Recipient Organization
WASTE HUB, LLC
5796 S KITTREDGE CT
AURORA,CO 80015
Performing Department
(N/A)
Non Technical Summary
Greek (strained) yogurt represents nearly half of the $5B U.S. yogurt industry and has grown at a rate of more than 60 percent per year for the past eight years. For every pound of milk used in the manufacture of Greek yogurt, only one-quarter to one-third ends up in the final product. The remaining waste is liquid acid whey, which contains more than 93 percent water, along with minerals, protein, lactose-based compounds. Acid whey is environmentally hazardous and there are few cash-positive options for disposal or reuse. Waste Hub LLC, under an exclusive sublicense from Catalytic Innovations LLC, has filed a patent application for an electrolysis process that will recover neutral water and separated proteins for recycle while generating fuel-cell electricity and pure carbon dioxide for sale. The process will use the award-winning, heterogenized, iridium-based, molecular oxidation catalyst, developed at Yale University, to selectively oxidize the organics using a fraction of the energy required for state-of-the-art electrolysis processes. Waste Hub will assemble and test a solids-separation and electrolysis unit to refine the Waste Hub process and verify technical and economic viability. We will further develop physics-based predictive models and use them for full-scale system design, economic forecasting, and preparation for a Phase II pilot with a major producer of Greek yogurt. This application is in response to Topic Area 8.4 - Air, Water, and Soils and addresses the cross-cutting USDA priority of Energy Efficiency and Alternative and Renewable Energy from agricultural waste.The hypothesis behind this project is that electrolysis using an iridium-based, heterogenized molecular oxidation catalyst on the anode and a platinum catalyst on the cathode will readily and durably oxidize the organic content of liquid acid whey with relatively low overpotential and will comprise an economically-sound alternative energy technology for processing liquid acid whey. The technical objectives are to confirm this hypothesis, namely:To demonstrate experimentally that acceptable rates of reaction and current density can be achieved using a continuous feed of liquid acid whey with low potential (<2 V).To determine the most cost-effective method of separating suspended solids (protein) and asses the ability to recycle the protein to the processTo collect samples and analyze the flow rates and composition of all outlet streams (H2, O2/CO2, water, solids) and use this information in the development and validation of a process simulation model of the entire Waste Hub system, including the fuel cell and CO2 liquefaction process.To produce designs and economic assessments of a scaled-up pilot and a full-scale system using the validated process model.The key research questions to be addressed in this Phase I project are as follows:What method of solids separation maximizes separation and prevents electrolysis performance degradation while preserving and recovering solids for reuse?What is the effect of solids loading on performance (outlet streams, durability, energy consumption) of the electrolysis system?What is the effect of applied potential on performance (outlet streams, durability, energy consumption) of the electrolysis system?Based on Phase I results, what would be the design, mass balance, energy balance, cost, and financial return of a pilot-scale Waste Hub system to be implemented in Phase II at Stonyfield, and of a complete commercial-scale Waste Hub system at 25,000 gal/day of liquid acid whey?Waste Hub will use samples of liquid acid whey provided by Stonyfield Farm in Londonderry, NH to conduct experiments in 1) suspended solids and protein separation and 2) electrolysis of filtered and non-filtered acid whey in which the anode catalyst, membrane material, and applied voltage will be varied to determine the operating conditions for best performance. Composition of inputs and outputs will be measured in each experiment, including feed and filtered acid whey in separation experiments and feed acid whey, anode gas output (CO2/O2), cathode gas output (H2), and effluent water. The experimental conditions and composition data will be used as inputs for a system design model to be developed in parallel.The system design model will be a relatively simple, steady-state, semi-empirical model with parameters adjusted within reason to achieve agreement with experimental data. We will take into account mass transfer from the fluid to the electrodes in the electrode chambers and the equilibrium chemistry of the half-reactions taking place at the electrodes. The model should yield reasonable estimates of power consumption, gas compositions leaving the electrodes, and organic composition of effluent water. We will not attempt to address the minor, non-reacting constituents of acid whey other than to track their concentrations through the process based on changes in water and organics content. MS Excel will be used to develop the model in Phase I and will be upgraded or integrated to a more sophisticated process modeling package (i.e. ChemCAD, ASPEN) in Phase II.
