Chlorine carbon filtration

Gelatinous Slime a) Destroy iron bacteria with a solution of hydrochloric acid, then constant chlorination, followed by activated carbon filtration or calcite filter. 

Chlorine can be removed from RO feed water using sodium bisulfite or carbon filtration (see Chapters 8.2.4 and 8.1.4, respectively). As discussed in Chapter 8.1.4, carbon in carbon filters can aide the growth of microbes so carbon filtration is typically not recommended for dechlorination of RO feed water unless the concentrations of organics is high enough to warrant its use, or if the dosage of sodium bisulfite is too low for accurate control. 

Chloramines can be removed from solution using carbon filtration, as noted in Chapter 8.1.4. However, the contact time for removal is about 4 times that of free chlorine. Chloramines can also be removed using sodium thiosulfate or bisulfite, and the reaction is fairly instantaneous. Note that with the carbon filtration removal method, some ammonia is created, which is toxic and should be considered when using an RO with chloramines for food processing and pharmaceutical applications (see Equation 8.2). However, as free chlorine is removed using sodium bisulfite, the chlorine-chloramine equilibrium can shift back to creating more free chlorine. In this case, complete removal of free chlorine cannot be assured. Carbon filters may be the best method to remove chloramines, but can take up to 30 minutes of residence time for complete reaction with the carbon. Ultraviolet radiation can also be used to destroy chloramines (see Chapter 8.1.8). 

Carbon filtration carbon removes chlorine and organics from RO feed water. 

Kralingen, Netherlands [83] Surface water Meuse River Coagulation Sedimentation Ozonation Dual layer filtration Carbon filtration Safety chlorination Protection against periodic taste/odor and toxic substances Removal of THM s produced by chlorination Removal of matter produced by or unsuccessfully removed by ozonation Particle size 0.8 mm Bed deptli 4 m Bed diameter 6 m Volume per filter 116 m" Contact time 12 min. 

Activated carbon A pound of carbon has a surface area of 125 acres and can absorb thousands of different contaminants. It is particularly effective on bad tastes and odors, chlorine, radon, most sediment, and volatile organic compounds (VOCs), but has little ability to alkalize water. Activated carbon filtration systems are available in many forms, including under-the-counter and counter-top options and units that fit inside pitchers and even in personal water bottles. 

The organic contamination is not appreciably removed by the steps of coagulation, chlorination, and filtration employed in water purification plants. Activated carbon is used in sufficient quantities to make the water palatable and eliminate foaming but relatively few substances cause foaming, and only the more odorous ingredients will give a perceptible taste at the dilutions usually present (Table 6 2). Therefore we must recognize that the hazards from... 

Besides decolorization, activated carbon adsorbents play an important role in variety of applications including process water treatment. Activated carbon filtration is a common method to improve parameters of the feed water for soft drinks production by elimination of undesirable compounds responsible for a bad taste or odor, to capture free chlorine remaining... 

The single most important use of chlorine-containing compounds is water disinfection. About 98% of the drinking water in the US and 96% of the waste water is treated with chlorine. There are four technologies that could replace chlorination membrane filtration, ultraviolet irradiation, filtration on activated carbon bed and treatment with ozone (ozonolysis). All of them are more expensive than chlorination, and none of them were studied in as much detail as chlorination was. If ozone is used, the by-products formed in the reactions of ozone with organic compounds have to be removed in a separate step using activated carbon. Overall, there is no viable alternative to chlorination today. 

Home Filtration Systems. The same filtration and purification methods used in large water treatment plants have been downscaled for home use. Faucet-mount filters use carbon filtration, ion-exchange filtration, and submicron filtration to reduce sediment, chlorine, lead, mercury, iron, herbicides, pesticides, insecticides, industrial solvents, volatile organic compounds, synthetic organic compounds, and tri-halomethanes (THMs, chlorine and its by-products). These apparatuses rapidly provide filtered water that tastes and smells better with less cloudiness. Shower filters typically use copper-zinc oxidation media and carbon filtration to remove chlorine for softer skin and hair. Whole-house-use water filters are plumbed into the main water line and commonly include a sediment pre-filter, then copper-zinc oxidation media and crushed mineral stone or natural pumice to reduce chlorine, then activated carbon to remove other chemicals. 

Activated carbon filtration systems are utilized for removing chlorinated solvents and volatile organic compounds (VOCs). These can be regenerated on- or off-site. 

Due to chlorines deleterious effects on polyamide membranes, it [and more specifically, free chlorine (i.e., hypcochlorite, + hypochlorous acid + chlorine gas + trichloride ion)] must be removed to prevent contact with the membranes. Dechlorination is relatively simple, typically using either sodium bisulfite to chemically remove free chlorine or carbon filtration to catalytically remove chlorine (see chapter 8.2.3. and 8.1.4, respectively). 

