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1.
Chemosphere ; 262: 128213, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182078

RESUMO

Although phosphine is ubiquitously present in anaerobic environments, little is known regarding the microbial community dynamics and metabolic pathways associated with phosphine formation in an anaerobic digestion system. This study investigated the production of phosphine in anaerobic digestion, with results indicating that phosphine production mainly occurred during logarithmic microbial growth. Dehydrogenase and hydrogen promoted the production of phosphine, with a maximum phosphine concentration of 300 mg/m3. The abundance of Ruminococcaceae and Escherichia was observed to promote phosphine generation. The analysis of metabolic pathways based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) and the MetaCyc pathway database revealed the highest relative abundance of replication and repair in genetic information processing; further, the cofactor, prosthetic group, electron carrier, and vitamin biosynthesis were observed to be closely related to phosphine formation. A phylogenetic tree was reconstructed based on the neighbor-joining method. The results indicated the clear evolutionary position of the isolated Pseudescherichia sp. SFM4 strain, adjacent to Escherichia, with a stable phosphate-reducing ability for a maximum phosphine concentration of 26 mg/m3. The response surface experiment indicated that the initial optimal conditions for phosphine production by SFM4 could be achieved with nitrogen, carbon, and phosphorus loads of 6.17, 300, and 10 mg/L, respectively, at pH 7.47. These results provide comprehensive insights into the dynamic changes in the microbial structure, isolated single bacterial strain, and metabolic pathways associated with phosphine formation. They also provide information on the molecular biology associated with phosphorus recycling.


Assuntos
Reatores Biológicos/microbiologia , Clostridiales/metabolismo , Escherichia/metabolismo , Redes e Vias Metabólicas , Microbiota , Fosfinas/análise , Anaerobiose , Clostridiales/genética , Escherichia/genética , Hidrogênio/metabolismo , Redes e Vias Metabólicas/genética , Nitrogênio/metabolismo , Fosfatos/metabolismo , Fosfinas/metabolismo , Fósforo/metabolismo , Filogenia , Esgotos/microbiologia
2.
Sci Total Environ ; 751: 141618, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-33167190

RESUMO

Some wastewater sources, such as agricultural waste and runoff, and industrial sewage, can degrade water quality. This study summarises the sources and corresponding mechanisms that trigger eutrophication in lakes. Additionally, the trophic status index and water quality index (WQI) which are effective tools for evaluating the degree of eutrophication of lakes, have been discussed. This study also explores the main nutrients (nitrogen and phosphorus) driving transformations in the water body and sediment. Lake Erhai was used as a case study, and it was found to be in a mesotrophic state, with N and P co-limitation before 2006, and only P limitation since 2006. Finally, effective measures to maintain sustainable development in the watershed are proposed, along with a framework for an early warning system adopting the latest technologies (geographic information systems (GIS), remote sensing (RS)) for preventing eutrophication.


Assuntos
Eutrofização , Lagos , China , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise , Qualidade da Água
3.
Food Chem ; 335: 127620, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32739810

RESUMO

A non-enzymatic browning reaction occurs easily in Dongbei Suancai (DS) during storage. Using the method of path analysis, the changes in contents of VC (ascorbic acid), polyphenol, reducing sugar, amino nitrogen, and 5-HMF (5-hydroxymethyl furfural) were investigated to analyze the direct pathways and determinants of browning caused by pre-production blanching at 100 °C (R-100), salt-addition increased from 2% to 6% (Y-6) and fermentation time extended from 30 d to 40 d (T-40), respectively. The results showed that R-100 could delay the browning by inhibiting two direct pathways of oxidative decomposition of VC and oxidation-polymerization of polyphenols, but T-40 could lead to an increase in degree of browning for which primary determinant was the interaction between polyphenol and reducing sugar, while Y-6 had no obvious effect on browning pathway and determinants. R-100 was thus deemed to be a good measure with inhibiting non-enzymatic browning in DS during storage.


