Bacterially mediated removal of phosphorus and cycling of nitrate and sulfate in the waste stream of a "zero-discharge" recirculating mariculture system

KROM, M.D., BEN DAVID, A., INGALL, E.D., BENNING, L.G., CLERICI, S., BOTTRELL, S., DAVIES, C., POTTS, N.J., MORTIMER, R.J.G. and VAN RIJN, J., 2014. Bacterially mediated removal of phosphorus and cycling of nitrate and sulfate in the waste stream of a "zero-discharge" recirculating mariculture system. Water Research, 56, pp. 109-121. ISSN 0043-1354


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Simultaneous removal of nitrogen and phosphorus by microbial biofilters has been used in a variety of water treatment systems including treatment systems in aquaculture. In this study, phosphorus, nitrate and sulfate cycling in the anaerobic loop of a zero-discharge, recirculating mariculture system was investigated using detailed geochemical measurements in the sludge layer of the digestion basin. High concentrations of nitrate and sulfate, circulating in the overlying water (~15 mM), were removed by microbial respiration in the sludge resulting in a sulfide accumulation of up to 3 mM. Modelling of the observed S and O isotopic ratios in the surface sludge suggested that, with time, major respiration processes shifted from heterotrophic nitrate and sulfate reduction to autotrophic nitrate reduction. The much higher inorganic P content of the sludge relative to the fish feces is attributed to conversion of organic P to authigenic apatite. This conclusion is supported by: (a) X-ray diffraction analyses, which pointed to an accumulation of a calcium phosphate mineral phase that was different from P phases found in the feces, (b) the calculation that the pore waters of the sludge were highly oversaturated with respect to hydroxyapatite (saturation index = 4.87) and (c) there was a decrease in phosphate (and in the Ca/Na molar ratio) in the pore waters simultaneous with an increase in ammonia showing there had to be an additional P removal process at the same time as the heterotrophic breakdown of organic matter.

Item Type: Journal article
Publication Title: Water Research
Creators: Krom, M.D., Ben David, A., Ingall, E.D., Benning, L.G., Clerici, S., Bottrell, S., Davies, C., Potts, N.J., Mortimer, R.J.G. and Van Rijn, J.
Publisher: Elsevier
Date: 2014
Volume: 56
ISSN: 0043-1354
Divisions: Schools > School of Animal, Rural and Environmental Sciences
Depositing User: EPrints Services
Date Added: 09 Oct 2015 09:50
Last Modified: 09 Jun 2017 13:12

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