Activated filter

The strains were cultured on Mandels medium + 1% citrus pectin for 5 days and the enzymatic activities of culture filtrates were determined on three substrates citrus pectin, polygalacturonic acid and filter paper, (a) extracellular proteins are in p.g/ml. (b) p>ectinolytic activities on pectin (PC) and on polygalacturonic acid (TO) and Pectin esterase (PE) are in units/ml. (c) total cellulolytic activity (filter paper, fp) are in mg of liberated reducing sugars/ml. 

A plate-and-frame filter press contains 16 frames and operates at a constant flow rate of 30 gpm. Each frame has an active filtering area of 4 ft2, and it takes 15 min to disassemble, clean, and reassemble the press. The press must be shut down for disassembly when the pressure difference builds up to 10 psi. What is the total net filtration rate in gpm for a slurry having properties determined by the following lab test. A sample of the slurry is pumped at a constant pressure differential of 5 psi through 0.25 ft2 of the filter medium. After 3 min, 1 gal of filtrate has been collected. The resistance of the filter medium may be neglected. 

A slurry is being filtered at a net rate of 10,000 gal/day by a plate and frame filter with 15 frames, with an active filtering area of 1.5 ft2 per frame, fed by a positive displacement pump. The pressure drop varies from 2 psi at start-up to 25 psi after 10 min, at which time it is shut down for cleanup. It takes 10 min to disassemble, clean out, and reassemble the filter. Your boss decides that it would be more economical to replace this filter with a rotary drum filter using the same filter medium. The rotary filter operates at a vacuum of 200 mmHg with 30% of its surface submerged and rotates at a rate of 5 min/rev. If the drum length is equal to its diameter, how big should it be ... 

Elimination takes place largely by way of the kidney, which acts like an active filter for all unwanted body substances, although sometimes it gets damaged in the process as we have already noted. Some elimination of ingested material that has not been absorbed also takes place by way of the bowel, or even, in the case of volatile materials such as alcohol, by... 

Besides the elimination of the sample-and-hold, oversampling converters also reduce the complexity of the anti-aliasing filter. Previous anti-aliasing filters required the use of high order active filters (11th order elliptic for example) that resulted in phase... 

Harmonic filters are broadly classified into passive and active filters. Passive filters, as the name implies, use passive components such as resistors, inductors, and capacitors. A combination of passive components is tuned to the harmonic frequency that is to be filtered. Figure 4.22 is a typical series-tuned filter. Here the values of the inductor and the capacitor are chosen to present a low impedance to the harmonic frequency that is to be filtered out. Due to the lower impedance of the filter in comparison to the impedance of the source, the harmonic frequency current will circulate between the load and the filter. This keeps the harmonic current of the desired frequency away from the source and other loads in the power system. If other harmonic frequencies are to be filtered out, additional tuned filters are applied in parallel. Applications such as arc furnaces require multiple harmonic filters, as they generate large quantities of harmonic currents at several frequencies. 

FIGURE 4.23 Active filter to cancel harmonic currents. 

Active filters use active conditioning to compensate for harmonic currents in a power system. Figure 4.23 shows an active filter applied in a harmonic environment. The filter samples the distorted current and, using power electronic switching devices, draws a current from the source of such magnitude, frequency composition, and phase shift to cancel the harmonics in the load. The result is that the current drawn from the source is free of harmonics. An advantage of active filters over passive filters is that the active filters can respond to changing load and harmonic conditions, whereas passive filters are fixed in their harmonic response. As we saw earlier, application of passive filters requires careful analysis. Active filters have no serious ill effects associated with them. However, active filters are expensive and not suited for application in small facilities. 

In modern designs of frequency converters, active filters are used for a drastic reduction of network feedback. 

Active carbon carbon Active filter -> analogfilter... 

Active filter A type of device composed of a combination of passive and active (amplifying) components. Frequently, the latter are transistors or operational amplifiers that require an external power supply to work. Active components commonly have high Q, and achieve resonance without the use of inductors. The Q value (goodness factor) is used to measure the quality of a filter. Thus, a filter has a high Q if it selects or rejects a narrow range of frequencies compared with its center frequency. Other filters that can be included into this class are ... 

Active filters utilize an operational amplifier as part of the circuit and allow the design of any RLC filter without the need of an inductance. Filters of this type include Buttersworth and Chebyshev filters. 

These are housings of metal or plastic containing one or more replaceable and renewable cartridges which contain the active filter element, usually based on a polymeric filter medium or in some cases, sintered stainless steel. They are useful as polishing filters where the level of solids to be removed is relatively low, to prevent the filter from blocking up. 

Close the urine in a glass vessel and let it putrefy for a month or more in a warm place. The odors involved with this process certainly class it as an outdoor activity. Filter the putrefied urine into a distillation train and slowly distil to dryness. Return the distillate to the solids that remain (the caput mortuum) and again digest for a month. Distil and repeat the cohobation of distillate on the solids a third time. 

Tab. 4. Physico-chemical characteristics of the activated and non activated filter supports...

Cartridge Clarifiers Cartridge clarifiers are units which consist of or use one or more replaceable or renewable cartridges containing the active filter element. The unit usually is placed in a line carrying the liquid to be clarified clarification thus occurs while the liquid is in transit. 

Fig. 127. Flame laser enhanced ionization spectrometry [670, 671]. (a) Flashlamp/dye laser, (b) high voltage, (c) trigger photodiode, (d) preamplifier, (e) pulse amplifier, (f) active filter, (g) boxcar averager, (h) chart recorder. (Reprinted with permission from Ref. [671]).

Catalytic performance of the nickel-activated filter discs... 

Apparently, the nickel-activated filter disc displayed an excellent catalytic performance for the decomposition of either benzene or naphthalene as tar model compound in the simulated biomass gasification gas at a typical filtration gas velocity when the reaction temperature was in the rai e of800-900 °C. 

Filter paper is cut in a circle, about 4 cm in diameter and soaked in pure water for 0.5 h, then soaked with 5 mol/L NaOH solution for 0.5 h. The filter paper is washed with pure water, then put in a conical flask which contains mixture of NaOH dimethyl sulfone EPI2 4 5, volume ratio. The conical flask is put in 50°C water bath for 1 h for activation. Then the mixture is poured out, the activated filter paper is washed with pure water and put into 0.3 mol/L fi-CD NaOH solution. This is allowed to react for 5 h at 50 C, and washed with pure water until the pH of cleaning solution is about 7. Finally, this is soaked with acetone and dried in the air. 

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