We Dewater Water Plants Too – Part Two Alum Sludge

Written by Tom Welch, October 26, 2015

Seneca Light & Water, serving the region of Oconee County in South Carolina, operates a 20 million gallons per day (MGD) Water Treatment facility that uses the 18,500-acre Lake Keowee as its source.  The original plant started in March of 1969 as a 4 MGD facility and has advanced to the current rating with several upgrades.

The Seneca water plant uses aluminum sulfate as a coagulant to lower the turbidity of the water.  After a series of processes, the waste aluminum sulfate is dewatered so that as little water as possible is hauled away with the solids.  Historically, a plate and frame press had been used.  Although that equipment provided a reasonably dry product, about 24% solids, the equipment was only able to run in batch processes, was labor intensive, and was not a clean process to work with.

In 2012, Seneca began a search to identify new dewatering techniques that could replace the aging plate and frame presses.  Several pilot studies were completed, and Schwing Bioset was invited to run their screw press pilot in May of 2013.  The pilot proved successful with a result of 27% solids, which was better than the performance of the existing plate and frame press, as well as the other screw press that had been tested.  The Schwing Bioset equipment was chosen as the best value and the new FSP 0403 screw press was designed into the new dewatering building that was commissioned in September of 2015.

The dewatered alum sludge is hauled to the nearby wastewater treatment plant and mixed with the dewatered Biosolids and then hauled jointly to the landfill.  Now in normal production, the FSP 0403 screw press is producing 30% solids on average with a high of 34%, which is even better than the pilot results.  This is all being done with a polymer dose of 5 pounds of active polymer per ton, which has proven to be very cost effective thus far.

Seneca Light & Water has met their goal of replacing their aged plate and frame technology with a very energy efficient screw press that allows continuous processing.

The new facility in Seneca, South Carolina, is Schwing Bioset’s second successful water plant startup in the Carolinas this year.

To read Part 1 of this blog, which discusses the screw press installation at a water plant using ferric, go here.

To learn more about our dewatering capabilities or this project specifically, contact this blog’s author, Tom Welch, and/or visit our website here: SBI Screw Presses. For other inquiries, call 715.247.3433, visit our website, or follow us on social media.