Jar Test

I was thinking about something to post here and I just remember my environmental analysis laboratory months ago. What is that?  Jar Test. In environmental industries, jar tests are mostly applied for the water treatment. Well I will just post a brief and simpler explanation for this jar test. More information can be surfed from the links shared bellow the post 😀

Jar testing is a method of simulating a full scale water treatment process, which provides  system operators a reasonable idea of the way a treatment chemical will behave and operate with a particular type of raw water.  Jar test used to help determine which treatment chemical will work best with their system’s raw water.

The picture in the post, it’s me when i was operating the jar test instrument with 6 beakers being stirred and already being added  with PAC.

In this determination we use chemical, like  Aluminum Sulfate, Polyaluminium Chloride(PAC) as the coagulant for the raw water.  The reaction between the chemicals and the water will form flock which will be settled down . The simple  understanding is, the colloid  from the raw water (which have negative ion) will react with Al3+ from the coagulant which make  the flock formed clump.

This Jar test is carried out with several beakers, usually we use 6 beakers. Then certain and different amounts of the coagulant is added usually, the addition of the chemical is in consecutive  range, e.g. we  add the coagulant agent in 35 ppm, 36 ppm, 37 ppm, 38 ppm, 39 ppm, 40 ppm (this is based on the estimated amount to the condition of the raw water). This range is applied from the previous calculation of how much the coagulant must be added to the raw water. After adding the chemicals to each beaker and stir each of them, watch the coagulation result. If the results show:

35 ppm is = turbid

36 ppm is = less turbid

37 ppm is = clearer

38 ppm is = much clearer

39 ppm is = very clear

40 ppm is = turbid

So, we the maximum concentration of the chemical added is on the 38 ppm. When it exceeds the 38 ppm, the turbidity formed is from the excessive chemical used to coagulate, it is not from the colloid of the raw water.  Then for the big scale of the raw water management is done by the calculation of the chemicals amounts and water.

Read more her: http://www.nesc.wvu.edu/pdf/dw/publications/ontap/2009_tb/jar_testing_dwfsom73.pdf

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