Physical-Chemistry Treatment

Approval in Chemistry and Biochemistry I and II.

Theoretical, theoretical-practical and laboratory classes.

Practical case study visits.

English

In order to guarantee a good quality of drinking water and improve the quality of wastewaters, it is necessary to carry out different types of physical-chemical treatments. The objective of this course is to provide students with the skills identified below:

– State the nature of substances to be removed in physical-chemical treatments: dissolved substances, colloidal dispersions, and suspended substances.

-Understand and describe the mechanisms involved in the different unit operations related to physical and chemical treatments.

-Apply the theoretical concepts of physical-chemical treatments in the context of treatment plants.

English

Module 1. Theoretical classes

1. INTRODUCTION: The importance of unit operations in the treatment of water and effluents.

2. EQUALIZATION AND HOMOGENEIZATION: Evaluation of the degree of homogenization.

3. GRADING, SCREENING, SCREENING. General operating principles and applications.

4. AGITATION AND MIXING: Concept of agitation and mixing. Streamline and vortex definition. Classification of agitators.

5. NEUTRALIZATION: Main chemical compounds used in the neutralization of wastewater and industrial effluents. Acid-base neutralization: potentiometric titration curve and dosage calculation. Neutralization with lime. Neutralization with lime mud.

6. HARDNESS: Definition of alkalinity and hardness. Calcium and magnesium hardness. Meaning of Langmuir Index.  Chemicals to be used in the treatment: bar diagram.

7. CHEMICAL OXIDATION/PRECIPITATION: Oxidation-reduction reactions and main oxidizing agents. Industrial wastewater applications.

8. OXYGEN TRANSFER: Transfer coefficient in clean water and wastewater. Effect of temperature, mixing intensity, tank geometry, and water characteristics. Aeration systems: diffusers and mechanics (surface and submerged).

9. SEDIMENTATION/FLOTATION: Description of the movement of particles within a fluid under the action of gravity. Types of sedimentation: discrete, flocculent, impeded, and thickening. Discrete sedimentation: Stokes equation and terminal velocity notion; calculation of the removal efficiency of suspended particles. Flocculent sedimentation: flocculent sedimentation test; removal percentage calculation.

10. FILTRATION/DEHYDRATION: Filtration mechanisms. Karman-Kozenny equation. Operation mode: constant pressure filtration and constant filtration speed filtration. Types of filters: filter press, screen filters, vacuum filters, granular media filters (slow and fast sand filters), and membrane filters (microfiltration, ultrafiltration, and nanofiltration).

11. ADSORPTION. ION EXCHANGE. INVERSE OSMOSIS. General operating principles and applications.

12. COAGULATION-FLOCCULATION- Colloidal substances. Mechanisms of surface electrical charge development. Colloidal stability. Concept of coagulant and flocculant. Colloid destabilization mechanisms – Electric double-layer model. Coagulation using electrolytes (Fe and Al salts) and polyelectrolytes. Determination of the required coagulant dose (Jar Test). Applications.

13. DISINFECTION – Disinfection Processes: Need for disinfection of drinking water and wastewater. Physical (heat and ultraviolet radiation) and chemical (chlorine, ozone, etc.) methods. Characteristics of a good disinfecting agent; mechanisms of action and factors that influence its action. Disinfection using chlorine compounds: Chlorine deficiency curve (breakpoint curve). The notion of free residual chlorine and chloramines and their disinfection capacity.

Module 2. Theoretical-practical classes

Tracing of sedimentation curves and analysis of suspended solids content, determination of sludge volumetric index; Determination of chlorine deficiency; Determination of residual chlorine and parameters; Analysis of free chlorine and chloramines in drinking water; Comparison of different types of coagulants and evaluation of process efficiency; Removal of hardness from water; Determination of the number of reagents needed and the amount of precipitate (sludge) formed during the softening process of water, by chemical precipitation. Representation of the initial and final composition of water in a bar diagram, after being submitted to a softening process.

• - Testes teórico - 50.0%
• - Pratica - 50.0%

NAO

Metcalf & Eddy, 2003, George Tchobanoglous, Franklin L. Burton, H. David Stensel;  Wastewater Engineering: Treatment and Reuse, 4th Edition;  McGrow Hill, 2003.

T. J. Casey , Unit Treatment Processes in Water and WasteWater engineering. John Wiley & Sons Inc. NY, 2004.