Wastewater

Wastewater treatment plays a vital role of protecting the environment and ultimately our public health.  Improperly treated wastewater discharges can spread disease, harm aquatic and wild life and degrade water quality.  The sole purpose of a wastewater plant is to protect the receiving stream and the downstream uses and users.  Some of those uses may include fishing, boating, swimming, domestic water supplies, agricultural water supplies, etc.

There are 2 parts to the wastewater treatment operation: 
   1. Treat the water to a level that meets the limits set in our discharge permit. 
   2.  Treat and properly dispose of the bio solids generated by the treatment process.

The process starts with the Sanitary Sewer Collection System.  The City of Estherville has approximately 70 miles of sewer and 4 pumping stations that make up the collection system. 

 The City of Estherville has a Grade IV Trickling Filter / Activated Sludge Wastewater Treatment Plant that was put on line July 1977.  These processes rely heavily on bacteria and microorganisms that remove contaminants from wastewater using them as “food.” 

The plant has a state certified laboratory on site.  The lab provides valuable data to aid in daily operations and successful wastewater treatment.

Plant staff consists of a superintendent,  lab technician and 4 operators.  The facility is staffed 365 days per year and operates continuously.  Employees work a rotating schedule to cover weekends and holidays.

The current design capacity of the plant is as follows:

Average Dry Weather Flow                     2.00 MGD (million gallons/day)
Average Wet Weather Flow                  3.50 MGD
Maximum Wet Weather Flow                8.00 MGD
Biological Oxygen Demand (BOD)         17,000 LBS/Day
Total Suspended Solids                             12,000 LBS/Day
TKN                                                                1,800 LBS/Day

BOD measurements are made to determine the strength of oxygen depleting bacteria present in wastewater.  Oxygen depleting bacteria will complete with aquatic life in the receiving stream and can cause fish kills.  Simply put, BOD measures the strength of organic wastes in water.

Total Suspended Solids measures the amount of solids present in wastewater.  Suspended solids can cause increased oxygen demands and cloudy, turbid conditions that degrade water quality.

Total Kjehldahl Nitrogen (TKN) measures the organic nitrogen and ammonia in wastewater.  These items are important to remove from wastewater flows.  Ammonia is toxic to aquatic life and nitrogen can cause algae blooms in receiving waters.

After completing all plant treatment processes, WWTP discharges in to the West Fork of the Des Moines River.

Bio Solids (Sewage Sludge) produced from wastewater treatment are stabilized by a digestion process and disposed of by land application on fields and pasture ground.  These solids make an excellent fertilizer high in nitrogen.