Grantee Research Project Results
2014 Progress Report: Struvite Recovery from Anaerobically Digested Dairy Manure
EPA Grant Number: SU835331Title: Struvite Recovery from Anaerobically Digested Dairy Manure
Investigators: Tao, Wendong , Mayer, Douglas , Mazinani, Ehsan , Ukwuani, Anayo
Current Investigators: Tao, Wendong , Mayer, Douglas , Mazinani, Ehsan , Ukwuani, Anayo , Agyeman, Fred , Abdulai, Hamidu , Austin, Scott , Das, Jonathan Masih , Robinson, Jesse , Stephan, Emily , White, Krystal , Wolcott, Scott , Elniski, Autumn
Institution: The State University of New York
EPA Project Officer: Page, Angela
Phase: II
Project Period: August 15, 2012 through August 14, 2014 (Extended to November 14, 2014)
Project Period Covered by this Report: August 15, 2013 through November 14,2014
Project Amount: $89,943
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2012) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Awards , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Chemical Safety , Sustainable and Healthy Communities
Objective:
The major objectives of this project are 1) to optimize struvite crystallization using velocity gradient as a control parameter of air-lift crystallizers; 2) to refine the combination ratio of manure filtrate to sludge digester liquor for elimination of the hindrance of high ionic strength to struvite precipitation while maintaining supersaturation of struvite ions; and 3) to set up and operate a pilot-scale system, including solid-liquid separation and struvite recovery from manure filtrate.
Progress Summary:
Struvite recovery requires manure filtrate to have total suspended solids below 1 g/L. We have completed five cycles of solid-liquid separation in six pebble filters in an on-campus greenhouse, comparing two loading modes. It was found that weekly small doses resulted in significantly faster filtration relative to one-time loading to 2-3 months of cycles. Three scaled-up pebble filters were set up in October 2013 and operated until August 2014 to produce manure filtrate. With the improved operation of larger pebble filters, manure filtrate with higher ammonia concentrations (1.2-1.7 mg N/L) was produced and stored for struvite tests. After consulting the Business Manager of Twin Birch Dairy, a farm waste (shredded corncobs) was chosen to mix with anaerobically digested dairy manure for enhancement of manure filtration. Doug Mayer is writing a master's thesis with the experimental results.
Struvite production with the 100% manure filtrate and diluted filtrate still posed challenges to increase recovery efficiency. Rather than using air-lift crystallizers, we performed flask tests to quickly identify the effects of stirring speed and pH on struvite precipitation with different dilution ratios of manure filtrate. Moreover, we tested solids formed at different sizes and changes of phosphorus forms along with struvite precipitation. Because the scanning electron microscope was out of service for periods, observation of the precipitates recovered needs to be completed in November 2014.
It was found that ammonia recovery could improve struvite recovery and produce another value-added product. Ammonia recovery decreases ionic strength which is possibly one of the major interferences to struvite recovery from anaerobically digested dairy manure. Both ammonia and struvite recovery requires high pH. We have completed ammonia recovery tests at 4 different temperatures and 2 different pH levels, and submitted a manuscript on the effects of temperature, pH and dissolved solids content on thermal stripping of ammonia from manure filtrate.
Future Activities:
The filtration system and scaled-up pebble filters have been operated to accumulate manure filtrate for struvite and ammonia recovery. Filtration rate is increased by frequent dosing and using an enhancing agent (corncob scraps). Diluting manure filtrate with a dilute solution like sludge digestion liquor appeared not to increase removal efficiency of orthophosphates, likely due to dissolution of particulate inorganic phosphorus in the filtrate, despite more precipitates could be collected. Ammonia recovery is more practical than combination of manure filtrate with sludge digester effluent for overcoming hindrance to struvite recovery from anaerobically digested dairy manure. Struvite recovery from dairy manure still has a limited efficiency as the other research groups have found.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 8 publications | 3 publications in selected types | All 3 journal articles |
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Tao W, Ukwuani AT. Coupling thermal stripping and acid absorption for ammonia recovery from dairy manure: ammonia volatilization kinetics and effects of temperature, pH and dissolved solids content. Chemical Engineering Journal 2015;280:188-196. |
SU835331 (2014) SU835331 (Final) SU835723 (Final) |
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Supplemental Keywords:
agricultural wastewater treatment; bio-based feedstocks; biofiltration technology; phosphorus recovery; sustainable design; waste to valueRelevant Websites:
Progress and Final Reports:
Original AbstractP3 Phase I:
Sustainably Overcoming Hindrance to Struvite Recovery from Anaerobically Digested Dairy Manure | Final ReportThe 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.