PROCESS INFORMATION
GLSD's plant is overseen through a central control room. Monitoring systems constantly check the operations of the plant, and keep watch over various functioning equipment. These systems provide real-time information on the status of many areas and operations in the wastewater treatment plant and main pumping station. The control room contains four separate computers to carry out the monitoring and control functions.
They operate as follows:
- GLSD's computer operating system runs a SCADA System Supervisory Control And Data Acquisition System.
- The computer has 512 megabytes of RAM with 4 gigabytes of hard drive.
- 8,100 points are monitored and controlled by SCADA.
- A high-speed fiber optics cable is used between the buildings.
- The system has a back-up, uninterruptible power source.
- Touch-screen monitors are used in the outer buildings.
Here are some interesting highlights about the plant:
Centrifuges
- Dewaters sludge. Capacity is 150 gallons per minute in at 4% solids; out at 30% solids.
- The rotating bowl is 100 inches long and 25 inches in diameter.
- The bowl rotates at 2,700 revolutions per minute, using a 150-horse-power electric motor.
Gravity Belt Thickeners
- Thickens sludge from 0.4% solids to 4% solids.
- Dewatering belts are more than nine feet wide.
- Belts rotate at approximately 80 feet per minute.
Screw Conveyors
- Convey dewatered sludge to a truck station or to the pelletizing plant.
- Actual screw auger varies in size from 12 inches to 16 inches in diameter.
- Screw augers rotate at 1,200 revolutions per minute.
- Each conveyor is fitted with a duct to remove odors that are sent to the biofilter for air cleansing.
Gravity Thickener Tanks
- Each tank holds 180,000 gallons of sludge.
- Each tank is 45 feet in diameter and 19 feet deep.
- New covers capture odors.
Fan Room
- Fan conveys odorous air to the biofilter for treatment.
- Two fans each rated at 12,000 cubic feet per minute of air movement.
- Each fan is manufactured out of non-corrosive fiberglass
Biofilter
- Used to clean odorous air from the sludge process.
- Each of four compartments (cells) is 24 feet wide and 72 feet long.
- Each cell is filled with three feet of wood chips/bark mulch/leaf compost blend.
- A thin bacterial film surrounding each media particle breaks down odorous substances.
Boiler Room
- Boilers are designed to operate on natural gas or methane gas produced in the digesters.
- Boilers circulate a mixture of 60% water and 40% antifreeze (Glycol) through piping to the sludge heat exchangers in the Digester Building.
- There are 10,300 gallons of Glycol in the piping system.
Digesters
- The digesters stabilize the sludge via a biological process.
- Each digester holds 1.4 million gallons of sludge.
- Each digester is 85 feet in diameter and is 40 feet tall, of which 20 feet is below ground.
- Each digester has four mixers for mixing sludge.
- The digester covers are movable vertically to accommodate storage of methane gas. The covers have a vertical range of 11 feet.
- Each digester, when the covers are as high as they go, can store 48,500 cubic feet of methane gas.
- The digester will produce up to 400,000 cubic feet per day of digester gas, equivalent to 260,000 cubic feet of natural gas.
Digester Building
- The Digester Building houses:
- Two inlet sludge heat exchangers,
- Three recirculation sludge heat exchangers,
- Four recirculation sludge pumps,
- Two digested sludge pumps,
- Three recirculation Glycol pumps,
- Two secondary Glycol pumps,
- Two influent Glycol pumps,
- Three methane gas compressors.
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