Soil microbial communities play an essential role in driving multiple functions (i.e., multifunctionality) that are central to the global biogeochemical cycles. Long-term fertilization has been ...reported to reduce the soil microbial diversity, however, the impact of fertilization on multifunctionality and its relationship with soil microbial diversity remains poorly understood. We used amplicon sequencing and high-throughput quantitative-PCR array to characterize the microbial community compositions and 70 functional genes in a long-term experimental field station with multiple inorganic and organic fertilization treatments. Compared with inorganic fertilization, the application of organic fertilizer improved the soil multifunctionality, which positively correlated with the both bacterial and fungal diversity. Random Forest regression analysis indicated that rare microbial taxa (e.g. Cyanobacteria and Glomeromycota) rather than the dominant taxa (e.g. Proteobacteria and Ascomycota) were the major drivers of multifunctionality, suggesting that rare taxa had an over-proportional role in biological processes. Therefore, preserving the diversity of soil microbial communities especially the rare microbial taxa could be crucial to the sustainable provision of ecosystem functions in the future.
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•Inorganic fertilization decreased soil multifunctionality.•Organic fertilization increased microbial diversity and multifunctionality.•Rare microbial taxa had an over-proportional role in multifunctionality.
Clean fuels are the critical requirement for industrialized world to combat emission of greenhouse gas. Hydrogen is one of the cleanest fuels that generates water as a result of combustion. ...Production of hydrogen from renewable and nonpolluting resources is an imperative task for sustainable clean fuel production. Biological processes provide an opportunity to produce hydrogen from renewable and economical bio-resources like biomass and solar energy through various processes such as direct/indirect photolysis, photo-fermentation, dark-fermentation, and CO gas-fermentation. This paper provides a comprehensive review on biological hydrogen production including organisms, type of substrates and their concentrations, role of chemical addition, operation conditions such as temperature, pH, and agitation, as well as illumination systems in case of light dependent processes. Further discussions in this work comprise various configuration of integrated biological processes of photolysis, dark, and photo-fermentation such as two component and three-component systems.
•Presentation of recent progresses on biological hydrogen production processes.•Discussion of challenges on applications of biological hydrogen routes.•Comparisons of various configurations of integrated biohydrogen generation systems.
Landfill leachate treatment in Brazil – An overview Costa, Alyne Moraes; Alfaia, Raquel Greice de Souza Marotta; Campos, Juacyara Carbonelli
Journal of environmental management,
02/2019, Volume:
232
Journal Article
Peer reviewed
The management of municipal solid waste (MSW) presents an ever increasing and more complex challenge in global terms. The disposal of MSW in landfills generates leachate, a liquid highly polluting to ...the aquatic environment. This review describes the state-of-the-art approaches to treatments applied to leachate in Brazil, highlighting the new technologies and alternatives that are still in the research phase, and compares the leachate treatment technologies applied around the world with the current scenario in Brazil. In Brazilian landfills, along with other technologies, the biological process is commonly applied, since this is a simple and economical approach and often it is the only technique used in small municipalities. The sanitary landfills in large Brazilian cities located in the states of São Paulo and Rio de Janeiro, invest in or outsource landfill activities, where apply advanced treatment technologies, such as membrane filtration. The use of membrane filtration technology in these cases reveals similarities with leachate treatments applied in the developed countries of North America and Europe. Brazilian researchers have highlighted the need to use efficient and economically viable technologies for the treatment of leachate in Brazilian landfills. However, the current scenario of MSW management in Brazil shows deficiencies related to the monitoring of sanitary landfills and limited information is available on the performance of leachate treatment systems.
•Brazil is a representative developing country of Latin America.•Leachate treatment technologies used in Brazilian landfills were reviewed.•The leachate treatment used around the world were discussed.•New alternatives on leachate treatment technologies in Brazil were evidenced.•Biological processes and membranes filtration stand out in leachate treatment.
Nowadays, sanitary landfilling is the most common approach to eliminate municipal solid waste, but a major drawback is the generation of heavily polluted leachates. These leachates must be ...appropriately treated before being discharged into the environment. Generally, the leachate characteristics such as COD, BOD/COD ratio, and landfill age are necessary determinants for selection of suitable treatment technologies. Rapid, sensitive and cost-effective bioassays are required to evaluate the toxicity of leachate before and after the treatment. This review summarizes extensive studies on leachate treatment methods and leachate toxicity assessment. It is found that individual biological or physical-chemical treatment is unable to meet strict effluent guidelines, whereas a combination of biological and physical-chemical treatments can achieve satisfactory removal efficiencies of both COD and ammonia nitrogen. In order to assess the toxic effects of leachate on different trophic organisms, we need to develop an appropriate matrix of bioassays based on their sensitivity to various toxicants and a multispecies approach using organisms representing different trophic levels. In this regard, a reduction in toxicity of the treated leachate will contribute to assessing the effectiveness of a specific remediation strategy.
