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Zhang T.,Washington State University | Bowers K.E.,Multiform Harvest Inc | Harrison J.H.,Washington State University | Chen S.,Washington State University
Water Environment Research | Year: 2010

Being a non-renewable resource and a source of potential water pollution, phosphorus could be recovered from animal manure in the form of struvite (MgNH4PO4·6H2O) to be used as a slow-release fertilizer. It was found recently that the majority of phosphorus in anaerobically digested dairy effluent is tied up in a fine suspended calcium-phosphate solid, thus becoming unavailable for struvite formation. Acidification and use of a chelating agent were investigated for converting the calciumassociated phosphorus in the digested effluent to dissolved phosphate ions, so that struvite can be produced. The results demonstrated that the phosphorus in the effluent was released into the solution by lowering the pH. In addition, the phosphorus concentration in the solution increased significantly with increased ethylenediaminetetraacetic acid (EDTA) concentration, as EDTA has a high stability constant with calcium. Most of the phosphorus (91%) was released into the solution after adding EDTA. Further, the freed phosphorus ion precipitated out as struvite provided that sufficient magnesium ions (Mg 2+) were present in the solution. Furthermore, the phase structure of the solid precipitate obtained from the EDTA treatment matched well with standard struvite, based on the data from X-ray diffraction analysis. These results provide methods for altering the forms of phosphorus for the design and application of phosphorus-removal technologies for dairy wastewater management.


Westerman P.W.,North Carolina State University | Bowers K.E.,Multiform Harvest Inc | Zering K.D.,North Carolina State University
Applied Engineering in Agriculture | Year: 2010

Tests for phosphorus reduction by increasing magnesium and pH to form struvite (magnesium ammonium phosphate hexahydrate (MgNH4PO 4·6(H2O)) were conducted using effluent from a covered earthen anaerobic digester for swine manure. A cone-shaped crystallizer system was constructed in the field and operated with direct pumping of covered digester liquid at a flow rate of 5.4 L/min (1.43 gal/min). Using the field system, 24 combinations of pH increase (0- to 1.5-pH units) and magnesium (Mg) addition (0, 20, 40, and 60 mg/L) were tested in short-term (30-min) tests. Up to 80% of the total phosphorus (TP) could be removed with the highest increases in pH and Mg. About 65% of TP was removed with the combination of 0.5-pH unit increase and addition of 40 mg/L of Mg. To test performance over longer periods, this combination was utilized in 40 tests each of 2-h duration during the period of September 2007 through October 2008. Reductions averaged 55 ± 10% (mean ± standard deviation) removal of TP and 65 ± 5% removal of orthophosphate phosphorus (OP). Analyses of samples of the solids removed from the crystallizer on six different dates indicated that N, P, and Mg were lower on average than theoretical values for pure struvite (5.71% N, 12.62% P, and 9.90% Mg) by 9.9%, 4.4%, and 6.2%. The solids included 1.8% calcium, indicating calcium compounds were being included in the formed material. Costs and returns were estimated for a commercial scale system and chemical costs and TP removal were estimated at selected levels of Mg addition and increase in pH. The net annual cost of the system for 60% removal of TP from digester effluent for a 1000-sow farrow-to-finish operation was estimated to be $0.0146/kg of live hog marketed. © 2010 American Society of Agricultural and Biological Engineers.


Shen Y.,Virginia Polytechnic Institute and State University | Ogejo J.A.,Virginia Polytechnic Institute and State University | Bowers K.E.,Multiform Harvest Inc
Transactions of the ASABE | Year: 2011

Phosphorus (P) can be recovered as struvite from liquid dairy manure as a way to recycle and reuse P. One of the factors that can inhibit struvite precipitation is the calcium (Ca) concentration in dairy manure. This study used modeling and laboratory experiments to investigate acidification and addition of Ca sequestering compounds (ethylenediaminetetraacetic acid and oxalic acid) as means of enhancing the precipitation and recovery of struvite from dairy manure. The Visual MINTEQ model was used to determine the desirable pH of manure at which all the particulate inorganic phosphates are released into solution and predict the quantities of struvite and other minerals that can be formed. The model results were validated experimentally using synthetic liquid and dairy manure. Both the model and experimental results showed that struvite can be precipitated from dairy manure with a high calcium-to-magnesium molar ratio (Ca:Mg) of 1.46 by acidifying manure to pH 4.5, adding EDTA or oxalic acid, and then raising the pH to 7.5. Adding magnesium to lower the Ca:Mg ratio was not effective in struvite precipitation. In addition, reducing the total suspended solids concentrations supported better struvite precipitation. © 2011 American Society of Agricultural and Biological Engineers.


