During the wastewater treatment process, the primary and secondary stages aim to remove the majority of suspended solids and organic contaminants before the effluent progresses to tertiary treatment. The primary treatment removes nearly 60% of settleable solids and the secondary treatment uses bacterial decomposition to remove nearly 85% of organic matter from sewage. The tertiary stage removes any filterable solids from wastewater before the effluent is discharged into the environment.
Below, we discuss key steps in the secondary wastewater treatment process and why communities need an experienced team of wastewater engineers to improve its efficacy.
All publicly owned treatment works (POTWs) must comply with secondary treatment standards established by the U.S. Environmental Protection Agency (EPA). These standards set minimum, technology-based requirements for wastewater treatment plants that are reflected in metrics like total suspended solids removal, five-day biochemical oxygen demand and pH. These secondary treatment standards also provide special considerations for treatment plants receiving flows from industrial wastes, combined sewers and others.
Crucial steps in the secondary wastewater treatment process that POTWs must follow in adherence with EPA-established standards include:
Advanced wastewater treatment techniques, alone or in combination, are increasingly implemented by POTWs to return more usable water to receiving lakes and streams. While the conventional activated sludge process is a proven system that is easy to control and operate, several POTWs use two alternative methods to improve secondary treatment performance. They are:
Determining the most effective secondary treatment system for your local wastewater treatment plant involves various factors, including influent quality and volume, types of wastewater contaminants, and system operation and maintenance costs. A team of experienced wastewater engineers can help municipal leaders make the right decisions about an effective and affordable secondary wastewater treatment process.
At Fehr Graham, we have helped communities across the Midwest evaluate, plan and design wastewater treatment solutions to protect the surrounding environment and maintain the quality of natural resources. Whether it is upgrading treatment systems, modeling collection systems, improving nutrient removal, complying with environmental standards or securing funding, our team of professional engineers will guide you to the best options for your community's POTW.
To learn more about how Fehr Graham can help improve the secondary wastewater treatment process at your local POTW, contact us or give us a call at 217.352.7688.