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•Suitable treatment technologies depend mainly on leachate COD, BOD/COD ratio, and landfill age.•Efficiencies, cost and environmental impacts are three major criteria for selecting treatment technologies.•A combination of two or more treatment technologies can achieve satisfactory removal efficiencies.•An appropriate matrix of bioassays should be developed to assess the toxic effects of leachate.
Limits in resource availability are driving a change in current societal production systems, changing the focus from residues treatment, such as wastewater treatment, toward resource recovery. ...Biotechnological processes offer an economic and versatile way to concentrate and transform resources from waste/wastewater into valuable products, which is a prerequisite for the technological development of a cradle-to-cradle bio-based economy. This review identifies emerging technologies that enable resource recovery across the wastewater treatment cycle. As such, bioenergy in the form of biohydrogen (by photo and dark fermentation processes) and biogas (during anaerobic digestion processes) have been classic targets, whereby, direct transformation of lipidic biomass into biodiesel also gained attention. This concept is similar to previous biofuel concepts, but more sustainable, as third generation biofuels and other resources can be produced from waste biomass. The production of high value biopolymers (e.g., for bioplastics manufacturing) from organic acids, hydrogen, and methane is another option for carbon recovery. The recovery of carbon and nutrients can be achieved by organic fertilizer production, or single cell protein generation (depending on the source) which may be utilized as feed, feed additives, next generation fertilizers, or even as probiotics. Additionlly, chemical oxidation-reduction and bioelectrochemical systems can recover inorganics or synthesize organic products beyond the natural microbial metabolism. Anticipating the next generation of wastewater treatment plants driven by biological recovery technologies, this review is focused on the generation and re-synthesis of energetic resources and key resources to be recycled as raw materials in a cradle-to-cradle economy concept.
Water scarcity and its pollution has become a concern in recent times. The disposal of nutrient-rich (nitrogen and phosphorous) wastewater is also one of the main cause of water pollution through ...eutrophication, reduced dissolved oxygen that poses threat to aquatic ecosystems. As a result, nutrient removal has become a mandate apart from the removal of organics. However, the removal of nutrients from sewage is a challenging task. Conversely, conventional biological treatment processes provide little relief in nutrient removal. The treated effluents from conventional biological processes do not achieve the stringent nutrient removal disposal standard limits and become primary cause of pollution in the receiving water bodies. This has stressed upon the need for eco-friendly, low-energy and cost-efficient nutrient removal treatment technologies. Various biological treatment combinations or variants are in use for the efficient removal of nutrients. The biological processes in itself or in combination with chemical processes are preferred over technologies based solely on physico-chemical processes for its treatment performance at lower cost. This review summarizes the existing treatment processes and their possible up-gradation with the aim to accomplish the marked effluent standards for the nutrients. The concept of conventional systems and advanced systems for nutrients (nitrogen and phosphorous) removal which are already developed or under development are deeply discussed. Further, the challenges of each treatment systems are abridged. Finally, the possible suggestions for the modification/retrofitting of existing treatment systems for achieving stringent disposal standards are pointed out.
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•Existing treatment technology for nutrient removal/recovery from wastewater was reviewed.•A lot of past research has addressed nutrients releases from conventional biological processes.•Nutrients removal is more challenging for highly loaded industrial wastewaters.•ANAMMOX for nutrient removal is efficient over conventional method.
The hospital wastewater imposes a potent threat to the security of human health concerning its high vulnerability towards the outbreak of several diseases. Furthermore, the outbreak of COVID-19 ...pandemic demanded a global attention towards monitoring viruses and other infectious pathogens in hospital wastewater and their removal. Apart from that, the presence of various recalcitrant organics, pharmaceutically active compounds (PhACs), etc. imparts a complex pollution load to water resources and ecosystem. In this review, an insight into the occurrence, persistence and removal of drug-resistant microorganisms and infectious viruses as well as other micro-pollutants have been documented. The performance of various pilot/full-scale studies have been evaluated in terms of removal of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), PhACs, pathogens, etc. It was found that many biological processes, such as membrane bioreactor, activated sludge process, constructed wetlands, etc. provided more than 80% removal of BOD, COD, TSS, etc. However, the removal of several recalcitrant organic pollutants are less responsive to those processes and demands the application of tertiary treatments, such as adsorption, ozone treatment, UV treatment, etc. Antibiotic-resistant microorganisms, viruses were found to be persistent even after the treatment of hospital wastewater, and high dose of chlorination or UV treatment was required to inactivate them. This article circumscribes the various emerging technologies, which have been used to treat PhACs and pathogens. The present review also emphasized the global concern of the presence of SARS-CoV-2 RNA in hospital wastewater and its removal by the existing treatment facilities.
