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Jar testing is a common laboratory procedure used at water and wastewater treatment plants to determine optimum conditions for the coagulation / flocculation process.
In a set of beakers a defined amount of water is mixed with varying amounts of coagulant, and through observation by a trained operator the optimal amount of coagulant can be determined. While jar testing is straight forward to perform, it does require typically about 2-3 hours, including preparation and settling time. Jar testing must be repeated regularly for surface water treatment plants since raw water quality can change rapidly with environmental conditions such as rain, increase in contamination debris, storm and run-off events, as well as seasonal impacts (snow melt, tree debris, algae growth, severe weather events, forest fires).
A significantly faster and more precise method is the measurement of zeta potential expressed in milli Volt (mV). Here, the water is exposed to an electric field using a benchtop or inline system, and the movement of colloidal particles indicates their net charge under the specific water conditions. Formation of particles due to aggregation and flocculation is enhanced when the net charge of the particles is close to zero1.
| In comparison | Jar Testing | Zeta Potential |
| Initial Investment ROI | Low Cost - simple ROI - not typically a factor. | Investment typically under Operational budget, ROI less than 12mos. |
| Operator Training level | Experience required | Easy to use by all |
| Quantitative Precise results | None - Subjective by operator | Quantitative and Precise results |
| Set-up and Calibration requirements | Operator dependent | No calibration required |
| Time to complete testing | 2-3hrs | Results within minutes, online system can produce ~400 results per day. |
| Impact on process optimization | Subjective and only based on latest test results. Cannot provide insight in near real time, little to no process optimization. | Significant operational improvement, cost savings, labor savings, sludge reduction, improved filter performance and lifetime with reduced maintenance. |
Varying raw water quality requires optimization of the flocculation/coagulation process during water treatment plant operation. The traditional jar test approximates the water plant pretreatment process, yet takes hours to complete testing and requires a trained operator with the skill and experience to find the optimal coagulant dosage. Zeta potential on the other hand is a simple physical technique based on light scattering. It assesses the net charge of particles, and when the water sample is close to neutral charge the formation of floc is favored.
For coagulant dose control, zeta potential offers clear advantages. Contact us to learn more about Malvern Panalytical’s Zetasizer system for zeta potential.
[1] “The Role of Zeta Potential in the Optimization of Water Treatment” U Nobbmann, A Morfesis, J Billica, K Gertig. NSTI Nanotech. Volume 3, 605-607 (2010)
Jar testing is a common laboratory procedure used at water and wastewater treatment plants to determine optimum conditions for the coagulation / flocculation process.
In a set of beakers a defined amount of water is mixed with varying amounts of coagulant, and through observation by a trained operator the optimal amount of coagulant can be determined. While jar testing is straight forward to perform, it does require typically about 2-3 hours, including preparation and settling time. Jar testing must be repeated regularly for surface water treatment plants since raw water quality can change rapidly with environmental conditions such as rain, increase in contamination debris, storm and run-off events, as well as seasonal impacts (snow melt, tree debris, algae growth, severe weather events, forest fires).
A significantly faster and more precise method is the measurement of zeta potential expressed in milli Volt (mV). Here, the water is exposed to an electric field using a benchtop or inline system, and the movement of colloidal particles indicates their net charge under the specific water conditions. Formation of particles due to aggregation and flocculation is enhanced when the net charge of the particles is close to zero1.
| In comparison | Jar Testing | Zeta Potential |
| Initial Investment ROI | Low Cost - simple ROI - not typically a factor. | Investment typically under Operational budget, ROI less than 12mos. |
| Operator Training level | Experience required | Easy to use by all |
| Quantitative Precise results | None - Subjective by operator | Quantitative and Precise results |
| Set-up and Calibration requirements | Operator dependent | No calibration required |
| Time to complete testing | 2-3hrs | Results within minutes, online system can produce ~400 results per day. |
| Impact on process optimization | Subjective and only based on latest test results. Cannot provide insight in near real time, little to no process optimization. | Significant operational improvement, cost savings, labor savings, sludge reduction, improved filter performance and lifetime with reduced maintenance. |
Varying raw water quality requires optimization of the flocculation/coagulation process during water treatment plant operation. The traditional jar test approximates the water plant pretreatment process, yet takes hours to complete testing and requires a trained operator with the skill and experience to find the optimal coagulant dosage. Zeta potential on the other hand is a simple physical technique based on light scattering. It assesses the net charge of particles, and when the water sample is close to neutral charge the formation of floc is favored.
For coagulant dose control, zeta potential offers clear advantages. Contact us to learn more about Malvern Panalytical’s Zetasizer system for zeta potential.
[1] “The Role of Zeta Potential in the Optimization of Water Treatment” U Nobbmann, A Morfesis, J Billica, K Gertig. NSTI Nanotech. Volume 3, 605-607 (2010)
