In the 1970s and 1980s, federal grants paid a majority of the costs to build or expand wastewater treatment plants. Many Publicly Owned Treatment Works (POTWs) constructed then had a lifespan of 40 to 50 years and have now reached the end of their service lives. Such wastewater treatment facilities face numerous challenges, including design inadequacies, limited treatment capacity, higher energy costs and the inability to meet effluent standards. Upgrading or replacing aging wastewater infrastructure is an obvious choice for the affected municipalities. However, since construction is often the most expensive option, retrofitting can be an economical alternative for wastewater treatment plants.
Below, we detail the reasons to retrofit a wastewater treatment plant in your community and how professional expertise can help you decide whether to replace or retrofit a treatment plant.
Because of increasing urban and semi-urban populations, POTWs often struggle to treat the increased effluent volume, working beyond their design capacities. Changing treatment standards and effluent limitation guidelines also stretch a treatment plant's capacity.
To handle higher volumes of wastewater and comply with stringent effluent regulations, municipalities often consider expanding their wastewater infrastructure by building a treatment plant. Two factors that heavily influence a municipality's decision to replace a wastewater treatment plant are:
Expanding the wastewater treatment plant requires standard components, including an oil/ water separator, a series of reactors, a clarifier, filtration equipment and a control panel. However, the actual makeup of the system requires more specific features and technology to meet local needs. Additional factors such as installation rates, operation costs, level of system automation, space requirements and construction make replacing a POTW with a new plant costly.
Newly designed POTWs incorporate the most effective, cutting-edge technology available. However, changing regulations and treatment environments can make a plant design obsolete quickly. As treatment objectives change, the resulting change does not necessarily require building a plant. Many municipalities choose to retrofit instead.
Retrofitting a wastewater treatment plant can benefit the affected municipality by:
However, retrofitting a wastewater treatment plant comes with its own challenges. Common complications include sequencing construction such that treatment continues throughout the project. Construction is comparatively easier to permit and build while meeting utility demands.
When upgrading a wastewater treatment plant or deciding between replacing or retrofitting a POTW, a municipality is often not equipped with the technical know-how to make the best decision. Teaming up with a wastewater engineering professional can help you make the right decision for your community's wastewater treatment infrastructure.
What works as the best method for wastewater treatment for other communities might not work for yours. That is why it is critical to assess the contaminants present in the effluent stream of your local POTW through a wastewater treatability study and inflow/infiltration study.The team of licensed engineers and operators at Fehr Graham can help you develop environmentally compliant and cost-effective solutions to improve the quality of wastewater effluents. Our expertise in inflow/infiltration studies, nutrient removal, collection system modeling, design and rehabilitation have assisted communities across the U.S. in upgrading their treatment systems.