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•The organic fraction in hospital wastewater has low biodegradability index.•Some bacteria in hospital effluents develop resistance to antibiotics and other drugs.•SARS-CoV-2 RNA in wastewater and COVID-19 affected people are positively correlated.•CWs and MBR have been efficient in terms of ARG and ARB inactivation.•30–80 mg min/L of chlorine can inactivate various ARG, ARB, and viruses.
Contaminants of emerging concern (CEC) discharged in effluents of wastewater treatment plants (WWTPs), not specifically designed for their removal, pose serious hazards to human health and ...ecosystems. Their impact is of particular relevance to wastewater disposal and re-use in agricultural settings due to CEC uptake and accumulation in food crops and consequent diffusion into the food-chain. This is the reason why the chemical CEC discussed in this review have been selected considering, besides recalcitrance, frequency of detection and entity of potential hazards, their relevance for crop uptake. Antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been included as microbial CEC because of the potential of secondary wastewater treatment to offer conditions favourable to the survival and proliferation of ARB, and dissemination of ARGs. Given the adverse effects of chemical and microbial CEC, their removal is being considered as an additional design criterion, which highlights the necessity of upgrading conventional WWTPs with more effective technologies. In this review, the performance of currently applied biological treatment methods for secondary treatment is analysed. To this end, technological solutions including conventional activated sludge (CAS), membrane bioreactors (MBRs), moving bed biofilm reactors (MBBRs), and nature-based solutions such as constructed wetlands (CWs) are compared for the achievable removal efficiencies of the selected CEC and their potential of acting as reservoirs of ARB&ARGs. With the aim of giving a picture of real systems, this review focuses on data from full-scale and pilot-scale plants treating real urban wastewater. To achieve an integrated assessment, technologies are compared considering also other relevant evaluation parameters such as investment and management costs, complexity of layout and management, present scale of application and need of a post-treatment. Comparison results allow the definition of design and operation strategies for the implementation of CEC removal in WWTPs, when agricultural reuse of effluents is planned.
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•Fate of CEC relevant for crop uptake during secondary treatment was analysed.•Target CEC selection resulted from the indications of the NEREUS COST Action.•Effects of secondary treatment on microbial CEC (ARBs and ARGs) fate were described.•Most applied and promising technologies for urban wastewater treatment were compared.•Impact of CEC removal on WWTP upgrading, design and operation was discussed.
•Organic waste biorefinery is a concept for waste management.•Biorefineries can extract high value products from organic waste.•The heterogeneity of waste implies additional complexity in ...biorefineries.•Technological, strategic and market constraints affect implementation.
The concept of biorefinery expands the possibilities to extract value from organic matter in form of either bespoke crops or organic waste. The viability of biorefinery schemes depends on the recovery of higher-value chemicals with potential for a wide distribution and an untapped marketability. The feasibility of biorefining organic waste is enhanced by the fact that the biorefinery will typically receive a waste management fee for accepting organic waste. The development and implementation of waste biorefinery concepts can open up a wide array of possibilities to shift waste management towards higher sustainability. However, barriers encompassing environmental, technical, economic, logistic, social and legislative aspects need to be overcome. For instance, waste biorefineries are likely to be complex systems due to the variability, heterogeneity and low purity of waste materials as opposed to dedicated biomasses. This article discusses the drivers that can make the biorefinery concept applicable to waste management and the possibilities for its development to full scale. Technological, strategic and market constraints affect the successful implementations of these systems. Fluctuations in waste characteristics, the level of contamination in the organic waste fraction, the proximity of the organic waste resource, the markets for the biorefinery products, the potential for integration with other industrial processes and disposal of final residues are all critical aspects requiring detailed analysis. Furthermore, interventions from policy makers are necessary to foster sustainable bio-based solutions for waste management.
The biological functions debate is a perennial topic in the philosophy of science. In the first full-length account of the nature and importance of biological functions for many years, Justin Garson ...presents an innovative new theory, the 'generalized selected effects theory of function', which seamlessly integrates evolutionary and developmental perspectives on biological functions. He develops the implications of the theory for contemporary debates in the philosophy of mind, the philosophy of medicine and psychiatry, the philosophy of biology, and biology itself, addressing issues ranging from the nature of mental representation to our understanding of the function of the human genome. Clear, jargon-free, and engagingly written, with accessible examples and explanatory diagrams to illustrate the discussion, his book will be highly valuable for readers across philosophical and scientific disciplines.
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