Removal , days

Anaerobic digestion of wastewater from jam industries was studied in a continuous reactor with different OLRs and the optimum OLR was 6.5 kgCOD/m3/day when it was operated with 3 days HRT. The biodegradability of wastewater in batch experiments was about 90%. The removal effciency of total COD and soluble COD were found to 82% and 85%, respectively. The specific methane production was 0.28 m3/kg of COD removed/day (Mohan and Sunny, 2008). 

Chemical oxygen demand (COD) removed/day = 33301b/day Methane generation = 0.162 lb COD destroyed/ft CH4 produced Methane recovery efficiency = 80%... 

Notes Recont soil = recontaminated soil, which was clean soil to which TCDD was added. Decent soil = soil from which chlorinated hydrocarbons had been removed. Days are expressed as mean +/- standard deviation... 

The researcher concluded that the days beyond 10 would be dropped for they held no benefit in interpreting the study. Also, because the range of y is so great, 0-7009, most statisticians would have performed a centering transformation on the data (xf = x,- — x) to reduce the range spread, but this researcher wanted to retain the data in the original scale. The researcher also removed days prior to day 2, hoping to make a better polynomial predictor. The statistical model that was iteratively fit was... 

In aerobic processes, the mean sludge residence time is typically 5 to 10 days. The hydraulic residence time is typically 0.2 to 0.3 days. Suspended growth aerobic processes are capable of removing up to 95 percent of BOD. 

A convenient source of the enzyme is castor oil seeds. The oil of the seeds is itself an ester, and therefore if the action of the enzyme is to be demonstrated on an extraneous ester, the castor oil must first be completely removed by extraction with ether. This, however, is a long process and may require several days for completion. The hydrolysing action of the enzyme on the oil in I he seed can however be demonstrated as described on p. 512. 

Sodamide should never be stored in a stoppered bottle from which samples are to be removed intermittently, since dangerous mixtures may result when the substance is exposed for 2-3 days to even limited amounts of air at the ordinary temperature. As a safe practice, sodamide should be used immediately after preparation, and should not be kept longer than 12-24 hours unless it be under an inert solvent. Even small amounts of unused sodamide should be removed from the apparatus in which it was made by washing with methyl or ethyl alcohol. In all cases where a yellowish or brownish colour develops, due to the formation of oxidation... 

The vanadium pentoxide catalyst Is prepared as follows Suspend 5 g. of pure ammonium vanadate in 50 ml. of water and add slowly 7 5 ml. of pure concentrated hydrochloric acid. Allow the reddish-brown, semi-colloidal precipitate to settle (preferably overnight), decant the supernatant solution, and wash the precipitate several times by decantation. Finally, suspend the precipitate in 76 ml. of water and allow it to stand for 3 days. This treatment renders the precipitate granular and easy to 6lter. Filter the precipitate with suction, wash it several times with cold 5 p>er cent, sodium chloride solution to remove hydrochloric acid. Dry the product at 120° for 12 hours, grind it in a mortar to a fine powder, and heat again at 120° for 12 hours. The yield of catalyst is about 3 - 5 g. 

Pure commercial ethyl acetate is allowed to stand for 2 days over anhydrous calcium chloride, the desiccant removed by filtration, and the ester is then finally dried over anliydrous calcium sulphate for several hours. 

Recovery of the wopropyl alcohol. It is not usually economical to recover the isopropyl alcohol because of its lo v cost. However, if the alcohol is to be recovered, great care must be exercised particularly if it has been allowed to stand for several days peroxides are readily formed in the impure acetone - isopropyl alcohol mixtures. Test first for peroxides by adding 0-6 ml. of the isopropyl alcohol to 1 ml. of 10 per cent, potassium iodide solution acidified with 0-6 ml. of dilute (1 5) hydrochloric acid and mixed with a few drops of starch solution if a blue (or blue-black) coloration appears in one minute, the test is positive. One convenient method of removing the peroxides is to reflux each one litre of recovered isopropyl alcohol with 10-15 g. of solid stannous chloride for half an hour. Test for peroxides with a portion of the cooled solution if iodine is liberated, add further 5 g. portions of stannous chloride followed by refluxing for half-hour periods until the test is negative. Then add about 200 g. of quicklime, reflux for 4 hours, and distil (Fig. II, 47, 2) discard the first portion of the distillate until the test for acetone is negative (Crotyl Alcohol, Note 1). Peroxides generally redevelop in tliis purified isopropyl alcohol in several days. 

