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1.
Ecotoxicol Environ Saf ; 214: 112072, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33691243

RESUMEN

The Green Revolution faced a great cost to meet ever-increasing demands for food, where indiscriminate use of agrochemicals resulted in non-friendly habitats. Therefore, the development of a sustainable approach to better crop production of onion seeds (Allium cepa L.) is very crucial. It is time to use organic waste as a replacement for agrochemicals by using arbuscular mycorrhizal fungi (AMF) and Trichoderma. Fish waste as representative of food waste acts as a leading cause of contamination of the environment. The interaction of AMF and Trichoderma viride on biomass, total soluble protein, mycorrhizal colonization, amino acids, phosphatases and phosphorus and nitrogen contents of onion plants grown in fish waste amended soil was studied. Fish waste has caused a slight increase in onions biomass, total free amino acids, and soluble protein content while with AMF and T. viride dual inoculation more increments were recorded; such increases were related to an increase in mycorrhizal colonization. T. viride application significantly increased the mycorrhizal colonization levels, but these were significantly reduced with waste addition. Analysis of amino acids in plants showed that their concentrations had changed as a result of waste addition combined with AMF and/or T. viride. The effectiveness of fish waste combined with low cost and health/environmental safety leads to a prediction that the introduction of fish waste coupled with fungi will become a more popular feature of agriculture in the future.


Asunto(s)
Micorrizas/fisiología , Cebollas/fisiología , Trichoderma/fisiología , Agricultura , Aminoácidos/metabolismo , Biomasa , Alimentos , Hongos/metabolismo , Hypocreales , Micorrizas/metabolismo , Nitrógeno/metabolismo , Cebollas/química , Monoéster Fosfórico Hidrolasas/metabolismo , Fósforo/metabolismo , Eliminación de Residuos , Suelo , Trichoderma/metabolismo
2.
Huan Jing Ke Xue ; 42(4): 1847-1860, 2021 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-33742820

RESUMEN

In this work, the influence of an integrated method based on calcium nitrate, denitrifying bacteria, and zirconium-modified zeolite (CN+DB+ZZ) on the transport and transformation of nitrogen (N) and phosphorus (P) in sediments was investigated, and the risk of nitrate release from the calcium nitrate-injected sediment was evaluated. The effects of the single calcium nitrate injection (CN), calcium nitrate, and denitrifying bacteria combined treatment (CN+DB) and the combined treatment using calcium nitrate injection and zirconium-modified zeolite capping (CN+ZZ) on the mobilization of N and P in sediment were compared, and the nitrate releasing risk of these methods was also evaluated. The results indicated that although CN treatment could effectively control the P release from the sediment, this method could not effectively control the release of ammonium-nitrogen from sediment and has a high risk of releasing nitrate-nitrogen. The CN+DB combined method not only could effectively control the liberation of sedimentary P but also reduce the risk of nitrate-nitrogen release from the calcium nitrate-injected sediment compared with the single CN method. However, the CN+DB combined method could not effectively control the release of ammonium-nitrogen from the sediment. The CN+ZZ combined treatment not only could effectively prevent the release of sedimentary P but could also greatly reduce the release of ammonium-nitrogen from the sediment. However, the CN+ZZ combined method could result in a substantial release of nitrate-nitrogen from the calcium nitrate-injected sediment. The CN+DB+ZZ combined technology could effectively control the release of P from sediment as well as greatly reduce the risk of ammonium-nitrogen release from the sediment. Furthermore, the CN+DB+ZZ combined method resulted in a significant reduction of nitrate-nitrogen released from the calcium nitrate-injected sediment compared with the CN and CN+ZZ treatment methods. The prevention of the dissolution of the P-bound iron oxide/hydroxide in the sediment, the reduction of redox-sensitive P in sediment, and the improvement of the phosphate and ammonium adsorption abilities of sediment by the CN+DB+ZZ combined method is critical to control the release of phosphorus and ammonium-nitrogen from sediment using this method. Results of this study reveal that the CN+DB+ZZ combined technology could be a promising method for the control of phosphorus and ammonium-nitrogen release from sediments.


