•Ability of AWBs for heavy metal detoxification was evaluated.•Influential factors on heavy metal biosorption were presented.•Insights of binding mechanism were revealed and essential tools were ...introduced.•Merits and demerits of pretreatment methods for better biosorbents were highlighted.•Recommendation to use AWBs as green and cost-effective biosorbents was made.
This critical review discusses the potential use of agricultural waste based biosorbents (AWBs) for sequestering heavy metals in terms of their adsorption capacities, binding mechanisms, operating factors and pretreatment methods. The literature survey indicates that AWBs have shown equal or even greater adsorption capacities compared to conventional adsorbents. Thanks to modern molecular biotechnologies, the roles of functional groups in biosorption process are better understood. Of process factors, pH appears to be the most influential. In most cases, chemical pretreatments bring about an obvious improvement in metal uptake capacity. However, there are still several gaps, which require further investigation, such as (i) searching for novel, multi-function AWBs, (ii) developing cost-effective modification methods and (iii) assessing AWBs under multi-metal and real wastewater systems. Once these challenges are settled, the replacement of traditional adsorbents by AWBs in decontaminating heavy metals from wastewater can be expected in the future.
Summary
Mutants in lipid metabolism often show a lethal phenotype during reproduction that prevents investigating a specific role of the lipid during different developmental processes. We focused on ...two non‐specific phospholipases C, NPC2 and NPC6, whose double knock‐out causes a gametophyte‐lethal phenotype. To investigate the role of NPC2 and NPC6 during vegetative growth, we produced transgenic knock‐down mutant lines that circumvent the lethal effect during gametogenesis. Despite no defect observed in leaves, root growth was significantly retarded, with abnormal cellular architecture in root columella cells. Furthermore, the short root phenotype was rescued by exogenous supplementation of phosphocholine, a product of non‐specific phospholipase C (NPC) ‐catalyzed phosphatidylcholine hydrolysis. The expression of phospho‐base N‐methyltransferase 1 (PMT1), which produces phosphocholine and is required for root growth, was induced in the knock‐down mutant lines and was attenuated after phosphocholine supplementation. These results suggest that NPC2 and NPC6 may be involved in root growth by producing phosphocholine via metabolic interaction with a PMT‐catalyzed pathway, which highlights a tissue‐specific role of NPC enzymes in vegetative growth beyond the gametophyte‐lethal phenotype.
Significance Statement
We show that a lethal pair of bacterial toxin‐like phospholipase C in gametogenesis, NPC2 and NPC6, moonlights as a root growth modulator by producing phosphocholine from phosphatidylcholine.
Machine learning techniques have gained prominence for the analysis of resting-state functional Magnetic Resonance Imaging (rs-fMRI) data. Here, we present an overview of various unsupervised and ...supervised machine learning applications to rs-fMRI. We offer a methodical taxonomy of machine learning methods in resting-state fMRI. We identify three major divisions of unsupervised learning methods with regard to their applications to rs-fMRI, based on whether they discover principal modes of variation across space, time or population. Next, we survey the algorithms and rs-fMRI feature representations that have driven the success of supervised subject-level predictions. The goal is to provide a high-level overview of the burgeoning field of rs-fMRI from the perspective of machine learning applications.
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•Swine wastewater is a suitable medium for microalgae growth and biomass production.•Pollutants in swine wastewater can be removed by harvesting microalgae.•Correlations between ...microalgae and toxicants/bacteria need further investigation.•Harvested biomass from wastewater has great potential to convert into bioenergy.
Ever-increasing swine wastewater (SW) has become a serious environmental concern. High levels of nutrients and toxic contaminants in SW significantly impact on the ecosystem and public health. On the other hand, swine wastewater is considered as valuable water and nutrient source for microalgae cultivation. The potential for converting the nutrients from SW into valuable biomass and then generating bioenergy from it has drawn increasing attention. For this reason, this review comprehensively discussed the biomass production, SW treatment efficiencies, and bioenergy generation potentials through cultivating microalgae in SW. Microalgae species grow well in SW with large amounts of biomass being produced, despite the impact of various parameters (e.g., nutrients and toxicants levels, cultivation conditions, and bacteria in SW). Pollutants in SW can effectively be removed by harvesting microalgae from SW, and the harvested microalgae biomass elicits high potential for conversion to valuable bioenergy.
DNA-RNA hybrid structures have been detected at the vicinity of DNA double-strand breaks (DSBs) occurring within transcriptional active regions of the genome. The induction of DNA-RNA hybrids ...strongly affects the repair of these DSBs, but the nature of these structures and how they are formed remain poorly understood. Here we provide evidence that R loops, three-stranded structures containing DNA-RNA hybrids and the displaced single-stranded DNA (ssDNA) can form at sub-telomeric DSBs. These R loops are generated independently of DNA resection but are induced alongside two-stranded DNA-RNA hybrids that form on ssDNA generated by DNA resection. We further identified UPF1, an RNA/DNA helicase, as a crucial factor that drives the formation of these R loops and DNA-RNA hybrids to stimulate DNA resection, homologous recombination, microhomology-mediated end joining and DNA damage checkpoint activation. Our data show that R loops and DNA-RNA hybrids are actively generated at DSBs to facilitate DNA repair.
