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1.
Ying Yong Sheng Tai Xue Bao ; 31(1): 157-164, 2020 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-31957392

RESUMO

Understanding the effects of long-term fertilization on soil organic phosphorus fractions and wheat yield in the Loess Plateau can provide theoretical support for improving phosphorus conversion, utilization, and rational use of fertilizer. We examined the effects of different fertilizer treatments on soil organic phosphorus fractions, wheat yield and soil properties of a farmland in the long-term (1984-2016) positioning test station of Changwu loess soil. There were eight treatments, including no fertilizer (CK), single application of nitrogen fertilizer (N), single application of phosphorus fertilizer (P), application of nitrogen and phosphorus fertilizer (NP), single application of organic fertilizer (M), nitrogen combined with organic fertilizer (MN), phosphorus combined with organic fertilizer (MP), nitrogen and phosphorus combined with organic fertilizer (MNP). The results showed that the range of soil organic phosphorus content was 244.7-429.1 mg·kg-1 after long-term fertilization. Except for the N treatment, organic phosphorus content was significantly increased by 15.4%-47.9% compared to CK. Long-term application of phosphorus fertilizer changed the content of organic phosphorus fractions in the surface soil (0-20 cm). The treatments of MP and MNP significantly increased the contents of labile organic phosphorus and moderately labile organic phosphorus. The treatments of N, P and NP significantly reduced the content of moderately stable organic phosphorus. The treatments of N, P, NP, MN, MP, MNP all significantly increased the highly stable organic phosphorus. The ratio of soil organic phosphorus fractions to total organic phosphorus content was in order of moderately labile organic phosphorus > highly stable organic phosphorus > labile organic phosphorus > moderately stable organic phosphorus. After long-term fertilizer application, the combination of nitrogen and phosphorus fertilizers, especially with organic fertilizers, significantly increased wheat biomass yield and grain yield. Among all the examined soil properties, organic matter, Olsen-P and total inorganic phosphorus were significantly positively correlated with wheat yield. MP and M could significantly increase the content of Olsen-P, total phosphorus, total inorganic phosphorus, labile organic phosphorus and moderately labile organic phosphorus in the loess soil of Loess Plateau. Our results indicated that the organic and phosphorus fertilizers could improve soil phosphorus components that could be more easily absorbed by crops. In summary, the combination of nitrogen and phosphorus fertilizers, especially with organic fertilizers, could increase soil phosphorus supply in the region and promote the wheat yield, which is important for improving soil quality in the Loess Plateau.


Assuntos
Fósforo , Solo , Agricultura , Fazendas , Fertilizantes , Esterco , Nitrogênio , Triticum
2.
Ying Yong Sheng Tai Xue Bao ; 31(1): 282-292, 2020 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-31957406

RESUMO

Brown tide that occurred in Qinhuangdao coastal waters from 2009 to 2015 caused huge losses of local marine aquaculture and coastal tourism, with devastating effects on marine ecosystems. Nutrients are important biogenic elements for algal growth. It is of great significance to examine the fluctuation characteristics of nutrients in the process of brown tide to understand the nutritional mechanism of brown tide. Based on the survey data of 30 stations located in Qinhuangdao coastal area from April to June 2014, we analyzed nutrient characteristics during the occurrence of brown tide and its relationship with the population dynamics of Aureococcus anophagefferens. The results showed that the concentration of dissolved nitrogen (DN) in April, May and June 2014 was 265.65, 355.36 and 323.71 µg·L-1 respectively, and the concentration of dissolved organic nitrogen (DON) was 196.98, 242.88 and 177.69 µg·L-1, accounting for 74.2%, 68.3% and 54.9% of DN, respectively. The concentration of dissolved phosphorus (DP) in April, May and June was 15.95, 11.39 and 11.14 µg·L-1 respectively. In April and May, PO43--P accounted for a large proportion of the DP, 74.8% and 80.9% respectively. In June, the proportion of PO43--P in DP fell to 33.8%, and the proportion of dissolved organic phosphorus (DOP) in DP rose to 66.2%. The concentration of SiO32--Si in April, May and June was 70.95, 181.13 and 120.68 µg·L-1, respectively. Except for dissolved inorganic nitrogen (DIN) in May and DON, the distribution of other nutrients had clear characteristics that it decreased gradually from inshore to the offshore, with the relatively high concentrations in river mouth. Through R-factor analysis and nutrient structure analysis, it was found that in April, brown tide was at the development stage, and DOP might be the main driving factor for the growth of A. anophagefferens. In May, brown tide was at the maintenance stage, and water temperature became the main controlling factor. When water temperature was higher than 12 ℃, brown tide could occur. In June, brown tide began to decay, and PO43--P had greater effects on the community structure of phytoplankton. DON was the important factor causing the outbreak of brown tide, with a concentration threshold of 150 µg·L-1 and the ratio DON/DIN being greater than 1.