Patent
Multiform Harvest Inc | Date: 2012-02-03

Methods and compositions for chemical drying and for producing struvite.


Patent
Multiform Harvest Inc | Date: 2014-06-04

Methods and systems for recovery of phosphorus from wastewater and producing inorganic phosphorus complexes.


Patent
Multiform Harvest Inc | Date: 2012-11-13

Methods and systems for recovery of phosphorus from wastewater and producing inorganic phosphorus complexes.


Patent
Multiform Harvest Inc | Date: 2016-05-09

Methods and compositions for chemical drying and for producing struvite.


Grant
Agency: Department of Agriculture | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 89.38K | Year: 2010

This project develops a commercial process for modifying phosphorus recovered from dairy manure and other waste streams into marketable feed and fertilizer products. Phosphorus release from dairies and other concentrated feeding operations is a growing environmental problem. Meanwhile, domestic supplies of mined phosphorus are rapidly depleting, confronting U.S. agriculture with serious cost impacts in the near future. Successful modification of a die pelletizer enabling the crystalline struvite recovered from waste organic matter to be converted into a phosphorus-rich pellet will be a low-cost means of "recycling" this nutrient. It will then be possible to transport phosphorus from where it is a problem - animal feeding operations -- to where it is needed - produce farms and greenhouses. The employment of commonly available infrastructure to process a new, bio-based phosphorus fertilizer and nutritional supplement will be particularly attractive to feed and fertilizer dealers already positioned to process and retail these items. A market for struvite will also encourage wider adoption of anaerobic digesters at animal feeding operations, since the struvite can be most efficiently extracted from manure management systems. Modified in the way this project envisions, struvite will be easily transportable, provide a slow-release source of phosphorus and nitrogen when incorporated into soil, and be digested by animals as a nutritional supplement. This research will also explore opportunities for incorporating struvite into multi-nutrient products, enabling fertilizer distributors to customize "bio-based" fertilizers as they currently do with synthetic nutrient formulas. Unmodified struvite, as it emerges from manure waste streams, is unfortunately too fine to be efficiently handled by fertilizer distributors or be incorporated with other substances. The struvite therefore requires an "upgrade" to its compaction to make its texture consistent with other substances typically handled by agricultural supply facilities. Multiform estimates such an upgrade will more than triple the value of struvite. If this project can arrive at a commercially viable process for compacting struvite that avoids the cost of a specialized processing facility, it will reduce the time required to deliver struvite to market by several years, and avoid capitalization costs of half a million dollars or more. Furthermore, a standardized method for utilizing commonly available die pelletizers to render granulized struvite will make the product available across a very wide market.


Grant
Agency: Department of Agriculture | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 448.95K | Year: 2012

Multiform Harvest Inc. ("Multiform") produces the fertilizer struvite, which is magnesium ammonium phosphate hexahydrate. Multiform produces the struvite by extracting it from wastewaters containing excess phosphorus. Multiform sells into two markets: 1) wastewater generators who need to reduce the phosphorus content of the wastewater; and 2) consumers of the nutrients provided by the struvite produced at the wastewater generator sites. The SBIR project focuses on the second market (nutrient consumers). This project, of which the phase I is complete, seeks to further improve the economics of the struvite extraction technology, thus accelerating its adoption, by developing means to convert the crude struvite produced by the extraction process to a higher-value, specialized product. The activities planned for phase II of the project aim to work out continuous, commercially useful processes and apparatuses to produce the high-value products (pellets and formed products such as spikes and tablets) for which the first phase provided product specifications and laboratory-scale, batch type means of producing. Specifically, the technical objectives are (1) Verify market information achieved through Phase I research for five targeted products through direct consultation with buyers. Present upgraded struvite products to buyers and verify that they are ready for commercial sale at a known value; (2) Confirm that struvite products meet buyer nutritional and performance specifications through greenhouse growing trial; (3) Identify potential processes for commercial-scale continuous drying and forming, and identify the necessary struvite conditions and formulas; (4) Develop and monitor continuous manufacturing processes for pelletizing and forming products at laboratory scale; (5) Design and build prototype a manufacturing system capable of drying and forming struvite into one or more target products; and (6) Determine capital and production costs for full operating system, and compare with market data for profit estimate for one or more systems.


Patent
Multiform Harvest Inc | Date: 2012-06-18

Methods for inhibiting, preventing, and disrupting flocculations in wastewater treatment streams.

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