Wastewater is now considered to be a vital reusable source of water reuse and saving energy. However, current wastewater has multiple limitations such as high energy costs, large quantities of ...residuals being generated and lacking in potential resources. Recently, great attention has been paid to microbial fuel cells (MFCs) due to their mild operating conditions where a variety of biodegradable substrates can serve as fuel. MFCs can be used in wastewater treatment facilities to break down organic matter, and they have also been analysed for application as a biosensor such as a sensor for biological oxygen which demands monitoring. MFCs represent an innovation technology solution that is simple and rapid. Despite the advantages of this technology, there are still practical barriers to consider including low electricity production, current instability, high internal resistance and costly materials used. Thus, many problems must be overcome and doing this requires a more detailed analysis of energy production, consumption, and application. Currently, real-world applications of MFCs are limited due to their low power density level of only several thousand mW/m2. Efforts are being made to improve the performance and reduce the construction and operating costs of MFCs. This paper explores several aspects of MFCs such as anode, cathode and membrane, and in an effort to overcome the practical challenges of this system.
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•MFCs are a promising technology for wastewater treatment and energy production.•Costs of MFC material fabrication and electricity production are challenged.•Current instability and high internal resistance are also problematic issues.•Membrane fouling and low rate of growth of microbes limit the MFCs' application.•Practical version of tonne scale MFC is proposed and tested with real wastewaters.
The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the perspective of treatment technologies, pollutant removals, operating load and effluent ...discharge standards. By the end of 2013, 3508 WWTPs have been built in 31 provinces and cities in China with a total treatment capacity of 1.48×108m3/d. The uneven population distribution between China's east and west regions has resulted in notably different economic development outcomes. The technologies mostly used in WWTPs are AAO and oxidation ditch, which account for over 50% of the existing WWTPs. According to statistics, the efficiencies of COD and NH3–N removal are good in 656 WWTPs in 70 cities. The overall average COD removal is over 88% with few regional differences. The average removal efficiency of NH3–N is up to 80%. Large differences exist between the operating loads applied in different WWTPs. The average operating loading rate is approximately 83%, and 52% of WWTPs operate at loadings of <80%, treating up to 40% of the wastewater generated. The implementation of discharge standards has been low. Approximately 28% of WWTPs that achieved the Grade I-A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918–2002) were constructed after 2010. The sludge treatment and recycling rates are only 25%, and approximately 15% of wastewater is inefficiently treated. Approximately 60% of WWTPs have capacities of 1×104m3/d–5×104m3/d. Relatively high energy consumption is required for small-scale processing, and the utilization rate of recycled wastewater is low. The challenges of WWTPs are discussed with the aim of developing rational criteria and appropriate technologies for water recycling. Suggestions regarding potential technical and administrative measures are provided.
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•3508 wastewater treatment plants (WWTPs) were summarized.•Population distribution and economic development caused regional difference of WWTPs.•Pollutant removal, operating load, discharge standards in 7 regions were presented.•Suggestions regarding potential technical and administrative measures were provided.
•This review focuses on agro-industrial wastes/by-products as low-cost biosorbent.•Current studies on heavy metal, dye, organic and nutrient biosorption are reviewed.•The effectiveness of biosorbents ...and their modification are discussed.•Parameters affecting the biosorptive capacity are reviewed.•Maximum biosorption capacity of different typical lignocellulosics is reported.
Biosorption on lignocellulosic wastes and by-products has been identified as a proper alternative to the existing technologies applied for toxic metal ion and dye removal from wastewater streams. This paper deals with utilization of typical low cost wastes and by-products produced in different food agricultural and agro-industries as biosorbent and reviews the current state of studies on a wide variety of cheap biosorbents in natural and modified forms. The efficiency of each biosorbent has been also discussed with respect to the operating conditions (e.g. temperature, hydraulic residence time, initial metal concentration, biosorbent particle size and its dosage), chemical modification on sorption capacity and preparation methods, as well as thermodynamics and kinetics.
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•Anaerobic digestion for production of VFAs, biohydrogen and methane.•Specific bioreactor arrangements for VFAs, biohydrogen and methane.•Optimization of temperature, pH, OLR and ...retention time for each product.•Chemical additives and specific treatment process for individual AD product.
The anaerobic digestion process has been primarily utilized for methane containing biogas production over the past few years. However, the digestion process could also be optimized for producing volatile fatty acids (VFAs) and biohydrogen. This is the first review article that combines the optimization approaches for all three possible products from the anaerobic digestion. In this review study, the types and configurations of the bioreactor are discussed for each type of product. This is followed by a review on optimization of common process parameters (e.g. temperature, pH, retention time and organic loading rate) separately for the production of VFA, biohydrogen and methane. This review also includes additional parameters, treatment methods or special additives that wield a significant and positive effect on production rate and these products’ yield.
Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and ...hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes' removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater.
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•Biological antibiotics and hormones treatment process for swine wastewater was reviewed.•Mechanisms of antibiotics/hormones removal can be biosorption and biodegradation.•Conventional AS and AD are ineffective for antibiotics & hormones removal.•MBRs/hybrid MBRs and constructed wetlands can improve toxicants removal.•Modified conventional bioreactors are also efficient in antibiotics and hormones removal.
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