CE 256 Lab Report 8

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New Mexico State University *

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256L

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Civil Engineering

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Apr 3, 2024

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Coagulation and Flocculation Lab #8 CE 256L M02 Lab Date: 11/09/22 Report Due: 11/16/22 Submitted to Dr. Yanyan Zhang. Group Members: Louis Mauriot, Cristian Sanchez, Omar Saucedo, Cristina Esquivel, Brittany Hymer, Jessica Novak, Sophia Fuente, Alyssa Newman, Gabriela Guadarrama
Table of Contents INTRODUCTION ........................................................................................................................................... 3 PROCEDURE ................................................................................................................................................. 3 RESULTS ....................................................................................................................................................... 4 DISCUSSION ................................................................................................................................................. 5 REFERENCES ................................................................................................................................................ 6 APPENDIX .................................................................................................................................................... 6 List of Tables Table 1: Results for Ferric Chloride Dose List of Figures Figure 1: Graphical Plot of Dose VS. pH Figure 2: Graphical Plot of Dose VS. Turbidity Figure 3: Excel Data Details for Graphs
INTRODUCTION Water quality control is essential to prevent potential health hazards that can have devastatingly critical consequences on several thousands or millions of citizens of an urban area which can range from a town to a city. We have previously covered in one of our initial laboratories experiments that bacteria and silt are not only undesirable on an aesthetic scale, but also are the prime causation of turbidity in water. Filtration is a solution to help remove turbidity in water as we observed previously. However, this technique is reliable only to a limited extent. Most turbidity can be removed by filtration but very small sized colloids that possess an electrical charge can remain. Colloids can only be removed through coagulation and flocculation. The electric charge is neutralized or weakened through coagulation. Coagulating chemicals such as aluminum III or iron III are the most efficient and ideal ones to use. The cations contained within the chemicals surround the charged colloid particles causing a reduction of electrostatic repulsion among the particles. Consequently, they merge. The process of coagulation ends here and so begins the process of flocculation which can be described as a physical process that can be visually observed. This latter entails the grouping of large aggregates or flocs that form during a gentle mixing process in the post coagulation phase of the experimental procedure. PROCEDURE Since we have 3 different coagulants to test, the class is broken into 3 groups so that each can test an individual coagulant. We are equipped with 2-liter beakers, syringes, and our assigned coagulant. To prevent leaks from happening during the experimental procedure, it is important to make sure that the plugs located on the side of the beakers are safely sealed in the holes. Each beaker is filled with thoroughly mixed bentonite sample all the way to the 2-liter mark which can be found on the side of the beaker. This mixed bentonite sample is in a large bucket located in the back of the room. Using a pH meter, the initial pH is measured. Then, with the assistance of a hatch turbidimeter, the initial turbidity is also measured. On average, the numerical measurement acquired should gravitate around 28 NTU. All beakers are then placed and aligned on the experimental set up of the stirring machine. The light is turned on. We then use about six 50ml capacity syringes and fill them with the necessary amount of coagulant. Our group was assigned the coagulant known as ferric chloride. Therefore, we filled each syringe with 10, 20, 30, 50ml and two additional syringes with 50 ml each for the beaker that will contain 100ml of coagulant. Once the syringes filled, each group member acquired a syringe and was on standby for their assigned beaker. Next, the stirring paddles of the machine are lowered into the beakers. As soon as the stirring mechanism is activated and put on the fastest RPM, the amount of coagulant contained within each syringe is added to its respective beaker. The rapid mixing process only lasts about 30 seconds. The speed of the stirring machine is then reduced to 30 RPM for a duration of 15 minutes. The stirring machine is then halted, the paddles are lifted, and the beakers are left to settle for an additional 15 minutes. We then collect samples from each beaker and measure the corresponding final turbidity and pH of each. All data is recorded and can be found in the tables in the results section of this lab report. RESULTS
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