Assuntos
Ecossistema , Água do Mar , China , Nitrogênio , Nutrientes , Fósforo
3.
Ying Yong Sheng Tai Xue Bao ; 31(1): 333-339, 2020 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-31957412

RESUMO

A large amount of azo dye wastewater is discharged into the environment, with serious risks to ecosystems and human health. Therefore, the development of treatment technology of azo dye wastewater was of practical significance. Photocatalytic methods showed promising application prospects due to easy to implement and effective. In this study, layered black phosphorus nanosheet (LBP) was used as a catalyst through liquid phase exfoliation method. Methyl orange (MO) was employed as a model azo dye to investigate the catalytic mechanism of LBP. The dominant transient species involved in the photocatalytic reaction was probed by quenching and fluorescence probe experiments. Degradation pathways of MO were proposed according to degradation products identified by the liquid chromatography-mass spectrometry. The results showed that degradation rate (kobs) of MO at acidic condition (pH=3.0) or alkaline condition (pH=11.0) was higher than that at neutral condition (pH=7.0). Degradation pathways of MO included that the azo bond was attacked by hydroxyl radicals (·OH) photogenerated by the LBP, and the intermediate products were further oxidized by ·OH to produce N, N-dimethyl-4-(2-p-phenylmethylhydrazine) aniline, 2-(dimethylamino)-5-((4(dimethylamino) phenyl) diazenyl) phenol and N, N-dimethyl-4-nitroaniline.


Assuntos
Ecossistema , Fósforo , Compostos Azo , Águas Residuárias
4.
Ground Water ; 58(1): 27-34, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30843187

RESUMO

We have established a monitoring record of phosphate (PO4 3- ) migration in the Long Point, ON campground septic system plume that now spans 26 years. Previously, at year 16 (2006), a P plume 16 m in length was documented and provided a good fit with an analytical advection dispersion model when a P migration velocity of 0.8 m/yr was used (retardation factor of 37) and when P behaved in an otherwise conservative manner (sorption only). However, between years 16 and 26 (2016), the P plume length expanded by only 2 m (0.2 m/yr) and increased in depth by only 0.5 m. The zone of abrupt P depletion at depth occurs close to the zone where SO4 2- concentrations increase in response to NO3 - oxidation of pyrite. Scanning electron microscope images of sand grains from the nose of the P plume reveal abundant authigenic mineral coatings of considerable thickness (∼5 to 20 µm), with Fe as the dominant cation and containing 1 to 3 wt % P. This evidence suggests that P is now being attenuated along a reaction front that coincides with the zone where pyrite oxidation is occurring. P migration may now be controlled by the rate of migration of the pyrite oxidation front and this is several times slower than the previously indicated rate in the shallower, sorption-controlled portion of the plume. Monitoring at Long Point has demonstrated the danger of embracing an overly simplistic conceptual model when attempting to predict wastewater P migration in groundwater and also highlights the unique insight provided by a long-term monitoring record.


Assuntos
Água Subterrânea , Fósforo , Ferro , Oxirredução , Sulfetos
5.
Water Res ; 169: 115206, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31669898

RESUMO

Phosphonates are an important type of phosphorus-containing compounds and have possible eutrophication potential. Therefore, the removal of phosphonates from waste streams is as important as orthophosphate. Herein, we achieved simultaneously removal and recovery of phosphorus from nitrilotris (methylene phosphonic acid) (NTMP) using an electrochemical cell. It was found that the C-N and C-P bonds of NTMP were cleaved at the anode, leading to the formation of orthophosphate and formic acid. Meanwhile, the converted orthophosphate reacted with coexisting calcium ions and precipitated on the cathode as recoverable calcium phosphate solids, due to an electrochemically induced high pH region near the cathode. Electrochemical removal of NTMP (30 mg/L) was more efficient when dosed to effluent of a wastewater treatment plant (89% in 24 h) than dosed to synthetic solutions of 1.0 mM Ca and 50 mM Na2SO4 (43% in 168 h) while applying a current density of 28 A/m2 and using a Pt anode and Ti cathode. The higher removal efficiency of NTMP in real waste water is due to the presence of chloride ions, which resulted in anodic formation of chlorine. This study establishes a one-step approach for simultaneously phosphorus removal and recovery of calcium phosphate from non-orthophosphates.


