Nanofiltration has been widely recognized as a promising technology for the removal of micromolecular organic components from natural water. This research mainly investigated the potential use of sodium hydroxide naoh and \ud sodium hypochlorite naocl as the chemical cleaning agents to restore the permeate flux of organically fouled nanofiltration nf. In other words, operating under fo mode may offer an extraordinary advantage of significantly reducing or. Membrane chemical cleaning is an integral part of operation for microand ultrafiltration systems in the water industry and has significant impact on process operations. Nanofiltration methods for removal of some organic. Membrane fouling, chemical cleaning and separation performance assessment of a chlorineresistant nanofiltration membrane for water recycling applications.
Precise nanofiltration in a foulingresistant selfassembled membrane with. Natural organic matter fouling behaviors on superwetting. Fouling and cleaning experiments were performed with organic foulants that simulate effluent organic matter and selected cleaning agents using a laboratoryscale crossflow test unit. May 08, 2018 to find the optimum chemical cleaning efficiency of edta on the dense organic fouling layer in crossflow mode, the steps used to form the dense fouling layer and the membrane cleaning procedure are as follows. To unravel the mechanisms of organic fouling and chemical cleaning, it is critical to understand the foulantmembrane, foulantfoulant, and foulantcleaning agent interactions at the molecular level. If normalized membrane performance drops 30 to 50%, it may be impossible to fully restore the performance back to baseline conditions. Pdf natural organic matter fouling and chemical cleaning. Li and others published revealing the mechanisms of organic fouling and chemical cleaning of nanofiltration membranes find, read and cite all the research you. Awc c225 iron reducing agent for removal of ferric hydroxide fouling during membrane cleaning. In general, chemical cleaning can be broadly classified based on cleaning agents into six categories.
Removal of organic matter from soft water by loose. Department of civil, construction, and environmental engineering, oregon state university, corvallis, oregon 97331, and department of chemical engineering, environmental engineering program, yale university, new haven, connecticut 065208286. Effect of fouling on removal of trace organic compounds by. Cleaning inplace was conducted by flushing and soaking the fouled membranes with a solution of an alkali and an acidic cleaning agent. Fouling layer measurements included total organic carbon toc, adenosine triphosphate, polysaccharides, proteins, and heterotrophic plate counts. Thesis submitted in a partial fulfilment of the requirements for the degree of master of science in technology. This paper examines the chemical cleaning inplace of fouling formed on three flat sheet membranes mw, cq, and gm during uf of rendering plant secondary effluent. Cleaninginplace was conducted by flushing and soaking the fouled membranes with a solution of an alkali and an acidic cleaning agent. Ro and nf membranes have very rough surfaces and a high chemical affinity for oil and other organic components of produced water, characteristics causing their extreme susceptibility to surface fouling by organics. Chemical cleaning agents especially like alkaline cleaners are most widely employed to restore the membrane performance. Additionally, in all membrane cleaning processes, operation needs to be stopped before the backwash begins for microfiltration ultrafiltration and chemical cleaning or direct osmosis cleaning begins for ro or nf 15. Optimization of chemical cleaning of organicfouled.
Thesis submitted in a partial fulfilment of the requirements for the. Unesco eolss sample chapters water and wastewater treatment technologies membrane technology for organic removal in wastewater h. Pdf fouling and subsequent chemical cleaning are two important issues for sustainable operation of nanofiltration nf membranes in water quality. Precise nanofiltration in a foulingresistant selfassembled. Selecting membrane cleaning methods and materials having dealt with reverse osmosis system design and configuration factors in the first part of this fourpart series on membrane cleaning, and the problems of fouling in part 2, the author now turns to chemical methods for cleaning these systems. Organic fouling and chemical cleaning of nanofiltration. Natural organic matter fouling and chemical cleaning of. Unlike ro, which needs chemical cleaning reagents to loosen the compact fouling layer, fo achieves much higher cleaning efficiency by simple physical scouring. Inorganic fouling or scaling is caused by the accumulation of particles when the concentration of the chemical species exceeds its saturation. Chemical cleaning of nanofiltration membranes fouled by organic matters 993 journal of engineering science and technology july 2016, vol. Fouling and cleaning characteristics of reverse osmosis ro.