Asunto(s)
Contaminantes Químicos del Agua , Zeolitas , Bacterias , Compuestos de Calcio , Sedimentos Geológicos , Nitratos , Nitrógeno/análisis , Fósforo , Contaminantes Químicos del Agua/análisis , Circonio
3.
Huan Jing Ke Xue ; 42(4): 1861-1869, 2021 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-33742821

RESUMEN

Nitrogen and phosphorus are the leading causes of water eutrophication, and it is challenging to remove nitrogen and phosphorus effectively through a single water remediation method. In this study, an aerobic denitrifying bacterium (AD-19) isolated from eutrophic water was used to construct an immobilized biofilm and combined with Phoslock® to remove nitrogen and phosphorus from the water. The phosphorus control efficiency of Phoslock®, nitrogen removal performance of the denitrifying bacteria, and combined remediation performance for the eutrophic water were studied. The results demonstrated that the removal rate of PO43--P in the simulated eutrophic water reached 95% with a dosing ratio of 80 (mass ratio of Phoslock® to PO43--P), and phosphorus release from sediment was effectively inhibited at the same time. Strain AD-19, which was identified as Pseudomonas sp. Using the 16S rDNA method, had a good heterotrophic nitrification and aerobic denitrification ability, and more than 97% of the nitrogen was removed when NH4+-N or NO3--N was used as the nitrogen source. The feasibility of the combined remediation of the eutrophic water was demonstrated using a lake simulation device. Furthermore, this technique was used to restore a eutrophic pond in a park in Wuhan city. After 16 days of treatment, the water quality indices for nitrogen and phosphorus were improved from worse than Grade Ⅴ to Grade Ⅲ (GB 3838-2002, Ministry of Environmental Protection of China, 2002) and remained stable for more than 270 days, indicating that Phoslock® combined with the immobilized biofilm could quickly and effectively restore eutrophic water as well as maintain the water quality for long periods.


Asunto(s)
Fósforo , Agua , Bacterias , China , Desnitrificación , Nitrificación , Nitrógeno , Fósforo/análisis
4.
Huan Jing Ke Xue ; 42(4): 1930-1938, 2021 Apr 08.
Artículo en Chino | MEDLINE | ID: mdl-33742828

RESUMEN

In order to clarify the characteristics of anaerobic ammonia oxidizing (ANAMMOX) sludge and the succession rule of bacteria based on particle size differentiation, the performance change and microbial community structure of ANAMMOX floc sludge during the formation of particles in the reaction system of a high ammonia-nitrogen biofilter were studied. The results indicated that the specific activity (SAA) and tolerance of the ANAMMOX granular sludge (AnGS) were significantly improved by increasing the particle size, and the SAA of R4(>4.75 mm) was up to 426.8 mg·(g·d)-1, but it also had adverse effects on mass transfer. The results of the high-throughput sequencing showed that dynamic changes between bacterial genera were common. When the particle size was less than 4.75 mm, the increase in particle size strengthened the stability of the bacterial flora, the ammonia oxidizing bacteria (AOB) with more flocs were eliminated, and the nitrogen removal ratio gradually stabilized. R3 (2.8-4.75 mm) exhibited the most specific flora composition, and the functional bacteria Candidatus Kuenenia accounted for 52.7%, while the R4 community complexity increased. Furthermore, the proportion of functional bacteria decreased, and the abundance of heterotrophic bacteria increased, which negatively affected the particle structure. In addition, the R3 microorganism has the best gene function expression level, which is significantly better than small particles in gene replication repair and energy conversion. Finally, the evolution of AnGS was analyzed through the OTU matrix between the samples. These results have some guiding significance for the optimization of the AnGS system and will be helpful for the application of the ANAMMOX process.


Asunto(s)
Amoníaco , Aguas del Alcantarillado , Anaerobiosis , Reactores Biológicos , Nitrógeno , Oxidación-Reducción , Tamaño de la Partícula
5.
Huan Jing Ke Xue ; 42(2): 819-830, 2021 Feb 08.
Artículo en Chino | MEDLINE | ID: mdl-33742876

