Utility Facility - 60 Day Holding Pond - Case Study
The Attala Plant for Entergy Corporation in Mississippi was experiencing seasonal algae blooms in their 60-day Holding pond in 2017. The utility plant water process is as follows:
In the past, Entergy® was unable to use “traditional treatment methods” (Copper Sulphate based algaecides), and because the 60-Day pond also receives runoff from local agricultural areas (nutrient load) the algae growth was getting worse each year. Affected water will then run into the 7-day pond, where optimal conditions exist for proliferation (shallow stagnant water, loads of sunlight).
The specific issues experienced at the Entergy® plant caused by this algae overgrowth were:
- Small, weak, light flocculation
- Clogged sand filters
- Biological fouling of the RO membranes and heat exchangers
- Excessive chemical consumption in the cooling towers to treat the increase biologicals
- Excessive costs to treat incoming raw water for plant use
The Algae Culprit
A sample of the algae was sent off to Mississippi State University for analysis and it was identified as Microcystis, a Blue-Green Algae. It was determined that this particular Microcystis sample did not have any toxins, and therefore was not considered an HAB.
The Trial Solution – Ultrasound
In 2017, Entergy® obtained and installed an ultrasound unit from SonicSolutions Algae Control, (SS-600 model) to install into their 60-day pond. The pond is approximately 11 acres, and 10 feet deep.
The Trial period was 90-days. After the first 30 days, the small algae bloom was noticeably dying and floating on the surface of the water.
After the 90-day trial was complete, Entergy® extended the use of the ultrasound unit and noticed the following results:
- Decreased TOC in the water and plant inlet water
- Decreased Labor in Clarifier operations
- Decreased chemical consumption
- Decreased Maintenance in Raw Water Supporting Systems
- Substantial Financial Savings
“This device is proven to be effective for a low-cost treatment of Blue-Green Algae and Green Algae in surface water,” says the treatment plant operator.