Animal Health Component
40%
Research Effort Categories
Basic
20%
Applied
40%
Developmental
40%
Goals / Objectives
Waste Hub LLC is a Colorado small business whose mission is to take a proactive role in creating valuable alternatives to disposal for industrial waste streams. In cooperation with Stonyfield Farm, Yale University, and Catalytic Innovations LLC, Waste Hub is developing a breakthrough electrolysis technology to address a national challenge in the dairy industry. We have demonstrated at laboratory scale that catalytic electrolysis may be used effectively to convert what is now a high-volume, expensive, and environmentally hazardous liquid acid whey stream into recyclable water and protein, bio-derived hydrogen energy, and salable liquefied carbon dioxide. Greek yogurt is a rapidly-growing segment of the dairy industry, providing a healthy food option that is consumed in high volume by the public. However, the long-term sustainability of Greek yogurt manufacture is challenged by the generation of two to three pounds of liquid acid whey waste for every pound of yogurt product. Disposal is expensive because of the acidity (pH between 4 and 5) and high biological oxygen demand (BOD) of acid whey. Further, the options for productive use are limited and few if any of the available options produce a positive economic return for the manufacturer.Waste Hub's application is in response to Research Topic 8.4 Air, Water, and Soils and NIFA National Challenge Area 6 (Water) because we are developing a technology that has the commercial objective of cost-effectively treating and recycling enormous amounts of hazardous wastewater in the dairy industry. This application also addresses the USDA cross-cutting priority of developing alternatives to fossil fuels and the reduction of energy consumption by converting the hydrogen content of the organic fraction in acid whey to electricity via a fuel cell.The Waste Hub team has developed patent-pending technology that uses electrolysis to treat liquid acid whey (Sheehan 2015), neutralizing and removing organic contaminants from the waste stream. This is coupled with an exclusive sublicense from Catalytic Innovations to a patent-pending electrolysis catalyst chemistry that was developed at and is owned by Yale University (Sheehan et al. 2014). This technology, published in March of 2015 in Nature Communications (Sheehan et al. 2015), currently holds the world record for efficiency in electrolytic water and hydrocarbon oxidation processes. It has also resulted in finalist nominations for the Institute of Chemical Engineers Global Energy Award and the Collegiate Inventors Competition. In this Phase I SBIR project, Waste Hub will develop a physics-based design model and assemble, test, and demonstrate a pilot-scale electrolyzer using liquid acid whey waste from the Stonyfield Farm Greek yogurt manufacturing plant in Londonderry, New Hampshire. While we will only sample and discard the outlet streams from the process in this Phase for purposes of design and development of a complete pilot in Phase II, the ultimate objectives of the technology are to provide a cash-positive technology option for Greek yogurt manufacturers that will 1) generate electricity from the hydrogen using a PEM fuel cell, 2) separate oxygen and liquefy the CO2 stream for sale, and 3) recycle pre-filtered solids and clean effluent water to the yogurt manufacturing process.The hypothesis behind this project is that electrolysis using an iridium-based, heterogenized molecular oxidation catalyst on the anode and a platinum catalyst on the cathode will readily and durably oxidize the organic content of liquid acid whey with relatively low overpotential and will comprise an economically-sound alternative energy technology for processing liquid acid whey. The technical objectives are to confirm this hypothesis, namely:To demonstrate experimentally that acceptable rates of reaction and current density can be achieved using a continuous feed of liquid acid whey with low potential (<2 V).To determine the most cost-effective method of separating suspended solids (protein) and asses the ability to recycle the protein to the processTo collect samples and analyze the flow rates and composition of all outlet streams (H2, O2/CO2, water, solids) and use this information in the development and validation of a process simulation model of the entire Waste Hub system, including the fuel cell and CO2 liquefaction process.To produce designs and economic assessments of a scaled-up pilot and a full-scale system using the validated process model.The key research questions to be addressed in this Phase I project are as follows:What method of solids separation maximizes separation and prevents electrolysis performance degradation while preserving and recovering solids for reuse?What is the effect of solids loading on performance (outlet streams, durability, energy consumption) of the electrolysis system?What is the effect of applied potential on performance (outlet streams, durability, energy consumption) of the electrolysis system?Based on Phase I results, what would be the design, mass balance, energy balance, cost, and financial return of a pilot-scale Waste Hub system to be implemented in Phase II at Stonyfield, and of a complete commercial-scale Waste Hub system at 25,000 gal/day of liquid acid whey?
