Cinnaminson Sewerage Authority
Cinnaminson, New Jersey

The Cinnaminson Sewerage Authority Wastewater Treatment plant was built in the 1960's and designed as a secondary treatment plant discharging into the Delaware River. The design flow capacity of the plant is 2 MGD; it currently has flows of 1.2 MGD. The plant has flow equalization, primary & secondary clarification, hypochlorite disinfection, and two 320,000 gallon mechanical mixing aeration tanks. Primary sludge is dewatered through Somat screw presses and shipped dry while secondary sludge is separated through a dissolved air flotation process and is shipped at 3% solids.

Prior to treating with PHS, the plant was experiencing difficulty in maintaining it's permit requirements. Secondary clarifiers were encountering denitrification with suspended solids washing over the weirs into the contact tanks, causing TSS levels in the effluent to be twice the allowable limit.

The CSA decided to address the issues, hiring outside sources to bring the plant back into compliance and within seven months the plant was in compliance. Challenges still were facing the authority with denitrification in the secondary clarifiers, caustic soda used to balance the pH, setteble solids ranging daily from 700 to 800 mg/l, and polymers were used in the daily treatment process.

Within one month from starting PHS treatment to the plant, setteble solids were at 400 mg/l, SVI readings of 125 to 150 were common, caustic soda used for pH control was eliminated, and the addition of polymer was discontinued. Denitrification that plagued the secondary clarifiers was now almost non-existent, water from the SVI test after thirty minutes of settling was now clear and transparent, and sodium hypochlorite used in the contact tanks for disinfection was reduced 30%.

Because of the success taking place, the authority made the decision to continue treating the plant with PHS as part of the daily treatment process.

Following six months of treatment of the plant with PHS, scheduled system maintenance was to be performed on both aeration tanks thus leaving the plant with one operating tank while the other was being serviced.

During this maintenance it became evident the plant could operate sufficiently with just one aeration tank, a situation that had never before been encountered. Upon conclusion of the plant maintenance the decision was made to leave the second tank out of service and see just how long this increased biological process would continue.

Treatment with PHS continued and the biological activity within the plant remained high allowing the second aeration tank to remain off line.

At the conclusion of the first year, the second aeration tank remained off line and signs of a healthy floc were being seen daily. Improved settling in the secondary clarifiers continued and the overflow and dentrification plaguing the secondary clarifiers was eliminated.

Pictured above are the two CSA aeration tanks. Each tank has a volume of 320,000 gallons. The tank shown on the left side of the picture was taken out of service, six months after the start of PHS treatment to the plant.

Challenges from mechanical problems in the plant gave need for the second aeration tank to be put back in service. These challenges lasted just four months and upon conclusion of the mechanical repairs the second aeration tank was then again taken out of service.

BOD influent averages 290 mg/l, with influent flow consistent at 1.2 MGD. With these loading characteristics and one aeration tank in service, secondary sludge production decreased by 24% with the percent solids of the secondary liquid sludge increasing from 3% to 4%.

Adjustments to dissolved oxygen levels were made on a trial basis to lower nitrate levels in the effluent. Levels below 10 mg/l. were attained, a remarkable accomplishment for a plant not designed for dentrification.

Biological improvements due to PHS treatment is just one part of the story. Significant financial gains from a combination of reduced labor, electric savings, and a reduction in chemicals have also been made.

These savings are quite typical among plants using PHS. In each case the size of a plant determines it's savings; nevertheless the savings are always significant.

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