House of Quality Planning Matrix for Evaluating Wastewater Nutrient Management Technologies at Three Scales Within a Sewershed

Nutrients (nitrogen and phosphorus) can be removed or recovered from wastewater at different points in the collection and treatment process, for example, from individual buildings or households, from the conveyance (sewer) system, or at the centralized treatment plant. Multiple technologies are available for nutrient removal and recovery at any of these points of application, but the appropriateness of a candidate technology depends on the scale of application; a technology that is appropriate for nutrient removal/recovery at a large centralized treatment plant may not be appropriate at an individual household. Hence, a need exists for a tool that enables municipalities to select scale- A nd context-specific technologies for nutrient management. Accordingly, the objectives of this article are (1) to review nutrient management technologies that are available at the building, community, and city scales and (2) to develop a planning matrix that evaluates the appropriateness of nutrient management technologies at these three scales based on ten practical characteristics. The planning matrix developed herein is similar in structure to a house of quality (HoQ), which is a quality function deployment method typically used in commercial businesses to determine how well a product meets the needs of its customers. Because each sewershed (i.e., the area and population served by a treatment plant and its associated sewer network) is unique, the planning matrix can be customized to determine the most appropriate nutrient management technologies for any given municipality and therefore represents a flexible tool for sewershed-scale nutrient management. We apply the new planning matrix to identify emerging nutrient recovery technologies (e.g., ion exchange, chemical precipitation, and membrane bioreactors) that may be preferable alternatives to current baseline technologies. At each scale, the technologies ranked as best by the HoQ method are consistent with those commonly employed in practice at present. However, future trends will likely affect technologies, weightings, and scores and therefore change the ranking of the technologies.