scholarly journals Coagulation/flocculation prior to low pressure membranes in drinking water treatment: a review

2020 ◽  
Vol 6 (11) ◽  
pp. 2993-3023
Author(s):  
Tyler A. Malkoske ◽  
Pierre R. Bérubé ◽  
Robert C. Andrews
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Drinking Water Treatment ◽  
Low Pressure ◽  
Floc Properties ◽  
The Impact

Coagulation/flocculation has been grouped into three typical configurations and the impact of each examined in terms of floc properties and membrane fouling.

scholarly journals Application of Coagulation–Membrane Rotation to Improve Ultrafiltration Performance in Drinking Water Treatment

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 643
Author(s):  
Hongjian Yu ◽  
Weipeng Huang ◽  
Huachen Liu ◽  
Tian Li ◽  
Nianping Chi ◽  
...  
Keyword(s):  
Shear Stress ◽  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Drinking Water Treatment ◽  
Permeate Flux ◽  
Organic Removal ◽  
Cake Layer ◽  
The Impact

The combination of conventional and advanced water treatment is now widely used in drinking water treatment. However, membrane fouling is still the main obstacle to extend its application. In this study, the impact of the combination of coagulation and ultrafiltration (UF) membrane rotation on both fouling control and organic removal of macro (sodium alginate, SA) and micro organic matters (tannic acid, TA) was studied comprehensively to evaluate its applicability in drinking water treatment. The results indicated that membrane rotation could generate shear stress and vortex, thus effectively reducing membrane fouling of both SA and TA solutions, especially for macro SA organics. With additional coagulation, the membrane fouling could be further reduced through the aggregation of mediate and macro organic substances into flocs and elimination by membrane retention. For example, with the membrane rotation speed of 60 r/min, the permeate flux increased by 90% and the organic removal by 35% in SA solution, with 40 mg/L coagulant dosage, with an additional 70% increase of flux and 5% increment of organic removal to 80% obtained. However, too much shear stress could intensify the potential of fiber breakage at the potting, destroying the flocs and resulting in the reduction of permeate flux and deterioration of effluent quality. Finally, the combination of coagulation and membrane rotation would lead to the shaking of the cake layer, which is beneficial for fouling mitigation and prolongation of membrane filtration lifetime. This study provides useful information on applying the combined process of conventional coagulation and the hydrodynamic shear force for drinking water treatment, which can be further explored in the future.

Fouling of low-pressure membranes during drinking water treatment: effect of NOM components and biofiltration pretreatment

2013 ◽  
Vol 14 (3) ◽  
pp. 453-460 ◽  
Author(s):  
I. Rahman ◽  
S. Ndiongue ◽  
X. Jin ◽  
M. I. Van Dyke ◽  
W. B. Anderson ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Drinking Water Treatment ◽  
Low Pressure ◽  
Pilot Scale ◽  
Substantial Improvement ◽  
Raw Water ◽  
Minimal Impact ◽  
Detection Analysis

Fouling is a major challenge for low-pressure membrane drinking water treatment systems. Previous research has demonstrated that under the right conditions, biofiltration is an effective method to reduce fouling of low-pressure polymeric membranes. This study provides additional insight into the effect of biofiltration as a pretreatment for fouling reduction by using river water with different raw water quality characteristics than has been examined in previous studies. Two parallel pilot-scale dual media (sand/anthracite) biological filters were operated continuously over a period of 14 months. Liquid chromatography–organic carbon detection analysis confirmed that the parallel biofilters performed similarly with both averaging on 21% biopolymer removal. Raw and treated water biopolymer concentrations were correlated, with increased absolute removals occurring at higher raw water concentrations. Ultrafiltration (UF) membrane fouling experiments showed substantial improvement in performance following biofiltration pretreatment by reducing hydraulically irreversible and reversible fouling rates by 14–68% and 8–55%, respectively. The results also reaffirm the importance of biopolymers at concentrations as low as ∼0.1 mg/L on irreversible and reversible UF membrane fouling and a minimal impact of humic substances.

Coupling continuous sand filtration to ultrafiltration for drinking water treatment: Improved performance and membrane fouling control

2018 ◽  
Vol 567 ◽  
pp. 18-27 ◽  
Author(s):  
Yuanqing Guo ◽  
Langming Bai ◽  
Xiaobin Tang ◽  
Qiaojin Huang ◽  
Binghan Xie ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Drinking Water Treatment ◽  
Sand Filtration ◽  
Fouling Control ◽  
Improved Performance

scholarly journals Improving chemical cleaning of fouled membranes in a drinking water treatment plant

2019 ◽  
Vol 19 (8) ◽  
pp. 2330-2337
Author(s):  
Susumu Hasegawa ◽  
Yasuhiro Tanaka ◽  
Naokazu Wake ◽  
Ryosuke Takagi ◽  
Hideto Matsuyama
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Humic Substances ◽  
Sodium Hypochlorite ◽  
Membrane Fouling ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Water Treatment Plant ◽  
Chemical Cleaning ◽  
Water Treatment Plants

