The Ins and Outs of a Septic System

How often to do you think about where the water goes when you flush your toilet? Maybe never until the toilet doesn’t flush or there is wastewater backing up into the tub. Many homes throughout the U.S. are connected to a utility but onsite wastewater disposal systems are also common. According to the Environmental Protection Agency (EPA), an estimated 4 billion gallons of wastewater nationwide is collected, treated, and released from onsite wastewater systems per day.

Onsite wastewater disposal systems can be effective in the removal of pathogens (bacteria and viruses) but can also be major contributors of nitrogen and phosphorous to groundwater and surface waters; a potential problem that is propagated due to septic systems not always being correctly sited, installed, or maintained. Groundwater represents about 97 percent of the earth’s fresh water resource and needs to be protected from potential sources of contamination. Nitrates in drinking water supplies may adversely affect public health and are linked with methemoglobinemia (blue-baby syndrome), increased risk of cancer, and other possible health effects. Excessive nutrients, such as phosphorous and nitrogen, in surface waters can lead to eutrophication and decreased dissolved oxygen leading to adverse effects on aquatic species.

The most common type of onsite wastewater system is a septic system which generally consists of a septic tank and soil absorption system. If a septic system fails to treat wastewater properly, namely complete denitrification, this may lead to contamination of groundwater and surface water. The focus of our Coggle is on nitrogen cycling through a septic system and the ultimate fate of nitrogen released to the environment.

After exploring the coggle, you should be able to answer the following questions: ?

What are the sources of nitrogen input to wastewater?
What makes the septic tank and anaerobic environment?
What types of microbes transform ammonia or ammonium to nitrite, and what do they gain from it?
What happens to nitrogen present in wastewater? Can it pollute groundwater?

Brought to you by Kimberly Fitzgerald, Aasne Hoveid, Ankur Sachan, and Tonya Bear  



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