Awc c226 high ph powder cleaning chemical for ro membrane cleaning. Natural organic matter nom, a very important precursor of disinfection byproducts, is currently considered as the major cause of membrane fouling. Cho encyclopedia of life support systemseolss uf refers to membranes that have pore diameters from 0. Severe fouling may require intense chemical cleaning or membrane replacement. From art to science charles liu, scott caothien, jennifer hayes, tom caothuy scientific and laboratory services, pall corporation, 25 harbor park dr. This paper examines the chemical cleaninginplace of fouling formed on three flat sheet membranes mw, cq, and gm during uf of rendering plant secondary effluent. Fouling studies of a polyamide nanofiltration membrane by. Because fouling strongly depends on the feed water quality, especially the ionic composition. Nanofiltration involves the removal of dissolved or suspended solutes ranging from 1 to 10 nm in size. However, this issue has not been adequately addressed primarily for two reasons. Chemical cleaning, typically utilizing citric acid, is the primary means of removing foulants in nf systems. Hydraulically reversible fouling can be removed physically e. Optimization of chemical cleaning of organicfouled reverse.
Chemical use scale inhibitor and caustic may be required for process control to prevent scaling or fouling. Tannic acid was used as a model organic foulant for natural organic matter analysis since the main characteristics are similar, and calcium ions were added at different concentrations to explore the antipollution capability of fo membranes. Chemical cleaning frequency depends on feed water quality. In the case of mineral fouling, chemical cleaning agents are used.
Membrane cleaning is triggered when certain operating conditions are exceeded, and may require the use of naoh, na 4edta, hcl, na 2s 2o 4, or h 2o 2. This increases the operating costs of a treatment plant. Doc as an indicator for organic fouling is probably neither proper nor adequate. The applicability of salt cleaning for control of membrane. Membrane technology for organic removal in wastewater. Request pdf organic fouling and chemical cleaning of nanofiltration membranes. Novel foulingreducing coatings for ultrafiltration. In other words, operating under fo mode may offer an extraordinary advantage of significantly reducing or even eliminating the use of chemical cleaning.
Chemical and physical aspects of cleaning of organicfouled reverse osmosis membranes. Fouling and subsequent chemical cleaning are two important issues for sustainable operation of nanofiltration nf membranes in water quality control applications. Novel foulingreducing coatings for ultrafiltration, nanofiltration, and reverse osmosis membranes. Fouling in membrane filtration and remediation methods.
This research mainly investigated the potential use of sodium hydroxide naoh and\ud sodium hypochlorite naocl as the chemical cleaning agents to restore the permeate flux of organically fouled nanofiltration nf. Hajibabania et al effect of fouling on removal of trace organic compounds by nf 73 figure 1. To unravel the mechanisms of organic fouling and chemical cleaning, it is critical to understand the foulant. Separation and purification technology, 189 170175. Avoiding and controlling fouling is the most important challenge for successful membrane filtration. Cellulose acetate membranes do not tolerate low or high ph values, whereas polyamide membranes generally can be cleaned down. Reactive micromixing eliminates fouling and concentration. A physical impact of organic fouling layers on bacterial. The fouling behavior during forward osmosis fo was investigated. Membrane fouling and chemical cleaning in three fullscale. The high fouling potential of this water also makes it difficult for the nf membrane to maintain stable performance over the life of the membrane. Heffernan r1, habimana o1, semiao aj2, cao h1, safari a1, casey e3.
Accelerated fouling conditions were achieved with foulant. It is a major obstacle to the widespread use of this technology. To unravel the mechanisms of organic fouling and chemical. Revealing the mechanisms of organic fouling and chemical. Optimization of chemical cleaning of organicfouled reverse osmosis membranes 5c. Moe tin, george anioke, osamu nakagoe, shuji tanabe, hitoshi kodamatani, long d. The unique low fouling feature of the esna1lf nanofiltration membrane makes it ideally suited for difficult organic laden feedwaters. Organic fouling and chemical cleaning of nanofiltration membranes. Ro membrane fouling and cleaning during normal operation over a period of time, ro membrane elements are subject to fouling by. Abstract the present study compares the fouling properties of two selected and wellcharacterized hydrophobic denoted hpoa and hydrophilic denoted tpia natural organic matters nom fractions with a commercial polyamide pa nanofiltration nf membrane denoted nf55. Organic fouling and its effects on trace organic retention by three nanofiltration nf membranes were investigated in this study. The resistance removal was found hovering around 9899% at the applied pressures of 1418 bar.
