Dissolved oxygen monitoring, water

Oxygen pitting of boiler tubes by boiler feed water due to inadequate de-aeration is also a problem, but controllable by proper maintenance of de-aerators, coupled with regular boiler feed water analysis, or, preferably, continuous dissolved-oxygen monitoring. 

In general terms, toxicity tests are conducted in a laboratory or a room controlled for light and temperature. The test solutions containing the test species are monitored for pH, temperature, dissolved oxygen, and water hardness. Daily observations on lethal and... 

Water treatment monitoring and control is often a knife-edge operation and must be tailored to the overall operation of the boiler because waterside and gas-side problems usually are interlinked. Consequently (and as with other types of WT boiler), not only should the utility boiler FW be essentially free of dissolved oxygen to prevent waterside pitting corrosion of the economizer and other boiler components, but also the temperature must be high enough to prevent dewpoint condensation and subsequent acid attack on the gas side of the economizer tubes. 

Electrodes are capable of measurement at around the 1 ppm level. They are simple, robust and portable. As such there is considerable potential for their employment in ecological studies and they can provide constant monitoring of dissolved oxygen, e g. in river waters. The potential for their employment in monitoring industrial liquors is clear, as is their applications in biological investigations of oxygen transport. 

Implementation Confirmation of the in situ monitors results is obtained when river water samples are brought to the lab and tested for dissolved oxygen using a lab dissolved oxygen probe (a polarographic electrode-based measurement) and the classic Winkler oxygen titration method. 

Monitor dissolved oxygen levels regularly. Dissolved oxygen levels in water are affected by elevation, temperature, and salinity (17). Maintain values between 4 and 7.8 mg/L levels near the higher end of that range are especially favorable to health. 

Since crushed basalt has been recommended as a major backfill component (1), experiments were completed to evaluate the rate of dissolved oxygen consumption and the redox conditions that develop in basalt-water systems under conditions similar to those expected in the near-field environment of a waste package. Two approaches to this problem were used in this study (l)the As(III)/As(V) redox couple as an indirect method of monitoring Eh and (2) the measurement of dissolved oxygen levels in solutions from hydrothermal experiments as a function of time. The first approach involves oxidation state determinations on trace levels of arsenic in solution (4-5) and provides an estimate of redox conditions over restricted intervals of time, depending on reaction rates and sensitivities of the analyses. The arsenic oxidation state approach also provides data at conditions that are more reducing than in solutions with detectable levels of dissolved oxygen. 

Lower the intake of the pump and a dissolved oxygen meter probe into the well slightly above or in the middle of the screened interval. Purge the well at a rate 300-500 milliliter/minute (ml/min). Check the water level periodically to monitor the drawdown, which should not exceed 4-8 in. If the pumping rate is unknown, measure the evacuated volume in a graduated container and monitor the time to establish the rate. 

Various physical and chemical properties were monitored sequentially by Gibs et al. (2000) during well purging as indicators of stabilisation of the water in the well. Turbidity was correlated with the concentrations of Fe, Al and Mn in oxic ground-water, but appeared to be independent of conductivity, pH, temperature or dissolved oxygen. Pb and Cu were related to the sum of the Fe, Al and Mn. 

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