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The Clean Water Plant Today
Why is Wastewater Treatment Necessary?
Wastewater contains large amounts of excess nutrients such as phosphorous and nitrogen that could overwhelm the watershed if they were directly discharged into the Noordeloos Creek. The Zeeland CWP "cleans" the wastewater to remove those excess nutrients. Clean water meeting National EPA standards is returned to the creek and the captured nutrients are processed and recycled in a controlled application as agricultural fertilizer.
The Clean Water Plant
The Zeeland Clean Water Plant uses a Biological Nutrient Removal (BNR) process in our activated sludge plant to remove phosphorous and nitrogen from the wastewater before it is discharged into the Noordeloos Creek. The plant treats an average of 2.1 million gallons a day (MGD). This means micro-organisms are used to remove the waste products in the water using very little, if any chemicals at times.
The plant is staffed 365 days a year to make sure the community's wastewater is cleaned. Plant operations are carefully monitored and controlled using state of the art process technology to ensure utility efficiency, while maintaining State and Federal compliance standards that provide the highest quality of water discharged from the plant to the Noordeloos Creek. We use ultraviolet disinfection technology to ensure the public can safely use the lakes and streams the plant discharges to.
The Water Treatment Process
Plant Headworks
- Wastewater flows by gravity and nine lift stations to the plant by a system of underground trunk sanitary sewers in the City of Zeeland, Zeeland Township and parts of Holland Township.
- Screening structures remove inorganic materials from the water.
- Grit (inorganic sand and gravel material) is removed by a vortex grit removal system.
- The sewage then flows by gravity into the primary treatment.
Primary Treatment
- Velocity of the flow is slowed using five large primary tanks to allow heavier organic materials to settle out of the water. These solids contain excess nutrients such as nitrogen and phosphorous. The primary effluent then flows by gravity into one of the two Aeration trains for Biological Nutrient Removal (BNR) process. The solids that have settled are digested in an Aerobic Digestor which are part of our biosolids reduction process.
- The water now is slightly cleaner, though it still has dissolved nutrients and minimal solids that still need to be removed.
Secondary Treatment
- The secondary process utilizes a Biological Nutrient Removal (BNR) treatment system. Large volumes of microscopic organisms are kept suspended in tanks using diffused air bubbles (like you would see in an aquarium). These microbes are normally present in nature and thrive on the dissolved nutrients. Secondary treatment is concentrating this natural process to remove excess nutrients such as phosphorous and nitrogen from the water.
Final Clarification
- The flow now goes into circular settling tanks. All of the microbes that consumed the nutrients settle to the bottom and are returned either to the secondary process or the solids handling process. Clean, clear water flows out of these tanks over weirs and into the last stages of treatment.
Disinfection and Discharge
- Because of the concentrated human use of the water it needs to be disinfected before being returned to the watershed. This is accomplished by exposing the flow to Ultraviolet Light, which removes pathogenic organisms and treats the water to meet body contact standards.
- The final step is a cascade aeration system (like a waterfall). This restores oxygen to the water before it is finally returned to the watershed.