Biofilters made of Ulva and periphyton differ in their effectiveness in removing ammonia and nitrate from mariculture effluents. Our research evaluated the practicality of a combination of these two biofilters in improving the overall removal of dissolved N, where efficient removal of ammonia by the seaweed is followed by efficient removal of nitrate by periphyton. A paired Ulva-periphyton biofilter was exposed to various areal loads of ammonia and nitrate, the primary nitrogen forms in fishpond effluents. A first upstream macroalgae biofilter stocked with Ulva was fed with fishpond effluents at different areal loads of ammonia and nitrate, while a second downstream periphyton biofilter was paired for further nitrogen removal from the effluent. Ulva removed ammonia at a rate of 0.7–5.4 g TAN m−2 d−1, in correlation with the TAN areal load, with Vmax of 5.1 and Km of 4.4 g TAN m−2 d−1. Downstream periphyton was exposed to a lower TAN, but nitrate-rich effluent, and revealed similar capacities for the removal of both N forms, at removal rates of up to 1.7 and 1.8 g N m−2 d−1, respectively. Compared to nitrate, areal load of TAN had a greater impact on the removal dynamics of both N forms by periphyton. Overall, the paired biofilter resulted in a nearly total depletion of ammonia (97%) and efficient nitrate removal (67%), when areal loads in fishpond effluents were below 2 and 4 g N m−2 d−1 of TAN and NO3-N, respectively.
Bibliographical noteFunding Information:
The research was supported by the United States - Israel Binational Agricultural Research and Development (BARD), Grant No. IS 4995 17R, and by Vaadia-BARD Postdoctoral Fellowship Award No. FU-530-2015. The authors thank all the staff at the National Center for Mariculture and in particular H. Chernova and A. Zalmanzon, for the nutrient analyses, D. Ben Ezra, V. Odintzov, L. Shauli, and L. Breyl for operating the experimental system and their help with sampling and analyses. All authors materially participated in the research and in the manuscript preparation. Lior Guttman is the corresponding author, research leader and coordinator. Amir Neori contributed in data analyses and the preparation of the manuscript. Suzanne Boxman and Roy Barkan performed the experiments and nutrient analyses. Ben Shahar contributed in preparation and analyses of the data sets. Andrea M. Tarnecki, Nathan P. Brennan and Kevan L. Main participated in the preparation of the manuscript. Muki Shpigel participated in the design of the experiment and in the preparation of the manuscript.
© 2019 Elsevier B.V.
ASJC Scopus subject areas
- Agronomy and Crop Science