Assuntos
Fermentação , Reação de Maillard , Verduras/química , Ácido Ascórbico/análise , Carboidratos/análise , Furaldeído/análogos & derivados , Furaldeído/análise , Nitrogênio/análise , Oxirredução , Polifenóis/análise
4.
Sci Total Environ ; 750: 141665, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182169

RESUMO

Reusing microplastics and zeolite waste as free ammonia (FA)-mitigating carrier particle was proven a value-added step towards promoting the serviceability of fluidized bed bioreactor (FBBR) in treating wastewater with a low carbon to nitrogen ratio (i.e. C/N <3.0) in this study. Ammonia (NH4+) adsorption property capacitates zeolite as an FA mitigator. The microplastics and reused zeolite were processed into reused-zeolite/microplastic composite particle (RZ), whose merit of FA mitigation was fully developed via an optimally thermal modification to process modified-zeolite/microplastic particle (MZ). The 171-day biological nutrient removal (BNR) performance in a single integrated fluidized bed bioreactor (SIFBBR) shows that the bioreactor with MZ particle (SIFBBR-MZ) achieved nitrogen removal efficiency 10.0% higher than the bioreactor with RZ particle (SIFBBR-RZ) over the enhanced short-cut nitrification and denitrification. Analysis of microbial community structure unveils that the long-term lower FA inhibition favored more significant ammonia-oxidizing bacteria (AOB) enrichment and acclimated specific MZ biofilm predominant by nitrite (NO2-) denitrifier, contributing to the outperformance in nitrogen removal. Apart from fluidization energy conservation, the techno-economic analysis confirms that using MZ as an FA-mitigating carrier could be of great benefit for FBBR system: realizing waste utilization, reducing carbon addition and alleviating sludge treatment.


Assuntos
Nitrogênio , Águas Residuárias , Amônia , Reatores Biológicos , Carbono , Desnitrificação , Nitrificação , Plásticos , Eliminação de Resíduos Líquidos
5.
Sci Total Environ ; 750: 142296, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182197

RESUMO

This study proposed a novel one-stage plug-flow microaerobic sludge blanket (PMSB) with membrane aerated for treating low carbon to nitrogen (C/N) ratio municipal sewage. The performance of simultaneous nitrification, denitrification, and anammox in the reactor was investigated. The results illustrated that the removal efficiencies of ammonium and total nitrogen (TN) were 93.2% and 87.1% with a C/N ratio of 4. High throughput sequencing revealed that aerobic bacteria, anaerobic bacteria and facultative anaerobe could co-exist at the same time in the sludge blanket. Meanwhile, a notable correlation between the oxygen concentration and the distance of the membrane module was analyzed. It was shown that the microbial community of functional bacteria developed in different aeration sites due to the oxygen concentration gradient. Microbial community structure was analyzed depending on the sludge stratification in the sludge blanket.


Assuntos
Nitrificação , Esgotos , Reatores Biológicos , Desnitrificação , Nitrogênio , Oxirredução
6.
Sci Total Environ ; 750: 141699, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33182212

RESUMO

In the attempt to close nutrient cycles, organic fertilizers and soil improvers are getting interest as renewable P sources for crops. However, both the P availability of these compounds for crops and the underlying mechanisms are not fully understood. In this study composts (n = 8), biochars (n = 5), animal manure and processed animal manure (n = 13), digestates and processed digestates (n = 15) and blends of digestates with compost/animal manure/mineral fertilizers (n = 15) were analyzed for chemical composition, organic matter stability and P use efficiency (PUE). Biodegradability (=holocellulose/lignin ratio) proved to be a good indicator for organic matter stability and can successfully replace time-consuming incubation experiments in standard analyses of organic fertilizers. The PUE of digestates, struvites, animal manure products and blends of digestate with compost/animal manure/mineral fertilizers was determined by the NH4+-N, Mg and Fe content of the organic fertilizers. The PUE can be predicted by PUE = 61.34 + 8.59*NH4+-N/P + 42.25*Mg/P - 8.09*Fe/P (R2 = 0.71). As increasing amounts of NH4+-N and Mg stimulate the formation of soluble struvite crystals, increasing PUE is explained by an increasing amount of P as struvite. The PUE of biochars and composts was determined by the Ca/P and Al content of the organic fertilizers. Here, PUE can be predicted by PUE = 88.87-1.07*Ca/P + 6.08*Al/P (R2 = 0.93). As increasing amounts of Ca stimulate the formation of highly stable apatite crystals, increasing PUE is explained by an increasing amount of P in the form of apatite.


