A cost optimization study of flux and fouling rate for UF in the water industry

2008 ◽  
Vol 8 (1) ◽  
pp. 113-120 ◽  
Author(s):  
G. K. Pearce
Keyword(s):  
Membrane Fouling ◽  
Cost Optimization ◽  
Plant Size ◽  
Operating Pressure ◽  
High Flux ◽  
Chemical Cleaning ◽  
Critical Flux ◽  
Membrane Area ◽  
Optimization Study ◽  
The Relationship

Designing a commercial UF/MF system is an exercise in compromise. Selecting a high flux reduces capex by minimizing the membrane area required, but increases operating costs due to the increased chemical cleaning frequency, higher waste disposal volumes, and higher operating pressure. Most commercial systems are designed to run at fluxes significantly above the critical flux, so a degree of fouling and a reliance on chemical cleaning is inherent to the design. This paper examines the relationship between flux and membrane fouling rate through a review of experimental field data. The analysis shows that fouling rate increases exponentially with flux, with a function dependent upon the characteristics of the feed. The paper then presents the results of a cost optimization study in which Total Water Cost (TWC) is evaluated as a function of feed source and plant size for different CIP cleaning frequencies. The minimum TWC occurs in all cases for CIP frequencies of between 1/week and 1/month. Smaller plants with low fouling feeds have an optimum near 1 CIP/week using a relatively high flux design. In contrast, feeds with higher fouling propensity, and medium or large plant sizes have a TWC optimum close to 1 CIP/month, and should use a lower design flux. It is suggested that the flux corresponding to the TWC optimum should be designated the sustainable flux.

Monitoring of transparent exopolymer particles (TEP) in a membrane bioreactor (MBR) and correlation with other fouling indicators

2008 ◽  
Vol 58 (10) ◽  
pp. 1903-1909 ◽  
Author(s):  
T. de la Torre ◽  
B. Lesjean ◽  
A. Drews ◽  
M. Kraume
Keyword(s):  
Linear Correlation ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Membrane Systems ◽  
Transparent Exopolymer Particles ◽  
Critical Flux ◽  
Capillary Suction ◽  
Acidic Fraction ◽  
The Relationship

The occurrence of Transparent Exopolymer Particles (TEP), an acidic fraction of polysaccharides, was monitored for more than six months in the activated sludge of three MBR units, and the relationship between TEP and other fouling indicators was studied. These compounds consist mainly of exopolysaccharides of a sticky nature, a characteristic which makes them a group of interesting substances in processes like sedimentation, flocculation and membrane fouling. The relationship between capillary suction time (CST) and polysaccharides (PS) was linear for the three tested sludges, although the correlation with TEP concentrations was stronger. A slight linear correlation of both TEP and PS was found with the critical flux (CF) measured with a small filtration test cell, which was submerged in the membrane tank to assess the filterability performance of the sludge in situ. However, the correlation CF-PS was clearer. The relationship between TEP, polysaccharides and sludge filterability highlights the potential of this parameter for the monitoring of membrane systems.

scholarly journals Clinical Autopsy of a Reverse Osmosis Membrane Module

2021 ◽  
Vol 3 ◽  
Author(s):  
Graciela Gonzalez-Gil ◽  
Ali Reza Behzad ◽  
Andreia S. F. Farinha ◽  
Chengyan Zhao ◽  
Szilard S. Bucs ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Full Scale ◽  
Operating Pressure ◽  
Reverse Osmosis Membrane ◽  
Polysulfone Membrane ◽  
Membrane Area ◽  
Microbial Cells ◽  
Imaging Results ◽  
Starting Point

