By: Bruce Hardboss, PE
This article discusses minimum sewage wastewater chlorine-tablet-feeder design considerations. As a wastewater engineer, I routinely see application of wastewater tablet feeders for chlorination designs that are not well thought out. This article will highlight the NORWECO tablet feeder designs since we feel that the NORWECO tablet feeders are the best on the market. The principles that we present are recommendations for you to implement in your design.
Tablet feeders generally have some sort if tube which is filled with the chlorine tablets. The tube is easily removed for re-filling. As noted in the figure below, the tube is slotted on the bottom, which allows the wastewater to contact the chlorine tablets, dissolving them, and thusly chlorinated in the wastewater stream. The tube feeder product that you select should have a removable tube, such as the NORWECO design.
The second design consideration should include some sort of tiered flow. As in the figure above, as the flow is increased the width and depth of the tiered flow should also be increased. This allows for, under low flow conditions, wetting of only the first tablet in the tablet tube. This tiered flow design significantly reduces the rate that the tablets are expended. In addition, under low flow conditions better chlorination due to contact with the first tablet is achieved. The tablet feeder that you select should have a tiered flow design.
Tablet feeder that you select should also have a minimum warranty of 20-years. Tablet feeders that come with a 20-year warranty, generally, are made from superior materials that resist corrosion, cracking and deterioration. So if the tablet feeder that you select does not have a 10-year warranty. I would suspect that the materials used are substandard.
The NORWECO tablet feeders also come within a unique feature. At the base of the tablet feeder holding tube, 4 inch PVC piping can be glued or sealed on the top of the tablet feeder. This feature allows you to bury the tablet feeder deeper than the standard riser tubes. The PVC piping thickness can be increased to schedule 80, which allows for superior protection of the feeder riser tubes from the surrounding soil. Alternatively, the NORWECO IT series tablet feeders include plastic direct burial risers, which are generally used in commercial applications. As we increase daily wastewater flow-rates, the tablet feeders increase the number of tablet feeder tubes, as noted in the figure below:
Increased Number of Chlorine Tubes With Increased Flow Rates
As you shop around for your next tablet feeder, we strongly recommend the NORWECO line of products. NORWECO is been in operation for over 100 years. NORWECO’s products are seasoned, and continuously improved. If you are considering purchasing or installing a tablet feeder in your present system, then please consider the designs options that we have presented in this article. If you are interested in our NORWECO products, please click on any one of the images in this article, or merely go to the NORWECO products page on this website. Our recommendations are written by a registered professional engineer with a strong background in wastewater engineering.
If you have any questions, then please feel free to contact us at www.wastewatertreatmentplant.org.