Assuntos
Compostagem , Esterco , Animais , Carvão Vegetal , Fertilizantes/análise , Nitrogênio/análise , Solo , Estruvita
7.
J Environ Sci (China) ; 99: 10-20, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183686

RESUMO

Nitrogen-rich graphitized carbon microspheres (NGCs) with hierarchically porous were constructed by self-assembly. Under different heat treatment conditions, the structure, morphology and properties of NGCs were studied by using multiple characterization techniques. The results showed that the chemical microenvironments (e.g. surface chemistry, degree of graphitization and defective, etc.) and microstructures properties (e.g. morphology, specific surface area, particle size, etc.) could be delicately controlled via thermal carbonization processes. The degradation of ofloxacin (OFLX) by NGCs activated peroxymonosulfate (PMS) was studied systematically. It was found that the synergistic coupling effect between optimum N or O bonding species configuration ratio (graphitic N and C=O) and special microstructure was the main reason for the enhanced catalytic activity of NGC-800 (calcination temperature at 800°C). Electron paramagnetic resonance (EPR) experiments and radical quenching experiments indicated that the hydroxyl (•OH), sulfate (SO4•-) and singlet oxygen (1O2) were contributors in the NGC-800/PMS systems. Further investigation of the durability of chemical structures and surface active sites revealed that undergo N bonding species configuration reconstruction and cannibalistic oxidation during PMS activation reaction. The used NGC-800 physicochemical properties could be recovered by heat treatment to achieve the ideal catalytic performance. The findings proposed a valuable insight for catalytic performance and controllable design of construction.


Assuntos
Carbono , Nitrogênio , Microesferas , Ofloxacino , Peróxidos
8.
J Environ Sci (China) ; 99: 187-195, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183696

RESUMO

Periodically hydrologic alterations driven by seasonal change and water storage capacity management strongly modify physicochemical properties and chlorophyll-a (Chl-a) and their interactions in dam-induced lakes. However, the extent and magnitude of these changes still remain unclear. This study aimed to determine the effects of periodically hydrologic alterations on physicochemical variables and Chl-a in the dam-induced urban Hanfeng Lake, upstream of Three Gorges Reservoir. Shifts in Chl-a and 13 physicochemical variables were recorded monthly in the lake from January 2013 to December 2014. Chl-a was neither seasonal nor inter-annual differences while a few physical variables such as flow velocity (V) exhibited significantly seasonal variabilities, and chemical variables like total nitrogen (TN), nitrate-nitrogen (NO3-N), total phosphorus (TP), dissolved silica (DSi) were markedly inter-annual differences. Higher TN:TP (40:1) and lower NO3-N:DSi (0.8:1) relative to balanced stoichiometric ratios suggested changes in composition of phytoplankton communities and potentially increased proportion of diatom in Hanfeng Lake. Chl-a was predicable by combination of dissolved oxygen (DO), TN and DSi in dry season, and by V alone in wet season. During the whole study period, Chl-a was solely negatively correlated with TN:TP, indicating decline in N concentration and increase in P could therefore increase Chl-a. Our results highlight pronounced decoupling of linkages between Chl-a and physicochemical variables affected by periodically hydrologic alterations in dam-induced aquatic systems.


Assuntos
Eutrofização , Lagos , China , Clorofila/análise , Clorofila A , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise
9.
J Environ Sci (China) ; 99: 80-89, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183719

RESUMO

Dissolved organic matter (DOM) derived from various composts can promote significant changes of soil properties. However, little is known about the DOM compositions and their similarities and differences at the molecular level. In this study, the molecular compositions of DOM derived from kitchen waste compost (KWC), green waste compost (GWC), manure waste compost (MWC), and sewage sludge compost (SSC) were characterized by electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The molecular formulas were classified into four subcategories: CHO, CHON, CHOS, and CHONS. The KWC, MWC, and SSC DOM represented the highest fraction (35.8%-47.4%) of CHON subcategory, while the GWC DOM represented the highest fraction (68.4%) of CHO subcategory. The GWC DOM was recognized as the nitrogen- and sulfur-deficient compounds that were less saturated, more aromatic, and more oxidized compared with other samples. Further analysis of the oxygen, nitrogen-containing (N-containing), and sulfur-containing (S-containing) functional groups in the four subcategories revealed higher organic molecular complexity. Comparison of the similarities and differences of the four samples revealed 22.8% ubiquitous formulas and 17.4%, 11.1%, 10.7%, and 6.3% unique formulas of GWC, KWC, SSC, and MWC DOM, respectively, suggesting a large proportion of ubiquitous DOM as well as unique, source-specific molecular signatures. The findings presented herein provide new insight into the molecular characterization of DOM derived from various composts and demonstrated the potential role of these different compounds for agricultural utilization.


