Chemical filter system

A typical physical-chemical treatment system incorporates three "dual" medial (sand anthracite) filters connected in parallel in its treatment train. The major maintenance consideration with granular medial filtration is the handling of the backwash. The backwash will generally contain a high concentration of contaminants and require subsequent treatment. 

Figure 4-73. Flow scheme for GAF filter-bag pressure filter system for liquids. Courtesy of GAF Corporation, Chemical Group, Greenwich, Conn.

This is usually prepared by either a base-exchange method using sodium zeolite, by a lime-soda ash process, or by the addition of sodium hexametaphosphate. In addition to the bacteria derived from fhe mains water, additional flora of Bacillus spp. and Staphylococcus aureus may be introduced into systems which use brine for regeneration and from the chemical filter beds which, unless treated, can act as a reservoir for bacteria. 

Later, an improved system for C02 photofixation was reported by the same authors.164 The new system consisted of 6.5 x 1(T5 M tris(2,2 -bipyridine)ruthenium(II), Ru(bpy)3, as the photosensitive electron donor, methyl viologen (MV2+, 20 mM) as the electron acceptor, and triethanolamine (TEOA, 0.6 M) as a sacrificial electron donor in a C02-saturated aqueous solution (Fig. 18). Under irradiation with a 300-W high-pressure Hg lamp with a CuS04 chemical filter (A > 320 nm), formic acid, which was detected by isotachophoresis, was produced in quantum yields of ca. 0.01%. Recently, however, Kase et al.165 have repeated this experiment using a 13C02 tracer and have claimed that the formic acid obtained was produced not by C02 reduction but rather by oxidative cleavage of TEOA. 

A. The filter system shall include a- series redundant-parallel Chemical Biological Radiological (CBR) filter assembly with a capability of placing a detector between the adsorber banks to warn of "breakthrough". The system shall provide accessibility to filters for repairs, maintenance and leak testing. 

Those elements of conventional laboratory design that must be refined for facilities in which toxic chemicals will be handled are presented. Alarms, communications, construction materials, containment cabinets, filter systems, floor plans, security, compressed gases, and waste disposal are discussed. Emphasis is given to design considerations dictated by the use of large numbers of fume hoods. 

Explosion phenomena have occurred in all types of confined and unconfined units reactors, separation and storage units, filter systems, pipe lines, and so forth. Typical reactions that may cause explosions are oxidations, decompositions, nitrations, and polymerizations. Examples of chemical and processing system characteristics that increase the potential for an explosion are the following ... 

Mittal, et al. reported the proximate chemical composition of a number of different samples collected in the model card room at North Carolina State University (31). Samples in this study included a coarse trash which was comprised of relatively large, mostly lint-free particulate matter that fell to the floor of the condenser filter chamber in a Pneumafil filter system (Model FCV8-3MTRK) (31). The second sample set was separated by the sonic sifting procedure from the condenser trash. Another set of samples was collected from an electrostatic precipitator located in the air conditioning return of the model card room. Results of ash analyses are shown in Table VII. 

Landrum et al. (1984) developed a methodology in which the water is pumped over a SEP-PACK filter system. The premise of their methodology is that sorbed chemical in the water will pass through the filter, while the freely dissolved chemical in the water will adhere to the filter. Yin and Hasset (1988) and Sproule et al. (1991) have applied gas-sparging techniques to measure C. The principle of this technique is that only freely dissolved chemical in the water will tend to partition into the gas phase. CWD is then estimated from the gas phase concentration and KAW, the air-water partition coefficient. 

No doubt the chemical process operators watched in amazement as they started up the filter system with the newly replaced cartridges and they observed rusty colored smoke. Investigators theorized the tin spontaneously caught fire within the hot chlorine atmosphere. Apparently, the cartridges burned with sufficient heat to initiate an iron-in-chlorine fire on the filter body. Operations promptly blocked the upstream chlorine valves and the fire continued to burn until the fire quickly consumed the chlorine gas. The fire destroyed the steel shell of the filter and several inches of downstream piping, but no injuries were reported. 

Vortex filters supplied by Sonitec, Inc., ("Vortisand " filters— Vortisand is a registered trademark of Sonitec, Inc., Holyoke, MA) come complete with a chemical cleaning system. This system is used every 3-8 backwash sequences to reduce filter media fouling... 

We have 12 separate filter systems at the site ranging from 333 to 15,000 CFM (Inclosure 23). A typical application is the ADS - the facility used to destroy the nerve agents GB VX by chemical neutralization (Inclosure 2U) GB with NaOH and VX by an acid chlorination process. The actual filter system installation is shown in Inclosure 25 and has a capacity of 15,000 CFM. These filter units consist of a low efficiency particulate prefilter, a high efficiency particulate HEPA filter. 

Figure 24. CAMDS chemical agent destruct facility filter system...

The steps involved in purification include harvesting of the bioreactor, followed by inactivation of cells and concentration of the starting material, which is the cells, or the medium when the product is secreted. Concentration is achieved by using centrifugation or membrane filter systems by ultrafiltration. Cells are disrupted using the physical, chemical or enzymatic method that is best suited to the particular situation (Hopkins, 1991 Papoutsakis, 1991). 

The disinfection efficiency is dependent on the UV dosage as well as the physical and chemical conditions of the water and air to be disinfected. It is found that an UV irradiation dose of 8-14 mJ/cm is required to meet the 3-log inactivation of Cryptosporidium spp. oocysts (i.e., 99.9% killing) and 12-20 mJ/cm is necessary to achieve at least 3-log inactivation of Giardia spp. cysts in drinking water disinfection (13). The UV can also be used in seawater disinfection. A filter system combined with a series of 0.45-pm filters can reduce by as much as 60% of the bacteria in raw seawater. An UV dose 63.6 mJ/cm is enough to achieve 4-log Vibrio and Pseudomonas bacteria reduction (14). 

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