Heat exchange processes in open wastewater treatment facilities

Summary

The paper dwells upon studying heat and mass transfer processes between waste liquid passing through open wastewater treatment complexes and the environment. Under the conditions of operating facilities heat and mass transfer results in the waste liquid temperature increase or decrease depending on the time of year; and that leads, provided other things equal, to a change in the quality of treatment. The possibility of using mathematical models for open wastewater structures that describe heat and mass transfer processes used in heating engineering is considered. The study was carried out by analyzing domestic and foreign sources on heat and mass transfer. Changes in the temperature of waste liquid in open facilities were determined by calculation for a specific facility and compared with actual measurement data at the same facility. During the study, items of heat loss and input were established for the winter and summer periods of the year in three open structures: primary settling tanks, aeration tanks and secondary settling tanks. A mathematical model has been tested that determines the change in the temperature of the waste liquid depending on the residence period in the structures. The method for calculating primary settling tanks, aeration tanks and secondary settling tanks has been improved that provides for accounting at the design stage of the treatment facilities of the changes in the temperature of waste liquid during treatment, which eliminates deterioration in the quality of waste water treatment at any time of the year.

Key words

heat-mass exchange , aeration tanks , heat loss and input , primary and secondary settling tanks , wastewater quality , temperature variation