Abstract Recently, membrane filtration systems have become increasingly common in drinking water treatment plants. In this industry, preventing membrane fouling is of utmost importance. Many studies on the relationship between raw water components and membrane fouling have been performed in laboratory conditions. However, very few studies have analyzed the components of foulants on the fouled membrane as operated in actual drinking water treatment plants. By analyzing these components in plant-conditions, membrane fouling will be more effectively prevented. In this study, we analyzed the components of foulants extracted with 0.1 N NaOH from a fouled membrane operated in a drinking water treatment plant in Japan. Our analysis revealed that the main foulants were humic substances. In order to dissolve the accumulated humic substances, additional chemical cleaning was attempted with 500 ppm sodium hypochlorite. As a result, it was found that humic substances were dissolved and filtration resistance significantly decreased. Additionally, the removal of inorganic foulants was also greater after chemical cleaning with 500 ppm sodium hypochlorite, as inorganic foulants trapped within humic substances were released to the membrane surface as hydroxides by the additional sodium hypochlorite cleaning and were dissolved by the periodic citric acid cleaning.

scholarly journals Bacterial Colonization of Pellet Softening Reactors Used during Drinking Water Treatment

2010 ◽  
Vol 77 (3) ◽  
pp. 1041-1048 ◽  
Author(s):  
Frederik Hammes ◽  
Nico Boon ◽  
Marius Vital ◽  
Petra Ross ◽  
Aleksandra Magic-Knezev ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Organic Carbon ◽  
Bacterial Colonization ◽  
Flow Cytometric Analysis ◽  
Drinking Water Treatment ◽  
Strong Base ◽  
Water Treatment Process ◽  
Chemically Induced ◽  
The Impact

ABSTRACTPellet softening reactors are used in centralized and decentralized drinking water treatment plants for the removal of calcium (hardness) through chemically induced precipitation of calcite. This is accomplished in fluidized pellet reactors, where a strong base is added to the influent to increase the pH and facilitate the process of precipitation on an added seeding material. Here we describe for the first time the opportunistic bacterial colonization of the calcite pellets in a full-scale pellet softening reactor and the functional contribution of these colonizing bacteria to the overall drinking water treatment process. ATP analysis, advanced microscopy, and community fingerprinting with denaturing gradient gel electrophoretic (DGGE) analysis were used to characterize the biomass on the pellets, while assimilable organic carbon (AOC), dissolved organic carbon, and flow cytometric analysis were used to characterize the impact of the biological processes on drinking water quality. The data revealed pellet colonization at concentrations in excess of 500 ng of ATP/g of pellet and reactor biomass concentrations as high as 220 mg of ATP/m3of reactor, comprising a wide variety of different microorganisms. These organisms removed as much as 60% of AOC from the water during treatment, thus contributing toward the biological stabilization of the drinking water. Notably, only a small fraction (about 60,000 cells/ml) of the bacteria in the reactors was released into the effluent under normal conditions, while the majority of the bacteria colonizing the pellets were captured in the calcite structures of the pellets and were removed as a reusable product.

Pretreatment Process of Nanofiltration for Silting Density Index Reduction in Drinking Water Treatment System

2013 ◽  
Vol 777 ◽  
pp. 467-471 ◽  
Author(s):  
Liang Wang ◽  
Ying Chun Li ◽  
He Zhao ◽  
Zhao Hui Zhang ◽  
Bin Zhao ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Membrane Fouling ◽  
Sodium Dodecyl ◽  
Drinking Water Treatment ◽  
Hybrid Process ◽  
Transmembrane Pressure ◽  
Sand Filtration ◽  
Density Index ◽  
One Year

Calcium ions, magnesium ions, and silicate were the main reasons for the high silting density index (SDI) of natural waters. Therefore, they posed serious membrane fouling problems in the nanofiltration (NF) system, which restricted the wide application of this excellent drinking water treatment technology. In this study, the sand filtration and the micro-flocculation/sand filtration hybrid process were investigated as the pretreatment process of NF for SDI reduction. Compared with the sand filtration, the hybrid process of micro-flocculation/sand filtration was more effective for SDI reduction. When polyaluminium chloride (PAC) was used as the flocculant at a dose of 10 mg/L and the filtration rate of the sand filter was controlled at 10 m/h, the SDI value in the effluent of the pretreatment process maintained below 3. As a result, the subsequent NF system stably ran for one year. 68% CODMn was removal by NF. The membrane fouling during the operation was quite slight as the transmembrane pressure (TMP) increased by 17% after one-year use. Chemical cleaning with sodium tripolyphosphate (2%) and sodium dodecyl benzene sulfonate (0.25%) at 6 months interval could effectively recover the flux loss of the NF membrane.

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