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1.
Use of microalgae based technology for the removal of antibiotics from wastewater: A review.
Leng, L, Wei, L, Xiong, Q, Xu, S, Li, W, Lv, S, Lu, Q, Wan, L, Wen, Z, Zhou, W
Chemosphere. 2020;:124680
Abstract
The antibiotic resistance induced by the release of antibiotics to the environment has urged research towards developing effective technologies for antibiotic removal from wastewater. Traditional technologies such as activated sludge processes are not effective for antibiotic removal. Recently, microalgae-based technology has been explored as a potential alternative for the treatment of wastewater containing antibiotics by adsorption, accumulation, biodegradation, photodegradation, and hydrolysis. In this review, the toxicities of antibiotics on microalgae, the mechanisms of antibiotic removal by microalgae, and the integration of microalgae with other technologies such as ultraviolet irradiation (photocatalysis), advanced oxidation, and complementary microorganism degradation for antibiotic removal were discussed. The limitations of current microalgae-based technology and future research needs were also discussed.
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2.
Research progress and application prospect of anaerobic biological phosphorus removal.
Yang, F, Zhang, C, Rong, H, Cao, Y
Applied microbiology and biotechnology. 2019;(5):2133-2139
Abstract
Anaerobic biological phosphorus removal has proposed a new direction for the removal of phosphorus from wastewater, and the discovery of phosphate reduction makes people have a more comprehensive understanding of microbial phosphorus cycling. Here, from the perspective of thermodynamics, the bioreduction reaction of phosphate was analyzed and its mechanism was discussed. The research progress of phosphate reduction and the application prospects of anaerobic biological phosphorus removal from wastewater were introduced, pointing out the situation and guiding the further research in this field.
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3.
A review on removing antibiotics and antibiotic resistance genes from wastewater by constructed wetlands: Performance and microbial response.
Liu, X, Guo, X, Liu, Y, Lu, S, Xi, B, Zhang, J, Wang, Z, Bi, B
Environmental pollution (Barking, Essex : 1987). 2019;(Pt A):112996
Abstract
Pollution caused by antibiotics has been highlighted in recent decades as a worldwide environmental and health concern. Compared to traditional physical, chemical and biological treatments, constructed wetlands (CWs) have been suggested to be a cost-efficient and ecological technology for the remediation of various kinds of contaminated waters. In this review, 39 antibiotics removal-related studies conducted on 106 treatment systems from China, Spain, Canada, Portugal, etc. were summarized. Overall, the removal efficiency of CWs for antibiotics showed good performance (average value = over 50%), especially vertical flow constructed wetlands (VFCWs) (average value = 80.44%). The removal efficiencies of sulfonamide and macrolide antibiotics were lower than those of tetracycline and quinolone antibiotics. In addition, the relationship between the removal efficiency of antibiotics and chemical oxygen demand (COD), total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and ammonia nitrogen (NH3-N) concentrations showed an inverted U-shaped curve with turning points of 300 mg L-1, 57.4 mg L-1, 40 mg L-1, 3.2 mg L-1 and 48 mg L-1, respectively. The coexistence of antibiotics with nitrogen and phosphorus slightly reduced the removal efficiency of nitrogen and phosphorus in CWs. The removal effect of horizontal subsurface flow constructed wetlands for antibiotic resistance genes (ARGs) had better performance (over 50%) than that of vertical wetlands, especially for sulfonamide resistance genes. Microorganisms are highly sensitive to antibiotics. In fact, microorganisms are one of the main responsible for antibiotic removal. Moreover, due to the selective pressure induced by antibiotics and drug-resistant gene transfer from resistant bacteria to other sensitive strains through their own genetic transfer elements, decreased microbial diversity and increased resistance in sewage have been consistently reported. This review promotes further research on the removal mechanism of antibiotics and ARGs in CWs.
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4.
Bio-conversion of photosynthetic bacteria from non-toxic wastewater to realize wastewater treatment and bioresource recovery: A review.
Lu, H, Zhang, G, Zheng, Z, Meng, F, Du, T, He, S
Bioresource technology. 2019;:383-399
Abstract
Generating or recycling water and resources from wastewater other than just treating wastewater is one of the most popular trends worldwide. Photosynthetic bacteria (PSB) wastewater treatment and resource recovery technology is one of the most potential methods. PSBs are non-toxic and contain lots of value-added products that can be utilized in the agricultural and food industries. They are effective to degrade pollutants and synthesize useful biomass, thus realizing wastewater treatment, bioresource production, and eliminating waste sludge. If all the nutrients in wastewaters could be bio-converted by PSB, then pollutant reductions and economic benefits would be achieved. This review paper firstly describes and summarizes this technology, including PSBs classification, metabolism, and the market application. The feasibility, technical procedures, bioreactors, pollutant removal, and bioresource production are also summarized, compared and evaluated. Issues that concern the advantages and industrialization of this technologies at the plant scale are also discussed.
