Wastewater Collection & Treatment Process
Wastewater Collection Grinder Pump
The Glacial Lakes Sanitary Sewer & Water District (GLSSWD) collects wastewater from three cities and six lake systems. The wastewater is collected and conveyed to the treatment plant utilizing a complex network of gravity and pressure sewers, pumping stations, and force mains. The GLSSWD service area includes and extends north to the City of New London, west to Lake Florida, south to the City of Kandiyohi, and east to Diamond Lake.
Maintenance regarding the GLSSWD wastewater collection system is an ongoing process. Crew members are out daily monitoring, inspecting, repairing, cleaning, flushing, and performing all the duties necessary to keep the system operational.
Lift Station Lift Station
The GLSSWD currently has 26 pumping stations (lift stations) that it maintains. These stations are monitored twenty four hours a day utilizing wireless technology. On call staff are on duty to respond to any alarm situation whenever it may occur.
When wastewater reaches the wastewater treatment plant, it goes through a series of steps to clean up the wastewater to meet permit requirements as mandated by the Minnesota Pollution Control Agency before discharge can occur.
Step I Preliminary Treatment
This process involves the use of mechanical equipment to remove the larger physical items such as rags and plastics that cannot be broken down in the secondary process. Step I is also where the grit is removed from the wastewater. Grit is inorganic material that if left in the system would fill tanks and wear out the plant pumping systems. All grit and screening are disposed of in a sanitary landfill.
Step II Secondary Treatment Aeration Basin
The GLSSWD wastewater treatment plant utilizes an activated sludge process as secondary treatment to remove organics from the wastewater. The activated sludge process is a biological process where microorganisms consume and live off of the organic material in the wastewater. The activity of the microorganisms removes the organics from the wastewater and changes its characteristics allowing for future separation of the microorganisms and the treated wastewater.
Another vital part of the activated sludge process is the interduction of dissolved oxygen. The provided dissolved oxygen is required to sustain microorganism life. Microorganisms need food and oxygen to survive. The organic material in the wastewater is their food and their oxygen is provided by mechanical means.
Step III Final Clarification
After secondary treatment, the wastewater goes through a settling process. The microorganisms (or what is also known as solids) flow as part of the secondary water into a clarification or settling tank. Here the solids settle to the bottom of the tank and the clear water flows over a weir on to the next step. Most of the settled solids are recycled back to secondary treatment to keep the required balance of microorganisms to incoming organic matter satisfied.
Step IV Filtration
Although the water entering the filtration process has reached a high state of treatment already, to be certain that all particulate matter is removed, it is filtered through twelve inches of sand and eighteen inches of antracite.
Step V Disinfection
After filtration, the water flow moves into the chlorine contact tank. Here chlorine is added for disinfection purposes to remove fecal coliform. After chlorination, the water is dechlorinated and aerated before it leaves the contact tank. This is done to help protect the aquatic life of the receiving stream, which is the middle fork of the Crow River.