Particle count and size alteration for membrane fouling reduction in non-conventional water filtration

2004 ◽  
Vol 50 (12) ◽  
pp. 273-278 ◽  
Author(s):  
A. Adin
Keyword(s):  
Activated Sludge ◽  
Ferric Chloride ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Positive Impact ◽  
Iron Chloride ◽  
Particle Count ◽  
Membrane Flux ◽  
Total Particle ◽  
Stirred Cell

If coagulation is not completely successful and produces aggregates which are too small, fouling may increase. In some cases, a deep-bed filter could perhaps provide a solution. The paper examines these effects using experimental results for different waters. Activated sludge effluents, stormy seawater containing microalgae and spent filter backwash water (SFBW) were coagulated by alum or ferric chloride. Sand filtration tests were carried out. Tests were performed in a membrane filtration stirred cell, filtration pilot plant equipped with SDI analyzer (seawater) and pilot UF plant (SFBW). For activated sludge effluent, alum residual ratio curves of turbidity and total particle count (TPC) followed one another. With ferric chloride, low coagulant dosage showed negative turbidity removal. Contact granular filtration reduced membrane fouling intensity. Increasing the dose resulted in higher improvement in membrane flux. For seawater, a filter run period under storm conditions reached 35 hours with satisfactory filtrate quality. An iron chloride dose of 0.3 mg/l during normal conditions and 0.5 mg/l for stormy condition should be injected, mixed well before the filters, while maintaining 10 m/hr filtration rate and pH 6.8 value. For SFBW, alum flocculation pretreatment of SFBW was effective in reducing turbidity, TPC, viruses and protozoa. SFBW settling prior to flocculation did not enhance turbidity and TPC removal. The largest remaining particle fraction after alum flocculation was 3-10 μm in size, both Cryptosporidium and Giardia are found in this size range. Coagulation enhanced the removal of small size particles, a positive impact on reducing membrane fouling potential.

Performance and membrane fouling in a pilot scale SBR process coupled with membrane

2003 ◽  
Vol 47 (1) ◽  
pp. 139-144 ◽  
Author(s):  
H. Shin ◽  
S. Kang
Keyword(s):  
Membrane Fouling ◽  
Batch Reactor ◽  
Pilot Scale ◽  
Nitrifying Bacteria ◽  
Endogenous Respiration ◽  
Aeration Time ◽  
Membrane Flux ◽  
Start Up ◽  
Cell Test ◽  
Stirred Cell

The performance of the pilot-scale submerged membrane coupled with sequencing batch reactor (SM-SBR) for upgrading effluent quality was investigated in this study. The reactor was operated with 3-hour cycle with alternating anoxic and aerobic conditions to treat organics, nitrogen and phosphate. Despite various influent characteristics, COD removal was always higher than 95%. Sufficient nitrification was obtained within a few weeks after start-up and during the stable period, complete nitrification occurred despite short aeration time. Total nitrogen (TN) removal efficiency was reached up to 85%. Membrane flux was critical for TN removal so that the decrease of flux by membrane fouling led to increase of HRT, and it caused the endogenous respiration of microorganisms such as nitrifying bacteria. The stirred cell test revealed the significant role of the soluble fraction in membrane permeability and dissolved solids played a major role in the short-term fouling mechanism. The cake resistance by the soluble COD fraction of supernatant or soluble microbial products (SMP) was investigated as a major part of total resistance.

Effluent pretreatment by iron coagulation applying various dose-pH combinations for optimum particle separation

1998 ◽  
Vol 38 (6) ◽  
pp. 27-34 ◽  
Author(s):  
A. Adin ◽  
Y. Soffer ◽  
R. Ben Aim
Keyword(s):  
Particle Size ◽  
Ferric Chloride ◽  
Wastewater Reuse ◽  
Transport Systems ◽  
Particle Removal ◽  
Turbidity Removal ◽  
Particle Count ◽  
Aluminium Sulfate ◽  
Total Particle ◽  
Size Groups

Wastewater reuse often requires particle destabilization and removal to protect water transport systems and membranes from clogging. Flocculation process of activated sludge effluent applying ferric chloride is examined and comparison with alum (aluminium sulfate) application is made in this work. Optimum flocculation conditions are determined based on the removal efficiency of different particle size groups and on turbidity as a function of coagulant dosage and pH. Results show that the best removal for ferric chloride coagulant occurs at pH 4-5 and dosage of 20-30 mgl−1. Settled water total particle count (TPC) of particle size ≥2μm was reduced by more than 99%, while turbidity removal reached 86%. Zeta potential measurements and visual observations indicate domination of adsorption and charge neutralization mechanisms. Best removal with alum occurred at pH 6-7 while dosing 30 mgl−1 and higher. Destabilization mechanism of adsorption and sweep coagulation is proposed. Generally alum performed somewhat better than iron for turbidity removal and worse for TPC removal. CMD (count mean diameter) is proposed for particle removal index: the higher the TPC removal, the lower the CMD.

