Advanced nutrient removal from surface water by a consortium of attached microalgae and bacteria: A review.
TL;DR: This critical review summarizes the fundamentals and status of attached microalgae-bacteria consortium for advanced nutrient removal from surface water and key advantages are the various nutrient removal pathways, reduction of nutrients to very low concentration, and diversified photobioreactor configurations.
About: This article is published in Bioresource Technology.The article was published on 2017-10-01. It has received 213 citations till now. The article focuses on the topics: Photobioreactor.
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TL;DR: This review comprehensively describes the current research on the possible roles and applications of microalgae for removing PCs from aqueous media and summarizes several novel approaches including constructing microbial consortia, acclimation, and cometabolism for enhanced removal of PCs by microalgal.
352 citations
TL;DR: This review provides a comprehensive summary of recent literature, an overview of approaches and treatment systems, and breakthrough in the field of algal-mediated removal of PPCPs in wastewater treatment processes, highlighting microalgae as a promising and sustainable approach to efficiently bio-transform or bio-adsorb P PCPs.
218 citations
TL;DR: The most recent work on microalgal-bacterial interaction mechanisms is recapitulates, and the diverse biotechnological applications of microalGal-b bacterial consortia are described, which include wastewater treatment, biomass harvesting, and electricity generation.
Abstract: Microalgae have emerged as a renewable and sustainable candidate for bioenergy production coupled with pollutant removal from wastewater. However, costly biomass harvesting, insufficient biomass productivity, and energy-intensive extraction methods are major bottlenecks restricting their large-scale development. To break through such limitations, researchers have focused on the technologies towards consolidating microalgal-bacterial consortia, which exhibit numerous advantages related to economy, energy, and environment, due to the cooperative interactions between microalgae and bacteria. This paper recapitulates the most recent work on microalgal-bacterial interaction mechanisms, and describes the diverse biotechnological applications of microalgal-bacterial consortia. Based on this review, the interaction mechanisms cover substrate exchange, cell-to-cell signaling, and horizontal gene transfer. Nutrient availability, growth phase, and cultivation conditions are major factors affecting their interactions. In terms of wastewater treatment, attached microalgal-bacterial consortia are economically feasible and technically superior compared to suspended microalgal-bacterial consortia. Appropriate carrier, bioreactor type, operation mode, operational factor, and further perspectives for engineering attached microalgal-bacterial consortia are critically assessed. Bacteria play an important role in promoting microalgal growth, enhancing bio-flocculation and facilitating cell wall disruption, and thus expanding the application potential of microalgal biofuel production. The current state of other promising biotechnological applications of microalgal-bacterial consortia (particularly mitigation of CO2 emissions, microalgal bloom control, and electricity generation) and the appropriate strategies to enhance their practical applications are discussed. The major challenges to scale up microalgal-bacterial consortia and corresponding recommendations for further research are also addressed.
168 citations
TL;DR: In this paper, a critical evaluation of recent literature was carried out to synthesize knowledge related to mechanisms of interaction between microalgae and bacteria consortia for nutrient removal from wastewater.
132 citations
TL;DR: In this paper, a review of the recent progress in the fixed-bed and immobilized nanophotocatalysts and their applications for resolving the environmental concerns is presented.
Abstract: Advanced oxidation processes (AOPs) introduce a hopeful technology for the removal of water polluted with hard degradable organic compounds. Today, one of the main effective AOP technologies to degrade these hazardous organics is via the photocatalytic process. The present review focuses on the recent progress in the fixed-bed and immobilized nanophotocatalysts and also their applications for resolving the environmental concerns. Various organics elimination using a variety of photocatalysts and innovative reactors are discussed. This critical review summarizes the recent progress in the synthesis and modification (physical and chemical) of semiconductors. Furthermore, different ways of photocatalysts immobilization are explained in details. By considering different dangerous chemicals present in wastewater and different industries, catalytic methods used by researchers to degrade these organic compounds are reviewed. In addition, the degradation pathway of some organics through the catalytic operation is described.
128 citations
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TL;DR: The discovery and cultivation of a completely nitrifying bacterium from the genus Nitrospira, a globally distributed group of nitrite oxidizers, and the genome of this chemolithoautotrophic organism encodes the pathways both for ammonia and nitrite oxidation.
