Jar Test in Water Treatment

The objective of the jar test is to find the optimal ______, coagulant dose, and the theoretical amount of alkalinity that would be consumed at the optimal dose.

In the first jar test, the optimal pH chosen was ___.

The optimal alum dose estimated from the second jar test was about ___ mg/L.

To pinpoint the optimal conditions, the laboratory technician would vary the alum dose between ___ and 15 mg/L.

From Figure 6-11, the optimum pH was estimated to be ___ and the optimum dose was estimated to be 12.5 mg/L.

In the jar test, the laboratory technician would probably try to repeat the test using a pH of 6.25 and varying the alum dose between 10 and 15 to pinpoint the ___ conditions.

COV is defined as the coefficient of variation with time where COV is the ______ of concentration

The standard deviation is defined as the sum of (Ct minus C) squared divided by n-1, where Ct is the concentration of the sample and n is the number of ______

The design criteria may include a COV of 1 to 10 percent with an average of 5 percent, a Gt range of 350–1700, a mixing time of 1 to 3 s, and a maximum headloss of 0.6 to 0.9 m. The design should specify that the mixing elements be ______

According to Bayer et al. (2003), three elements in mixers designed for turbulent flow will yield a COV of about 10 percent, while six elements will yield a COV of about 1 percent for Reynolds number greater than 5,000. Turbulent flow may be assumed for water entering water treatment plants from ______ sources

The selection process for mixers is highly dependent on the approach suggested by the ______ for their mixer

The method suggested by Bayer et al. (2003) is to select the number of mixing elements to achieve the desired COV, where three elements yield a COV of about 10 percent and six elements yield a COV of about 1 percent for mixers designed for turbulent ______

Because of the time delay in conducting the test, other techniques such as zeta potential measurements and the use of a streaming current detector (SCD) have been used to augment the ______ test.

None of these relieve the operator of the necessity of a significant amount of attention. Monitoring of the chemical feed system to detect clogging of the lines and maintenance of the mixers ranks second in the need for close O&M oversight. Appropriate mixing energy is an important part of optimization of the chemical ______.

Excess dosing with coagulant to compensate for inefficient mixing not only is uneconomical in terms of chemical usage, it is expensive in terms of ______ production.

All of the design calculations in this chapter were based on the design flow, that is, the maximum daily flow rate at the end of the design life. Because the minimum flow rate at start-up will probably be considerably less than the design flow, operational problems may be severe. It is highly recommended that the design be evaluated at minimum flow ______.

Most drive failures are caused when the unit is started at the top rotational speed. O&M manuals should note that mixers should be started at low speed to avoid very high torque force and a high ______ requirement.

Suggestions from operators include the following: Because of the time delay in conducting the test, other techniques such as zeta potential measurements and the use of a streaming current detector (SCD) have been used to augment the ______ test.