Membrane filtration of high turbidity sources

2001 ◽  
Vol 1 (5-6) ◽  
pp. 325-330 ◽  
Author(s):  
M.A. Thompson
Keyword(s):  
Surface Water ◽  
Membrane Filtration ◽  
Suspended Solids ◽  
Water Sources ◽  
Feed Water ◽  
Membrane Systems ◽  
Water Supplies ◽  
High Turbidity ◽  
Large Water ◽  
Pressure Driven

Membrane filtration processes have become widely used for low turbidity water sources that require particle removal and disinfection. In cases where the feed water contains high turbidity levels or high fouling tendencies, pre-treatment has been required to allow the membranes to operate efficiently. Submersion membranes have allowed direct treatment on many of these water supplies but operate under vacuum. This presents limitations on operating flux and design conditions for incorporating into existing facilities. The treatment unit designs are also very expensive to implement for small water treatment applications. A recently developed pressure driven ultrafiltration (UF) membrane is being tested on several different water sources and has demonstrated exceptional operation on high turbidity feed water sources. The module design includes a single potted end with the membrane fibers looped on the bottom to allow draining of solids from the module. The UF membrane filters outside to inside and has been operated on feed water turbidity levels up to 200 ntu. The availability of a pressure driven hollow fiber membrane that can efficiently filter high suspended solids water sources can provide a cost effective solution for many small to medium sized water supplies. Conditioning the feed water with a coagulant or direct filtration of high turbidity feed water can be used depending on the organic material present without settling or other clarification process. This eliminates the need for additional structural pretreatment and reduces overall system cost and size. Current limitations include the module size that makes this cost prohibitive for very large systems. Larger membrane systems where high-suspended solids are present in the feed water have been utilizing immersion membrane technologies more and more over the past few years. These systems typically operate under a vacuum and can be used for large water treatment plants as their design allows large filtration modules such as Memcor's CMFS filter block at 880 m3/hr. This allows significant capital cost reductions and allows membrane filtration to be competitive to conventional filtration technologies for virtually all filtration applications. This paper will review the economics and performance of both pressure driven and immersion membrane systems for small to large water supply systems on feed water containing high-suspended solid levels. Actual testing data for the new pressure driven hollow fiber UF membrane and immersion membrane systems will be provided on different water supplies including unconditioned surface water, filter backwash water and coagulated surface water.

Legionella and Public Water Supplies

1988 ◽  
Vol 20 (11-12) ◽  
pp. 5-10 ◽  
Author(s):  
J. S. Colbourne ◽  
P. J. Dennis ◽  
R. M. Trew ◽  
C. Berry ◽  
G. Vesey
Keyword(s):  
Surface Water ◽  
Heat Shock ◽  
Distribution Systems ◽  
Potable Water ◽  
Water Sources ◽  
Water Supplies ◽  
Indirect Immunofluorescent Assay ◽  
Water Mains ◽  
Legionnaires Disease ◽  
Indirect Immunofluorescent

A survey for legionella in public water supplies in England failed to detect culturable L.pneumophila in all but samples from taps in buildings; however, the organism was detected in underground and surface water sources and distribution systems using an indirect immunofluorescent assay (IFA) to L.pneumophila serogroup 1. Culturability was related to water temperatures above 20°C. In water mains L.pneumophila was associated with biofilms or sediment. Non-culturable L.pneumophila detected in potable waters by IFA were recovered by heat shock experiments demonstrating their viability. Although the strain found in potable water is rarely asociated with disease, monoclonal expression, a virulence marker, was altered by heat shock. These findings have implications for the prevention of legionellosis and may explain the sporadic nature of legionnaires disease in the community.

Evaluation of a MF membrane system composed of pre coagulation-sedimentation and chlorination for water reuse

2006 ◽  
Vol 54 (10) ◽  
pp. 115-121 ◽  
Author(s):  
S.H. Lee ◽  
B.C. Lee ◽  
S.Y. Moon ◽  
Y.S. Choi ◽  
N.Y. Jang ◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
River Water ◽  
Removal Efficiency ◽  
Membrane Filtration ◽  
Transmembrane Pressure ◽  
Stable Operation ◽  
Feed Water ◽  
Promising Alternative ◽  
Sedimentation Process

In this research, we investigated the variation of transmembrane pressure and permeate water quality in pre-coagulation and sedimentation with iron based coagulant, and chlorination of feed water for PVDF (Polyvinylidene fluoride) based MF membrane filtration. NaClO was fed to the membrane module at a dosage of 0.5 mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were employed. In the case of river surface water, the transmembrane pressure increased abruptly in 500 hours operation. On the contrary, no significant increase in transmembrane pressure was observed for coagulated water and coagulated-settled water for 1200 hours operation. The turbidity of permeate was lower than the detection limit for all applied waters. The removal efficiency for humic substances in coagulated water and coagulated-settled water was approximately ten times higher than that in surface river water. And, the removal efficiency for TOC and DOC was approximately two times higher than that in surface river water. From the results of the operation, it can be observed that it is possible to maintain stable operation at 0.9 m3/m2-day filtration flux through a combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when the pre-coagulation-sedimentation process was combined with pre-chlorination. With respect to fouling reduction and operation efficiency increase in membrane filtration, the pre-coagulation/sedimentation process is a promising alternative.

scholarly journals Comparative hazard evaluation of enteric bacteria in two surface water sources in Akure, Nigeria