Assuntos
Compostagem , Espectrometria de Massas , Nitrogênio , Esgotos , Solo
10.
Chemosphere ; 262: 127838, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32768756

RESUMO

Nitrogen and heavy metals can co-occur in various industrial wastewaters such as coke-oven wastewater. Removal of these contaminants is important, but cost-efficient removal technology is limited. In this study, we examined the usefulness of nitrate-dependent ferrous iron oxidation (NDFO) for the simultaneous removal of nitrate and heavy metals (iron and zinc), by using an NDFO strain Pseudogulbenkiania sp. NH8B. Based on the batch culture assays, nitrate, Fe, and Zn were successfully removed from a basal medium as well as coke-oven wastewater containing 5 mM nitrate, 10 mM Fe(II), and 10 mg/L Zn. Zinc in the water was most likely co-precipitated with Fe(III) oxides produced during the NDFO reaction. Simultaneous removal of nitrate, Fe, and Zn was also achieved in a continuous-flow reactor fed with a basal medium containing 10 mM nitrate, 5 mM Fe(II), 4 mM acetate, and 10 mg/L Zn. However, when the reactor is fed with coke-oven wastewater supplemented with 10 mM nitrate, 5 mM Fe(II), 4 mM acetate, and 10 mg/L ZnCl2, the reactor performance significantly decreased, most likely due to the inhibition of bacterial growth by thiocyanate or organic contaminants present in the coke-oven wastewater. Use of mixed culture of NDFO bacteria and thiocyanate/organic-degrading denitrifiers should help improve the reactor performance.


Assuntos
Reatores Biológicos , Metais Pesados/química , Nitratos/química , Eliminação de Resíduos Líquidos/métodos , Betaproteobacteria , Coque , Desnitrificação , Compostos Ferrosos , Ferro , Nitrogênio , Óxidos de Nitrogênio , Oxirredução , Águas Residuárias , Zinco
11.
Chemosphere ; 262: 127863, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32768758

RESUMO

Aquatic plants litters from constructed wetlands might become pollutants without proper treatment. Due to its high carbon and low nitrogen contained, Iris pseudacorus litters have potential to be used as carbon source to enhance denitrification process in advanced treatments of secondary effluent from wastewater treatment plants. This study investigated the characteristics of carbon release form Iris pseudacorus litters and its performance on enhancement of nitrogen removal. The batch experiment showed that the organic carbon release process can be simulated by combining dissolution and hydrolysis process, and it was found that dissolved organic matters mainly consisted of 60% sugar and 35% humic acid-like compounds from the neutral detergent solution and hemicellulose of litters. The long-term operation of lab-scale constructed wetlands revealed a high nitrogen removal of 78.81-90.39% in treating the synthetic wastewater treatment plants effluent with the equivalent dosage of 25-150 g litters m-2 d-1. Furthermore, it is possible to establish an Iris pseudacorus self-consumed constructed wetland to reuse all of the litters produced during the operation. These findings can contribute to the understanding of the dynamics of carbon release from Iris pseudacorus litters and recycled utilization of plant biomass in the constructed wetlands.


Assuntos
Desnitrificação , Nitrogênio/análise , Eliminação de Resíduos Líquidos/métodos , Áreas Alagadas , Biomassa , Carbono , Iris (Planta) , Reciclagem , Águas Residuárias
12.
Chemosphere ; 262: 127822, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799144

RESUMO

In this research, for the first time, three kinds of landfill leachate (young (YL), mature (ML) and mixed (MYL) leachate) were treated in a semi-aerobic aged refuse biofilter (SAARB) to compare the effectiveness of, and microbial changes in, this biofilter when treating leachates that have significantly different characteristics. The SAARB achieved stable removal of organic matter from all three leachates and reduced the concentrations of aromatic substances. The best treatment was achieved with YL, followed in order by MYL and ML. The removal of nitrogen from all three leachates by the SAARB was particularly significant. The microbial abundance and diversity in the media of the SAARB changed after treatment of the three leachates, and the order of change from small to large was ML# < MYL# < YL#. The microbial communities were mainly affected by (and negatively correlated to) the relative content of refractory organics in leachate. Proteobacteria was the dominant microorganism. Deinococcus-thermus responded most to the quality of leachate being treated, increasing in relative abundance as the content of refractory organics increased. This was opposite to the response of Chloroflexi. In YL# the dominant species at the genus level was Thauera, and in ML# the dominant species were Truepera and Iodidimonas. The microbial activity and metabolic intensity were enhanced after treatment of the different leachates. The expression of nitrification-related genes was the strongest and the total abundance was the highest when YL was treated. This study promotes the optimization and application of SAARB.