Due to the fact that free chlorine is in equilibrium with monochloramine, water treated by chloramination should be treated for removal prior to RO membranes. Although most membrane manufacturers allow for a chloramine exposure of about 300,000 ppm-hrs, this exposure is calculated based on PURE chloramine. There are several methods to remove chloramine (e.g., sodium thiosulfate, UV, ascorbic acid) the most common methods are carbon filtration and sodium bisulfite. Empty bed contact time (EBCT) for fresh carbon can be as short as 10 minutes, while used carbon can require up to 30 minutes of EBCT for removal. The reaction for sodium bisulfite is as follows and has rapid kinetics. ... 

Chlorine (or other disinfectant) is required to minimize the potential for fouling the membranes with microbes (see Chapters 8.2.1, 8.2.2, and 8.5.2.1). Once membranes are fouled with microbes, it is very difficult to remove them. A free chlorine residual of about 0.5 to 1.0 ppm in the pretreatment system is desirable. Feed water to the RO must be dechlorinated prior to the membranes because the membranes are sensitive to oxidizers, which will degrade the membrane. Sodium bisulfite is the preferred method to dechlorinate unless the RO feed water has a high organic concentration, in which case, carbon filtration at a flow rate of 2 gpm/ft is recommended. (see Chapters 8.1.4 and 8.2.3) Sodium metabisulfite is typically about 33% active, and the stoichiometic dosage of sodium metabisulfite is about 1.8 ppm per ppm free chlorine. So, the stoichiometric dosage of 33% active sodium metabisulfite is 5.4 ppm. For safety, a factor of 1.5 is used to increase the dosage of sodium metabisulfite to ensure complete elimination of free chlorine. 

Porous carbon and graphite are used ia filtration of hydrogen fluoride streams, caustic solutions, and molten sodium cyanide ia diffusion of chlorine iato molten aluminum to produce aluminum chloride and ia aeration of waste sulfite Hquors from pulp and paper manufacture and sewage streams. 

Pretreatment For most membrane applications, particularly for RO and NF, pretreatment of the feed is essential. If pretreatment is inadequate, success will be transient. For most applications, pretreatment is location specific. Well water is easier to treat than surface water and that is particularly true for sea wells. A reducing (anaerobic) environment is preferred. If heavy metals are present in the feed even in small amounts, they may catalyze membrane degradation. If surface sources are treated, chlorination followed by thorough dechlorination is required for high-performance membranes [Riley in Baker et al., op. cit., p. 5-29]. It is normal to adjust pH and add antisealants to prevent deposition of carbonates and siillates on the membrane. Iron can be a major problem, and equipment selection to avoid iron contamination is required. Freshly precipitated iron oxide fouls membranes and reqiiires an expensive cleaning procedure to remove. Humic acid is another foulant, and if it is present, conventional flocculation and filtration are normally used to remove it. The same treatment is appropriate for other colloidal materials. Ultrafiltration or microfiltration are excellent pretreatments, but in general they are... 

D. 3,3-Diahlarothietane 1,1-dioxide. Thietane 1,1-dioxide (5.0 g, 0.047 mol) Is placed In a 500-mL, three-necked, round-bottomed flask equipped with a reflux condenser, magnetic stirrer, and chlorine gas bubbler. Carbon tetrachloride (350 mL) Is added and the solution Is irradiated with a 250-watt sunlamp (Note 5) while chlorine Is bubbled through the stirred mixture for 1 hr (Note 9). Irradiation and chlorine addition are stopped and the reaction mixture is allowed to cool to room temperature. The product Is collected by filtration as a white solid (4.0-4.4 g, 49-53%), mp 156-158°C (Note 10). The product can be used without further purification or It can be recrystallized from chloroform. 

Color None Decaying organic material and metallic ions causing color may cause foaming in boilers hinders precipitation methods such as iron removal, hot phosphate softening can stain product in process use Coagulation, filtration, chlorination, adsorption by activated carbon... 

Color Boiler foaming Presents problems with iron removal Discoloration of mantifactured produce Adsorption (activated carbon Coagulation Filtration Chlorination... 

Discussion. This method is based upon the precipitation of lead chlorofluoride, in which the chlorine is determined by Volhard s method, and from this result the fluorine content can be calculated. The advantages of the method are, the precipitate is granular, settles readily, and is easily filtered the factor for conversion to fluorine is low the procedure is carried out at pH 3.6-5.6, so that substances which might be co-predpitated, such as phosphates, sulphates, chromates, and carbonates, do not interfere. Aluminium must be entirely absent, since even very small quantities cause low results a similar effect is produced by boron ( >0.05 g), ammonium (>0.5 g), and sodium or potassium ( > 10g) in the presence of about 0.1 g of fluoride. Iron must be removed, but zinc is without effect. Silica does not vitiate the method, but causes difficulties in filtration. 

The co-precipitation technique starts with an aqueous solution of nitrates, carbonates, chlorides, oxychlorides, etc., which is added to a pH-controlled solution of NH4OH, allowing the hydroxides to precipitate immediately. This method requires water-soluble precursors and insoluble hydroxides as a final product. The hydroxides are filtered and rinsed with water when chlorides are employed as starting materials and chlorine is not desired in the final product. After drying the filtrate, it is calcined and sintered. This method is being applied very successfully for oxygen-ion conducting zirconia ceramics [30],... 

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