2020 ◽  
Vol 15 (3) ◽  
pp. 826-839
Author(s):  
A. O. Olalemi ◽  
O. M. Ige ◽  
O. T. Oladejo ◽  
O. R. Yusuf ◽  
B. Akinmolayan
Keyword(s):  
Surface Water ◽  
Water Samples ◽  
Membrane Filtration ◽  
Positive Relationship ◽  
Rank Correlation ◽  
Enteric Bacteria ◽  
Water Sources ◽  
Hazard Evaluation ◽  
Potential Health ◽  
Faecal Pollution

Abstract This study was carried out to determine the level of enteric bacteria in two surface water sources (river and stream) commonly used for domestic, recreational and agricultural purposes in Akure, Nigeria. This is to gain a better understanding of the level of faecal pollution of the water sources and the potential health risks associated with usage of the waters for human activities. Water samples were collected from the river and the stream from May to September, 2019 (n = 24). The concentration of enteric bacteria in the water samples was determined using the membrane filtration technique, while the physicochemical characteristics of the water samples were determined using the standard method. Results revealed that the concentration of Escherichia coli ranged from 3.00 to 4.78 log10 cfu/100ml and 3.48 to 5.75 log10 cfu/100ml in water samples from the river and stream respectively; Bifidobacterium ranged from 4.18 to 5.00 log10 cfu/100ml and 3.87 to 4.66 log10 cfu/100ml in water samples from the river and stream respectively; Salmonella ranged from 3.30 to 4.30 log10 cfu/100ml and 2.60 to 4.32 log10 cfu/100ml in water samples from the river and stream respectively. Water temperature ranged from 22.1 to 28.5 °C and 23.64 to 25.56 °C in the river and stream respectively; turbidity ranged from 12.28 to 29.11 NTU and 17.07 to 61.80 NTU in the river and stream respectively. Spearman's rank correlation showed that Salmonella had positive relationship with temperature (r = 0.556) in water samples from the stream whereas Bifidobacterium exhibited a positive relationship with dissolved oxygen (r = 0.557) in water samples from the river. While the stream appeared to have a higher turbidity than the river, the level of enteric bacteria in the river was higher than that in the stream. Based on microbiological water quality categories, the findings from this study demonstrated that the level of enteric bacteria in the river and stream suggests strong faecal pollution that may pose potential risks of diarrheal diseases to humans. Water from these two surface water sources must be treated before use in order to protect human health.

scholarly journals Application of Compact Piping Sedimentation Unit as Pretreatment for Ultrafiltration Plant

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Amira Mohamed Nagy ◽  
Mohamed ElHosseiny El-Nadi ◽  
Nany Ali Hassan Nasr ◽  
Hossam Mostafa Hussien
Keyword(s):  
Water Quality ◽  
Retention Time ◽  
Suspended Solids ◽  
Total Suspended Solids ◽  
Water Source ◽  
Water Sources ◽  
Feed Water ◽  
Removal Efficiencies ◽  
Inclined Plates

Abstract The study aimed to create a compact pretreatment unit before the ultrafiltration modules. This unit targeted to improve the inlet water quality to meet the average values of the feed water quality required for the ultrafiltration plants according to the manufacturer. The used unit in this study was a pipe worked as a sedimentation unit with inclined plates to apply the plate settler technology. The suitability of using this unit was determined by using varied water sources with different Total Suspended Solids (TSS) concentrations and different retention times. The removal efficiencies for the low TSS water source reached 96.47 %, 82.94 %, 64.80 % & 30.59 % with retention time 30 minutes, 15 minutes, 5 minutes & 20 seconds respectively. For the medium TSS water source at the same retention times, the removal efficiencies reached 97.33 %, 92.87 %, 86.10 % & 63.89 %. For the high TSS water source, the removal efficiencies reached 98.64 %, 93.86 %, 87.51 % & 76.23 %. These results make the sedimentation unit able to work as an effective pretreatment unit for the ultrafiltration units for all water sources.

Potential impacts of global warming on water resources in southern California

2003 ◽  
Vol 47 (7-8) ◽  
pp. 165-168 ◽  
Author(s):  
M. Beuhler
Keyword(s):  
Global Warming ◽  
Surface Water ◽  
Water Resources ◽  
Southern California ◽  
Salt Water ◽  
Scenario Planning ◽  
Potential Range ◽  
Water Supplies ◽  
Sea Levels ◽  
Rising Sea Levels

Global warming will have a significant impact on water resources within the 20 to 30-year planning period of many water projects. Arid and semi-arid regions such as Southern California are especially vulnerable to anticipated negative impacts of global warming on water resources. Long-range water facility planning must consider global climate change in the recommended mix of new facilities needed to meet future water requirements. The generally accepted impacts of global warming include increased temperature, rising sea levels, more frequent and severe floods and droughts, and a shift from snowfall to rain. Precipitation changes are more difficult to predict. For Southern California, these impacts will be especially severe on surface water supplies. Additionally, rising sea levels will exacerbate salt-water intrusion into freshwater and impact the quality of surface water supplies. Integrated water resources planning is emerging as a tool to develop water supplies and demand management strategies that are less vulnerable to the impacts of global warming. These tools include water conservation, reclamation, conjunctive use of surface and groundwater and desalination of brackish water and possibly seawater. Additionally, planning for future water needs should include explicit consideration of the potential range of global warming impacts through techniques such as scenario planning.

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