1.0 INTRODUCTION Raw water and wastewater is normally turbid containing solid particles of varying sizes. Turbidity in water is caused by suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter, and plankton and other microspic organisms. Particles with sizes greater than 50 µm settle fairly rapidly. The settling velocities of colloidal particles of sizes less than 50 µm are very slow. Thus, these particles are encouraged to collide leading to coalescence of particle to form flocs particles, which are bigger and heavier. These particles will have higher settling velocities and easily settle out. A very important step in water and wastewater treatment is the coagulation-flocculation process which is widely used, due to its simplicity and cost-effectiveness. Coagulation and flocculation consist of adding a floc-forming chemical reagent into water or wastewater to encourage the nonsettleable colloidal solids (or particles) to collide, leading to coalescence of particle to form flocs particles (which are bigger and heavier). 2.0 OBJECTIVE The objective of jar test is: To determine the optimal coagulant dose which will produce the highest removal of a given water turbidity. To identify the most common coagulant used in the coagulant process. To determine the most effective and optimum dosage of coagulant for a particular mixing intensity and duration. To understand the complex interrelationships that exists between the chemicals and the constituents of the water being treated, as well as other factors such as pH, temperature, intensity and duration of mixing. 3.0 EQUIPMENTS AND MATERIALS No. Name Image 1 Jar test apparatus with six 1 2 3 rotating paddles blade Beakers ( six) pH meter 2 . 4.0 PROCEDURES 3 .4 5 Turbidity meter Pipette REAGENT Aluminum sulfate (alum) with a known concentration or anionic/cationic coagulant such as ferrous sulfate and ferric chloride. The speed was reduced to 30 rpm for about 20 minutes. 9. Figure 4. 500 ml of settled water for each beaker was separated and was putted into another beaker. The flocculation process was observed and the floc formation was recorded in the final 10 minutes by referring to the chart of particles size provided. The wastewater sample was started stirring rapidly (70 rpm) for 3 minutes. 4.4. The temperature. 11. The prepared wastewater was placed in 6 different beakers (plexiglass graduated beakers) with one litre each. 3. 10. The stirrer was stopped when the stirring period was over and the floc was allowed to settle for about 5 minutes.5 5.3. The wastewater sample was prepared. pH and turbidity for each beaker of the clarified water was determined and recorded. pH and tubidity of the water sample were measured. 2. The temperature. 2. 1-5 ml of coagulant (alum) was added by using a measuring pipette into beaker 1. 6. 7. The sample was premixed to obtain consistent condition in all jars.1. The blade was inserted into the beakers and the depth of the blade was calculated.1 5. 8. while no alum was added in beaker 6 because it acts as a control sample.0 RESULTS AND DATA ANALYSIS JAR TEST (Set the coagulant dose) 4 . 75 4 10.Initial turbidity: __9.11_____ pH adjustment (base: _ 3_____ mg/L of _NaOH pH adjustment (acid : ___0___ mg/L of __HCl__ Coagulant concentration: ____8.27 9.13 4.08 1 2 3 4 5 control 23 70 30 23 70 30 23 70 30 23 70 30 23 70 30 23 70 30 70 70 70 70 70 70 6.37 7.78 5 10.71 6 11.12 2 10.99_____ NTU Initial pH: __6.59 4.37 3.24 3 10.5 %___ mg/L Jar No PH Coagulant dose (mg/L) Agitate (minute) Fast (rpm) Slow (rpm) Settling depth (mm) Turbidity (NTU) Floc formation (final 10 minutes) * 1 11. 5 .22 Size F Size E Size C Size C Size B Size A * Floc formation can be recorded by referring to the measurement scale as depicted in Figure 1. Figure 1: Scale for measurement of floc sizes 6.0 DATA ANALYSIS 6 . 37 for the turbidity.From the graph. . 7 .1.From the data that have been recorded. ii. the optimum value for coagulant dose is 4 mg/L. 2. Beaker 4 has the lowest value for the turbidity that is 3.22.59. Beaker 5 has the highest value of turbidity among the six beakers that is 9.13. 3. From the graph. With the aid of a graph: i. Show the relationship between turbidity with respect to coagulant dosage. Beaker 2 has the second highest value of turbidity that is 7. Show the relationship between pH with respect to coagulant dosage. Compare the level of turbidity in each sample. get the optimum value for coagulant dose of the coagulation process. Beaker 3 has the value of 4.37 for the turbidity. The last beaker that is beaker 6 has the second lowest value of turbidity that is 4. . it shows that beaker 1 has the value of 6.27. It can be refers to a chemical process in which the described as a physical or a mechanical destabilization of non-settleable particles process in which the coagulated clumps or takes place. By using aluminum sulphate. Differentiate between coagulation and flocculation process. These particles form lumps flocs are joined together. the mechanism is : Al3+ + 3H2O Al(OH)3 + 3H Describe the mechanism of reaction if the aluminum sulphate is replaced by ferum chloride (FeCl3). What is the common coagulant used? -Aluminum sulfate or alum is commonly used as coagulant reagent. with the help of coagulant 3. it basically Flocculation means to form flocs. 8 .7. -FeCl3 + 3H2O Fe(OH) 3 + 3HCl 2. Coagulation Flocculation Coagulation means to curdle.0 DISCUSSION 1. During the flocculation. 6. The velocity or the speed of flocculator is one of the important factors during coagulation. One of them is make sure that the small bottle used to determine the turbidity is cleaned and dried first before use. it will produce an amount of floc but if it continues to be at high speed. the speeds of the flocculator need to be reduced from 80 rpm to 30 rpm. 9 . Discuss the caution that you consider and errors occur (if any) during the experiment. 5. the floc formation will disappeared and there will be no left to be observed. Why? - At high speed. -The temperature of water sample -The pH reading of water sample -The turbidity of water sample -The alkalinity of water sample 7. the coagulant mix and bring the fine particles produced during coagulation into contact with each other. - From the experiment. there some precaution during the experiment. Second is making sure that the equipment used to determine the pH is washed with distilled water first before put it into the sample water. Describe how the coagulant works during coagulation-flocculation process? - Coagulant with charges opposite to those of the suspended solids are added to the water to neutralize the negative charges on dispersed non-settleable solids such as clay and organic substances during coagulation. During the experiment. List another three important factors influencing coagulation. So that.4. Lastly. make sure that the wastewater is neutral before proceeding with the next procedures. the speed of the flocculator needed to be reduce. jar test is an experimental method where optimal conditions are determined empirically rather than theoretically. The values that are obtained from the experiment are correlated and adjusted in order to account for the actual treatment system. This is because the lowest turbidity value is the beaker that was added with 4 mg/L of coagulant.8. Based on the graph. The two graphs drawn is between pH with respect to coagulant dosage and between turbidity with respect to coagulant dosage. Jar test are meant to mimic the conditions and process that take place in the clarification portion of water and wastewater treatment plants. the optimum coagulant dosage obtained is 4 mg/L. 10 .0 CONCLUSION As a conclusion. 0 APPENDIX FIGURE 2 : WATER SAMPLE TEST FIGURE 3: NaOH SOLUTION 11 .9. 0 REFERENCES http://www.sswm.comflocculation.html http://sarat212.com/2013001/03/jar-test/ 12 .filtronics.info/content/coagulation-floccuation http://www.10.wordpress.