Optimization of operation modes and improvement of operation conditions of surface runoff treatment facilities

Summary

Common drawbacks of packaged units for urban runoff treatment are considered. The task of the study was regulating and optimizing the operation modes of the existing facilities in order to improve the effluent quality to meet the standards. By the example of the unit that was most suitable for the generally accepted treatment process flow scheme the analysis of the operation of a laminar sedimentation tank module under design conditions was carried out. To determine the operation efficiency in the hydrodynamic mode physical experiments (by adding a chemically inactive tracer to wastewater being treated) and computer simulation were carried out. To upgrade the laminar sedimentation tank the chemical treatment stage was introduced into the process flow scheme. Adding coagulant provided for improving the treatment efficiency; however, the required concentrations of suspended solids in effluent downstream the sedimentation tank (10 mg/dm3) were not met. The efficiency of the sedimentation tank in hydrodynamic mode was improved by using stepped feed and distributed collection of wastewater in a modular unit as well as by using an air distribution system located in the lower central part of the laminar sedimentation tank module. This type of the design provided for coarse bubble aeration over the entire surface area of the chamber at the required mixing rate. The implemented design changes in the laminar sedimentation tank module resulted in the efficiency of urban runoff treatment before the further tertiary treatment meeting the regulatory requirements.

Key words

reagent treatment , lamella settler , computer modeling , urban runoff , packaged modular water treatment unit , hydrodynamic mode , air distribution system

Heat-mass-exchange packing for evaporative cooling with a developed drip irrigation mode (to be discussed)

Summary

A new heat-mass-exchange packing supporting an intensive drip flow mode for evaporative cooling of water in the water recycling systems of industrial enterprises is presented. The data of an experimental study in the field of hydrodynamics of a new cascade heat-mass-exchange packing supporting intensive drip flow mode are given. The characteristics of the packing device are given in comparison with packings that have received wide industrial application. A classification technique for processing experimental data for heat-mass-exchange packings as a criterion dependence of the modified Reynolds criterion on the hydraulic resistance coefficient is presented. The technique provides for a shot time test of packing materials for their industrial use. Heat-mass-exchange packings focused on the process of evaporative cooling of recycling water will extend over a certain range on the graph λ = f(Rem). An algorithm for calculating the main geometrical and process parameters of a small-sized sectional fan-type cooling tower with intensive drip flow modes for cooling industrial recycling water is presented. The prospect of using the developed heat-mass-exchange packings in the form of a module for disinfecting recycling water in the electric field is noted. This will ensure the constancy of the surface properties of the packing elements and the maintenance of the initial hydrodynamic characteristics, as well as will allow partial preventing the biofilm from overgrowing microorganisms of all heat exchange surfaces of the process equipment.

Key words

recycling water system , hydraulic resistance , hydrodynamic mode , heat exchange packing , retaining ability , small-sized cooling tower

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