Written by Abis Zaidi
The Atlantic County Utilities Authority (ACUA) operates a 40 million gallon per day wastewater treatment facility in Atlantic City, NJ. The facility also accepts wastewater, FOG, and biosolids from fourteen municipalities in the County for treatment and disposal. All of this sludge is dewatered and then conveyed for final disposal in the multiple hearth incinerator. Dewatering and incineration are one of the most important processes for this facility, as incineration is the only mode of disposal.
The Authority relies on two dewatering centrifuges for their dewatering needs, though only one centrifuge is needed to handle their waste flow. Their standard operating procedure is to send one of their two centrifuges to the manufacturer for its complete preventive maintenance cycle, while the other one is operational. Typically, it takes 4-6 months for their centrifuge to be returned from the factory. The worst-case scenario for ACUA is that their operational/installed centrifuge has a failure while one is in the factory for overhauling. Unfortunately, this did happen twice in 2023.
When this happened, the Authority scrambled to find solutions to dewater their sludge to continue meeting effluent limits and removing solids from the plant. The Authority needed to dewater at least 2,650 dry #/hr to keep MLSS concentration within a reasonable range. One possible solution was to haul liquid sludge to Delcora (Delaware County Regional Authority), but the costs of this option were prohibitively expensive. Estimated costs were $10,000 – $15,000/day to haul roughly 120,000 to 200,000 gallons of sludge to Delcora, which is 70 miles from ACUA.
The only solution that was economically and logistically reasonable was the rental of a Schwing Bioset trailer mounted FSP 1103 screw press. This unit is capable of producing up to 4,000 dry #/hr, which is more than what the Authority required. Schwing Bioset was able to deliver a mobile FSP 1103 from its fleet within a few days to avert the impending crisis at the plant.
Schwing Bioset was not only able to save the Authority hundreds of thousands of dollars, but it was also able to impress ACUA with the simplicity and robustness of its screw press with the customer stating, “It’s extremely forgiving, unlike our centrifuges.” The Authority was so impressed that it commissioned a complete study to determine if it was feasible to replace their centrifuges with Schwing Bioset’s Screw Presses. The conclusion of the study was to add a 3rd centrifuge to accommodate redundancy requirements not achieved by the duty/standby arrangement presently employed due to other spatial constraints. However, the main features of the screw press that attracted the Authority the most were:
- Ease of operation. Customer’s statement: “Operators who had never seen a screw press before were able to get fully trained to operate the machine on their own within a day or two.”
- No need to ever send the screw press to the factory for any preventive or reactive maintenance.
- Schwing Bioset builds screw presses large enough to handle the flow of a 40 MGD plant.
- Schwing Bioset screw presses utilize lip seals which is the only wear part (sacrificial part) in the screw press. It can easily be replaced on site by plant personnel instead of sending the entire machine to the factory. Besides acting as a sacrificial part of the machine, this elastomer lip on the screw flight adds the following advantages:
- It eliminates metal to metal contact.
- It cleans the machine screens from the inside allowing continuous operation.
- It creates a tight seal between screen and the screw that allows the screw press to maintain higher positive pressure on the sludge increasing dewatering performance over other screw presses that do not utilize sealing lips.
To learn more about our rental and mobile equipment, or how Schwing Bioset can help your operation, please contact us or explore our website for more information.
