Phosphorus removal, modified

Modified ASM2d model including pH effect on enhanced biological phosphorus removal... 

The PAC activated slndge system is a modified activated sludge process. PAC is added to the aeration tank where it is mixed with the biological solids. The mixed liquor solids are settled and separated from the treated effluent in a gravity clarifier. Polyelectrolyte will normally be added prior to the clarification step to enhance solids-liquid separation. If phosphorus removal is necessary, alum is often added at this point. Even with polyelectrolyte addition, tertiary filtration is normally required to reduce the level of effluent suspended solids. The clarifier nnderflow solids are continuously returned to the aeration tank. A portion of the carbon-biomass mixture is wasted periodically to maintain the desired solids inventory in the system. 

A) a-Bromoisocaproic Acid.—Five hundred grams (4.3 moles) of commercial isocaproic acid is mixed with 250 cc. of benzene in a 2-1. round-bottomed flask, and the water and benzene are removed by distillation through a short column until the temperature of the vapors reaches ioo°. The temperature rises rapidly as soon as the last of the benzene is removed. The residual acid is cooled to room temperature, 743 g. (4.65 moles, 243 cc.) of dry bromine (Note 1) is added, and the flask is fitted with a long condenser and placed in an oil bath. The top of the condenser is connected to an empty 500-cc. Erlenmeyer flask which acts as a safety flask, and this in turn leads to a gas-absorption trap (Note 2). Ten cubic centimeters of phosphorus trichloride is added to the mixture through the top of the condenser, and the flask is heated to 80-85°. The bromination proceeds smoothly at this temperature and is allowed to continue for eight to fifteen hours until the dark red color of bromine disappears from the condenser. When it has, the temperature is raised to 100-105° and kept there two hours. The contents of the flask are transferred to a i-l. modified Claisen flask or a flask attached to a Widmer column and distilled. The fraction... 

Naphthoyl chloride is conveniently prepared from /3-naphthoic acid (Org. Syn. 17, 65) and phosphorus pentachlo-ride. A mixture of 57.4 g. (0.33 mole) of acid and 69 g. (0.33 mole) of phosphorus pentachloride in a 250-cc. modified Claisen distilling flask is warmed on a steam bath in a hood. As soon as the vigorous reaction sets in, the flask is removed from the steam bath until the rapid evolution of hydrogen chloride has moderated, then warmed on the steam bath for one-half hour. After removal of the phosphorus oxychloride at diminished pressure, using a water pump, the acid chloride is distilled. The fraction boiling at i6o-i62°/i 1 mm. (bath temperature 170-180°) weighs 57 60 g. (90-95 per cent of the theoretical amount) and melts at 51-52°. The distillation should be carefully conducted, and a quite colorless product should result. 

The formulations may also be modified to remove all metals and phosphorus-containing compounds on the basis that this produces the potential to market an environmentally acceptable or green product. At present this concept is unlikely to take serious hold around the world, and therefore the formulation shown is representative of what may be employed in naturally soft waters. 

The attachment of the strongly electronegative phosphinyl (P—O) group to an imine, usually via reaction of an oxime with a chlorophosphine, also gives highly electrophilic imines which are reduced by NaBFWTHF and various modified borohydride and LAH derivatives " under mild conditions. The product A-phosphinylamines are protected forms of primary amines since removal of the phosphorus substituent is accomplished under mild acidic conditions. Entries 12 and 13 (Table 16) present representative reductions and illustrate (entry 13) that highly diastereoselective reductions of cyclic systems to axial amine derivatives are accomplished with LiBHBu s. Enantioselective reductions of A-diphenylphosphinyl imines to optically active amine derivatives have also been reported (Chapter 1,7, this volume). ... 

This process is based on the fact that a certain amount of soap is required for the hydrated silica to adsorb phospholipids from the oil. Since no caustic is used in physical refining process (Section 5.10), hydrated silica becomes ineffective in the physical process and does not remove any amount of phospholipids from the oil. In the modified physical refining process, the oil is analyzed for ppm of phosphorus. The required amount of caustic solution is added to the oil to produce soap. The concentration of soap produced (ppm) must match the ppm of phospholipids in the oil. The oil and caustic solution are mixed in a high shear mixer. Hydrated silica is added to the oil in a vacuum vessel. The remainder of the process is similar (bleaching, and so forth) to the physical refining process. 

Modified physical refining process also eliminates effluent discharge but removes more phosphorus and trace metals than the physical refining process. 

For application of zeolites as catalysts in industrial processes, high activity and easy removal of coke deposits are required. To meet these requirements, small crystals of zeolites (0.5-1.0 (im) should be advantageously used. On the other hand, the para-shape selectivity of zeolites in alkylaromatic transformations is connected especially with large crystals of the ZSM-5 zeolite structure, modified by silicon, boron, magnesium and phosphorus [1-5], However, no definite conclusion has been drawn on the contribution of various species to restricted transport of the bulkier isomers through the zeolite crystals, selectivity of the initial... 

Several steps are required to convert D-mannose (244) into compound (245) from which, by phosphorylation with diphenyl phosphorochloridate and triethylamine, followed by hydrogenolysis, (246) may be obtained. Attempts to modify this latter substance at C(l) so as to introduce a further phosphorus-containing function have not been. successful. The bis(isopropylidene) derivative (247) reacted with tetraethyl methylenebisphosphonate to give (248), together with its C(l) epimer and (249). Treatment of the anomers of (248) with p-toluenesulphonic acid in acetone so as to remove the 4,6-isopropylidene group, and further phosphorylation (same reagents). 

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