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5.
Influence of surfactants on anaerobic digestion of waste activated sludge: acid and methane production and pollution removal.
He, Q, Xu, P, Zhang, C, Zeng, G, Liu, Z, Wang, D, Tang, W, Dong, H, Tan, X, Duan, A
Critical reviews in biotechnology. 2019;(5):746-757
Abstract
The objective of this study is to summarize the effects of surfactants on anaerobic digestion (AD) of waste activated sludge (WAS). The increasing amount of WAS has caused serious environmental problems. Anaerobic digestion, as the main treatment for WAS containing three stages (i.e. hydrolysis, acidogenesis, and methanogenesis), has been widely investigated. Surfactant addition has been demonstrated to improve the efficiency of AD. Surfactant, as an amphipathic substance, can enhance the efficiency of hydrolysis by separating large sludge and releasing the encapsulated hydrolase, providing more substance for subsequent acidogenesis. Afterwards, the short chain fatty acids (SCFAs), as the major product, have been produced. Previous investigations revealed that surfactant could affect the transformation of SCFA. They changed the types of acidification products by promoting changes in microbial activity and in the ratio of carbon to nitrogen (C/N), especially the ratio of acetic and propionic acid, which were applied for either the removal of nutrient or the production of polyhydroxyalkanoate (PHA). In addition, the activity of microorganisms can be affected by surfactant, which mainly leads to the activity changes of methanogens. Besides, the solubilization of surfactant will promote the solubility of contaminants in sludge, such as organic contaminants and heavy metals, by increasing the bioavailability or desorbing of the sludge.
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6.
Pepper mild mottle virus: A plant pathogen with a greater purpose in (waste)water treatment development and public health management.
Symonds, EM, Nguyen, KH, Harwood, VJ, Breitbart, M
Water research. 2018;:1-12
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Abstract
An enteric virus surrogate and reliable domestic wastewater tracer is needed to manage microbial quality of food and water as (waste)water reuse becomes more prevalent in response to population growth, urbanization, and climate change. Pepper mild mottle virus (PMMoV), a plant pathogen found at high concentrations in domestic wastewater, is a promising surrogate for enteric viruses that has been incorporated into over 29 water- and food-related microbial quality and technology investigations around the world. This review consolidates the available literature from across disciplines to provide guidance on the utility of PMMoV as either an enteric virus surrogate and/or domestic wastewater marker in various situations. Synthesis of the available research supports PMMoV as a useful enteric virus process indicator since its high concentrations in source water allow for identifying the extent of virus log-reductions in field, pilot, and full-scale (waste)water treatment systems. PMMoV reduction levels during many forms of wastewater treatment were less than or equal to the reduction of other viruses, suggesting this virus can serve as an enteric virus surrogate when evaluating new treatment technologies. PMMoV excels as an index virus for enteric viruses in environmental waters exposed to untreated domestic wastewater because it was detected more frequently and in higher concentrations than other human viruses in groundwater (72.2%) and surface waters (freshwater, 94.5% and coastal, 72.2%), with pathogen co-detection rates as high as 72.3%. Additionally, PMMoV is an important microbial source tracking marker, most appropriately associated with untreated domestic wastewater, where its pooled-specificity is 90% and pooled-sensitivity is 100%, as opposed to human feces where its pooled-sensitivity is only 11.3%. A limited number of studies have also suggested that PMMoV may be a useful index virus for enteric viruses in monitoring the microbial quality of fresh produce and shellfish, but further research is needed on these topics. Finally, future work is needed to fill in knowledge gaps regarding PMMoV's global specificity and sensitivity.
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Nutrient removal and biomass production: advances in microalgal biotechnology for wastewater treatment.
