Nutrient Recovery from Anaerobically Digested Dairy Manure Using Dissolved Air Flotation (DAF)

Porterfield, Katherine K.; Faulkner, Joshua W.; Roy, Eric D.

doi:10.1021/acssuschemeng.9b06419

Cited by 19 publications

(7 citation statements)

References 37 publications

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“…Dissolved air flotation (DAF) recovers the majority of P from the post-screw press liquid digestate fraction by flocculating and separating the P-rich secondary fine solids [22]. DAF-separated fine solids have been shown to contain 85 ± 12% of the P in post-screw press dairy manure digestate [23] and also have a lower moisture content (e.g., 20.4 ± 3.0% total solids) than manure or pre-separation digestate (e.g., 4.1 ± 0.3% total solids), making transportation more economically feasible on-and off-farm [23]. With most of the P removed-the remaining liquid effluent has a higher N:P ratio that more closely matches crop needs, making it more appropriate to use on-farm without adding excess P to soils [22,23].…”

Section: Introductionmentioning

confidence: 99%

Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers

Porterfield

Joblin²,

Neher

et al. 2020

Sustainability

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Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v) ratios with plant foods consisting of fine solids upcycled (i.e., transformed into a higher quality product) by drying and blending with other organic residuals. A plate competition assay was conducted to assess the fine solids’ potential to suppress the plant pathogen Rhizoctonia solani. Plant foods were comprised of 2.0–2.1% N, 0.8–0.9% P and 0.6–0.8% K. Extractions indicated that plant foods contained a mixture of plant-available and slow-release P. At 6% v/v plant food, dry biomass of marigold and tomato were six-times greater than the unamended control and not significantly different from a market alternative treatment. Fine solids exhibited negligible potential to suppress R. solani. This study indicates that DAF-separated fine solids could be used to support horticulture, providing information for design of a circular economy approach to dairy manure nutrient management. Life cycle assessment and business model development for this nutrient recovery strategy are necessary next steps to further guide sustainability efforts.

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Section: Introductionmentioning

confidence: 99%

Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers

Porterfield

Joblin²,

Neher

et al. 2020

Sustainability

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“…dewatering, filtration, thermochemical conversion) could make future transport and export of manures more viable (e.g. Porterfield et al., 2020 ). They could also provide “waste to wealth opportunities” and transform perceptions so that P containing waste streams can be seen as valued resources which can be transformed into circular and sustainable products.…”

Section: Resultsmentioning

confidence: 99%

Phosphorus stocks and flows in an intensive livestock dominated food system

Rothwell

Doody

Johnston

et al. 2020

Resources, Conservation and Recycling

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Current use and management of phosphorus (P) in our food systems is considered unsustainable and considerable improvements in the efficiency of P use are required to mitigate the environmental impact of poor P stewardship. The inherent low P use efficiency of food production from animals means food systems dominated by livestock agriculture can pose unique challenges for improving P management. This paper presents the results of a substance flow analysis for P in the Northern Ireland (NI) food system for the year 2017 as a case study for examining P stewardship in a livestock dominated agricultural system. Imported livestock feed was by far the largest flow of P into the NI food system in 2017 (11,700 t ± 1300 t) and P from livestock excreta the largest internal flow of P (20,400 ± 1900t). The P contained in livestock slurries and manures alone that were returned to agricultural land exceeded total crop and grass P requirement by 20% and were the largest contributor to an annual excess soil P accumulation of 8.5 ± 1.4 kg ha −1 . This current livestock driven P surplus also limits the opportunities for P circularity and reuse from other sectors within the food system, e.g. wastewater biosolids and products from food processing waste. Management of livestock P demand (livestock numbers, feed P content) or technological advancements that facilitate the processing and subsequent export of slurries and manures are therefore needed.

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“…Dissolved air flotation (DAF) is a wastewater treatment strategy that flocculates and separates fine solids not captured by a screw press and has only recently been adapted for treating dairy manure (Frear et al., 2018; Liu et al., 2016). Dissolved air flotation–separated fine solids have been shown to contain the majority (85 ± 12%) of P remaining in post‐screw press dairy manure digestate, but at <25% total solids, they are still too heavy to transport long distances (Porterfield, Faulkner, et al., 2020). Products made from DAF‐captured dairy manure fine solids thermally dried to 45% total solids have demonstrated substantial fertilization value for vegetables and flowers and could potentially be marketed as bagged plant food products for horticultural production (Porterfield, Joblin, et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Assessment of lime‐conditioned dairy manure fine solids captured using dissolved air flotation for fertilization in horticulture

Porterfield

VanOrnum²,

Roy

2021

J of Env Quality

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Dissolved air flotation (DAF) has shown potential to substantially improve phosphorus (P) mass balance on dairy farms by capturing P associated with fine solids from liquid manure, enabling new management options. However, at <25% total solids, further dewatering is necessary to facilitate export of recovered fine solids off farm for use in bagged or bulk products. Physical conditioners such as quicklime (QL) and lime kiln dust (LKD) are commonly used to enhance mechanical dewatering of biosolids, but their effect on the properties and fertilization value of DAF‐captured manure fine solids has not been documented. We generated plant foods using DAF‐captured dairy manure fine solids conditioned with 3, 4.5, and 6% m/m QL or LKD and dewatered using a benchtop press for comparison with thermally dried fine solids. Tomato (Solanum lycopersicum L.) seedlings were grown in a soilless substrate amended with 6% v/v plant food and in an unamended control. Thermally dried and LKD plant foods produced significantly greater seedling biomass than QL plant foods and the unamended control. Quicklime‐ and LKD‐conditioned fine solids contained approximately 30× and 10× less water‐extractable P than thermally dried fine solids, respectively, likely due to precipitation of Ca‐P minerals. The elevated pH (≥10) of the lime‐conditioned fine solids could have also suppressed plant growth. These effects limit horticultural applications but could be beneficial in agricultural field settings where slow‐release P is desirable. Research beyond this preliminary assessment is needed to determine the practicality and sustainability of the approach along with longer‐term nutrient bioavailability.

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Nutrient Recovery from Anaerobically Digested Dairy Manure Using Dissolved Air Flotation (DAF)

Cited by 19 publications

References 37 publications

Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers

Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers

Phosphorus stocks and flows in an intensive livestock dominated food system

Assessment of lime‐conditioned dairy manure fine solids captured using dissolved air flotation for fertilization in horticulture

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