Great Neck Wastewater Treatment Plant Upgrades

To keep pace with the growing needs of more than 25,000 Long Islanders, the Great Neck Water Pollution Control District initiated significant upgrades at its wastewater treatment plant (WWTP) during the course of the facility’s 100-plus-year history.

In 2018, the 3.2 million gallons per day (MGD) plant was slated for another round of enhancements that would enable it to process 5.3 MGD of residential and commercial flows, as well as restaurant grease hauled in from throughout the Town of North Hempstead in Nassau County. But the District desired more than just upgraded digesters and increased capacity—it also had set its sights on ambitious operational and financial efficiencies.

In partnership with Gannett Fleming, the district began a forward-thinking initiative to better manage flows and leverage the facility’s operations to generate enough power for half of its total energy consumption.

The improvement project included three major elements:

1. Upgrades to three existing anaerobic digesters.
2. A new 65-kilowatt cogeneration microturbine to join two microturbines already in place.
3. A commercial grease receiving station that accepts grease from local haulers and supports the waste-to-energy process.

In addition to cost savings, the upgraded plant draws 160 kW less power from the utility grid— creating additional grid capacity and ensuring a more sustainable future for the entire community.

The Great Neck WWTP is one of only a few facilities in the U.S. to feature a grease receiving station, which takes in commercial grease from local haulers. It allows haulers to offload grease without assistance from plant personnel.

Housed within a new 2,500-square-foot digester utility building, the system accommodates both gravity and pumped deliveries. Upon selection of either mode, the appropriate valves, grinders, and pumps are automatically placed into the process train.

The plant’s upgraded digesters can produce up to 50 cubic feet per minute (CFM) of methane versus the 12 to 20 CFM of a standard WWTP. Harnessing the methane for on-site energy generation increases the facility’s self-sufficiency and significantly reduces its energy costs.

The three microturbines provide more than half of the plant’s base load and 100% of the heat required for digester operation and space heating in several buildings. In all, the project reduced the district’s average electric bill by more than 68% per month— more than $500,000 per year.

• Automated grease receiving station enables the efficient collection of hauled-in grease.
• Digester upgrades increase methane production up to 50 CFM.
• New cogeneration microturbine boosts power production and fulfills half of the facility’s energy needs.
• Significant upgrades to the plant’s supervisory control and data acquisition (SCADA) system automate the new treatment processes, enhancing operational efficiency.
• New 10,000-gallon grease storage tank stores and mixes grease with warm, digested sludge prior to feeding into the digesters.

• Upgrades enable processing of 5.3 MGD of residential and commercial flows.
• Power generation for half of the facility’s total energy consumption.
• Average monthly electrical bill reduced by approximately 68%.
• Efficient receipt of restaurant grease supports the waste-to-energy process.

• Silver Award, 2022, American Council of Engineering Companies (ACEC) New York, Engineering Excellence Awards.