RESUMEN

Periphytic algae are often used as an indicator to evaluate water quality. Here, the community structure of periphytic algae and its relationship with environment factors were analyzed in the main stream of the Songhua River during the summers of 2014 to 2019. The status and trends in ecological water quality were also evaluated based on bioassessments. Phytoplankton species belonging to 4 phyla and 58 genera were recorded, including 28 Bacillariophyta genera, 17 Chlorophyta genera, 10 Cyanophyta genera, and 3 Euglenophyta genera; Bacillariophyta, Chlorophyta, and Cyanophyta accounted for 48.28%, 29.31%, and 17.24% of the community, respectively. Cell densities varied between 1.29×104 and 8.42×104 ind·cm-3, with an average of 4.35×104 ind·cm-3. The dominant genera were Cyclotella, Melosira, Asterionella, Cymbella, Synedra, Pinnularia, Navicula, and Scenedesmus. The physicochemical water quality showed notable changes during the past six-year monitoring period. Specifically, the dissolved oxygen content increased year on year; ammonia nitrogen, total phosphorus, and total nitrogen first increased and then decreased; and, overall, water quality significantly improved in 2019. Relationship between periphytic algae and environmental factors was further examined using redundancy analysis (RDA), which showed that time was the main factor driving the succession of algal community structure. Dissolved oxygen (DO), ammonia nitrogen (NH4+-N), total nitrogen (TN), total phosphorus (TP), five-day biochemical oxygen demand (BOD), and chemical oxygen demand (COD) were also important environmental variables affecting algal community structure.


Asunto(s)
Diatomeas , Ríos , China , Monitoreo del Ambiente , Nitrógeno/análisis , Fósforo/análisis , Fitoplancton , Estaciones del Año , Calidad del Agua
6.
Huan Jing Ke Xue ; 42(2): 977-987, 2021 Feb 08.
Artículo en Chino | MEDLINE | ID: mdl-33742894

RESUMEN

Studying the influence of precipitation patterns on plant community diversity, soil C:N:P ecological stoichiometric characteristics, and the relationships between key soil factors and plant community diversity is of great significance for the protection of plant community diversity in desert grasslands. This paper was studied in the desert steppe of the west of Loess Plateau using a three-year precipitation manipulation experiment (40% reduction in precipitation, 20% reduction in precipitation, natural precipitation, 20% increase in precipitation, and 40% increase in precipitation), explored the influence of changes in precipitation in dry and wet years on the diversity of plant community and soil C:N:P ecological stoichiometric characteristics. And we also explored the relationship between soil C:N:P ecological stoichiometric characteristics and the key soil factors and the diversity of plant community under changes in precipitation. The results showed that in a normal year and the drier year (2013 and 2015), Patrick richness and Shannon-Wiener diversity index were significantly low under the 20% reduction treatment compared with the control and 40% increase treatments, respectively. During the wetter year, Patrick richness and Shannon-Wiener diversity index were no different between any of the precipitation treatments. In the normal year and the drier year, the soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents and the carbon-nitrogen ratio (C:N), carbon-phosphorus ratio (C:P), and nitrogen-phosphorus ratio (N:P) all decreased with an increase in precipitation (the decrease in the C:N ratio was statistically significant). During the wetter year, SOC, TN, C:P, and N:P increased with an increase in precipitation. During the normal year, precipitation treatments had no significant influence on soil water content, having a limited influence on the plant community. TN, N:P, SOC, C:N, and microbial biomass nitrogen (MBN) had a more prominent influence on plant community diversity. In the wetter year, precipitation was abundant leading to a rise in soil nutrients. Water was not the most important factor limiting to plant growth whereas soil water content, soil nutrients, and ecological stoichiometric characteristics jointly regulate plant community diversity. In the drier years, precipitation treatments had a significant impact on soil water content, whereby an increase in precipitation led to high losses of soil nutrients. Therefore, soil water content was the most important factor affecting plant community diversity during drier years. These observations indicate that under dry and wet years, plant community diversity and soil C:N:P ecological stoichiometric characteristics have variable responses to precipitation and soil C:N:P effect on plant community were also different. These results provide a theoretical basis for the protection and management of desert steppe systems under future projected changes in precipitation.


Asunto(s)
Carbono , Suelo , Carbono/análisis , China , Pradera , Nitrógeno/análisis , Plantas , Microbiología del Suelo
7.
Huan Jing Ke Xue ; 42(2): 1004-1012, 2021 Feb 08.
Artículo en Chino | MEDLINE | ID: mdl-33742897