Feed water was secondary wastewater effluent, river water, and surface water. The development of new nanofiltration membranesisof particular interest for lowcost treatment of wastewaters to remove organic contaminants, including socalled contaminants of emerging concern. Membrane autopsies were used for fouling characterization. The use of nanofiltration to obtain drinking water is a recent concept. Elimelech, organic fouling and chemical cleaning of nanofiltration membranes. Carboxyls are inherent functional groups of thinfilm composite polyamide nanofiltration nf membranes, which may play a role in membrane performance and fouling. Effects of tannic acid on membrane fouling and membrane. Optimization of chemical cleaning of organic fouled reverse osmosis membranes 5c. Chemical cleaning of organicfouled reverse osmosis membranes. Natural organic matter fouling and chemical cleaning of nanofiltration membranes.
Removal of organic matter from soft water by loose nanofiltration membranes. Membrane fouling and cleaning were studied in three reverse osmosis ro plants. Chemical and physical aspects of cleaning of organic fouled reverse osmosis membranes. Chemical cleaning of flat sheet ultrafiltration membranes. Role of organic fouling layer on the rejection of trace.
Apr 15, 2016 nanofiltration has been widely recognized as a promising technology for the removal of micromolecular organic components from natural water. Their surface presence is attributed to incomplete reaction of acyl chloride monomers during the membrane active layer synthesis by interfacial polymerization. Dec 15, 2014 a physical impact of organic fouling layers on bacterial adhesion during nanofiltration. The goal of chemical cleaning is to restore the transmembrane pressure tmp of the. More efforts are made on the study of organic fouling, which is predominant in water. Fouling and subsequent chemical cleaning are two important issues for sustainable operation of. Effects of membrane fouling on the nanofiltration of trace. Membrane cleaning is more direct and quick to restore the permeability of spiral wound nanofiltration membrane modules. The unique low fouling feature of the esna1lf nanofiltration membrane makes it ideally suited for difficult organicladen feedwaters. Fouling and subsequent chemical cleaning of nanofiltration nf membranes used in water quality control applications are often inevitable. Membrane fouling, chemical cleaning and separation. From art to science charles liu, scott caothien, jennifer hayes, tom caothuy. Low ph powder ro cleaning chemical for dissolution of silicate scales. Elimelech, chemical and physical aspects of natural organic matter nom fouling of nanofiltration membranes, j.
The nanofiltration technique lies between ultrafiltration and reverse osmosis techniques, and it is considered a lowcost process and is capable of removing pesticides, organic matter, desalination of sea water, oil process and pollutants from industrial wastewater. Chemical cleaning of fouled polyethersulphone nanofiltration. To find the optimum chemical cleaning efficiency of edta on the dense organic fouling layer in crossflow mode, the steps used to form the dense fouling layer and the membrane cleaning procedure are as follows. Chemical cleaning of organicfouled reverse osmosis ro membranes is systematically investigated. Fouling and cleaning characteristics of reverse osmosis. Reverse osmosis ro is the most ecient desalination process for almost any water source, but it is susceptible to membrane fouling, which can reduce product water quality and raise energy consumption. If a commercial chemical agent is used, its composition is often unknown to public domain 21. Ultrafiltration has been used in the past for water treatment in manufacturing industries and wastewater treatment.
Membrane fouling is a process whereby a solution or a particle is deposited on a membrane surface or in membrane pores in a processes such as in a membrane bioreactor, reverse osmosis, forward osmosis, membrane distillation, ultrafiltration, microfiltration, or nanofiltration so that the membranes performance is degraded. Chemical cleaning removes the fouling by soaking and flushing the membrane with a solution that can contain acids, alkalis, oxidants, surfactants, chelants, and enzymes. In order to unravel the effect of carboxyl group density on organic. Improved antifouling properties of polyamide nanofiltration. Filtration protocol for compaction, fouling and rejection test. As the available ground water, fresh water and clean water sources are depleting globally, ronf technologies are being applied to surface waters, wastewater and ground waters. Nanofiltration methods for removal of some organic compounds. On the other hand, chemically reversible fouling can only be removed by chemical cleaning methods, while irreversible fouling is permanent. Effective for removal of carbonate, phosphate and hydroxide scales. Fouling can be reduced through energyintensive pretreatment, delayed by membrane coatings, and partially reversed by cleaning. Chemical cleaning of fouled polyethersulphone nanofiltration membranes with ethylenediaminetetraacetic acid this study mainly investigated the potential use of ethylenediaminetetraacetic acid edta as the chemical cleaning agent to restore the permeate flux of organically fouled polyethersulfone pes nanofiltration nf membranes under. The detection of some complex organic compounds is made by using the gas chromatography as detection method.
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