Challenge

The Gallitzin, PA water supply is a spring fed system.  The five springs have elevated levels of turbidity, which are influenced by rainfall.  The raw water contains an average turbidity level of 10 NTU with spikes up to 30 NTU.  As such, the city of Gallitzin needed a way to cost effectively protect against pathogens while improving the aesthetics of the water supply.

Solution

Gallitzin constructed a two-train treatment plant that incorporates a Microfloc® Trident® water treatment system.

• Each tank consists of a first stage high-rate upflow adsorption clarifier and polishing filter.
• The clarifier incorporates buoyant media, held in place by a retaining screen, to provide in-bed coagulation, flocculation and initial solids removal.
• Solids collected in the clarifier are removed by introducing air to expand and agitate the bed, with raw water used to flush away the solids.
• Polishing filtration consists of 30 inches of mixed media directly retained by an air/water underdrain.
• The system is equipped with automatic chemical feed, chemical monitoring and a chemical control system, allowing unattended operation.
• A built-in safeguard shuts down the plant if effluent turbidity exceeds 0.4 NTU, allowing the plant to run unattended during overnight hours.

Results

The Department of Environmental Protection (DEP) evaluated the Trident® system to determine the ability of the plant’s individual unit processes to continuously provide an effective barrier to the passage of microorganisms.  A goal of the study was to produce a finished water turbidity of 0.1 NTU. They reviewed a year’s worth of operating data and also connected an on-line particle counter to obtain effluent particle count data.  The DEP gave the plant an “acceptable” performance rating for its ability to remove Giardia and Cryptosporidium oocysts.

• DEP test results demonstrated excellent removal of both turbidity and microscopic particles.
• The compact system saves up to 80% of the building floor space required for some conventional systems of the same flow capacity.
• Automatic operation is provided.
• The plant can run unattended during overnight hours.
• The Trident water treatment package provides an effective and cost efficient method of meeting the new EPA Surface Water Treatment Rule.