In this lab , students will be exposed on how to carry out a jar test in order to determine the optimum coagulant dose in the flocculation tank.
1.2 Objective
To determine the effectiveness of chemical coagulation of water or wastewater.
1.3 Learning Outcomes
At the end of the laboratory activities, students would be able to: i. arry out and determine the optimum dose of alum in flocculation process. ii. Analyse data and present in technical format.
1.4 Theory.
!ar test is a method of stimulating a full scale water treatment process , providing system operators a reasonable idea of the way a treatment chemical will behave and operate with a particular type of raw water. It entails entails adjusting the amount of treatment chemicals and the se"uence in which they are added to samples of raw water held in jars. The sample is then stirred so that the formation, development and settlement of floc can be watched just as it would be in full scale treatment plant. The tests are therefore used to determine the most effective doses of coagulant for a specific water in the control of coagulation and flocculation at a water treatment plant, especially when water "uality fluctuates rapidly.
2.0 Problem tatement
#ach group is re"uired to test and determine the correct amount of coagulant $alum% dose $mg&l% for removing the solid contents from three $'% raw water sources such as river , pond and lake or any other sources.
'.( Apparatus
!ar test beaker, river water.
3.2 Procedures
i. )sing ( liter graduated cylinder , add ( liter of raw water to each jar test beakers. The p* and turbidity were recorded ii. A stock solution by dissolving (+.+ grams of alum into (,+++ m distilled water was prepared. #ach (.+ m of this stock solution is e"uivalent to (+ mg& $ppm% . iii. -ose each beaker with increased amounts of the stock solution, see table below for an example of increment.
!ar ( 1 ' 2 0 3
m Alum tock Added + 1 ' 2 0 3
/g& Alum -osage (0.+ 1+.+ 10.+ '+.+ '0.+ 2+.+
iv. ower the stirring paddles , started the stirrer and operate it for ( min at a speed of 4+ rpm and reduce to '+ rpm for (0 min. v. The stirrer was stoped and recorded how long it takes for the floc to settle to the bottom of the beaker. vi. Allow the flocs to settle for 1+ min. The turbidity of the supernatant was determined.
'.' -ata Ac"uisition Turbidity Test
(
1
'
Average
Initial Turbidity $5T)%
2'1
21(
2+3
21+
p* value Test
(
1
'
Average
Initial p*
3.20
3.23
3.24
3.23
!ar
hemicals Alum 6inal p*
Turbidity Alum
6inal
(
mg & +
3.10
mg & +
Turbidity 107
1
1
3.'+
1
((0
'
'
3.12
'
30.+
2
2
3.'2
2
'1.3
0
0
3.+2
0
30.'
3
3
3.+2
3
(20
Graph of Turbidity Against Alum Dosage 300 250 200 Turbidity (NTU)
Graph of Turbidity Against Alum Dosage
150 100 50 0 0
1
2
3
4
5
6
7
Alum Dosage (mg/L)
2.+ -I)I85 9robably the single most valuable tool in operating and controlling a chemical treatment process is the variable speed,multiple station jar test unit. arious type of chemical or different does of a single chemical are added to sample portions of wastewater and all portions of the sample are rapidly mixed. After rapid mixing,the sample are slowly mixed to approximate the conditions in the plant. /ixing is then stopped and the the floc formed is allowed to settle. The appearance of the floc, the time re"uired to form a floc and the settling conditions are recorded. The supernatant is analy;ed for turbidity , suspended solids and p*.
The jar test is a laboratory procedure that simulates coagulation & flocculation with differing chemical doses. The purpose of the procedure is to estimate the minimum coagulant dose re"uired to achieve certain water "uality goals .amples of water to be treated are placed in several jar ,various amounts of chemicals are added to each jar, stirred and the settling of solids is observed. The lowest dose of chemical that provides satisfactory settling in the dose used to treat the water. =ased on our data we can conclude that the higher amount of chemical added, the lower will be its p* values. If the number of aluminium is lower, the time of floc will increase and also settling rate. The settling rate time is higher starting from jar ( and decreasing until jar 3.
0.+ 85)I85 As conclusion, this experiment is successfully been done and it is because the objective of this experiment which to conduct various experiments on chemical coagulation and flocculation and to determine the optimum dose combination of coagulant aid $when used% which will produce the highest removal of turbid water sample has achieved.
hands on? understanding of the treatment process for removing suspended solids from water.
3.+ @#6#@#5# (. !ar Test. @etrieved !une 1',1+(3 from ab /anual of #< '0( 2. !ar Test. @etrieved !une 12,1+(3 from the oogle https:&&www.google.com&searchB"CvacuumDpumpDforDjarDsuspendedDsolidsEbiw • 3. !ar Test. @etrieved !une 10,1+(3 from the 5orweco aboratory $google% https:&&www.norweco.com&html&lab&testFmethods&102+efp.htm •