Assuntos
Reatores Biológicos/microbiologia , Microbiota/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Resíduos de Alimentos , Nitrogênio , Eliminação de Resíduos , Poluentes Químicos da Água/análise
13.
Sci Total Environ ; 750: 141664, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32835963

RESUMO

Anoxic biodesulfurization has been achieved in several bioreactor systems that have shown robustness and high elimination capacities (ECs). However, the high operating costs of this technology, which are mainly caused by the high requirements of nitrite or nitrate, make its full-scale application difficult. In the present study, the use of biologically produced nitrate/nitrite by nitrification of two different ammonium substrates, namely synthetic medium and landfill leachate, is proposed as a novel alternative. The results demonstrate the feasibility of using both ammonium substrates as nutrient solutions. A maximum elemental sulfur production of 95 ±â€¯1% and a maximum H2S EC of 141.18 g S-H2S m-3 h-1 (RE = 95.0%) was obtained using landfill leachate as the ammonium source. Next Generation Sequencing (NGS) analysis of the microbial community revealed that the most common genera present in the desulfurizing bioreactor were Sulfurimonas (91.8-50.9%) followed by Thauera (1.1-24.2%) and Lentimicrobium (2.0-9.7%).


Assuntos
Compostos de Amônio , Sulfeto de Hidrogênio , Poluentes Químicos da Água , Biocombustíveis , Reatores Biológicos , Desnitrificação , Nitrogênio
14.
Sci Total Environ ; 750: 141221, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846250

RESUMO

Improved coastal management has decreased anthropogenic nutrient input over the past few decades, leading to phosphorus depletion. It has been hypothesized that phosphorus depletion in coastal environments leads to declines in macroalgae abundance. Perennial canopy-forming temperate macroalgae can experience the effects of limited phosphorus availability during seasonal phosphorus depletion periods. When nutrients are sufficient, they are stored in algal tissues after luxury uptake and are available to support growth during phosphorus-depleted conditions. Cultivation of mature and actively growing juvenile brown alga (Sargassum macrocarpum) under different nutrient conditions provided individuals with different tissue nutrient concentrations. The maximum photosynthetic rates of these individuals were examined under nutrient-depleted conditions to evaluate "storage capacity", which we defined as the amount of stored phosphorus that can support maximum growth. Maximum photosynthetic rate was used as a proxy for maximum growth rates. The experiments revealed that growth rates of juveniles increased when stored phosphorus content was high. In contrast, the maximum growth rates tended not to increase with an increase in stored phosphorus content in mature individuals. The phosphorus storage capacities for juvenile and mature individuals were approximately 19 and more than 16 weeks, respectively, suggesting that individual alga can endure several months of phosphorus depletion.


Assuntos
Fósforo , Sargassum , Humanos , Nitrogênio , Nutrientes , Fotossíntese
15.
Sci Total Environ ; 750: 141626, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32858296

RESUMO

Challenges such as long-term cultivation and sludge floatation are common in flocculent sulfide-oxidizing autotrophic denitrification (SOAD) systems. The present study aims to optimize the granulation of SOAD sludge by mainly adjusting the reactor configuration and mixing mode. Three liquid-lift upflow reactors viz. a reactor equipped with a three-phase separator (Reactor A), a modified version of Reactor A equipped with a hydraulic regulator (Reactor B), and a reactor with a mounted baffle and intermittent mechanical mixing (Reactor C). These reactors were operated for more than 160 days. The results showed that dense and compact granules with 200 µm of diameter developed within 40 days and gradually increased to approximately 400 µm in Reactor C, which had a volatile suspended solids (VSS) concentration of 7500 mg VSS/L of sludge concentration; this Reactor C was also subject to modified reactor configuration and operating conditions. In comparison, filamentous granules formed in Reactor A due to a low substrate loading and granules formed in Reactor B but with significant biomass loss caused by sludge flotation. Both of the reactors only have ≤1000 mg VSS/L VS 7500 mg VSS/L in Reactor C. Also, Reactor C having 0.77 h of hydraulic retention time (HRT) and 0.94 kgNO3--N/m3 d & 1.87 kgS2--S/m3 d of nitrogen and sulfide loading rate, respectively, showed a better performance in terms of nitrate removal (89%) and sulfur conversion (above 70%) due to its enrichment by the typical autotrophic denitrifiers (39.0% of Thiobacillus, 22.4% of Sulfurimonas) in the granules. Our findings provide a method to optimize the design and operation of granulation reactors that can be extended to similar processes treating organic-deficient wastewaters.