RESUMEN

Ground-level ozone (O3) pollution frequently co-occurs with drought and nitrogen (N) deposition during the growing season. It is important to understand how the carbon dynamics of plants respond to O3 pollution in drier and N-enriched environments. Here we present the patterns of non-structural carbohydrates and its components (soluble sugar and starch) in the leaves and fine roots in poplar clone 546 (Populus deltoides cv. '55/56'×P. deltoides cv. 'Imperial') for one growing season at two O3 concentrations (control, charcoal-filtered air, and elevated O3, non-filtered air+40 nmol·mol-1 of O3), two watering regimes (well-watered and reduced watering at 40% of well-watered irrigation), and two soil nitrogen addition treatments[no addition and the addition of 50 kg·(hm2·a)-1]. The results showed that O3 stress significantly increased the content of soluble sugar in leaves and starch in fine roots but decreased the content of starch and total non-structural carbohydrate (NSC) in leaves. Drought stress significantly reduced the content of starch and total NSC in leaves but increased the contents of soluble sugar and total NSC in fine roots. Nitrogen addition had no significant effect on NSC and its components in leaves and fine roots. NSC and its components in leaves and fine roots were positively correlated with photosynthetic rate and biomass. With an increase in the number of environmental stress factors, NSC in leaves showed a significant downward trend while NSC in fine roots showed a significant upward trend. The study demonstrates that environmental stress can promote the transformation of starch into soluble sugars in plant leaves and the transfer of NSC from leaves to roots for storage, which may be a coping strategy for plants exposed to environmental stress.


Asunto(s)
Ozono , Populus , Carbohidratos , Sequías , Nitrógeno , Hojas de la Planta , Raíces de Plantas
8.
Huan Jing Ke Xue ; 42(3): 1433-1442, 2021 Mar 08.
Artículo en Chino | MEDLINE | ID: mdl-33742940

RESUMEN

The loss of nitrogen (N) and phosphorus (P) from aquaculture has caused eutrophication of freshwater systems. Here, surface flow constructed wetland (SFCW) planted with Myriophyllum elatinoides were used to treat swine wastewater from a medium-sized hoggery in subtropical Central China. Inflow concentrations of NH4+-N, TN, TP, and COD ranged from 535.4 to 591.09, 682.09 to 766.96, 57.73 to 82.29, and 918.4 to 1940.43 mg·L-1, respectively. The mean removal efficiencies of NH4+-N, TN, TP, and COD were 97.4%, 97.1%, 91.0%, and 90.2%, respectively, and CW1 had the largest contributions of 37.3%, 38.4%, 43.3%, and 27.4%, respectively. Plant N and P uptake ranged 23.87-79.96 g·m-2 and 5.34-18.98 g·m-2, accounting for 19.1% and 20.2% of removal, respectively. Sediment N and P accumulation ranged 19.17-56.62 g·m-2 and 10.59-26.62 g·m-2, accounting for 19.8% and 61.7% of removal, respectively. Multiple linear regression showed that environmental factors explained 79.9% of the N removal and 70.1% of the P removal; DO was the main factor affecting N removal, and sediment adsorption was the key process in P removal. These results show that M. elatinoides constructed wetland can efficiently treat swine wastewater, thereby reduce the discharge of pollutants downstream.


Asunto(s)
Aguas Residuales , Humedales , Animales , China , Nitrógeno/análisis , Fósforo , Porcinos , Eliminación de Residuos Líquidos
9.
Huan Jing Ke Xue ; 42(3): 1469-1476, 2021 Mar 08.
Artículo en Chino | MEDLINE | ID: mdl-33742944

RESUMEN

Properties of landfill leachate are complex. Therefore, leachate should be treated by combined processes with both biological and advanced methods. Due to the shortage of engineering-scale assessment data about the pollutant treatment contribution of individual process units, existing optimization methods still lack theoretical support. Here, a membrane biological reactor (MBR)+nanofiltration (NF) system with a capacity of 800 m3·d-1 was examined. Conventional physiochemical parameters and fluorescent parameters were examined to analyze the contribution of each process unit to treating mature landfill leachate. Furthermore, the transformation of dissolved organic matter (DOM) was evaluated using excitation emission matrix fluorescence spectroscopy-parallel factor (EEMs-PARAFAC). Results showed that the biological treatment removed soluble nitrogen (dissolved nitrogen, DN) by 74.7%, 54.6% occurred in the first-stage denitrification unit. The external ultrafiltration unit reduced dissolved chemical oxygen demand (COD) and dissolved organic carbon (DOC) by 92.2% and 93.3%, respectively. The nanofiltration unit effectively removed heavy metals and salts. Based on the tracking of DOM using fluorescent parameters, the first-stage denitrification unit was found to remove 75.4% of protein-like substances. The ultrafiltration unit mainly retained DOM with high hydrophilicity, while humus with high aromaticity was mainly retained by nanofiltration. The higher the degree of humification, the better the interception effect that was obtained. This indicates that biological treatment using the MBR process can be simplified, and ultrafiltration should prove reliable at preventing clogging during the treatment of mature landfill leachate.