Assuntos
Organofosfonatos , Fósforo , Fosfatos de Cálcio , Fosfatos , Águas Residuárias
6.
Waste Manag ; 102: 106-113, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31670228

RESUMO

Hydrothermal carbonization (HTC) has drawn increasing interest for the disposal of solid wastes with a high moisture content, while minimal attention has been paid to HTC treatment of wetland plants and the corresponding phosphorus (P) transformation. In order to evaluate its feasibility for wetland plants treatment, hydrochars from different wetland plants were produced at different temperatures (200 °C, 220 °C, 240 °C, and 260 °C) and characterized, and the transformation of P was investigated. In comparison with wetland plant derived biochars, the derived hydrochars had a moderate pH (5.0-7.7), more oxygen-containing groups, and higher energy density (18.0-27.1 MJ kg-1). These properties were affected by hydrothermal temperature and feedstock choice. In contrast to high water-soluble P in biomass (71.0-73.2% of total P), more recalcitrant P species formed in hydrochars, implying that HTC treatment could achieve P immobilization and reduce P leaching loss. Nuclear magnetic resonance (NMR) results indicated that monoester-P and soluble orthophosphate were transformed to insoluble orthophosphate during the HTC treatment. Therefore, HTC is a promising treatment technique for wetland plants to produce valuable char with P reclamation.


Assuntos
Fósforo , Áreas Alagadas , Biomassa , Carbono , Temperatura Ambiente
7.
Water Res ; 169: 115255, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31698148

RESUMO

Biochar derived from enhanced biological phosphorus removal (EBPR) sludge could be a potential phosphorus (P) fertilizer. Soil microorganisms play a regulating role on the turnover of P in soil. When the EBPR sludge biochar is added to soil, it would inevitably interact with soil microorganisms. Thus, for the wise use of the EBPR sludge biochar, it is imperative to understand the interaction between the biochar and soil microorganisms. In this study, Pseudomonas putida (P. putida), a common soil microorganism, was applied to investigate the biotransformation of P in two EBPR sludge biochars. The results reveal that P released from biochar produced at 700 °C (E700) was more easily absorbed by P. putida than that released from biochar produced at 400 °C (E400). This is attributed to the higher polyphosphates (poly-P) content in E700 and poly-P has higher affinity to P. putida surface compared to orthophosphates. Furthermore, E400 has a negative effect on intracellular poly-P formation in P. putida, which is probably caused by the oxidative stress induced by the free radicals from E400. As intracellular poly-P plays a critical role on bacteria survival and their interaction with surrounding environment, high-temperature biochar (E700) in this case would be more suitable for soil remediation.


Assuntos
Fósforo , Esgotos , Biotransformação , Carvão Vegetal , Solo
8.
Water Res ; 169: 115228, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31698149

RESUMO

Phosphorus has been successfully eliminated from wastewater by biological techniques of enhanced biological phosphorus removal (EBPR) process, which relies on a specific microbiota of polyphosphate accumulating organisms (PAOs) that accumulate phosphate as polyphosphates (poly-P). Most methods for quantification of poly-P pools suffer from low accuracy and specificity. More powerful and implementable P-analysis tools are required for poly-P quantification, which will help in improved evaluation of processes in laboratory and full-scale EBPR systems. This study developed two methods to quantify poly-P pools by releasing the poly-P from the cell. During experimental optimization, it was observed that two different methods resulted in the highest phosphate release: acetate addition at a pH of 4.8 and exposure to EDTA solution with a concentration of 1% (w/v). Treatment with EDTA resulted in a higher amount of phosphate release from all sludge samples. This was characterized by P-release of 1.5-2.5 times higher than the control tests. In contrast, treatments with acetate addition at a low pH exhibited that P-release depended upon the types of the sludge samples. The highest P-release amount and rate were found in highly-enriched PAO sludge samples, but with fewer influences on the sludge collected from WWTP, which may be attributed to the lower fraction of PAOs in the sludge. Overall, the proposed approaches to quantify the poly-P concentration can be applied in simple, user-friendly, and cost-effective ways.