Assuntos
Desnitrificação , Esgotos , Reatores Biológicos , Nitrogênio , Sulfetos , Eliminação de Resíduos Líquidos
16.
Sci Total Environ ; 751: 141659, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32882552

RESUMO

Addition of carbon-based byproducts in urban soil is gaining popularity as a plant growth stimulator, soil quality enhancer and fostering green land vegetation. A 60-day trial experiment was carried out for investigating the impacts of sugarcane, neem and bamboo mixed biochar and polyvinyl chloride (PVC), polyethylene (PE) and polyethylene terephthalate (PET) mixed plastic char (1:100, 2:100 and 4:100 char: soil ratio) on physico-chemical properties of soil and growth of Dendrocalamus strictus saplings. It was found that available phosphorus increased from 412.16 to 586.88 kg h-1 which could be attributed to reduced metal ion activity due to increase in the soil pH (7.75-7.81) and CEC (98.07-131.04 mEq 100 g-1). The application of both the char enhanced the quality of soil and thereby helped in achieving higher crop yields. Both biochar and plastic char increased the soil pH, total organic carbon, available phosphorus and nitrogen in the soil. Additionally, the results showed an entirely positive influence of the chars on plant height thereby making it more suitable for the improvement of agricultural system and reducing the dependency on market-based fertilizers.


Assuntos
Carbono , Solo , Carvão Vegetal , Fertilizantes/análise , Nitrogênio/análise , Fósforo
17.
Sci Total Environ ; 751: 141703, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32882553

RESUMO

Ammonium removal in wastewater treatment plants requires a large number of energy input, such as aeration and the addition of organics. Alternative, more economical technologies for nitrogen removal from wastewater are required. This study comprehensively investigated the feasible of microbial electricity coupled with Fe(III) reduction promoting the anaerobic ammonium removal. It was found that electrostimulation coupled with Fe(III) reduction (bioelectrochemical systems-Fe(III) (BES-Fe(III)) reactor) enhanced the anaerobic ammonium removal by 50.38% and 38.8% compared with the BES reactor and Fe(III) reactor, respectively. The ammonium removal rate reached the highest value of 80.62 ± 0.26 g N m-3·d-1 in the Fe(III)-BES reactor comparable to conventional wastewater treatment plants (WWWTPs). The improvement of ammonium removal might be the synergistic effect of BES and Feammox process on reaction process and microorganisms. Firstly, the addition of Fe2O3 could improve the electrochemical characteristics by enriching iron-reducing bacterial (FeRB). Secondly, the improved ammonium removal could be due to nitrite generated from Feammox process driving the anodic ammonium oxidation. Additionally, the ammonium removal improvement might be the effect of BES on the Fe2+ leaching so as to accelerate the Fe (II)/Fe(III) cycle. In agreement, higher abundance of FeRB and iron-oxidizing bacteria was detected in the Fe(III)-BES reactor. This study provides a lower energy consumption and operational cost technology compared with the conventional partial nitrification/denitrification, which was more than 800 times less than for the conventional wastewater treatment.


Assuntos
Compostos de Amônio , Terapia por Estimulação Elétrica , Anaerobiose , Reatores Biológicos , Desnitrificação , Compostos Férricos , Nitrogênio/análise , Oxirredução , Águas Residuárias
18.
Chemosphere ; 262: 128387, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182114

RESUMO

Soil degradation caused by watermelon continuous cropping obstacle is a serious problem in China. Compost, as a soil conditioner, has great potential in improving soil degradation. In order to explore how compost affects the soil quality under continuous cropping obstacle, associations among soil chemical characteristics, microbial community structures and agronomic variables were analyzed and compared. Results showed that soil pH, available potassium, alkali-hydrolyzable nitrogen and organic matter changed significantly after using maize straw compost and sludge compost, which indicated the feasibility of composts as soil remediations. This is also reflected on the significant changes of soil microbial community. Mizugakiibacter, as the main reason of watermelon continuous cropping obstacle, decreased significantly after using compost products. It also showed a negative connection with most chemical characteristics. Rhodanobacter and Galbibacter increased significantly after using compost products, which were positively related to most chemical characteristics. The increase of them was helpful to reduce Mizugakiibacter. Beneficial bacteria were positively related to beneficial fungi (Chaetomium and Chrysosporium). The increase of them and the decrease of Verticillium also helped to improve microbial community structure. The results indicated that compost as a useful and inexpensive technique could alleviate soil degradation caused by watermelon continuous cropping obstacle.