Coagulation as a pretreatment of SFBW for membrane filtration

2002 ◽  
Vol 2 (5-6) ◽  
pp. 301-306 ◽  
Author(s):  
A. Nasser ◽  
Z. Huberman ◽  
L. Dean ◽  
F. Bonner ◽  
A. Adin
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Size Range ◽  
Water Source ◽  
Protozoan Parasites ◽  
Pilot Studies ◽  
Major Barrier ◽  
Particle Count ◽  
Filtration Cycle ◽  
Granular Filtration

Granular filtration has been incorporated as a major barrier to prevent the dissemination of disease-causing agents by drinking water. Particles and pathogens such as Giardia lamblia and Cryptosporidium parvum retained in the filters are then washed by utilizing clean water. This study was conducted, primarily, to evaluate coagulation as a pretreatment for the Spent Filter Backwash Water (SFBW) treatment by ultrafiltration (UF). SFBW Samples were collected from four different water treatment plants and carefully analyzed. Jar-tests and backwash pilot studies were performed in the laboratory. Depending on the water source, protozoan parasites and viruses were found to be prevalent in SFBW. The results show that turbidity cannot serve as a surrogate for the microbial load of the SFBW. Alum flocculation pretreatment of SFBW was found to be effective in reducing turbidity, particle count, viruses and parasites, consequently it may also reduce membrane fouling. Settling the SFBW prior to flocculation did not enhance the removal of turbidity and particle count as compared to the unsettled SFBW samples. This finding might imply that settling would not be required prior to UF. The largest remaining particle fraction after alum flocculation was 3-10 μm in size, both Cryptosporidium and Giardia are found in this size range. Coagulation enhanced the removal of small size particles and may result in extending the filtration cycle by reducing the SFBW fouling potential.

Practical experiences from membrane filtration plants for humic substance removal

2000 ◽  
Vol 41 (10-11) ◽  
pp. 33-41 ◽  
Author(s):  
H. Ødegaard ◽  
T. Thorsen ◽  
E. Melin
Keyword(s):  
Molecular Weight ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Organic Molecules ◽  
Basic Design ◽  
Treatment Efficiency ◽  
Membrane Cleaning ◽  
Membrane Flux ◽  
Practical Experiences ◽  
Membrane Treatment

Humic substances are high molecular weight, organic molecules that give the water a yellow/brownish colour. They are normally removed from water by coagulation. During the last 10 years around 70 membrane filtration plants for drinking water supply have been built in Norway. The paper outlines the basic design of these plants and gives information on choice of membrane, treatment efficiency, membrane flux, membrane fouling, membrane cleaning and disposal of wastes as well as general operating experiences. It is concluded that the owners of the membrane filtration plants are quite satisfied and that the method will be used in increasingly larger plants.

Occurrence of EPS in activated sludge from a membrane bioreactor treating municipal wastewater

2004 ◽  
Vol 50 (12) ◽  
pp. 293-300 ◽  
Author(s):  
H. Evenblij ◽  
J.H.J.M. van der Graaf
Keyword(s):  
Activated Sludge ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Municipal Wastewater ◽  
Water Phase ◽  
Simple Filtration ◽  
Paper Filter ◽  
Influence Of Substrate ◽  
Set Up ◽  
Substrate Addition

EPS are supposed to be among the causes of membrane fouling in membrane bioreactors (MBR). In this work they are measured as total proteins and total polysaccharides. Theoretical and empirical considerations of biomass membrane filtration lead to the conclusion that EPS in the water phase is decisive for the filterability of activated sludge. In this study therefore different ways of separating the water phase from the biomass are investigated, where a simple filtration over a paper filter turned out to be sufficient. Subsequently, a simple batch test set up was used to investigate the influence of substrate conditions on the amount of EPS in the water phase. Dilution of the biomass does not result in changes. Dilution together with substrate addition leads to an increase both in proteins and polysaccharides. Replacement of the water phase leads to no significant changes in protein concentration, but polysaccharide concentration may vary considerably. This phenomenon is more pronounced after replacement of the water phase and substrate addition.