Assuntos
Ácido Acético , Fósforo , Anaerobiose , Reatores Biológicos , Polifosfatos , Esgotos
9.
Water Environ Res ; 92(1): 138-148, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31486194

RESUMO

Nutrient enrichment facilitates algal outbreaks in eutrophic shallow lakes. To further understand the influence of various inorganic nutrient forms on cyanobacterial blooms, a nitrate (NO3 ), ammonium (NH4 ), and orthophosphate (PO4 ) amendment experiment was conducted in a large shallow lake of China (Lake Taihu) during summer. The results showed that the photosynthetic performance of phytoplankton responded more positively to phosphorus (P) than nitrogen (N), and NH4 addition stimulated higher algal photosynthetic activities in P-enriched waters. Individual inorganic N or PO4 addition significantly activated cyanobacteria and green algae. Meanwhile, the N plus P amendment promoted higher biomass of the planktonic microbial community, and the dual addition of NH4  + PO4 yielded the highest chlorophyll a concentration. NH4 additions provisionally promoted higher green algae than cyanobacteria biomass in the beginning, while cyanobacteria dominated again with increasing NH4 :PO4 ratios. These results revealed that increasing ammonium would enhance the increase in phytoplankton biomass in advance and prolong the duration of algal blooms. Hence, based on the control of P loading, the reduction in external inorganic N focusing on ammonium sources (such as ammonia N fertilizer) at the watershed scale would help to alleviate eutrophication and cyanobacterial blooms over the long term in Lake Taihu. PRACTITIONER POINTS: Ammonium addition stimulated higher algal photosynthetic activities in P-enriched waters. Individual inorganic N or PO4 addition significantly activated cyanobacteria and green algae. The dual addition of NH4  + PO4 yielded the highest chlorophyll a concentration. Increasing NH4 would enhance the increase in phytoplankton biomass in advance and prolong the duration of cyanobacterial blooms.


Assuntos
Cianobactérias , Lagos , Baías , Biomassa , China , Clorofila A , Eutrofização , Nitrogênio , Nutrientes , Fósforo , Fitoplâncton
10.
Bioresour Technol ; 297: 122420, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31784248

RESUMO

The feasibility of mixed dye wastewater treatment was evaluated with a novel integrated bioprocess that consisted of a hybrid anaerobic reactor (HAR) with a built-in bioelectrochemical system, an aerobic biofilm reactor (ABFR) and a denitrification reactor (DR). The position of the DR significantly affected chemical oxygen demand (COD) and colority in effluent, and placing the DR after the ABFR improved effluent quality probably due to minimization of the undesired autoxidation of aromatic amine in dye wastewater. The optimal integrated process of HAR + ABFR + DR efficiently treated mixed dye wastewater, and concentrations of COD and TN were decreased down to 75 ± 18 mg/L and 12.91 ± 0.31 mg/L, respectively, along with colority 48 ± 4 times. Total phosphorus reduced to below 0.5 mg/L with coagulation using poly aluminum chloride, and the effluent quality fully met the discharge standard. This comprehensive study suggests the feasibility of the BES based process for practical application to mixed dye wastewater treatment.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Nitrogênio , Fósforo
11.
Bioresour Technol ; 297: 122454, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31786040

RESUMO

The microbial community in endogenous denitrification and denitrifying phosphorus removal treatment at transcription level was unknown. This study first confirmed the expression of actually active bacteria in endogenous denitrification and denitrifying phosphorus removal system to treat low C/N municipal wastewater. No external carbon source was added to influent wastewater. The cDNA high throughput sequencing showed that Candidatus Accumulibacter was the most effective polyphosphate accumulating organisms (PAOs) that actually worked rather than Dechloromonas, which was different from the result at gene level. Reverse transcriptional PCR (RT-PCR) and analysis of Variance (ANOVA) suggested that the ratios of dead or dormant bacteria could monitor wastewater treatment process. Identification of active microbial community at transcription level demonstrated that the synergy of endogenous denitrification by glycogen accumulating organisms (GAOs) and denitrifying phosphorus removal by Candidatus Accumulibacter fully utilized the internal carbon source, and effectively solved the problem of carbon source deficiency in municipal wastewater treatment.