After 12-24 hours of reflux the reaction is, for the most part, complete. The reaction mix will be a dark brown. So what does one do about all those brown particles and junk. Well, usually there aren t any. The solution should be uniformly dark. If any solids can be seen it means that they are insoluble in ethanol and can be removed from solution by gravity or vacuum filtration through a coffee filter or some paper towels. If it takes a day to drip through the filter then so-be-it. The ethanol with its payload of isosafrole will... 

The next day comes and the hung-over chemist wakens to see a dark red solution stirring away. In some cases where the chemist had made an enormous batch of this stuff, there may be seen a small mass of crystalline precipitate at the bottom of the flask. This is no big deal and will go away in the next step. If the chemist had made this in a flat-bottomed flask (which she really should have for convenience) then the ice tray is removed, the flask returned to the stir plate, a distillation setup attached, and the acetone is vacuum distilled from the flask. After all the acetone has come over the chemist can proceed in two different ways. One way is to just keep on distilling the solution until all of the formic acid has been removed. The chemist knows that just about all the formic has been removed when there is about 300mL of thick black liquid remaining in the reaction flask and hardly any clear formic acid is dripping over into the collection flask. If one were to swirl the reaction flask, the liquid will appear syrupy and kind of coat the sides of the flask. This is more evident when the flask cools. A quick sniff of the flask may indicate that some formic is still in there, but it should be too minimal to be of any concern. 

The problem with removing large amounts of formic acid by distillation is that it takes a long time to do so. Really big batches can take an entire day to distill. So a second option [10] after removal of the acetone would be to cool the formic acid solution then extract the whole thing with ether. The black ether layer is then washed with an ice cold 5% sodium carbonate (Na2C03) solution to neutralize any formic acid that was carried over, then washed... 

Panels then move into a cooling device, normally a wheel or rack, where they are held individually and air is circulated between them to remove the majority of heat remaining in the boards after pressing. It is desirable to reduce the average board surface temperature to about 55°C. This temperature is sufficient to complete the cure of adhesive in the core of the board. The heat also helps to redistribute moisture uniformly within the boards, because the board surfaces are drier than the core when the boards come out of the press. Warm boards are normally stacked for several hours to a day to allow for resin cure and moisture equalization. 

The cooled, dried chlorine gas contains - 2% HCl and up to 10% O2, both of which are removed by Hquefaction. A full scale 600-t/day plant was built by Du Pont ia 1975. This iastaHatioa at Corpus Christi, Texas operates at 1.4 MPa (13.8 atm) and 120—180°C and uses tantalum-plated equipment and pipes. Oxidation of HCl Chloride by JSHtricHcid. The nitrosyl chloride [2696-92-6] route to chlorine is based on the strongly oxidi2iag properties of nitric acid... 

A typical large three-phase ferroalloy furnace using prebaked carbon electrodes is shown in Eigure 4. The hearth and lower walls where molten materials come in contact with refractories are usually composed of carbon blocks backed by safety courses of brick. In the upper section, where the refractories are not exposed to the higher temperatures, superduty or regular firebrick may be used. The walls of the shell also may be water-cooled for extended life. Usually, the furnace shell is elevated and supported on beams or on concrete piers to allow ventilation of the bottom. When normal ventilation is insufficient, blowers are added to remove the heat more rapidly. The shell also may rest on a turntable so that it can be oscillated slightly more than 120° at a speed equivalent to 0.25—1 revolution per day in order to equalize refractory erosion or bottom buildup. 

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