Immersed membranes activated sludge process applied to the treatment of municipal wastewater

1998 ◽  
Vol 38 (4-5) ◽  
pp. 437-442 ◽  
Author(s):  
Pierre Côté ◽  
Hervé Buisson ◽  
Matthieu Praderie
Keyword(s):  
Activated Sludge ◽  
Membrane Filtration ◽  
Municipal Wastewater ◽  
Pilot Scale ◽  
Activated Sludge Process ◽  
Hybrid Techniques ◽  
Membrane Flux ◽  
Aeration Conditions ◽  
New Generation ◽  
Better Than

An immersed membrane activated sludge process has been evaluated at pilot scale by Anjou Recherche. This process represents a new generation of hybrid techniques, which aims at coupling biological treatment and membrane filtration functions, in a configuration adapted to the treatment of municipal wastewater. The process was evaluated under extended aeration conditions, but with concentrations of biomass of between 15 to 25 gMLSS/l, which corresponded to volumetric loadings of between 1.2 to 2.3 kg COD/m3/d. Under these conditions, COD and TKN removal were better than 96% and 95%, respectively. The membrane ensured total removal of suspended solids and produced treated water of excellent bacteriological quality. The sludge production stabilized at 0.20 gDS/kg COD removed. The membrane flux was stable for all conditions tested.

Recycling of spent filter backwash water using coagulation-assisted membrane filtration: effects of submicrometre particles on membrane flux

2010 ◽  
Vol 61 (8) ◽  
pp. 1923-1929 ◽  
Author(s):  
Chihpin Huang ◽  
Jr-Lin Lin ◽  
C. L. Wu ◽  
C. P. Chu
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Zeta Potential ◽  
Pore Size ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Treatment Plant ◽  
Membrane Flux ◽  
Filter Backwash Water

Membrane separation technology has been widely used for recycling of spent filter backwash water (SFBW) in water treatment plant. Membrane filtration performance is subject to characteristics of the particles in the SFBW. A bench-scale microfiltration (MF) coupled with pre-coagulation was set up to evaluate the recovery efficiency of SFBW. Effect of particle size distribution and zeta potential of the coagulated SFBW on the membrane filtration as well as the coagulation strategies were investigated. Pore clogging was more severe on the membrane with 1.0 μm pore size than on the membrane with 0.5 μm pore size due to the fact that submicrometre particles are dominant and their diameters are exactly closed to the pore size of the MF membrane. Pre-settling induced more severe irreversible fouling because only the submicrometre particles in the water become predominant after settling, resulting in the occurrence of more acute pore blocking of membrane. By contrast, pre-coagulation mitigates membrane fouling and improves membrane flux via enlarging particle size on membrane surface. The variations of zeta potential in response to coagulant dosing as well as fractal dimension were also compared with the performance of the subsequent filtration. The result showed that pre-coagulation induced by charge neutralization at the optimum dosage where the zeta potential is around zero leads to the optimal performance of the subsequent membrane filtration for SFBW recycling. At such condition, the fractal dimension of coagulated flocs reached minimum.

Membrane foulants and fouling mechanisms in microfiltration and ultrafiltration of an activated sludge effluent

2010 ◽  
Vol 62 (9) ◽  
pp. 1975-1983 ◽  
Author(s):  
S. T. Nguyen ◽  
F. A. Roddick ◽  
J. L. Harris
Keyword(s):  
Activated Sludge ◽  
Humic Substances ◽  
Membrane Fouling ◽  
Cake Filtration ◽  
Flux Enhancement ◽  
Fouling Mechanism ◽  
Membrane Flux ◽  
Filtration Model

Membrane fouling in microfiltration (MF) and ultrafiltration (UF) of an activated sludge (AS) effluent was investigated. It was found that the major membrane foulants were polysaccharides, proteins, polysaccharide-like and protein-like materials and humic substances. MF fouling by the raw effluent was governed by pore adsorption of particles smaller than the pores during the first 30 minutes of filtration and then followed the cake filtration model. UF fouling could be described by the cake filtration model throughout the course of filtration. Coagulation with alum and (poly)aluminium chlorohydrate (ACH) altered the MF fouling mechanism to follow the cake filtration model from the beginning of filtration. The MF and UF flux improvement by coagulation was due to the removal of some of the foulants in the raw AS effluent by the coagulants. The MF flux improvement was greater for alum than for ACH whereas the two coagulants performed equally well in UF. Coagulation also reduced hydraulically irreversible fouling on the membranes and this effect was more prominent in MF than in UF. The unified membrane fouling index (UMFI) was used to quantitatively evaluate the effectiveness of coagulation on membrane flux enhancement.

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