The United States Environmental Protection Agency estimates that there are 1.2 trillion gallons of sewage dumped into the United States’ waterways every year. This sewage comes from households, industries, and restaurants. As a result, 40% of this country’s lakes have become so polluted that aquatic life has been threatened. Furthermore, these lakes have become unsafe for either fishing or swimming.
On a daily basis, wastewater treatment facilities process roughly 34 billion gallons of wastewater. When someone uses a self-serve car wash, for example, their car requires an average of three to five gallons of water.
Tunnel car wash facilities are another wastewater example. These facilities process between 100 to 1,000 cars every day, and each car uses an average of 80 gallons of water.
There are several processes that pertain to the treatment of wastewater. The primary treatment of wastewater involves the removal of suspended solid waste and the reduction of its biochemical oxygen demand (BOD). In addition to reducing BOD by 20% to 30%, suspended solids may be reduced by approximately 60%. This is because the microorganisms need to consume a specific amount of oxygen in order to break down the organic material that may be present.
The secondary treatment of wastewater involves additional biological processes that address the dissolved organic matter. In other words, this is the organic matter that wasn’t processed during the primary treatment. During this step of the process, approximately 85% of the BOD and the suspended solids are processed.
After this, the disinfection process begins. This usually involves injecting a chlorine solution into the wastewater. While the dosage will depend on the wastewater’s strength and other conditions, common dosages tend to be between five to 15 mg/l. The chlorine may need to be in direct contact with the wastewater for up to two hours in order to address advanced wastewater treatment requirements. An example of this would be when using reclaimed wastewater for specific types of irrigation.
The Importance of Replacing and Repairing Wastewater Systems
In order to repair and replace water, wastewater, and stormwater systems, it is estimated that over $180 billion would be required. When these necessary infrastructure investments are made, the potential result is a reduction in water pollution and healthier communities. Furthermore, once these projects are begun, approximately 1.9 million jobs are expected to be created.