Project Methods
Investigation of Solids SeparationThe objective of this task is to evaluate cross-flow filtration, settling, and flocculation as potential methods for solids separation.Cross-Flow Filtration: We will use a low-pressure pump to deliver 1 gal/hr of raw liquid acid whey from a stirred storage beaker through a cross-flow membrane filter holder with three different grades of membrane/filter to filter solids for 30 minutes each. The pressure upstream of the filter will be monitored to assess plugging of the filter over time. Samples of fluid downstream of the filter will be taken initially and then every ten minutes. After each test, the filter will be removed and weighed to determine the amount of solids separated. The solids will then be removed, washed, and pressed with 250 ml of deionized water. The following data will be collected and analyses conducted for each test:pH, total suspended and dissolved solids (ASTM D5907-13), total organic carbon (ASTM D7573-09), total protein (Kjeldahl or Dumas method), and true protein (Kjeldahl or Dumas method with protein precipitation using trichloroacetic acid) of input and output acid whey samples.Upstream pressure vs timePercent solids removed by mass over the 30 minute testSettling: Two stainless steel settling containers will be arranged in series such that the first receives liquid acid whey at a rate of 1 gal/hr and transfers liquid via overflow to a second, equally-sized beaker. Fluid will be withdrawn from the top of the second beaker at 1 gal/hr for 30 minutes. Three tests will be conducted with three different beaker sizes to examine the effect of residence time. Samples downstream of the second beaker will be taken initially and then every ten minutes. The settled solids in each of the two beakers will be isolated at the end of each test by gently withdrawing the fluid from each beaker with minimal disruption of the solid layer. The solids will then be washed and pressed with 250 ml of deionized water. The following data will be collected and analyses conducted for each test:pH, total suspended and dissolved solids (ASTM D5907-13), total organic carbon (ASTM D7573-09), total protein (Kjeldahl or Dumas method), and true protein (Kjeldahl or Dumas method with protein precipitation using trichloroacetic acid) of input and output acid whey samples.Percent solids removed by mass over the 30 minute testFlocculation: We will use a low-pressure pump to deliver 1 gal/hr of raw acid whey from a stirred beaker into a stainless steel tank along with a pH-metered flow of dilute sulfuric acid. Precipitated proteins will be removed from the tank by skimming or filtration. The solids will then be washed and pressed with 250 ml of deionized water. The following data will be collected and analyses conducted for each test:pH, total suspended and dissolved solids (ASTM D5907-13), total organic carbon (ASTM D7573-09), total protein (Kjeldahl or Dumas method), and true protein (Kjeldahl or Dumas method with protein precipitation using trichloroacetic acid) of input and output acid whey samples.Percent solids removed by mass over the 30 minute testExperimental Research and Testing of ElectrolysisPreliminary proof-of-concept experiments show that, both with and without removal of solids from the liquid acid whey sample, an anode comprised of the molecular iridium oxidation catalyst supported on tin oxide-based mesoporous supports are capable of neutralizing liquid acid whey by oxidizing organics to CO2 and reducing water to H2 as shown by the catalytic currents in Figure 2. In these small lab-scale experiments, any solids present in the waste stream float to the top of the anode chamber by electroflotation. In similar schemes using small PEM electrolyzer test cells, the membrane was found to be functional in the presence of a filtered liquid acid whey sample. With these successful proof-of-concept experiments in mind, the objective of this task is to scale-up and optimize the components present in a small pilot-scale electrolyzer. As a part of this optimization process, the stability of each component will be tested rigorously, optimum operational parameters will be explored, and purity of the product streams will be determined.The electrochemical device contains an anode and cathode, each in its own respective chamber and separated by a bipolar membrane. Upon application of an electric potential from a DC rectifier, CO2 gas is generated from the oxidation of organic matter at the surface of the anode, while H2 gas is generated by the reduction of water at the cathode. Due to the overpotential required to achieve high rates of CO2 evolution, there will be some residual water oxidation at the anode, and as a result some O2 contaminating the CO2 stream. Determining the ratios of CO2 to O2 and the effect of the applied electric potential on those ratios is one of the goals of this project. Additionally, as demonstrated in the proof-of-concept experiments, the gas bubbles generated at the anode serve to float any remaining whey solids to the surface of the anode chamber, where they can then be skimmed and collected. Between the anode and cathode chambers, a bipolar membrane serves to spatially separate the output streams, and provides a channel by which the effluent water can be expelled from the electrolyzer. Since the majority of the liquid acid whey stream is water, the highest percent by weight output will also be this treated water. In order to scale-up and optimize this process for the pilot scale, the following tests must be performed:Nine 1-hour tests monitored using chronoamperometry [3 applied potentials, 3 solids loading (0, 0.75%, 1.5%) to determine to what extent electroflotation alone will it remove solids]Flow rate: 1 gal/hrMonitor flow rates of H2, O2/CO2, water over timeMonitor power consumption over timeSample collection every 15 minutes (H2 stream, O2/CO2 stream, water stream)H2 stream sample analyses (gas chromatography)O2/CO2 stream sample analyses (gas chromatography)Water stream sample analyses (pH, TSS, TDS, TOC, Total Protein, True Protein)Screen commercially available bipolar membrane technologiesExtended tests (>8 hours) under the best conditions identifiedProcess Modeling, Design and EconomicsIn this Phase I project, we will develop a mathematical model of the electrolysis process and validate predictions using the data concerning inputs and outputs generated in the electrolysis experiments. We will also use the model to interpret the results and optimize the process through parameter studies. In this Phase, we will develop a relatively simple, steady-state, semi-empirical model with parameters adjusted within reason to achieve agreement with experimental data. We will take into account mass transfer from the fluid to the electrodes in the electrode chambers and the equilibrium chemistry of the half-reactions taking place at the electrodes. The model should yield reasonable estimates of power consumption, gas compositions leaving the electrodes, and organic composition of effluent water. We will not attempt to address the minor, non-reacting constituents of acid whey other than to track their concentrations through the process based on changes in water and organics content. MS Excel will be used to develop the model in Phase I and will be upgraded to a more sophisticated process modeling package (i.e. ChemCAD, ASPEN) in Phase II.