Thesis
Characterization of factors affecting the production and utilization of struvite from dairy manure
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/102483
Abstract
When manure is applied to crops on a nitrogen basis, it often creates a buildup of phosphorus (P) in the soil. Phosphorus recovery as struvite is one strategy to capture excess P prior to land application. Dairy cow manure requires an acid addition to break the calcium phosphate bonds, and oxalic acid is desirable because, in addition to breaking bonds, its anion binds calcium. While struvite is reported to perform well in acidic soils, the relationship is unclear in alkaline soils. This thesis consisted of three experiments: 1) oxalic acid production by Aspergillus niger using whey permeate with varying lactose concentrations of 11% and 20% and fermentation temperatures of 30˚C and room temperature, 2) struvite precipitation from dairy manure after addition of commercial grade oxalic acid tested under varying pH points for maximum struvite production, and 3) an agronomic trial using triticale to compare the performance of struvite to monoammonium phosphate (MAP) in three different soil pHs. Results and discussion - 1) All fermentations produced oxalic acid; however, concentrations were below 10 mM. Future research should compare whey permeate with whey to ascertain if whey permeate is a suitable substrate for oxalic acid production. 2) Initially lowering the pH of the dairy manure to 6.0 and later raising the pH to 8.7 removed the most P (90%); however, this high pH can lead to magnesium phosphate precipitation and a pH of 6.0 was not low enough to completely disassociate the calcium from phosphate. Therefore I recommend initially lowering the pH to 5.5 and later raising it to pH 8.2 which achieved 80% P removal as struvite. Future research should compare struvite precipitation using commercial oxalic acid and oxalic acid solutions produced by Aspergillus niger, as fermentations would be an inexpensive source of organic acid. 3) Struvite treatments produced comparable concentrations of P in triticale to MAP, but struvite was inferior for dry matter yield and P uptake. Soil pH did not have a large effect on plant performance. Future research should compare granular and ground struvite with MAP using banded application and mixing with the soil in field scale studies.
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Details
- Title
- Characterization of factors affecting the production and utilization of struvite from dairy manure
- Creators
- Katherine Marguerite Brown
- Contributors
- Joe Harrison (Chair)Lawrence Fox (Committee Member) - Washington State University, Veterinary Clinical Sciences, Department ofAmber Adams-Progar (Committee Member) - Washington State University, Animal Sciences, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Animal Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900524804301842
- Language
- English
- Resource Type
- Thesis