Back to Lime Softening Techniques for Operators: AWWA Thought Leaders Series DVD
Hard water (water with elevated levels of primarily calcium and magnesium) is commonly softened using the chemical lime. Produced specifically for water treatment operator training, this new video illustrates and explains lime softening processes, chemistry, and feed calculations.
Water treatment operators benefit from watching this DVD by better understanding what hard water is, the problems it causes in the distribution system and for consumers, and how and why lime softening reduces hardness. Importantly, operators learn how to precisely calculate lime and soda ash dosages for removing hardness. What the video covers:
• Shows softening equipment and facilities, including lime silos, dry feeders, lime slakers, accelators (lime treatment units), and launders. Operators learn where the softening process fits into the water treatment train.
• Explains what types of contaminants are removed from water during lime softening, what chemicals are used for softening, and the importance of pH in the softening process.
• Concentrates on the chemical reactions taking place during softening, how to calculate lime and soda ash dosages, and the resulting water quality after softening. The video presents two methods of dosage calculation: a conventional method and one using milliequivalent diagrams.
• Presents typical operational problems created by lime softening, and offers solutions. The video briefly discusses the pros and cons of two other hardness removing techniques: spiractors and sodium hydroxide. Rounding out this practical program are the safe handling of lime and soda ash, the disposal of residuals and sludge, and recordkeeping.
This video is approximately 48 minutes.