Assuntos
Agricultura , Citrullus , Microbiota , Microbiologia do Solo , Álcalis , Bactérias , China , Compostagem , Fungos , Estudos Longitudinais , Nitrogênio/análise , Esgotos/química , Solo/química , Zea mays
19.
Chemosphere ; 262: 127939, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182115

RESUMO

Species specific nitrogen-to-phosphorus molar ratio (NPR) has been suggested for green microalgae. Algae can store nitrogen and phosphorus, suggesting that the optimum feed concentration dynamically changes as function of the nutrient storage. We assessed the effect of varying influent NPR on microalgal cultivation in terms of microbial community stability, effluent quality and biokinetics. Mixed green microalgae (Chlorella sorokiniana and Scenedesmus sp.) and a monoculture of Chlorella sp. were cultivated in continuous laboratory-scale reactors treating used water. An innovative image analysis tool, developed in this study, was used to track microbial community changes. Diatoms proliferated as influent NPR decreased, and were outcompeted once cultivation conditions were restored to the optimal NPR range. Low NPR operation resulted in decrease in phosphorus removal, biomass concentration and effluent nitrogen concentration. ASM-A kinetic model simulation results agreed well with operational data in the absence of diatoms. The failure to predict operational data in the presence of diatoms suggest differences in microbial activity that can significantly influence nutrient recovery in photobioreactors (PBR). No contamination occurred during Chlorella sp. monoculture cultivation with varying NPRs. Low NPR operation resulted in decrease in biomass concentration, effluent nitrogen concentration and nitrogen quota. The ASM-A model was calibrated for the monoculture and the simulations could predict the experimental data in continuous operation using a single parameter subset, suggesting stable biokinetics under the different NPR conditions. Results show that controlling the influent NPR is effective to maintain the algal community composition in PBR, thereby ensuring effective nutrients uptake.


Assuntos
Microalgas/fisiologia , Nitrogênio/análise , Fósforo/análise , Purificação da Água/métodos , Biomassa , Chlorella , Nutrientes , Fotobiorreatores , Scenedesmus , Águas Residuárias , Água
20.
Sci Total Environ ; 752: 141262, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32889253

RESUMO

This study evaluates spatiotemporal variability in the behavior of septic system derived nutrients in a sandy nearshore aquifer and their discharge to a large lake. A groundwater nutrient-rich plume was monitored over a two-year period with the septic system origin of the plume confirmed using artificial sweeteners. High temporal variability in NO3-N attenuation in the nearshore aquifer prior to discharge to the lake (42-96%) reveals the complex behavior of NO3-N and potential importance of changing hydrological and geochemical conditions in controlling NO3-N discharge to the lake. While PO4-P was retarded in the nearshore aquifer, the PO4-P plume extended over 90 m downgradient of the septic system. It was estimated that the PO4-P plume may reach the lake within 10 years and represents a legacy issue whereby PO4-P loads to the lake may increase over time. To provide broader assessment of the contribution of septic systems to P and N loads to a large lake, a regional scale geospatial model was developed that considers the locations of individual septic systems along the Canadian Lake Erie shoreline. The estimated P and N loads indicate that septic systems along the shoreline are only a minor contributor to the annual P and N loads to Lake Erie. However, it is possible that nutrients from septic systems may contribute to localized algal blooms in shoreline areas with high septic system density. In addition, disproportionate P and N loads in discharging groundwater may change the N:P ratio in nearshore waters and promote growth of harmful cyanobacteria. The study provides new insights into factors controlling the function of the reaction zone near the groundwater-lake interface including its impact on groundwater-derived nutrient inputs to large lakes. Further, the study findings are needed to inform septic system and nutrient management programs aimed at reducing lake eutrophication.


Assuntos
Água Subterrânea , Lagos , Canadá , Monitoramento Ambiental , Eutrofização , Nitrogênio/análise , Nutrientes , Fósforo/análise
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