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| Title: | Viability of wastewaster-derived algae as a source of nitrogen fertilizer |
| Authors: | Swenson, Nathan A. |
| Thesis Advisor: | Edinger-Marshall, Susan |
| Keywords: | Fertilizer
Nitrogen
Algae
Wastewater |
| Issue Date: | Jun-2009 |
| Publisher: | Humboldt State University |
| Abstract: | Wastewater algae were harvested from the dissolved air flotation unit at the Sunnyvale Water Pollution Control Plant in Sunnyvale, CA, to determine algal biomass suitability as a source of plant nutrition, specifically nitrogen. AlgaRhythms, Inc., an Arcata-based company, is interested in utilizing algae from treatment plants to further the development of wastewater algae as a fertilizer for use in retail markets.
The experiment compared the suitability of wastewater algae as a fertilizer by comparing dry shoot biomass production, total Kjeldahl nitrogen content of leaf tissue, and mineralizable nitrogen content of growth medium to inorganic, organic, and commercial fertilizers. Annual ryegrass, Lolium multiflorum, and Wisconsin Fast Plants, Brassica rapa, were used as indicator organisms in a greenhouse potted plant study. Application rates of algae and other nitrogen sources were 111, 222, and 445 kg N ha-1, along with four control groups that tested interactions with phosphorus, potassium, and micronutrients.
After 28 days of growth, Lolium multiflorum showed significant differences between fertilizers and application rates, with regard to dry biomass yield, but very little difference was shown in the mineralizable nitrogen in the potting medium or in the total Kjeldahl nitrogen content of the leaves. Scanning and transmission electron microscopy images of algal biomass were obtained to visually characterize isolated algae.
While lower application rates of algal biomass were not competitive with other fertilizers when considering yield, the highest application rate was similar to the
444 kg N ha-1 inorganic and commercial treatments, and the lowest application rate of organic fertilizer. With its slower mineralization rate, wastewater algae have the potential to be a useful fertilizer especially where nitrate leaching is common. The algal fertilizer also contains high levels of carbon, which could help depleted soils improve organic matter levels while providing a source of fertility. |
| Description: | Thesis (M.S.)--Humboldt State University, Natural Resources: Wildland Soil Science, 2009 |
| URI: | http://hdl.handle.net/2148/510 |
| Appears in Collections: | HSU Masters Theses
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