The desalination of seawater using reverse osmosis membranes is an attractive solution to global freshwater scarcity. However, membrane performance is reduced by (bio)fouling. Membrane autopsies are essential for identifying the type of fouling material, and applying corrective measures to minimize membrane fouling. Information from full-scale membrane autopsies guiding improved plant operations is scant in the formal literature. In this case-study, a reverse osmosis membrane from a full-scale seawater desalination plant with a feed channel pressure drop increase of about 218% over the pressure vessel was autopsied. The simultaneous determination of microbial cells, ATP, and total organic carbon (TOC) abundances per membrane area allowed estimating the contributions of biofouling and organic fouling. The abundance of microbial cells determined by flow cytometry (up to 7 × 108 cells/cm2), and ATP (up to 21,000 pg/cm2) as well as TOC (up to 98 μg/cm2) were homogeneously distributed on the membrane. Inorganic fouling was also measured, and followed a similar coverage distribution to that of biofouling. Iron (∼150 μg/cm2, estimated by ICP-MS) was the main inorganic foulant. ATR-FTIR spectra supported that membrane fouling was both organic/biological and inorganic. High-resolution SEM-EDS imaging of cross-sectioned membranes allowed assessing the thickness of the fouling layer (up to 20 μm) and its elemental composition. Imaging results further supported the results of homogeneous fouling coverage. Moreover, imaging revealed both zones with and without compression of the polysulfone membrane layer, suggesting that the stress due to operating pressure was heterogeneous. The procedure for this membrane autopsy provided a reasonable overview of the diverse contributors of fouling and might be a starting point to building a consensus autopsy protocol. Next, it would be valuable to build a RO membrane autopsy database, which can be used as a guidance and diagnostic tool to improve the management and operation of RO desalination plants.

The Relationship between Critical Flux and Membrane Fouling

2014 ◽  
Vol 535 ◽  
pp. 675-678
Author(s):  
Wei Ying Li ◽  
Jun Peng Zhang ◽  
Wen Ming Li
Keyword(s):  
Membrane Fouling ◽  
Sand Filtration ◽  
Short Term ◽  
Step Method ◽  
Critical Flux ◽  
Surface Features ◽  
On Line ◽  
The Relationship

The critical flux was chosen to show surface features of the membrane fouling and it was determined by the flux-step method. The critical flux of on-line coagulation-UF, sedimentation-UF and sand filtration-UF was investigated and its value was 86.5 L/m2h80.5L/m2h and 68.1L/m2h, respectively. At the same time, the increasing rate of TMP were always lower than the corresponding values measured for the short-term flux-step experiments.

The relationship between critical flux and fibre movement induced by bubbling in a submerged hollow fibre system

2005 ◽  
Vol 51 (6-7) ◽  
pp. 115-122 ◽  
Author(s):  
F. Wicaksana ◽  
A.G. Fan ◽  
V. Chen
Keyword(s):  
Membrane Fouling ◽  
Hollow Fibre ◽  
Transmembrane Pressure ◽  
Feed Concentration ◽  
Critical Flux ◽  
Improved Performance ◽  
Qualitative Relationship ◽  
The Relationship ◽  
Mechanical Movement ◽  
Fibre Characteristics

Bubbling has been used to enhance various processes. In this paper we deal with the effect of bubbling on submerged hollow fibre membranes, where bubbling is applied to prevent severe membrane fouling. Previous work with submerged hollow fibres has observed that significant fibre movement can be induced by bubbling and that there is a qualitative relationship between fibre movement and filtration performance. Therefore, the aim of the present research has been to analyse the link between bubbling, fibre movement and critical flux, identified as the flux at which the transmembrane pressure (TMP) starts to rise. Tests were performed on vertical isolated fibres with a model feed of yeast suspension. The fibres were subject to steady bubbling from below. The parameters of interest were the fibre characteristics, such as tightness, diameter and length, as well as feed concentration. The results confirmed that the critical fluxes are affected by the fibre characteristics and feed concentration. Higher critical flux values can be achieved by using loose fibres, smaller diameters and longer fibres. The enhancement is partially linked to fibre movement and this is confirmed by improved performance when fibres are subject to mechanical movement in the absence of bubbling.

Studies on Fouling and its Prevention in MBRs

2010 ◽  
Vol 5 (2) ◽  
Author(s):  
B. Siembida ◽  
P. Cornel ◽  
S. Krause ◽  
B. Zimmermann
Keyword(s):  
Activated Sludge ◽  
Membrane Fouling ◽  
Membrane Bioreactors ◽  
High Flux ◽  
Chemical Cleaning ◽  
Sustainable Operation ◽  
The One ◽  
The Impact ◽  
Very High ◽  
Mechanical Cleaning

Investigations of fouling alleviation and permeability decline in membrane bioreactors (MBR) were carried out at two pilot plants. On the one hand, the minimization of membrane fouling via adding abrasive granulates into activated sludge (submerged operated membrane) was tested. On the other hand, the impact of truly soluble compounds released into the liquid phase of activated sludge on fouling behavior was investigated. The first research into the impact of mechanical cleaning via adding granulates showed the unwanted formation of fouling layers was reduced as a result of abrasion processes. With this method continuous sustainable operation was achieved, without chemical cleaning and, at the same time, reaching very high flux levels up to 40 L/(m2·h) over more than 500 days (>16 months). The investigation of the effect of truly soluble compounds on membrane fouling showed that the permeability decline during 145 days of operation resulted predominantly from wastewater or activated sludge matter larger than 0.04 μm.