Assuntos
Microbiota , Águas Residuárias , Reatores Biológicos , Carbono , Desnitrificação , Glicogênio , Fósforo
12.
Bioresour Technol ; 297: 122406, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31787513

RESUMO

The objective of this study was to evaluate changes in phosphorus fractions during vegetable waste and chicken manure composting. High throughput sequencing, quantitative PCR, and multiple analysis methods were applied to investigate interconnections among phosphorus fractions, enzyme activity, and phoD-harboring bacterial community composition. We found the highest composting temperature reached 61 °C and phosphorus fractions presented significant differences during a 60-day composting. The content of plant-absorbable phosphorus, including water soluble phosphorus, available phosphorus, and citric acid phosphorus increased by 121%, 87%, and 63%, respectively. Additionally, phoD gene abundance significantly correlated with the activities of nine enzymes. Our findings emphasize that microbial activity plays an important role in phosphorus transformation during composting, and the final composting product could be good biological phosphorus fertilizer. To our knowledge, this is the first report indicating that enzyme activity, community composition and abundance of phoD-harboring bacteria have direct and indirect effects on phosphorus transformation during composting.


Assuntos
Compostagem , Fosfatase Alcalina , Animais , Bactérias , Galinhas , Esterco , Fósforo , Solo , Verduras
13.
Water Res ; 170: 115333, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31790887

RESUMO

Because the functions of these water and resource recovery facilities (WRRFs) stretches beyond simply meeting effluent requirements (i.e., also includes optimisation of products to be generated as recovered resources), a high level of accuracy is required in using mathematical models that virtually replicate (hence predict) WRRF system responses to dynamic conditions. The currently developed mathematical models embrace the majority of advances made towards tracking nitrogen (N) and phosphorus (P) through the entire WRRF, and significant effort has been made towards calibrating them to predict realistic outcomes. This paper presents the stepwise calibration of the PWMSA model (Ikumi et al., 2015) for aerobic (AerD) and anoxic-aerobic digestion (AAD) processes, through predictions of (i) mineral precipitation potential, in isolation to biological reactions (ii) AerD bioprocesses (including nitrification, orthophosphate (OP) release, and endogenous respiration), in isolation to mineral precipitation (iii) predicted interaction of the mineral precipitation and the biological processes of organic removal and nitrification, excluding P accumulating organisms (PAOs) and polyphosphate (PP) release during AerD, (iv) replicated interaction of mineral precipitation and bioprocesses of P release and nitrification kinetics (v) predicted PAO behavioural kinetics of anaerobic OP release with acetate uptake and aerobic PP uptake, in isolation to nitrification and (vi) predicted nitrate denitrification and anoxic OP release. The calibrated kinetic parameters allowed for the model capability of reproducing the data from the key biological, physical and chemical processes occurring in the various environments of sludge treatment (aerobic, anoxic and anaerobic) within satisfactory level of accuracy.


Assuntos
Fósforo , Esgotos , Reatores Biológicos , Desnitrificação , Cinética , Nitrogênio , Eliminação de Resíduos Líquidos
14.
Ecol Lett ; 23(2): 336-347, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31802606

RESUMO

The traditional view holds that biological nitrogen (N) fixation often peaks in early- or mid-successional ecosystems and declines throughout succession based on the hypothesis that soil N richness and/or phosphorus (P) depletion become disadvantageous to N fixers. This view, however, fails to support the observation that N fixers can remain active in many old-growth forests despite the presence of N-rich and/or P-limiting soils. Here, we found unexpected increases in N fixation rates in the soil, forest floor, and moss throughout three successional forests and along six age-gradient forests in southern China. We further found that the variation in N fixation was controlled by substrate carbon(C) : N and C : (N : P) stoichiometry rather than by substrate N or P. Our findings highlight the utility of ecological stoichiometry in illuminating the mechanisms that couple forest succession and N cycling.