Abinandan, S, Subashchandrabose, SR, Venkateswarlu, K, Megharaj, M
Critical reviews in biotechnology. 2018;(8):1244-1260
Abstract
Owing to certain drawbacks, such as energy-intensive operations in conventional modes of wastewater treatment (WWT), there has been an extensive search for alternative strategies in treatment technology. Biological modes for treating wastewaters are one of the finest technologies in terms of economy and efficiency. An integrated biological approach with chemical flocculation is being conventionally practiced in several-sewage and effluent treatment plants around the world. Overwhelming responsiveness to treat wastewaters especially by using microalgae is due to their simplest photosynthetic mechanism and ease of acclimation to various habitats. Microalgal technology, also known as phycoremediation, has been in use for WWT since 1950s. Various strategies for the cultivation of microalgae in WWT systems are evolving faster. However, the availability of innovative approaches for maximizing the treatment efficiency, coupled with biomass productivity, remains the major bottleneck for commercialization of microalgal technology. Investment costs and invasive parameters also delimit the use of microalgae in WWT. This review critically discusses the merits and demerits of microalgal cultivation strategies recently developed for maximum pollutant removal as well as biomass productivity. Also, the potential of algal biofilm technology in pollutant removal, and harvesting the microalgal biomass using different techniques have been highlighted. Finally, an economic assessment of the currently available methods has been made to validate microalgal cultivation in wastewater at the commercial level.
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8.
Microalgal Cultivation in Secondary Effluent: Recent Developments and Future Work.
Lv, J, Feng, J, Liu, Q, Xie, S
International journal of molecular sciences. 2017;(1)
Abstract
Eutrophication of water catchments and the greenhouse effect are major challenges in developing the global economy in the near future. Secondary effluents, containing high amounts of nitrogen and phosphorus, need further treatment before being discharged into receiving water bodies. At the same time, new environmentally friendly energy sources need to be developed. Integrating microalgal cultivation for the production of biodiesel feedstock with the treatment of secondary effluent is one way of addressing both issues. This article provides a comprehensive review of the latest progress in microalgal cultivation in secondary effluent to remove pollutants and accumulate lipids. Researchers have discovered that microalgae remove nitrogen and phosphorus effectively from secondary effluent, accumulating biomass and lipids in the process. Immobilization of appropriate microalgae, and establishing a consortium of microalgae and/or bacteria, were both found to be feasible ways to enhance pollutant removal and lipid production. Demonstrations of pilot-scale microalgal cultures in secondary effluent have also taken place. However there is still much work to be done in improving pollutants removal, biomass production, and lipid accumulation in secondary effluent. This includes screening microalgae, constructing the consortium, making use of flue gas and nitrogen, developing technologies related to microalgal harvesting, and using lipid-extracted algal residues (LEA).
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9.
Constructed Wetlands Revisited: Microbial Diversity in the -omics Era.
Sánchez, O
Microbial ecology. 2017;(3):722-733
Abstract
Constructed wetlands (CWs) constitute an interesting alternative option to conventional systems for wastewater treatment. This technology is based on the utilization of the concerted activity of microorganisms for the removal of contaminants. Consequently, knowledge on the microbial assemblages dwelling CWs and the different environmental factors which can alter their activities is crucial for understanding their performance. In the last decades, the use of molecular techniques to characterize these communities and more recently, application of -omics tools, have broaden our view of microbial diversity and function in wastewater microbiology. In this manuscript, a review of the current knowledge on microbial diversity in CWs is offered, placing particular emphasis on the different molecular studies carried out in this field. The effect of environmental conditions, such as plant species, hydraulic design, water depth, organic carbon, temperature and substrate type on prokaryotic communities has been carefully revised, and the different studies highlight the importance of these factors in carbon, nitrogen and sulfur cycles. Overall, the novel -omics open a new horizon to study the diversity and ecophysiology of microbial assemblages and their interactions in CWs, particularly for those microorganisms belonging to the rare biosphere not detectable with conventional molecular techniques.
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10.
A review: Driving factors and regulation strategies of microbial community structure and dynamics in wastewater treatment systems.
Chen, Y, Lan, S, Wang, L, Dong, S, Zhou, H, Tan, Z, Li, X
Chemosphere. 2017;:173-182
Abstract
The performance and stabilization of biological wastewater treatment systems 1are closely related to the microbial community structure and dynamics. In this paper, the effects and mechanisms of influent composition, process configuration, operating parameters (dissolved oxygen [DO], pH, hydraulic retention time [HRT] and sludge retention time [SRT]) and environmental condition (temperature) to the change of microbial community structure and process performance (nitrification, denitrification, biological phosphorus removal, organics mineralization and utilization, etc.) are critically reviewed. Furthermore, some strategies for microbial community structure regulation, mainly bioaugmentation, process adjustment and operating parameters optimization, applied in the current wastewater treatment systems are also discussed. Although the recent studies have strengthened our understanding on the relationship between microbial community structure and wastewater treatment process performance, how to fully tap the microbial information, optimize the microbial community structure and maintain the process performance in wastewater treatment systems are still full of challenges.