To fully comprehend the true cost effectiveness of any polyacrylamide or other type of polymer in your treatment process, it cannot be accomplished without first conducting full scale in-plant trials on the specific separation equipment utilized. To not perform such testing will not allow you to meet your goals of providing the most cost-effective product to your process nor your rate payers.
All polymers are comprised of varying parameters that when combined in your application determine not only the performance of that operation, but also factor in some of the operating costs. Not all of these varying parameters in polymers are the same, thus not able to perform identically in your site-specific applications. Percent charge, molecular weight, shear sensitivity, degree of structure, percent actives, etc., all play a role in performance criteria. That, plus your site-specific parameters such as separation process equipment, solids parameters (i.e. % feed, type, age, etc.) mixing energy, point of chemical application, etc., again all factor into the formula as well.
On-site Laboratory Bench-Scale Testing is only the first step in the overall process. Most technically advanced polymer supply companies provide this service to you at your facility. The sole purpose of this service is for the potential supply company to determine which product or products (generally 1 or 2) best performs in the application and is then chosen for in-plant process trials. Little else can be derived from this process and should be used only as a final determination as to which products require full-scale product selection. Generally, in these tests we provide the chemical at no cost to the end use customer. However, should your process require additional testing or if the potential sale amount does not cover costs, there may be charges associated with these tests. Any firm not offering this service to you is not fully engaged in the sale of polymers and should not be considered as a source of supply.
In-Plant Trial Processes are then conducted to evaluate the product/products chosen in the previous step. Full scale plant trials are needed to verify the actual product selections and dosages on the process equipment used in the treatment. No other method can verify the same. A detailed plant trial process needs to be developed, outlined and should be published in the bid specifications.
In-Plant Trials now are required to be conducted under similar operating conditions. After all, we are evaluating the various polymers at this point, not the solids separation process. It is imperative for you to establish the parameters of the testing process. Limiting the testing process to polymer feed rates, injection points, carrier/dilution water, and mixing energies focus attention on the polymer products. Forbidding changes in sludge feed rates, belt tensions, and speed again focus the attention on polymer performance.
In-plant trials will require additional testing and data recording than may normally be documented in daily treatment processes. Testing for Feed Solids, Filtrate/Centrate Solids, Cakes Solids, Polymer Solution Strength, and Feed Rates are all major factors that require monitoring. Some additional processes such as incineration costs, hauling/disposal costs, etc., may also be made part of the equation.
When all testing is completed and tabulated, and polymer costs obtained, it is then possible to input all the data into the following equation.
NOTE: Do not concern yourself with the percent actives in a liquid or emulsion polymer. The usage rate on an “as is” basis is the determining factor. The equalizing factor in determining the most cost effective polymer is:
Lbs. Polymer / Dry Ton Solids Processed
Do however, retain samples of the products run in the trials for comparison sake, should product performance drop off sometime later.
INITIAL DOSAGE
PERCENT RECOVERY
FINAL CORRECTED COSTED DOSAGE
KEY
- Polymer Product Designation
- Biosolids Feed Rate (lbs/unit)
- Biosolids Solids Concentration (% conc.)
- Polymer Feed Rate (lbs/unit)
- Polymer Make Up Concentration (% solids)
- Filtrate/Centrate Solids (% solids)
- Cake Solids (% solids)
- Polymer Cost ($/lb)
Should you wish to conduct a true evaluation of your treatment processes using polymers, please feel free to contact our offices to have one of our Chemical Application Specialists visit your facility.
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