Assuntos
Ecossistema , Fixação de Nitrogênio , China , Florestas , Nitrogênio , Fósforo , Solo , Árvores
15.
Waste Manag ; 102: 441-451, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31739278

RESUMO

The objective of this work was to determine the potential of using of solid and liquid digestate, as biofertilizer and soil amendment, and to address adverse unfertile soil erosion problems after analysing areas of potential use. We found a high concentration of organic carbon in a solid fraction of the digestate, which indicates a significant potential for returning carbon to the soil. The influence of digestate fertilization on soil fertility as a function of the amount of available phosphorus (P2O5) and potassium (K2O) in the 0-40 cm layer was found to be very important. The soil fertility category was changed from "high" (200-300 mg kg-1) to "very high" (>300 mg kg-1) according P2O5, using only 170 kg ha-1 of nitrogen in solid and liquid digestate rate. Fertilization with all phases and rates of digestate tend to increase the amount of K2O. The solid digestate fertilization using the 170 kg ha-1 N rate showed a significant increase (5 times) of mineral nitrogen content in the 0-40 cm soil layer. The advantage of solid digestate as a soil improver has been highlighted because it has a positive effect on soil fertility, quality, sustainability and durability. The amount of mobile humic acids (MHA) in eroded loamy Retisol increased 1.6 times in soil 0-40 cm layer with a fertilization rate of 170 kg ha-1 and 1.5 times - of 85 kg ha-1 of solid digestate compared to the untreated. Similar trends of MHA but in lower amount were identified when liquid digestate was applied.


Assuntos
Fertilizantes , Solo , Agricultura , Lituânia , Nitrogênio , Fósforo
16.
Bioresour Technol ; 297: 122418, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761632

RESUMO

The study evaluates 36 filamentous heterocystous cyanobacteria for the treatment of biogas slurry from pig farm and the accumulation of biomass for bioenergy production. The results showed that only the strains B, J, and L were able to adapt to a 10% biogas slurry. The removal rates of ammonia nitrogen, total nitrogen, and total phosphorus for strains J and L were 92.46%-97.97%, 73.79%-79.90%, and 97.14%-98.46%, respectively, higher than that of strain B. Strain J had the highest biomass productivity and lipid productivity. Based on the biodiesel prediction results, it was concluded that strains J and L are more suitable for biodiesel production. The estimation of theoretical methane potential suggests that the algal biomass of strain J also have the desirable possibility of biogas generation. In summary, algal strain J (Nostoc sp.) offers great potential for biogas slurry treatment and for the production of bioenergy.


Assuntos
Biocombustíveis , Cianobactérias , Animais , Biomassa , Fazendas , Fósforo , Suínos
17.
Bioresour Technol ; 297: 122517, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31830719

RESUMO

Effects of different mixing ratios between synthetic municipal wastewater (MW) and magnesium (Mg2+)-enriched nickel laterite ore wastewater (NLOWW) on growth of Chlorella sorokiniana (C. sorokiniana), photosynthetic activities, cellular biocomposition, nutrient and Mg2+ removal were investigated in photobioreactors. In the culture without NLOWW, wrinkled cells were observed with low biomass production. The culture mixed with 0.13% NLOWW obtained 1.89-fold higher biomass yield, 3.77-fold enhanced photosynthetic activity (Fv/Fm value), and improved nutrient removal (nitrogen by 102.2%, phosphorus by 39.3%). However, excessive Mg2+ at 100% NLOWW produced highest reactive oxygen species suppressing microalgal growth. The Mg2+ removal capacity increased with NLOWW loading. Moreover, microalgal assimilation primarily contributed to nutrient removal while absorption was the dominant Mg2+ removal pathway. Carbohydrate content in biomass increased with Mg2+ loading. Finally, the approach for MW/NLOWW treatment was demonstrated as economically feasible with revenue of $75.6 per kilogram biomass through a comprehensive economic model.


Assuntos
Chlorella , Microalgas , Biodegradação Ambiental , Biomassa , Níquel , Nitrogênio , Nutrientes , Fósforo , Águas Residuárias
18.
Toxicol Lett ; 320: 28-36, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31805340

