the formation of more loose fouling layers on the membranes.The study showed that sludge with strong compact sludge flocs and low concentration of suspended EPS and colloidal particles gave lower fouling propensity. It is known that the composition of the microbial community to some extent determines floc structure, which was not further determined here. However, presence of strong flocs are usually also supported when the concentration of divalent ions is high, the ionic strength is low and the reactor is well-aerated.

UR - http://www.lut.fi/web/en/nordic-filtration-symposium-2016

M3 - Conference abstract for conference

ER -

Christensen ML, Niessen W, Jørgensen MK. Impact of sludge flocs on membrane fouling in membrane bioreactors. 2016. Abstract fra Nordic Filtration Symposium, Lappeenranta, Finland.