Grantee Research Project Results
Final Report: Ultra-Thin, Magnetic Polymer Membranes for the Selective Removal of Macronutrients in Wastewater
EPA Contract Number: EPD17008Title: Ultra-Thin, Magnetic Polymer Membranes for the Selective Removal of Macronutrients in Wastewater
Investigators: Bowers, Carleen M
Small Business: NanoSonic Inc.
EPA Contact: Richards, April
Phase: I
Project Period: November 1, 2016 through April 30, 2017
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2016) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR)
Description:
The objective of this Phase I EPA program is to develop innovative technologies to selectively remove phosphorous from wastewater, and recover it as a valuable nutrient for further use. Phosphorous is a valuable, non-renewable nutrient found in wastewater. Agriculture depends on large amounts of phosphorous-based fertilizer, which is mined globally at a rate of 20 million metric tons per year. When present at high levels in water, however, this nutrient becomes a devastating pollutant to aquatic environments by spurring the over fertilization of our waters. Economic damages associated with the eutrophication of freshwater costs the U.S $2.2 Billion annually. Many phosphorous removal technologies rely on chemical precipitation or enhanced biological phosphorous removal. The limitation of these methods is that they incorporate phosphorous into solids, or sewage sludge, which preclude its potential for reuse. Despite its dual benefits, recovering phosphorous is not widely practiced due to limited the availability of technologies and the high cost. Technologies that rely on phosphorous recovery through struvite (magnesium ammonium phosphate) precipitation, for example, require costly chemical inputs. The only way to protect the environment from nutrient pollution and secure agricultural food production is to develop cost effective ways to recover phosphorous from wastewater.
Summary/Accomplishments (Outputs/Outcomes):
Through the Phase I effort, we designed, synthesized, and fabricated porous polymer microfiltration (MF) nanocomposite membranes for the removal and recovery of phosphorous. For fabrication of the membrane, we synthesized charged polymers that are mechanically durable and chemically stable at high temperatures (up to ~460ºC) and in the presence of chlorine and other oxidants. The active component for phosphorous removal is the presence of magnetic nanoparticles—designed and synthesized to selectively bind phosphorous in solution—in the nanocomposite membrane. We demonstrated the selective binding of phosphorous to the nanoparticles using X-ray Photoelectron Spectroscopy (XPS).
To produce the MF nanocomposite membranes, we used a phase inversion technique that resulted in very thin films (~20-30 µm thick) with pores size from raging from ~200 nm-1000 µm. Most commercial filtration membranes are ~100-300 µm thick. We characterized the water flux values in units of L/m2*hr (LMH) in collaboration with Environmental and Water Resources Engineering at Virginia Tech. At 3 psi, our ultra-thin membranes result in water flux values that are significantly higher than standard commercial UF/MF membranes, which have flux values between 85 and 171 LMH at pressures between 5 and 35 psi. When applying very low transmembrane pressures (< 1 psi), our nanocomposite membranes still produce good water flux values, indicating that these membranes would require minimal operating pressures and energy consumption upon installation. We analyzed the susceptibility of the membranes to fouling and reduced water flux using raw wastewater obtained from a local wastewater treatment facility. We measured a steady state decrease in flux by less than half; the decline in flux is due to membrane fouling as particles in the raw wastewater accumulation on the membrane and reduce filtration capacity by clogging the pores. Additional work is required to overcome the susceptibility towards fouling through modification of the membrane chemistry. We worked with TestAmerica Laboratories to determine phosphorous recovery levels using automated colorimetry (Method 365.4 SM4500-P B, H: Total Phosphorous by Colorimetric, Automated, Block Digester AA II). Preliminary analysis of phosphorous recovery indicates that the nanocomposite MF membranes are capable of recovering more than half the levels of phosphorous present in solution. Modifications of the nanocomposite membrane chemistry will be made to further maximize this recovery percentage.
Conclusions:
The objective of this Phase I EPA program was to develop innovative membrane technologies to selectively remove phosphorous from wastewater, and recover it as a valuable nutrient for further use. The only way to protect the environment from nutrient pollution and secure agricultural food production is to implement effective recovery technologies. Towards this goal, we designed, synthesized, and fabricated porous polymer microfiltration (MF) nanocomposite membranes to selectively bind and recover phosphorous found in wastewater. We synthesized polymers that are well-suited for long-term use as membranes; they are mechanically durable and chemically stable at high temperatures (up to ~460ºC) and in the presence of chlorine and other oxidants. The active component in the membrane for phosphorous removal is the presence of magnetic nanoparticles—designed and synthesized to selectively bind phosphorous in solution. These membranes produce high water flux, even at very low applied pressures, and are capable of significantly reducing phosphorous loading. Future work involves further increasing the phosphorous recovery capability and minimizing the membranes’ susceptibility to fouling. We will also scale the polymer synthesis and membrane fabrication for pilot scale production in-house.
Commercialization:
NanoSonic’s commercialization objective is to manufacture and sell nanocomposite filtration membranes for nutrient recovery from wastewater. The innovation will enhance existing wastewater treatment processes by performing two important functions: 1) removal of phosphorous from wastewater, thereby reducing discharge levels and meeting environmental regulations and 2) recovery of economically valuable nutrients for use in agriculture. The nanocomposite membranes also have market opportunity for recovering phosphorous from stormwater runoff, agriculture (i.e., dairy, poultry, cattle, and fish farming), and chemical manufacturing.
Innovative technologies for the treatment of water and the recovery of valuable nutrients for agricultural food production and security has value in the Global Market. The market associated with wastewater treatment equipment is worth over USD 35 billion and is expected to reach more than 55 billion by 2023, with a CAGR of >6%. The membrane market for wastewater treatment is expected to reach USD 3 billion by 2021, with a CAGR of 16%. Consumer and industry demand for low levels of phosphorous, both in water that is returned to the environment and in water used in food and pharmaceutical production, will continue to drive the market for wastewater treatment products. Furthermore, phosphorous recovered from wastewater will become a competitor to mined phosphorous as the demand for phosphorous-based fertilizer increases and exceeds the available supply. Recovery of valuable nutrients from wastewater presents an economic opportunity for wastewater treatment facilities, which would contribute to their financial stability. About 20% of all water globally is treated, providing a significant market for water treatment technologies that is expected to grow until at least 2025. As such, we will initially target markets in North America and Europe, with the intention of expanding sales globally.
There are currently three methods for removing phosphorous from wastewater: 1) using phosphorous accumulating organisms, 2) chemical precipitation in the secondary or tertiary clarification processes of water treatment plants, and 3) phosphorous uptake in constructed wetlands. These methods reduce discharge levels, but do not recover the valuable nutrient for reuse. Our thin nanocomposite filtration membranes represent a unique and highly effective approach for phosphorous removal and recovery.
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.