Overview
Jar testing, also known as bench testing, is a practical method to evaluate a plant’s chemical treatment process by using site-specific wastewater and observing how it reacts with different chemicals. Chemical use is essential in wastewater treatment and plays a critical role in processes such as phosphorus removal and polymer addition for solids thickening and separation.
Effective coagulation and flocculation—the process of using chemicals to clump together and remove suspended solids and organic matter from wastewater—can significantly impact overall treatment performance. Proper chemical dosing improves efficiency, reduces costs, and helps prevent overdosing, which can lead to unnecessary expenses and potential environmental harm.
Why Jar Test?
Many wastewater plants have used the same chemicals for years without reevaluating their effectiveness, often assuming that meeting compliance is sufficient. However, this can mask inefficiencies in chemical usage that lead to excessive costs and unintended environmental impacts.
Bench testing offers several benefits, including:
- Assessing a chemical’s effectiveness under real-world conditions
- Identifying the best chemical for a specific treatment application
- Determining optimal dosing ranges to improve efficiency
- Evaluating ideal dosing locations within the treatment process
- Enhancing process control and overall treatment performance
By fine-tuning chemical usage, utilities can save money, improve regulatory compliance, and minimize environmental harm.
Moonshot on-site in Victoria, Virginia assisting with jar testing as part of a process optimization effort. Photos courtesy of Nathan Coey.
How to Perform a Jar Test
Most wastewater treatment facilities with a basic lab setup already have the necessary supplies, including:
- Beakers (1- or 2-liter)
- Magnetic stirrer and stir bar
- Micropipette for precise chemical dosing
- 0.45-micron filter (if testing samples with significant particulates)
- pH meter to monitor acidity and alkalinity
- Spectrophotometer or colorimeter (such as Hach TNT or Powder Pillow method) for phosphorus testing
Steps:
- Collect wastewater samples from dosing locations within the plant. Be sure to number or mark each beaker with the sample location.
- Split samples into separate beakers of the same volume and measure initial concentrations of the target parameters (e.g., phosphorus, MLSS, TSS), depending on what is being analyzed to establish a baseline. Be sure to include pH to monitor any changes before and after chemical addition.
- Add chemicals in varying dosages to different beakers, again marking which dosages went into which sample, and stir at varying speeds to simulate coagulation and flocculation. Be sure to calculate your dosages based on the size of the sample beakers.
- After 5 to 10 minutes of mixing, followed by 15 to 30 minutes of settling, test the samples again to evaluate chemical performance.
- Compare results by calculating percentage removal rates of each sample to determine the most effective chemical and dosage.
Jar Testing for Phosphorus Removal
With increasingly stringent phosphorus limits, many utilities must improve their phosphorus removal strategies. Moonshot has worked with treatment plants to assess existing chemical phosphorus removal processes through jar testing. This approach enables plants to compare their current practices with alternative chemical solutions, maintaining compliance while minimizing costs.
Key Takeaways
Jar testing is a simple and cost-effective method for evaluating chemical usage, optimizing dosages, and assessing alternative treatment options. It helps utilities improve process efficiency, adapt to regulatory changes, save money, and reduce environmental impact. By regularly conducting bench testing, treatment plants can maintain high performance while ensuring sustainable and economical operations.
If you’d like a copy of a more detailed jar testing protocol, have additional questions, or are interested in having us visit your plant to assist with testing and process optimization, please feel free to contact us.
Nick Meurer
Utility Advisor
Moonshot Missions
Nick@moonshotmissions.orghttps://www.moonshotmissions.org/