Asunto(s)
Contaminantes Ambientales , Contaminantes Químicos del Agua , Análisis de la Demanda Biológica de Oxígeno , Nitrógeno , Ultrafiltración , Contaminantes Químicos del Agua/análisis
10.
Huan Jing Ke Xue ; 42(3): 1477-1487, 2021 Mar 08.
Artículo en Chino | MEDLINE | ID: mdl-33742945

RESUMEN

Sulfate reduction with ammonium oxidation (SRAO) in laboratory ANAMMOX reactors was considered as an autotrophic process mediated by ANAMMOX bacteria (AnAOB), in which ammonium, as an electron donor, was oxidized by the electron acceptor sulfate. This process was developed based on the transformations of nitrogenous and sulfurous compounds observed in natural environments. Reported results vary widely for conversion mole ratios (ammonium/sulfate) as do intermediate and final products of the sulfate reduction. Thus, hypotheses surrounding biological conversion pathways of ammonium and sulfate in ANAMMOX consortia are implausible. In this study, continuous reactor experiments and batch tests were conducted under micro-aerobic (-100 mV < ORP < 0 mV, 0.5 mg·L-1 < DO < 1 mg·L-1), anoxic (-300 mV < ORP < -100 mV, 0.2 mg·L-1 < DO < 0.5 mg·L-1) and anaerobic (ORP < -300 mV, DO < 0.2 mg·L-1) conditions with different inoculated sludge (ANAMMOX sludge and mixed sludge) to verify the SRAO phenomena and identify possible pathways of substrate conversion. The key findings were that SRAO occurred only where SRB existed under anoxic condition, and was absent under anaerobic conditions with ANAMMOX consortia. The analysis of the microbial community and functional gene expression showed that ammonium oxidation by AAOB coupled with sequential ANAMMOX is possibly responsible for the loss of ammonium under anoxic condition. Organic substances released through microbial decay contributed to heterotrophic sulfate conversion by SRB. AnAOB do not possess the ability to oxidize ammonium with sulfate as the electron acceptor. SRAO could, in fact, involve a combination of aerobic ammonium oxidation, ANAMMOX, and heterotrophic sulfate reduction processes, which are mediated via AOB, AnAOB, and SRB.


Asunto(s)
Compuestos de Amonio , Anaerobiosis , Reactores Biológicos , Nitrógeno/análisis , Oxidación-Reducción , Aguas del Alcantarillado , Sulfatos
11.
Environ Monit Assess ; 193(4): 208, 2021 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-33755795

RESUMEN

Increasing gaseous emissions of nitrogen (N) and sulfur (S) associated with oil sands development in northern Alberta (Canada) has led to changing regional wet and dry N and S deposition regimes. We assessed the potential for using bog plant/lichen tissue chemistry (N and S concentrations, C:N and C:S ratios, in 10 plant/lichen species) to monitor changing atmospheric N and S deposition through sampling at five bog sites, 3-6 times per growing season from 2009 to 2016. During this 8-year period, oil sands N emissions steadily increased, while S emissions steadily decreased. We examined the following: (1) whether each species showed changes in tissue chemistry with increasing distance from the Syncrude and Suncor upgrader stacks (the two largest point sources of N and S emissions); (2) whether tissue chemistry changed over the 8 year period in ways that were consistent with increasing N and decreasing S emissions from oil sands facilities; and (3) whether tissue chemistry was correlated with growing season wet deposition of NH4+-N, NO3--N, or SO42--S. Based on these criteria, the best biomonitors of a changing N deposition regime were Evernia mesomorpha, Sphagnum fuscum, and Vaccinium oxycoccos. The best biomonitors of a changing S deposition regime were Evernia mesomorpha, Cladonia mitis, Sphagnum fuscum, Sphagnum capillifolium, Vaccinium oxycoccos, and Picea mariana. Changing N and S deposition regimes in the oil sands region appear to be influencing N and S cycling in what once were pristine ombrotrophic bogs, to the extent that these bogs may effectively monitor future spatial and temporal patterns of deposition.


