A kinetic model for calculating total membrane fouling resistance in chemical cleaning process

Membrane fouling is one of the main drawbacks encountered during the practical application of membrane separation processes. Cleaning of a membrane is important to reduce fouling and improve membrane performance. Accordingly, an effective cleaning method is currently of crucial importance for membrane separation processes in water treatment. To clean the fouling and improve the overall efficiency of membranes, deep research on the cleaning procedures is needed. So far, physical, chemical, or combination techniques have been used for membrane cleaning. In the current work, we critically reviewed the fouling mechanisms affecting factors of fouling such as the size of particle or solute; membrane microstructure; the interactions between membrane, solute, and solvent; and porosity of the membrane and also examined cleaning methods of microfiltration (MF) membranes such as physical cleaning and chemical cleaning. Herein, we mainly focused on the chemical cleaning process. Factors affecting the chemical cleaning performance, including cleaning time, the concentration of chemical cleaning, and temperature of the cleaning process, were discussed in detail. This review is carried out to enable a better understanding of the membrane cleaning process for an effective membrane separation process.

Download Full-text

Applicability of Chemical Cleaning Process to Steam Generator Secondary Side, (I)

Journal of Nuclear Science and Technology ◽

10.1080/18811248.2004.9715456 ◽

2004 ◽

Vol 41 (1) ◽

pp. 44-54 ◽

Cited By ~ 8

Author(s):

Kazutoshi FUJIWARA ◽

Hirotaka KAWAMURA ◽

Hiromi KANBE ◽

Hideo HIRANO ◽

Hideki TAKIGUCHI ◽

...

Keyword(s):

Steam Generator ◽

Cleaning Process ◽

Chemical Cleaning ◽

Secondary Side

Download Full-text

TREATMENT TANK CORROSION STUDIES FOR THE ENHANCED CHEMICAL CLEANING PROCESS

10.2172/1023279 ◽

2011 ◽

Author(s):

B. Wiersma

Keyword(s):

Cleaning Process ◽

Chemical Cleaning ◽

Treatment Tank ◽

Corrosion Studies

Download Full-text

Optimal Water Backwashing Condition in Combined Water Treatment of Alumina Microfiltration and PP Beads

Membranes ◽

10.3390/membranes12010092 ◽

2022 ◽

Vol 12 (1) ◽

pp. 92

Author(s):

Hyungmin Cho ◽

Gihoon Yoon ◽

Minjae Kim ◽

Jin Yong Park

Keyword(s):

Water Treatment ◽

Membrane Fouling ◽

Treatment Process ◽

Membrane Separation ◽

Combined Process ◽

Water Treatment Process ◽

A Minor ◽

Membrane Shape ◽

Tubular Membranes ◽

Total Membrane

Membrane fouling is a dominant limit of the membrane separation process. In this research, the optimal water backwashing to solve the membrane fouling problem was investigated in the combined water treatment process of alumina MF and pure polypropylene (PP) beads. Additionally, the influence of membrane shape (tubular or seven channel) was examined, depending on the water backwashing period. The optimal backwashing time (BT) could be 20 s in the combined water treatment process, because of the highest total treated volume (VT) in our BT 6–30 s conditions. The optimal backwashing period (BP) could be 6 min, because of the minimum membrane fouling and the maximum VT in the combined process of tubular alumina MF and PP beads. The resistance of reversible membrane fouling (Rrf) showed a major resistance of total membrane fouling, and that of irreversible membrane fouling (Rif) was a minor one, in the combined process using tubular or seven channel MF. The Rif showed a decreasing trend obviously, as decreasing BT from NBW to 2 min for seven channel MF. It means that the more frequent water backwashing could be more effective to control the membrane fouling, especially irreversible fouling, for seven channel membranes than tubular membranes.

Download Full-text

Removal Characteristics of N-Nitrosamines and Their Precursors by Pilot-Scale Integrated Membrane Systems for Water Reuse

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph15091960 ◽

2018 ◽

Vol 15 (9) ◽

pp. 1960 ◽

Cited By ~ 11

Author(s):

Haruka Takeuchi ◽

Naoyuki Yamashita ◽

Norihide Nakada ◽

Hiroaki Tanaka

Keyword(s):

Membrane Fouling ◽

Water Reuse ◽

Pilot Scale ◽

Feed Water ◽

Water Reclamation ◽

Size Distributions ◽

Membrane Systems ◽

Chemical Cleaning ◽

Ro Membrane ◽

Feed Water Temperature

This study investigated the removal characteristics of N-Nitrosamines and their precursors at three pilot-scale water reclamation plants. These plants applies different integrated membrane systems: (1) microfiltration (MF)/nanofiltration (NF)/reverse osmosis (RO) membrane; (2) sand filtration/three-stage RO; and (3) ultrafiltration (UF)/NF and UF/RO. Variable removal of N-Nitrosodimethylamine (NDMA) by the RO processes could be attributed to membrane fouling and the feed water temperature. The effect of membrane fouling on N-Nitrosamine removal was extensively evaluated at one of the plants by conducting one month of operation and chemical cleaning of the RO element. Membrane fouling enhanced N-Nitrosamine removal by the pilot-scale RO process. This finding contributes to better understanding of the variable removal of NDMA by RO processes. This study also investigated the removal characteristics of N-Nitrosamine precursors. The NF and RO processes greatly reduced NDMA formation potential (FP), but the UF process had little effect. The contributions of MF, NF, and RO processes for reducing FPs of NDMA, N-Nitrosopyrrolidine and N-Nitrosodiethylamine were different, suggesting different size distributions of their precursors.

Download Full-text

Optimization of In Situ Backwashing Frequency for Stable Operation of Anaerobic Ceramic Membrane Bioreactor

Processes ◽

10.3390/pr8050545 ◽

2020 ◽

Vol 8 (5) ◽

pp. 545 ◽

Cited By ~ 1

Author(s):

Rathmalgodage Thejani Nilusha ◽

Tuo Wang ◽

Hongyan Wang ◽

Dawei Yu ◽

Junya Zhang ◽

...

Keyword(s):

Membrane Fouling ◽

Membrane Filtration ◽

Membrane Bioreactor ◽

Ceramic Membrane ◽

Pure Water ◽

Ex Situ ◽

Stable Operation ◽

Chemical Cleaning ◽

Cake Layer

The cost-effective and stable operation of an anaerobic ceramic membrane bioreactor (AnCMBR) depends on operational strategies to minimize membrane fouling. A novel strategy for backwashing, filtration and relaxation was optimized for stable operation of a side stream tubular AnCMBR treating domestic wastewater at the ambient temperature. Two in situ backwashing schemes (once a day at 60 s/day, and twice a day at 60 s × 2/day) maintaining 55 min filtration and 5 min relaxation as a constant were compared. A flux level over 70% of the initial membrane flux was stabilized by in situ permeate backwashing irrespective of its frequency. The in situ backwashing by permeate once a day was better for energy saving, stable membrane filtration and less permeate consumption. Ex situ chemical cleaning after 60 days’ operation was carried out using pure water, sodium hypochlorite (NaOCl), and citric acid as the order. The dominant cake layer was effectively reduced by in situ backwashing, and the major organic foulants were fulvic acid-like substances and humic acid-like substances. Proteobacteria, Firmucutes, Epsilonbacteria and Bacteroides were the major microbes attached to the ceramic membrane fouling layer which were effectively removed by NaOCl.

Download Full-text

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

Water Science & Technology Water Supply ◽

10.2166/ws.2019.114 ◽

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.

Download Full-text