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      Nitrogen and phosphate removal from wastewater with a mixed microalgae and bacteria culture

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          Highlights

          • Complex biological and non-biological interactions involved in the removal of ammonium and phosphate from domestic sewage.

          • A microbial consortium that included microalgae involved.

          • The biological removal activity was mainly influenced by the temperature and not light availability.

          • The biological removal activity correlated with the culture photosynthetic activity.

          • Abiotic factors were involved in both ammonia removal and phosphate precipitation.

          Abstract

          Microalgae are able to convert nutrients (nitrogen and phosphorus) from wastewater into biomass and bio-products, thus improving the sustainability of wastewater treatment. In High Rate Algal Ponds (HRAP), biomass productivity and water treatment efficiency are highly dependent on environmental parameters such as temperature, light intensity and photoperiod. The influence of temperature and photoperiod on biomass productivity and the removal of dissolved nitrogen and phosphorus from municipal wastewater by a native microalgae-bacteria consortium was assessed in batch cultures in view of the development of an HRAP at a larger scale. Temperature affected the growth rate and microalgae biomass production as well as ammonium and phosphate removal rates. At the temperatures 15 and 25 °C, the average total nitrogen and phosphorus removal extents ranged from 72 to 83% and 100% respectively. Additionally 33.0 ± 0.1% of the total nitrogen was eliminated by stripping at 25 °C, and 50 ± 2% was assimilated by the microorganisms under all conditions tested.

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          Most cited references 32

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          Heterotrophic cultures of microalgae: metabolism and potential products.

          This review analyzes the current state of a specific niche of microalgae cultivation; heterotrophic growth in the dark supported by a carbon source replacing the traditional support of light energy. This unique ability of essentially photosynthetic microorganisms is shared by several species of microalgae. Where possible, heterotrophic growth overcomes major limitations of producing useful products from microalgae: dependency on light which significantly complicates the process, increase costs, and reduced production of potentially useful products. As a general role, and in most cases, heterotrophic cultivation is far cheaper, simpler to construct facilities, and easier than autotrophic cultivation to maintain on a large scale. This capacity allows expansion of useful applications from diverse species that is now very limited as a result of elevated costs of autotrophy; consequently, exploitation of microalgae is restricted to small volume of high-value products. Heterotrophic cultivation may allow large volume applications such as wastewater treatment combined, or separated, with production of biofuels. In this review, we present a general perspective of the field, describing the specific cellular metabolisms involved and the best-known examples from the literature and analyze the prospect of potential products from heterotrophic cultures. Copyright © 2010 Elsevier Ltd. All rights reserved.
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            Algal-bacterial processes for the treatment of hazardous contaminants: a review.

            Microalgae enhance the removal of nutrients, organic contaminants, heavy metals, and pathogens from domestic wastewater and furnish an interesting raw material for the production of high-value chemicals (algae metabolites) or biogas. Photosynthetic oxygen production also reduces the need for external aeration, which is especially advantageous for the treatment of hazardous pollutants that must be biodegraded aerobically but might volatilize during mechanical aeration. Recent studies have therefore shown that when proper methods for algal selection and cultivation are used, it is possible to use microalgae to produce the O(2) required by acclimatized bacteria to biodegrade hazardous pollutants such as polycyclic aromatic hydrocarbons, phenolics, and organic solvents. Well-mixed photobioreactors with algal biomass recirculation are recommended to protect the microalgae from effluent toxicity and optimize light utilization efficiency. The optimum biomass concentration to maintain in the system depends mainly on the light intensity and the reactor configuration: At low light intensity, the biomass concentration should be optimized to avoid mutual shading and dark respiration whereas at high light intensity, a high biomass concentration can be useful to protect microalgae from light inhibition and optimize the light/dark cycle frequency. Photobioreactors can be designed as open (stabilization ponds or high rate algal ponds) or enclosed (tubular, flat plate) systems. The latter are generally costly to construct and operate but more efficient than open systems. The best configuration to select will depend on factors such as process safety, land cost, and biomass use. Biomass harvest remains a limitation but recent progresses have been made in the selection of flocculating strains, the application of bioflocculants, or the use of immobilized biomass systems.
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              The nutrient status of algal cells in continuous culture

               M DROOP (1974)
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                Author and article information

                Contributors
                Journal
                Biotechnol Rep (Amst)
                Biotechnol Rep (Amst)
                Biotechnology Reports
                Elsevier
                2215-017X
                29 April 2016
                September 2016
                29 April 2016
                : 11
                : 18-26
                Affiliations
                [a ]ECONOVING, University of Versailles-Saint Quentin en Yvelines, France
                [b ]University of Ibague, Colombia
                [c ]CentraleSupelec, Université Paris Saclay, Grande Voie des Vignes, 92295, France
                Author notes
                Article
                S2215-017X(16)30018-2
                10.1016/j.btre.2016.04.003
                5042296
                © 2016 The Author(s)

                This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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