Asunto(s)
Líquenes , Humedales , Alberta , Ascomicetos , Monitoreo del Ambiente , Nitrógeno/análisis , Yacimiento de Petróleo y Gas , Parmeliaceae , Azufre/análisis
12.
Sci Total Environ ; 764: 142917, 2021 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-33757240

RESUMEN

A full-scale sewage treatment plant in Xi'an city is discovered as the first mainstream anaerobic ammonia oxidation (anammox) treatment process in China. Whether its biological mechanism is the nitritation-anammox or partial denitrification (PD)-anammox brought violent controversy between two groups. As a third party, here we uncovered the mystery of the moving-bed biofilm reactor (MBBR) as a PD-anammox process by analyzing the diversity and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) of microbes in anoxic pond. Anammox bacteria was found in the MBBR anoxic tank, which abundance is 8.9 times of that in the common anaerobic-anoxic-oxic process, confirming the existence of anammox process. The denitrifying bacteria (DNB) content in the anoxic tank is 5.9 times of the content of ammonia oxidizing bacteria (AOB), thus the DNB-anammox system is proved at the microbial composition level. The PICRUSt analysis found that ammonium nitrogen is mainly derived from the deamination of urea. The functional genes NAR and AMO of DNB and AOB are 910.84 and 5.80 rpms, respectively. The NAR gene content is 157.0 times of the AMO gene content and it is proved at the genetic level that the nitrite in the anoxic pool is mainly derived from denitrification. This study demonstrated the feasibility and advantages of the PD-anammox in the anammox process, which is different from the traditional nitritation-anammox demonstrated in Strass Wastewater Treatment Plant, Austria and Changi Water Reclamation Plant, Singapore and provided an alternative option for the mainstream application of anammox.


Asunto(s)
Compuestos de Amonio , Desnitrificación , Anaerobiosis , Austria , Biopelículas , Reactores Biológicos , China , Nitrógeno , Oxidación-Reducción , Filogenia , Aguas del Alcantarillado , Singapur , Aguas Residuales/análisis
13.
Sci Total Environ ; 764: 142824, 2021 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-33757258

RESUMEN

Intensive agriculture and growing human populations are important nitrogen (N) sources thought to be associated with eutrophication. However, the contribution and seasonality of N delivery to streams from human activities is poorly understood and knowledge of the role of stream communities in the assimilation of N from human activities is limited. We used N and oxygen stable isotope ratios of dissolved inorganic N (DIN) and concentrations of artificial sweeteners to identify the relative contribution of key sources of anthropogenic N (i.e., fertilizers, human, and livestock waste) to tributaries of the Red River Valley (RRV), Manitoba, Canada. Water and algae were sampled in 14 RRV tributaries during snowmelt, spring, summer, and autumn; and water was sampled at three locations in the Red River in spring, summer, and autumn. δ15N values of DIN in tributary water differed seasonally and were greatest during snowmelt. Incorporation of ammonium δ15N provided evidence for the importance of manure N to tributaries during snowmelt. Fertilizer and municipal lagoons served as principal sources of N to streams in spring and summer. Human and livestock waste sources of N were the dominant contributor to algae at greater than 90% of sites and algae δ15N was greatest at sites downstream of municipal lagoons. We also showed that the tributaries contribute human and livestock waste N to the Red River, though much of the nitrate in the river originates outside of Manitoba. Overall, our study determined that the anthropogenic sources of N to RRV streams vary seasonally, likely due to regional hydrologic conditions. Our study also showed the potential of artificial sweeteners and ammonium δ15N as tools for identifying N sources to rivers. Moreover, we demonstrate the need for the management of N sources and the protection of stream function to control downstream transfer of N from landscapes to waterbodies.


Asunto(s)
Nitrógeno , Contaminantes Químicos del Agua , Canadá , Monitoreo del Ambiente , Humanos , Manitoba , Nitratos/análisis , Nitrógeno/análisis , Isótopos de Nitrógeno/análisis , Contaminantes Químicos del Agua/análisis
14.
Waste Manag ; 125: 220-234, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33711736

