The reliable collection, treatment, and disposal of wastewater is a critical public service. In central sewer systems, sewage flows from its source into an underground collection network of pipes and pumps that convey it to a centralized wastewater treatment facility (WWTF). Any failure in this system can significantly impact the environment, economy, and public health. Untreated wastewater may contain harmful microplastics, pharmaceuticals, toxic chemicals, bacteria, viruses, and nutrients. All spills and releases of untreated sewage are unlawful.
Wastewater treatment and disposal are regulated by the U.S. Environmental Protection Agency (EPA) and the Florida Department of Environmental Protection (FDEP, F.S. 403). Minimum state standards require primary treatment (removal of solids and particulates) and secondary treatment (disinfection) before disposal. However, these processes do not significantly reduce nitrogen and phosphorus levels, which can contribute to nutrient pollution when effluent is reused for irrigation. Advanced Wastewater Treatment (AWT) adds a third treatment stage to substantially lower nitrogen and phosphorus concentrations (Figure 1.1). Even after treatment, wastewater may still contain microplastics, pharmaceuticals, and persistent toxic chemicals.
Figure 1.1. Different levels of wastewater treatment discharge effluent of different quality and nutrient content. Source: Integration and Application Network University of Maryland Center for Environmental Science
Permitted wastewater disposal options vary based on treatment level and include surface water discharge, injection into wells and aquifers, release to infiltration basins and spray fields, or redistribution for non-potable uses such as irrigation. Any wastewater discharged directly into Southwest Florida water bodies and their direct tributaries must meet AWT standards (Grizzle-Figg Act 1987, F.S. 403.086I). The Act also mandates that AWT discharges will not degrade Outstanding Florida Waters, such as those in the Sarasota Bay Estuarine System.
