Due to revisions to Iowa’s Water Quality Standards, many communities are faced with more stringent NPDES Permit limits for bacteria and end-of-pipe ammonia limits. Communities may experience significant costs associated with upgrading existing or building new wastewater infrastructure to meet the proposed effluent limits. These conditions created a need to broaden the treatment options considered for managing wastewater in Iowa communities.
DNR has evaluated several new technologies for wastewater treatment that have been presented as provided in section 14.4.3 “Required Engineering Data for New Process Evaluation” in the Iowa Wastewater Design Standards. These technologies are not addressed by detailed design criteria in the Iowa design standards. These DNR assessments are based on the information and data from operating or pilot systems.
After research and data analysis, DNR staff developed technical design guidance for alternative wastewater treatment technologies. These assessments in addition to the applicable Iowa Wastewater Facilities Design Standards are intended to provide guidance to designers for project submittals to DNR for review and approval based on current empirical information relative to the capabilities of the process in various applications. These processes were evaluated for technical capability for treating small municipal systems with primarily domestic wastewater only without industrial or significant commercial loads.
These assessments are not design standards but when used in conjunction with design standards, should serve as expectations of the Department for permit approval. Based on information and experience, design standards may be developed in the future.