RESUMEN

Although microbial inoculants are promoted as a strategy for improving compost quality, there is no consensus in the published literature about their efficacy. A quantitative meta-analysis was performed to estimate the overall effect size of microbial inoculants on nutrient content, humification and lignocellulosic degradation. A meta-regression and moderator analyses were conducted to elucidate abiotic and biotic factors controlling the efficacy of microbial inoculants. These analyses demonstrated the beneficial effects of microbial inoculants on total nitrogen (+30%), total phosphorus (+46%), compost maturity index (C:N ratio (-31%), humification (+60%) and the germination index (+28%). The mean effect size was -46%, -65% and -40% for cellulose, hemicellulose, and lignin respectively. However, the effect size was marginal for bioavailable nutrient concentrations of phosphate, nitrate, and ammonium. The effectiveness of microbial inoculants depends on inoculant form, inoculation time, composting method, and experimental duration. The microbial inoculant effect size was consistent under different feedstock types and experimental scales. These findings imply that microbial inoculants are important for accelerating lignocellulose degradation. Higher mean effect sizes have tended to be published in journals with higher impact factors, thus researchers should be encouraged to publish non-significant findings in order to provide a more reliable estimation of effect size and clarify doubts about the benefits of microbial inoculants for composting.


Asunto(s)
Compostaje , Lignina , Nitrógeno/análisis , Nutrientes , Suelo
15.
Waste Manag ; 125: 293-302, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33721702

RESUMEN

The recovery of valuable materials from waste fits the principle of circular economy and sustainable use of resources, but contaminants in the waste are still a major obstacle. This works proposes a novel approach to recover high-purity phosphorus (P) and nitrogen (N) from digestate of municipal solid waste based on the combination of two independent membrane processes: electrodialytic (ED) process to extract P, and gas permeable membranes (GPM) for N extraction. A laboratory ED cell was adapted to accommodate a GPM. The length of waste compartment (10 cm; 15 cm), current intensity (50 mA; 75 mA) and operation time (9 days; 12 days) were the variables tested. 81% of P in the waste was successfully extracted to the anolyte when an electric current of 75 mA was applied for 9 days, and 74% of NH4+ was extracted into an acid-trapping solution. The two purified nutrient solutions were subsequently used in the synthesis of a biofertilizer (secondary struvite) through precipitation, achieving an efficiency of 99.5%. The properties of the secondary struvite synthesized using N and P recovered from the waste were similar to secondary struvite formed using synthetic chemicals but the costs were higher due to the need to neutralize the acid-trapping solution, highlighting the need to further tune the process and make it economically more competitive. The high recycling rates of P and N achieved are encouraging and widen the possibility of replacing synthetic fertilizers, manufactured from finite sources, by secondary biofertilizers produced using nutrients extracted from wastes.


Asunto(s)
Fósforo , Eliminación de Residuos Líquidos , Nitrógeno , Nutrientes , Fosfatos , Estruvita , Aguas Residuales
16.
Water Sci Technol ; 83(6): 1327-1334, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33767039

RESUMEN

Three carbon sources, namely sodium acetate, sewage and effluent, were used to simulate the process of phosphorus release in an actual sewage treatment plant, in order to explore the phosphorus release performance of the sludge, the relationship between phosphorus release and chemical oxygen demand (COD) in sewage, and the stability of phosphorus-rich sludge. The results showed that the type and concentration of carbon sources had significant effects on the rate of phosphorus release, reaction equilibrium time and phosphorus release amount. When sodium acetate was used as the carbon source, the phosphorus release rate reached 12.54 mg P (g VSS·h)-1, and tended to be stable at 4.0 hours. The phosphorus release amount in the first 2.5 hours accounted for 36.88% of the total phosphorus in the sludge. When sewage was used as the carbon source, the phosphorus release rate did not reach equilibrium even at 5.0 hours, and the phosphorus release amount increased by 1.0 mg L-1 for every 10.5 mg L-1 increase sewage COD within a certain range. When effluent was used as the carbon source, the visual phosphorus release amount was only 0.83 mg L-1 after standing for 24 hours and the actual phosphorus release amount was 17.98 mg L-1. These conclusions can provide technical support for the optimization of phosphorus removal in sewage treatment plants.


Asunto(s)
Fósforo , Aguas del Alcantarillado , Anaerobiosis , Reactores Biológicos , Carbono , Nitrógeno , Eliminación de Residuos Líquidos
17.
Water Sci Technol ; 83(6): 1335-1346, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33767040

RESUMEN

This study highlights the need to increase our understanding of the interplay between sensor drift and the performance of the automatic control system. The impact from biased sensors on the automatic control systems is rarely considered when different control strategies are assessed in water resource recovery facilities. Still, the harsh measurement environment with negative effects on sensor data quality is widely acknowledged. Simulations were used to show how sensor bias in an ammonium cascade feedback controller impacts aeration energy efficiency and total nitrogen removal in an activated sludge process. Response surface methodology was used to reduce the required number of simulations, and to consider the combined effect of two simultaneously biased sensors. The effects from flow variations, and negatively biased ammonium (-1 mg/L) and suspended solids sensors (-500 mg/L) reduced the nitrification aeration energy efficiency by between 7 and 25%. Less impact was seen on total nitrogen removal. There were no added non-linear effects from the two simultaneously biased sensors, apart from an interaction between a biased ammonium sensor and dissolved oxygen sensor located in the last aerated zone. Negative effects from sensor bias can partly be limited if the expected bias direction is considered when the controller setpoint-limits are defined.


