Commercial scale production of a Fe-6.5 wt. % Si sheet has been successfully developed. Presently manufactured sheets are in coil form, whose thickness ranges from 0.1 to 0.5 mm with a maximum width of 400 mm. Magnetic properties of the manufactured sheet have been investigated. The permeability of Fe-6.5 wt. % Si sheet is about 10 times higher than the conventional nonoriented silicon steel sheet. The core losses are less than half the conventional, and even less than that of the grain-oriented silicon steel sheet at frequencies over 400 Hz. Superior soft magnetic properties are attributed to the low magnetostriction and high electric resistivity of this alloy. It is well known that the Fe-6.5 wt. % Si alloy has poor ductility in conventional mechanical work. But investigation of the forming conditions has enabled the stamping and bending of alloy sheets. Low core losses and high permeability make Fe-6.5 wt. % Si sheet adequate for motor cores, transformer cores operating at high frequencies, and magnetic shielding. Application to the micromotor core shows that Fe-6.5 wt. % Si sheet reduces the consumption of no-load electric current by 25% in comparison with the conventional silicon steel.

The properties of a blofllm developed on a Rotating Biological Contactor (RBC), such as the spaclal distribution of blofllm density, bacterial population and Intrinsic biochemical reaction rates, were measured. The blofllm density and the number of heterotrophs, nltrlflers and denltrlflers per unit volume of blofllm Increased with the blofllm depth. However, the intrinsic reaction rates per unit blomass did not significantly change with depth. Based on the above evidence, experiments on simultaneous nitrification and denitrificatlon were carried out using a covered RBC in which the oxygen pressure was controlled. The experimental results demonstrated that nitrogen removal efficiency in an aerobic RBC depends on the oxygen partial-pressure in the air phase, water temperature, hydraulic detention time and ratio of the influent concentration of organlcs to ammonia nitrogen.

Simultaneous nitrification with denitrification was investigated using a single rotating biological contactor (RBC). The authors proposed two means to achieve simultaneous nitrification with denitrification in the single reactor: (1) to control oxygen transfer rate by reducing oxygen partial pressure (P02) in the air phase and (2) to develop a combined partially (aerobic) and fully (anaerobic) submerged RBC (CPFSR) reactor. For the former experiment, the maximum denitrification efficiency of 90 % was obtained at C:N ratio=6 and P02=0.10 atm. Moreover, heterotrophs, NH4- and NO2-oxidizers, and denitrifiers were distributed throughout the biofilm, suggesting that nitrification and denitrification can occur wheresoever the local environment meets their growth conditions. For the latter experiment, effects of type of organic matter and influent carbon:nitrogen ratio (C:N ratio) on the efficiency of simultaneous nitrification with denitrification were investigated using the CPFSR reactor. Acetate, ethylene-glycol, phenol, and poly-vinyl-alcohol (PVA) were used as carbon sources for denitrification. An excellent nitrification efficiency was obtained for all experimental runs and all organic substrates could be degraded and used for denitrification, indicating a great potential for simultaneous removals of nitrogen and xenobiotic compounds by the CPFSR reactor.

Simultaneous nitrification and denitrification (SND) occurs in a micro-aerobic biofilm. Using a partially submerged rotating biological contactor(RBC) whose air phase oxygen partial-pressure is controllable, an experimental investigation was made into the effects of the oxygen flux to the biofilm on the SND. The lower the oxygen flux the lower the nitrification efficiency and the higher the denitrification efficiency until the maximum nitrogen removal efficiency was obtained. The state was reached at an oxygen partial-pressure of about 0.1 atm. (oxygen flux= 0.35 g/m2/hour) in this study. Computer simulation of the SND was carried out based on the biofilm kinetic model proposed by the authors. There was adequate agreement between the experimental and simulation results. The simulation study demonstrated that the nitrification and denitrification occur mainly in the biofilm rotating through the air and water phase, respectively, and that the optimum disk rotating speed is around 3 rpm.

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