Nitrogen and phosphorus removal rates using small algal turfs grown with dairy manure

• Published in: Journal of applied phycology 2002-12, Vol.14 (6), p.469-473
• Main Authors: PIZARRO, C, KEBEDE-WESTHEAD, E, MULBRY, W
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Biological treatment of sewage sludges and wastes; Biotechnology; Environment and pollution; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Industrial applications and implications. Economical aspects; Use of agricultural and forest wastes. Biomass use, bioconversion
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1023/A:1022338722952

Conservation and reuse of nitrogen (N) and phosphorus (P) from animal manure is increasingly important as producers try to minimize transport of these nutrients from farms. An alternative to land spreading is to grow crops of algae on the N and P present in the manure. The general goal of our research is to assess nutrient recovery from animal manure using attached algae. The specific objective of this study was to evaluate the use of small subsections of algal turfs for determining N and P removal rates by attached algae under different loading rates of dairy manure. Algae were grown in a laboratory-scale algal turf scrubber (ATS) operated by recycling wastewater and adding manure effluent daily. Replicate subsections (0.032 m super(2)) of algal turf screens were removed and treated with five different loadings of anaerobically digested dairy manure containing 5 to 80 mg L super(-1) NH sub(4)-N and 1 to 20 mg L super(-1) PO sub(4)-P over a 2-h incubation period. NH sub(4)-N removal rates were biphasic with a fast initial rate followed by a slower rate. Biphasic rates were more pronounced for the lowest loading rates but less so for the higher ones. PO sub(4)-P removal rates were linear throughout the incubation period for all loading rates. N and P removal rates increased with increasing loading rate and biomass. In incubations using 1% dairy manure NH sub(4)-N and PO sub(4)-P removal rates averaged 0.72 and 0.33 g m super(-2) d super(-1), respectively. These rates were approximately 5 to 8-fold lower than rates measured on laboratory-scale ATS units using undisturbed turfs.