Asunto(s)
Oxígeno , Eliminación de Residuos Líquidos , Reactores Biológicos , Nitrificación , Nitrógeno , Oxígeno/análisis , Aguas del Alcantarillado
18.
Water Sci Technol ; 83(6): 1418-1428, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33767047

RESUMEN

Mathematical modelling was used to investigate the possibility to use membrane aerated biofilm reactors (MABRs) in a largely anoxic suspended growth bioreactor to produce the nitrate-nitrogen required for heterotrophic denitrification and the growth of denitrifying phosphorus accumulating organisms (DPAOs). The results indicate that such a process can be used to achieve a variety of process objectives. The capture of influent biodegradable organic matter while also achieving significant total inorganic nitrogen (TIN) removal can be achieved with or without use of primary treatment by operation at a relatively short suspended growth solids residence time (SRT). Low effluent TIN concentrations can also be achieved, irrespective of the influent wastewater chemical oxygen demand (COD)/total nitrogen (TN) ratio, with somewhat larger suspended growth SRT. Biological phosphorus and nitrogen removal can also be effectively achieved. Further experimental work is needed to confirm these modelling results.


Asunto(s)
Aguas del Alcantarillado , Eliminación de Residuos Líquidos , Biopelículas , Reactores Biológicos , Desnitrificación , Nitrógeno , Nutrientes , Fósforo
19.
Water Sci Technol ; 83(6): 1459-1469, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33767050

RESUMEN

Several water treatment techniques have been combined using the sequencing batch reactor with the membrane bioreactor for addressing water pollution. However, cleaning of the membrane is dependent on the approach involved as well as the operating conditions. In the present study, the sequencing-batch membrane bioreactor was used to treat real mixed municipal wastewater. The pollutant removal and membrane filtration performances were examined. The results show that the average removal rates of chemical oxygen demand (COD), total nitrogen, NH3-N, total phosphorus, and turbidity were 90.75, 63.52, 92.85, 87.58, and 99.48%, respectively, when the system was in continuous operation for 95 days. The membrane had a significant effect on COD and turbidity removal and provided stable performances for nitrogen and phosphorus removal. By observing the appearance of the membrane modules before and after the cleaning operation, it was concluded that the deposited sludge and granular sediment on the membrane surface can be effectively removed by hydraulic cleaning. In addition, recovery of membrane filtration performance to 60% of that of a new membrane can be achieved. Furthermore, we found that different sequences and duration of cleaning have different effects on the recovery of membrane filtration performance.


Asunto(s)
Eliminación de Residuos Líquidos , Aguas Residuales , Análisis de la Demanda Biológica de Oxígeno , Reactores Biológicos , Nitrógeno , Fósforo , Aguas del Alcantarillado
20.
Water Sci Technol ; 83(6): 1483-1498, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33767052

RESUMEN

In recent years, the use of microalgae as feedstock for many marketable products, such as animal/aqua feeds, bioplastics and fertilizers, has gained renewed interest due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrient content. An algal biorefinery at an industrial site has the potential to sustainably and profitably convert carbon dioxide emissions into microalgal biomass and concomitantly reduce nitrogen and phosphorus from wastewaters. Industrial wastewaters are a potential alternative to traditional media used for large-scale microalgal cultivation. Pulp and paper mills are major consumers of water resources and discharge a huge amount of water to nearby lakes or rivers. This study investigated whether pulp and paper mill waste water is suitable for microalgal cultivation with the aim of achieving significant biomass production. Six different process waters from one Canadian pulp and paper mill were tested with two freshwater green microalgae. All of these waters were unable to support growth of microalgae due to inadequate nutrient concentrations, colour, turbidity and possible toxicity issues.


Asunto(s)
Microalgas , Animales , Biocombustibles , Biomasa , Agua Dulce , Nitrógeno , Nueva Escocia , Aguas Residuales
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