The Holland Board of Public Works 2016 Annual Report
Water Reclamation: How it Works
Our facility uses a natural process, accelerated by modern technology, to restore the water and return it to the environment. In fact,the final effluent pumped into Lake Macatawa is cleaner than the lake itself.
The Holland Area Water Reclamation Facility treats water from the city and several surrounding townships. Water enters through two primary sanitary mains coming from the North and South. After treatment, the plant’s effluent is released into Lake Macatawa and is actually cleaner than the lake itself.
- Wastewater influent from the community enters the plant from the north and south.
- The influent streams combine at the headworks facility, which filters out inorganic solids larger than 1/4” by using mechanically cleaned bar screens. It also removes any sand and gravel with a vortex grit removal system.
- The flow splits between four primary clarifiers where heavier solids and organic matter settle to the bottom. Ferric chloride is added prior to the tanks to serve as a coagulant, sticking to the phosphorus in the flow stream and settling out with the solids.
- Flow from the primary clarifiers enters aeration basins where it mixes with oxygen and “activated sludge” from the secondary clarifiers. Microorganisms from the sludge begin to feed on any organic particles in the oxygen-rich environment.
- When the flow reaches the secondary clarifiers, the growing microorganisms clump and form larger masses which settle out most remaining suspended solids into “activated sludge.” Some of the sludge is then returned to aeration to replenish the microbes there.
- We disinfect the effluent flow from the clarifiers with sodium hypochlorite to kill any remaining harmful bacteria.
- HBPW can use some of the clean water to cool the nearby James De Young power plant before releasing it into the lake.