Grantee Research Project Results
Final Report: Sustainably Overcoming Hindrance to Struvite Recovery from Anaerobically Digested Dairy Manure
EPA Grant Number: SU836013Title: Sustainably Overcoming Hindrance to Struvite Recovery from Anaerobically Digested Dairy Manure
Investigators: Tao, Wendong , Arnold, Christopher , Wright, David , Mayer, Douglas , Leon, Eileen , Agyeman, Fred , Wen, Jianfeng , Martin, Lee , Moran, Sharon , Shi, Shun , Xu, Wenjie
Institution: The State University of New York
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text | 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:
Anaerobically digested dairy manure has high concentrations of orthophosphate, ammonium, and magnesium, which could be recovered at a higher pH (8.5-9.5) as struvite, MgNH4PO4∙6H2O. Struvite is a slow-release compound fertilizer. Struvite recovery from anaerobically digested dairy manure could remove orthophosphate and ammonium while providing revenues for farmers. However, high ionic strength and calcium interfere with struvite recovery from anaerobically digested dairy manure. This P3 project is to sustainably overcome the hindrance to struvite recovery from filtrate of anaerobically digested dairy manure. Specific objectives were to: 1) use furnace slag to raise pH for calcium precipitation and struvite recovery; 2) determine velocity gradient for efficient recovery of struvite in a batch crystallizer driven by an air-lift pump; 3) make proper use of dilution to minimize ionic strength and maximize orthophosphate activity for efficient struvite precipitation; and 4) assess the market share of struvite production with anaerobically digested dairy manure.
Unlike current use of chemicals for pH elevation and calcium removal, utilization of furnace slag and dilution will improve sustainability of struvite recovery. Utilization of dairy manure and furnace slag for struvite recovery makes productive use of agricultural and industrial wastes. The batch struvite crystallizer is an effective design and simple to operate. As a sustainable alternative to production of phosphorus fertilizers with non-renewable phosphate rocks, struvite production with dairy manure avoids air emission, wastewater discharge, tailings disposal, and mine drainage associated with phosphate mining and refining. A huge market share is expected for struvite production with digested dairy manure upon sustainable reduction of the hindrances.
Summary/Accomplishments (Outputs/Outcomes):
The SUNY ESF P3 project had a changing, but sustained team of graduate and undergraduate students. The P3 team has been partnering with two local dairy farms to separate suspended solids from anaerobically digested dairy manure and developing the struvite recovery technology. Struvite crystals have been recovered with a 7-L air-lift crystallizer from various types of dairy manure filtrate. The major findings are:
- Manure filtrate has high concentrations of magnesium, ammonium and phosphate, rendering a high potential of struvite recovery.
- Upward flow of manure filtrate through a filter packed with fine electric arc furnace slag is an effective design to raise manure filtrate pH above 9. Electric arc furnace slag filter is a cost-effective alternative to base solutions for pH elevation to meet the requirements for calcium removal and struvite recovery.
- Struvite crystallization is stabilized within 6-7 h at velocity gradients of 366-1377 /s in a batch air-lift crystallizer, but velocity gradient needs to be further examined to produce larger struvite pellets.
- Diluting manure filtrate with tap water decreases ionic strength, while supersaturation ratio may become low for efficient struvite crystallization. Alternative sources of dilution water need to be explored to remove more than 35% phosphate. The dilution water should be wastewaters rich in struvite ions and low in ionic strength such as sludge digester liquor.
Conclusions:
This P3 team has been moving technically closer to field applications. However, the technology still needs to be further developed for efficient struvite recovery, including further refining velocity gradient for the air-lift crystallizer and examine the effectiveness of alternative dilution water such as sludge digester liquor. A local dairy farm has agreed to host an on-farm pilot-scale system, including solid-liquid separation and struvite recovery. In combination with the on-farm anaerobic digestion, this project will provide dairy farms with a sustainable solution to farm nutrient management.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 8 publications | 2 publications in selected types | All 2 journal articles |
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Xia M, Tao W, Shayya W, Lu Z. Passive solid–liquid separation of anaerobically digested dairy manure using two-stage filtration. Biosystems Engineering 2012;111(4):392-397. |
SU836013 (Final) |
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Xia M, Tao W, Wang Z, Pei Y. Treatment of anaerobically digested dairy manure in a two-stage biofiltration system. Water Science & Technology 2012;65(11):1975-1981. |
SU836013 (Final) |
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Supplemental Keywords:
Agricultural wastewater treatment, Bio-based feedstocks, Biofiltration technology, Phosphorus recovery, Sustainable design, Waste to valueRelevant Websites:
Sustainably Overcoming Hindrance to Struvite Recovery from Anaerobically Digested Dairy Manure Exit
P3 Phase II:
Struvite Recovery from Anaerobically Digested Dairy Manure | 2013 Progress Report | 2014 Progress Report | 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.