4 Introduction to Process Analysis and Selection Treatment methods in which the application of physical forces predominate are known as physical unit operations Examples of physical unit operations include screening, mixing, sedimentation, gas transfer, filtration, and adsorption. Treatment methods in which the removal or conversion of constituents is brought about by the addition of chemicals or by other chemical reactions are known as chemical unit processes Examples of chemical unit processes include disinfection, oXidation, and precipitation Treatment methods in which the removal of constituents is brought about by biological activity are known as biological unit processes
4 Introduction to Process Analysis and Selection Treatment methods in which the application of physical forces predominate are known as physical unit operations. Examples of physical unit operations include screening, mixing, sedimentation, gas transfer, filtration, and adsorption. Treatment methods in which the removal or conversion of constituents is brought about by the addition of chemicals or by other chemical reactions are known as chemical unit processes. Examples of chemical unit processes include disinfection, oxidation, and precipitation. Treatment methods in which the removal of constituents is brought about by biological activity are known as biological unit processes
Unit operations and processes occur in a variety of combinations in treatment flow diagrams The rate at which reactions and conversions occur and the degree of their completion, is generally a function of the constituents invol ved, the temperature, and the type of reactor (i.e. container or tank in which the reactions take place) The fundamental basis for the analysis of the physical chemical, and biological unit operations and processes used for wastewater treatment is the materials mass balance principle in which an accounting of mass is made before and after reactions and conversions have taken place
Unit operations and processes occur in a variety of combinations in treatment flow diagrams. The rate at which reactions and conversions occur, and the degree of their completion, is generally a function of the constituents involved, the temperature, and the type of reactor (i.e., container or tank in which the reactions take place). The fundamental basis for the analysis of the physical, chemical, and biological unit operations and processes used for wastewater treatment is the materials mass balance principle in which an accounting of mass is made before and after reactions and conversions have taken place
Chlorine contact basin Gravity thickeners nd gravity bell thickener building ry clarifiers Dechlorination Final post-aeration iquid biosolids and effluent pumping BNR Anaerobic Influent pump Actors biosolids Septage station and storage pond receiving screening Fig 4-1 Overview of a biological nutrient removal(Bnr wastewater-treatment plant
Fig. 4-1 Overview of a biological nutrient removal(BNR) wastewater-treatment plant
4-1 Reactors used for the Treatment of Wastewater Types ofReactors Fig. 4-2 Definition sketch for various types of reactors used for wastewater treatment he principal types of reactors used for the treatment of wastewater. are )the batch reactor, 2) the complete-mix reactor(also known as the continuous flow stirred-tank reactor (CFSTR) in the chemical engineering literature) 3)the plug-flow reactor (also known as a tubular-flow reactor (4)complete-mix reactors in series (5) the packed-bed reactor (6)the fluidized-bed reactor
4-1 Reactors used for the Treatment of Wastewater Types of Reactors Fig. 4-2 Definition sketch for various types of reactors used for wastewater treatment The principal types of reactors used for the treatment of wastewater, are (1) the batch reactor, (2) the complete-mix reactor (also known as the continuousflow stirred-tank reactor (CFSTR) in the chemical engineering literature), (3) the plug-flow reactor (also known as a tubular-flow reactor), (4) complete-mix reactors in series, (5) the packed-bed reactor, (6) the fluidized-bed reactor
Batch reactor In the batch reactor, flow is neither entering nor leaving the reactor(i.e, flow enters, is treated, and then is discharged and the cycle repeats) The bod test is carried out in a batch reactor that are often used to blend chemicals or to dilute concentrated chemicals
Batch Reactor In the batch reactor, flow is neither entering nor leaving the reactor (i.e, flow enters, is treated, and then is discharged, and the cycle repeats). The BOD test is carried out in a batch reactor that are often used to blend chemicals or to dilute concentrated chemicals