Oxygen concentration/level/pressure

Atmospheric Reaeration. Interfacial properties and phenomena that govern oxygen concentrations in river systems include 1) oxygen solubility (temperature, partial pressure and surface dependency), 2) rate of dissolution of oxygen (saturation level, temperature and surface thin film dependency, i.e., ice, wind), and 3) transport of oxygen via mixing and molecular diffusion. A number of field and empirically derived mathematical relationships have been developed to describe these processes and phenomena, the most common of which is (32) ... 

The aeration requirements of the deep shaft (vertical shaft bioreactor using flotation technology) are provided by two, 100 hp rotary screw compressors rated at a pressure of 7 kg/m2 (100 psig). Dissolved oxygen (DO) levels of 4 mg/L are maintained in the head tank, and during the startup phase of the plant a DO meter measured a dissolved oxygen concentration of 25 mg/L at the shaft bottom. 

The cycles used to reduce the oxygen concentration to a target level are shown in Figure 7-2. In this case the vessel is initially at PL and is pressurized using a source of pure nitrogen at PH. The objective is to determine the number of pressure purge cycles required to reach the desired concentration. 

Vacuum/pressure vs. distance VOC concentrations in soil and groundwater under static and dynamic conditions C02 and 02 in soil vapor Increase in dissolved oxygen (DO) levels... 

Carbon dioxide produced in an aerobic fermentor should be desorbed from the broth into the exit gas. Figure 12.2 [11] shows, as an example, variations with time ofthe dissolved CO2 and oxygen concentrations in the broth, CO2 partial pressure in the exit gas, and the cell concentration during batch culture of a bacterium in a stirred fermentor. It can be seen that CO2 levels in the broth and in the exit gas increase, while the dissolved oxygen (DO) concentration in the broth decreases. 

An expanded version of the Stern-Volmer equation containing a factorial expansion of these same terms can also be employed to relate /q to oxygen levels in a more exact manner. Standard operation includes, at minimum, a daily calibration at a number of oxygen concentrations (at a fixed pressure and temperature) and use of the measured calibration coefficients to determine the concentration of oxygen in an unknown sample. 

Ozone is found at high altitudes in such concentration that, pressurized in a cabin to ground level or near ground level pressure, it could exhibit harmful effects on man and material. Protecting factors, such as heating in the compressor, decomposition in contact with various substances, and use of oxygen masks, lessen such harmful effects considerably. But the existence of such a hazard has to be known. Studies on the toxic effect of ozone on man indicate that such effect is restricted to the respiratory tract. Man seems to be more sensitive than the usual laboratory animals. In sensitive persons, concentrations as low as 2 p.p.m. may cause severe irritation within less than 1 hour. 

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