RESUMO

Fourteen amino acids protected at the N-terminal and at their side chains were screened for resolving the enantiomers of V-agents by NMR. While none of the shift reagents tested showed really effective separation in proton NMR, two of them (BOC-Gln(Xan)-OH, 16, and Z-Arg(Z)2-OH), 21, with 16 superior to 21) were found suitable to separate the enantiomers of all V-agent homologues involved in the test by 31P-NMR. Molar ratios investigated were 1:0.5, 1:1, 1:1.5, 1:2, and 1:3 with the V-agent set to 1 throughout the experiments. All these ratios were more or less effective, but 1:3 was found to separate the V-agents the most reliable way. It is postulated that three chiral solvating molecules are then coordinated around the organophosphate: ion pair formation with the amino nitrogen of the V agent side chain, hydrogen bonding provided by the PO unit, and extension of coordination at the phosphorus atom itself. After chiral separation of VX by semi-preparative LC-MS the enantiomers were examined with both configurations of 16 releasing four different 31P NMR peaks which correspond to four different complexes: R-S3, R-R3, S-R3, and S-S3. Comparing these results with literature data it is assumed that (+)-VX corresponds to the RP configuration and (-)-VX to the SP-configuration.


Assuntos
Aminoácidos/química , Espectroscopia de Ressonância Magnética/métodos , Compostos Organofosforados/química , Fósforo/química , Solventes/química , Cromatografia Líquida , Ligações de Hidrogênio , Estrutura Molecular , Compostos Organofosforados/isolamento & purificação , Espectroscopia de Prótons por Ressonância Magnética , Estereoisomerismo , Espectrometria de Massas em Tandem
19.
Water Res ; 170: 115363, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816567

RESUMO

For achieving energy-efficient wastewater treatment, a novel simultaneous nitrogen and phosphorus removal (SNPR) process, which integrated anammox, endogenous partial-denitrification and denitrifying dephosphatation in a sequencing batch reactor with granular sludge was developed to treat mainstream wastewater. After 200 days of operation, a simultaneous high-level nitrogen and phosphorus removal of 93.9% and 94.2%, respectively was achieved with an average influent C/N ratio of 2.9. Anammox pathway contributed 82.9% of the overall nitrogen removal because of the stable nitrite production from nitrate via endogenous partial-denitrification. In addition, phosphorus was mainly removed via denitrifying dephosphatation utilizing nitrate as the electron acceptor, resulting in a significant saving of carbon sources and oxygen demands. Further, adsorption/precipitation of phosphorus occurred in this novel SNPR process, which displaced the energy source to the metabolism of glycogen accumulating organisms (GAOs) for nitrite production and alleviated competition between phosphorus accumulating organisms (PAOs) and anammox for electron acceptor. Using 16S rRNA gene amplicon sequencing analysis, the study found that anammox bacteria (8.4%), GAOs (1.5%) and PAOs (1.1%) co-existed in this system, potentially resulting in simultaneous endogenous partial-denitrification, anammox and denitrifying dephosphatation. The above results demonstrated that the novel SNPR process is a promising technique for energy-efficient wastewater treatment.


Assuntos
Desnitrificação , Águas Residuárias , Reatores Biológicos , Nitrogênio , Fósforo , RNA Ribossômico 16S , Esgotos
20.
Water Res ; 170: 115361, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816568

RESUMO

Phosphorus removal is an important issue in the field of water and wastewater treatment. In this study, a starch-based flocculant (St-CTA), as an assisting agent, was fed after the application of traditional inorganic precipitant of ferric chloride (FeCl3) to remove inorganic and organic phosphorus from their respective simulated turbid wastewaters. The effects of various influencing factors, including CTA content of St-CTA, dosage, initial pH, initial turbidity, and initial total phosphorus (TP), were investigated systematically. This modified chemical sedimentation process assisted by St-CTA not only showed high efficient in removing TP and turbidity but also evidently reduced the required dosage of FeCl3. This combination exhibited better efficiency in removing organic TP than in removing inorganic TP from water. The synergistic mechanisms of FeCl3 and St-CTA were discussed in detail by combination of apparent removal effects and floc properties. St-CTA exhibits strong charge neutralization and bridging flocculation effects and can thus efficiently aggregate and precipitate various phosphorus and iron complexes previously formed through chemical sedimentation, adsorption, and chelation. Besides, the validation of this combination usage was further confirmed by treating a real wastewater, and half of the required FeCl3 dosage and one third of the total cost were saved after addition of only 0.4 mg/L St-CTA when 90% TP and 95% turbidity were reduced. This study thus provided a novel technique for the diminution of TP and turbidity in turbid wastewater, considerable reduction of FeCl3 dosage and final cost, and lowering of secondary pollution risk.


Assuntos
Fósforo , Purificação da Água , Floculação , Amido , Água
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