Grantee Research Project Results

Final Report: Phosphorus Removal and Recovery From Municipal Wastewater Using Nano-Enhanced Media

EPA Contract Number: EPD14010
Title: Phosphorus Removal and Recovery From Municipal Wastewater Using Nano-Enhanced Media
Investigators: Sengupta, Dr. Suvankar
Small Business: MetaMateria Technologies, LLC
EPA Contact: Richards, April
Phase: I
Project Period: May 1, 2014 through April 30, 2015
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2014) RFA Text | Recipients Lists
Research Category: SBIR - Wastewater, Stormwater, and Water Reuse , SBIR - Nanomaterials , Small Business Innovation Research (SBIR)

Description:

This Phase I Small Business Innovation Research (SBIR) project focused on the capture and recovery of phosphorus in wastewater from publically owned treatment works (POTW), typically processing near or under 1 million gallons of wastewater per day (MGD). An innovative nanostructured absorption media was used. Nutrients, such as phosphorus, cause pollution in streams and lakes and this degrades water. Phosphorus also is a valuable resource, and methods for recovering it are desirable.

Phosphorus, unlike most nutrients, accumulates and in many waters affects water quality, especially when soluble phosphorus is available for algae growth. Particularly disruptive is eutrophication, which creates oxygen-free dead zones in water bodies (lakes, estuaries or slow-moving streams). Phosphorus enhances the growth of blue-green cyanobacteria that can excrete dangerous levels of microcystin, a toxin. Phosphorus comes mainly from farm runoff and from municipal and industrial wastewater treatment. While excess phosphorus exists in aquatic environments worldwide, it is lacking in many soils where it is needed for agriculture. Phosphorous also is a commodity that will be increasingly in short supply during this century, with a majority of supply concentrated outside the United States. Cost-effective approaches to address the effects caused by phosphorus are needed, both at the discharge sources and to limit the growth of blue-green algae.

The purpose of this project was to examine phosphorous removal and recovery approaches from POTWs, using nanomodified media. The focus was on smaller facilities treating about 1 MGD or less, which represent more than 70 percent of municipal treatment facilities. An innovative porous nano-iron-based media (PO4 Sponge, developed by MetaMateria) was examined for the POTW application. This media can adsorb large amounts of phosphorous, which can then be chemically removed (regeneration) and the media reused repeatedly. Phosphate ions removed can be recovered (e.g., as calcium phosphate) for use in other applications, thus addressing several needs in managing nutrients.

In Phase I, the feasibility of using the nanostructured media was demonstrated using water collected from nearby POTW and other wastewater facilities. Wastewater was collected from six facilities containing different sources of waste influents, including different amounts of domestic and industrial wastewater constituents. Several facilities currently use biological and chemical treatment to reduce effluent phosphorus to below 1 mg/L, their permitted discharge level. Testing of water was needed to understand differences in PO4 media performance that might exist due to treatment processes being used or water with different chemistries, as a result of differences in wastewater constituents. This provided understanding of treatment needed and confidence for pilot demonstrations planned in Phase II. It also provided engineering-level information on POTW operations and input on capital and operational costs for existing phosphorus management approaches.

Summary/Accomplishments (Outputs/Outcomes):

The feasibility of using the nanostructured PO4 media was demonstrated using water collected from five nearby POTW and one private facility. Wastewater was from different sources of waste influents, including different amounts of domestic and industrial wastewater constituents. Several facilities currently use biological and chemical treatment to reduce effluent phosphorus to below 1 mg/L, their permitted discharge level. Information collected during the program shows a great need to develop for meeting lower effluent levels of 0.1 mg/L in the next 5–10 years, and this creates a more difficult task for smaller waste treatment facilities, which represent some 70 percent of the POTW facilities. A passive filter system that can be regenerated offers a simpler approach for smaller facilities and the nanomodified PO4 media has the potential to be economically competitive with more complex approaches used today and inherently less expensive than membrane systems. The ability to recover phosphorus in a form that can be used commercially is attractive and will meet an increasing demand being brought on by scarcity of existing sources. It also will lower carbon footprint and contribute to long-term societal goals.

Conclusions:

The Phase I results clearly indicate that the MetaMaterias nanomodified media can be effectively used to remove phosphorous in wastewater from reclamation facilities. The potential was successfully demonstrated by testing actual water collected from five POTW and one private facility. Water from five facilities was evaluated using column testing (along with isotherm studies) at Michigan State University. Wastewater collected from the City of Union facility was tested at MetaMateria in a simulated lagoon and sand filter. Encouraging results were obtained in all tests. It also was demonstrated that the phosphorous captured in the media can be removed and the media can be reused. Testing with water containing low concentration of phosphorous (~ 1 mg/L and less) demonstrated that media is capable of removing phosphorous down to very low levels (0.1-0.2 mg/L), which is difficult to achieve with conventional chemicals and/or biological processes.

Phosphorus removal appeared to be affected only by the influent concentration, which indicates little interference from various compounds that may populate different industrial and municipal sources of wastewater. Since the media successfully reduced reasonably low influent phosphorus concentrations (< 3 mg/L) to levels well below the needed requirements, there is merit in also looking at these types of applications.

Currently, biological phosphorus removal is the most cost-effective method to remove phosphorus from wastewater being discharged. However, this technology cannot always meet EPA regulations. Chemical addition of ferric chloride or alum often is used to supplement biological phosphorus removal, or solely when not feasible. Since State EPA regulations are expected to become more stringent in the coming decade, reducing phosphorus concentrations further after biological treatment will be needed to meet these requirements. The potential for a less complex filter system appears to exist, based upon the use of the nanomodified media and regeneration significantly reduces costs and provides for recovery of phosphorus in useful forms. This is especially true for smaller treatment facilities that can benefit from a simple, passive system, provided by the high capacity sorption media, as opposed to the surveillance and robust operational infrastructure required for chemical addition. Additionally, the use of chemicals to remove phosphorus below 1 mg/L requires an exponentially greater concentration for lower levels because it is equilibrium driven. This greatly increases costs and sludge production.

While this data from Phase I provide insight into the effectiveness and potential for applications of this media, further studies are required to fully quantify these findings. To determine the full, optimized efficiency of this media, a pilot-scale analysis must be conducted. Generating necessary design parameters also would help solve logistical and operational problems and devise multiple configurations to effectively integrate the media technology into the diverse treatment systems

Commercialization (Phase I activities): In this Phase I program, MetaMateria worked with five POTWs and one private treatment facility. Several environmental engineering firms also were contacted. Interest exists in supporting pilot testing by both POTWs and environmental engineering firms that felt they could arrange for test sites. Contacts were made in Maryland and Massachusetts, where phosphorus limits already are low. Wisconsin is another state that already has a 20 mandated, staged requirement for discharge below 0.075 mg/L.

Supplemental Keywords:

wastewater reclamation, phosphorus, nanomaterial, eutrophication

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