Abstract: Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be a two-step process catalysed by chemolithoautotrophic microorganisms oxidizing either ammonia or nitrite. No known nitrifier carries out both steps, although complete nitrification should be energetically advantageous. This functional separation has puzzled microbiologists for a century. Here we report on the discovery and cultivation of a completely nitrifying bacterium from the genus Nitrospira, a globally distributed group of nitrite oxidizers. The genome of this chemolithoautotrophic organism encodes the pathways both for ammonia and nitrite oxidation, which are concomitantly activated during growth by ammonia oxidation to nitrate. Genes affiliated with the phylogenetically distinct ammonia monooxygenase and hydroxylamine dehydrogenase genes of Nitrospira are present in many environments and were retrieved on Nitrospira-contigs in new metagenomes from engineered systems. These findings fundamentally change our picture of nitrification and point to completely nitrifying Nitrospira as key components of nitrogen-cycling microbial communities.
1,648 citations
TL;DR: In this paper, the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals are reviewed.
Abstract: Waste biomass is a cheap and relatively abundant source of electrons for microbes capable of producing electrical current outside the cell. Rapidly developing microbial electrochemical technologies, such as microbial fuel cells, are part of a diverse platform of future sustainable energy and chemical production technologies. We review the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals. Moreover, we examine the key challenges for implementing these systems and compare them to similar renewable energy technologies. Although commercial development is already underway in several different applications, ranging from wastewater treatment to industrial chemical production, further research is needed regarding efficiency, scalability, system lifetimes, and reliability.
1,469 citations
TL;DR: In this paper, the major nutrient components of different wastewater streams, the mechanisms of algal nutrient uptake, nutrient removal performance of various species of microalgae when cultured in wastewater, and current micro-algae production systems are discussed.
Abstract: Disposal of wastewater often results in high nutrient loading into aquatic environments, which may lead to favorable conditions for undesirable phytoplankton blooms. Microalgae are efficient in removing nitrogen, phosphorus, and toxic metals from wastewater under controlled environments. If key nutrients in the wastewater stream can be used to grow microalgae for biofuel production, the nutrients can be removed, thus significantly reducing the risk of harmful phytoplankton overgrowth. This review paper summarizes the major nutrient components of different wastewater streams, the mechanisms of algal nutrient uptake, nutrient removal performance of various species of microalgae when cultured in wastewater, and current microalgae production systems. Finally, new algae cultivation technologies applicable for biofuel production and nutrient recovery in polluted water bodies are discussed.
1,249 citations
TL;DR: The enrichment and initial characterization of two Nitrospira species that encode all the enzymes necessary for ammonia oxidation via nitrite to nitrate in their genomes, and indeed completely oxidize ammonium to nitrates to conserve energy are reported.
Abstract: Nitrification is a two-step process where ammonia is first oxidized to nitrite by ammonia-oxidizing bacteria and/or archaea, and subsequently to nitrate by nitrite-oxidizing bacteria. Already described by Winogradsky in 18901, this division of labour between the two functional groups is a generally accepted characteristic of the biogeochemical nitrogen cycle2. Complete oxidation of ammonia to nitrate in one organism (complete ammonia oxidation; comammox) is energetically feasible, and it was postulated that this process could occur under conditions selecting for species with lower growth rates but higher growth yields than canonical ammonia-oxidizing microorganisms3. Still, organisms catalysing this process have not yet been discovered. Here we report the enrichment and initial characterization of two Nitrospira species that encode all the enzymes necessary for ammonia oxidation via nitrite to nitrate in their genomes, and indeed completely oxidize ammonium to nitrate to conserve energy. Their ammonia monooxygenase (AMO) enzymes are phylogenetically distinct from currently identified AMOs, rendering recent acquisition by horizontal gene transfer from known ammonia-oxidizing microorganisms unlikely. We also found highly similar amoA sequences (encoding the AMO subunit A) in public sequence databases, which were apparently misclassified as methane monooxygenases. This recognition of a novel amoA sequence group will lead to an improved understanding of the environmental abundance and distribution of ammonia-oxidizing microorganisms. Furthermore, the discovery of the long-sought-after comammox process will change our perception of the nitrogen cycle.
1,225 citations
TL;DR: This review paper critically assesses the recent advances that have been achieved in this field, particularly relating to the areas of EBPR microbiology, biochemistry, process operation and process modelling.
1,058 citations