Designing CO2 Transmission Pipelines Without Crack Arrestors

2010 ◽  
Author(s):  
Graeme G. King ◽  
Satish Kumar
Keyword(s):  
Wall Thickness ◽  
Carbon Capture ◽  
Power Plants ◽  
Oil And Gas ◽  
Cost Optimization ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Design Work ◽  
Industrial Facilities ◽  
Pipeline Network

Masdar is developing several carbon capture projects from power plants, smelters, steel works, industrial facilities and oil and gas processing plants in Abu Dhabi in a phased series of projects. Captured CO2 will be transported in a new national CO2 pipeline network with a nominal capacity of 20×106 T/y to oil reservoirs where it will be injected for reservoir management and sequestration. Design of the pipeline network considered three primary factors in the selection of wall thickness and toughness, (a) steady and transient operating conditions, (b) prevention of longitudinal ductile fractures and (c) optimization of total project owning and operating costs. The paper explains how the three factors affect wall thickness and toughness. It sets out code requirements that must be satisfied when choosing wall thickness and gives details of how to calculate toughness to prevent propagation of long ductile fracture in CO2 pipelines. It then uses cost optimization to resolve contention between the different requirements and arrive at a safe and economical pipeline design. The design work selected a design pressure of 24.5 MPa, well above the critical point for CO2 and much higher than is normally seen in conventional oil and gas pipelines. Despite its high operating pressure, the proposed network will be one of the safest pipeline systems in the world today.

Optimization Study Based on the Mileage-Saving Method of Oil Distribution

2013 ◽  
Vol 779-780 ◽  
pp. 1805-1808
Author(s):  
Min Jie Zhu ◽  
Jian Wei Zhang
Keyword(s):  
Vehicle Scheduling ◽  
Oil Distribution ◽  
Optimization Study ◽  
Load Limit ◽  
Distribution Cost ◽  
The Relationship

In this paper,in view of the relationship between the distribution cost and the optimization path for oil distribution, based on the load limit of the vehicle scheduling, we tried to study the optimization path for oil distribution by the method of the mileage-saving. Keywords: Oil Distribution, Distribution Path, Distribution Cost, Mileage-saving Method

Orange juice ultrafiltration: characterisation of deposit layers and membrane surfaces after fouling and cleaning

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nurul Hainiza Abd-Razak ◽  
Y. M. John Chew ◽  
Michael R. Bird
Keyword(s):  
Shear Stress ◽  
Orange Juice ◽  
Surface Coverage ◽  
Fluid Shear Stress ◽  
Membrane Surface ◽  
Regenerated Cellulose ◽  
Fluid Shear ◽  
Chemical Cleaning ◽  
Membrane Area ◽  
Software Analysis

Abstract The influence of feed condition and membrane cleaning during the ultrafiltration (UF) of orange juice for phytosterol separation was investigated. UF was performed using regenerated cellulose acetate (RCA) membranes at different molecular weight cut-off (MWCO) values with a 336 cm2 membrane area and a range of temperatures (10–40 °C) and different feed volumes (3–9 L). Fluid dynamic gauging (FDG) was applied to assess the fouling and cleaning behaviours of RCA membranes fouled by orange juice and cleaned using P3-Ultrasil 11 over two complete cycles. During the FDG testing, fouling layers were removed by fluid shear stress caused by suction flow. The cleanability was characterised by using ImageJ software analysis. A Liebermann-Buchard-based method was used to quantify the phytosterol content. The results show that RCA 10 kDa filters exhibited the best separation of phytosterols from protein in orange juice at 20 °C using 3 L feed with a selectivity factor of 17. Membranes that were fouled after two cycles showed higher surface coverage compared to one fouling cycle. The surface coverage decreased with increasing fluid shear stress from 0 to 3.9 Pa. FDG achieved 80–95% removal at 3.9 Pa for all RCA membranes. Chemical cleaning using P3-Ultrasil 11 altered both the membrane surface hydrophobicity and roughness. These results show that the fouling layer on RCA membranes can be removed by fluid shear stress without affecting the membrane surface modification caused by chemical cleaning.

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