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1.
Bioresour Technol ; 333: 125082, 2021 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-33878502

RESUMEN

High concentrations of nitrous oxide were recovered from partial nitrification treated leachate in a microbial electrolysis cell (MEC) inoculated with a nosZ-deficient strain of Pseudomonas aeruginosa. N2O conversion efficiencies > 90% were achieved when a potential of 0.8 V was applied to the MEC. The ΔnosZ strain was enriched in the 0.8 V MEC, but Achromobacter dominated the non-current control. Nitric oxide reductase genes were highly expressed by ΔnosZ cells growing in the 0.8 V MEC, consistent with enhanced nitrous oxide production rates. Concentrations of phenazine derivatives and transcripts from phenazine biosynthesis genes were also high in the 0.8 V MEC. Phenazine derivatives are known to act as electron shuttles, enhance biofilm formation, and help ward off competitors, thereby increasing the survivability of the ΔnosZ strain in the MEC. These results show that applied current stabilized growth of the ΔnosZ strain in the reactor and allowed it to sustainably generate high concentrations of nitrous oxide.

2.
Bioresour Technol ; 330: 124965, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33735725

RESUMEN

With the increasing of data in wastewater treatment, data-driven machine learning models are useful for modeling biological processes and complex reactions. However, few data-driven models have been developed for simulating the microbial electrolysis cells (MECs) and traditional models are too ambiguous to comprehend the mechanisms. In this study, a new general data-driven two-stage model was firstly developed to predict CH4 production from in-situ biogas upgrading in the biocathode MECs via direct electron transfer (DET), named NARX-BP hybrid neural networks. Compared with traditional one-stage model, the model could well predict methane production via DET with excellent performance (all R2 and MES of 0.918 and 6.52 × 10-2, respectively) and reveal the mechanisms of biogas upgrading, for the new systematical modeling approach could improve the versatility and applicability by inputting significant intermediate variables. In addition, the model is generally available to support long-term prediction and optimal operation for anaerobic digestion or complex MEC systems.


Asunto(s)
Biocombustibles , Metano , Anaerobiosis , Reactores Biológicos , Electrólisis , Electrones , Aprendizaje Automático , Redes Neurales de la Computación
3.
Water Res ; 197: 117055, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33789202

RESUMEN

Biogas produced from anaerobic digestion usually contains 30%-50% CO2, much of which must be removed, before utilization. Bioelectrochemical biogas upgrading approaches show promise, however, they have not yet been optimized for practical applications. In this study, a bioelectrochemical system with low energy input (applied cathode potential of -0.5 V vs. standard hydrogen electrode, SHE) was used for in-situ biogas upgrading. High efficiency CO2 conversion (318.5 mol/d/m2) was achieved when the system was operated with an organic load of 1.7 kgCOD/(m3 d). Methane content in the upgraded biogas was 97.0% and CO2 concentrations stayed below 3%, which is comparable to biogas upgraded with more expensive and less sustainable physiochemical approaches. The high efficiency of this approach could likely be attributed to a significant enrichment of Methanothrix (92.7%) species on the cathode surface that were expressing genes involved in both acetogenic methanogenesis and direct electron transfer (DET). Electromethanogenesis by these organisms also increased proton consumption and created a higher pH that increased the solubility of CO2 in the bioreactor. In addition, CO2 removal from the biogas was likely further enhanced by an enrichment of Actinobacillus species known to be capable of CO2 fixation. Artificial neural network (ANN) models were also used to estimate CH4 production under different loading conditions. The ANN architecture with 10 neurons at hidden layers fit best with a mean square error of 6.06 × 10-3 and R2 of 0.99.


Asunto(s)
Biocombustibles , Metano , Reactores Biológicos , Dióxido de Carbono , Electrodos , Methanosarcinaceae
4.
Sci Total Environ ; 776: 145991, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33652319

RESUMEN

Volatile sulfur compounds (VSCs) generated and discharged as air pollutants from wastewater treatment plants (WWTPs) pose a threat to human health and the environment. This study characterized VSC emissions from a full-scale sequencing batch reactor (SBR) WWTP at the water-air interface for one year. Results demonstrated that higher ambient temperatures and aeration contributed significantly to VSC emissions as the highest emissions occurred over summer during the feeding synchronous aeration period. VSC emissions were related to chemical oxygen demand and sulfate concentrations in wastewater, and empirical formulas based on these values were proposed that can be used to model VSC emission fluxes from SBR WWTP. VSC emission factors (µg·ton-1 wastewater) throughout the SBR treatment process were: 361 ± 101 hydrogen sulfide (H2S), 82 ± 76 methyl mercaptan (MT), 61 ± 31 dimethyl sulfide, 17 ± 5 carbon disulfide, and 46 ± 24 dimethyl disulfide. H2S and MT were the dominant odors released. Findings from this study may be applicable for calculating VSC emissions during SBR wastewater treatment stages, and may be beneficial for determining methods and strategies to reduce VSCs.


Asunto(s)
Contaminantes Atmosféricos , Purificación del Agua , Humanos , Odorantes/análisis , Azufre , Compuestos de Azufre
5.
Environ Pollut ; 274: 116516, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33529890

RESUMEN

Anaerobic digestion (AD) with thermal hydrolysis pre-treatment (THP) is an effective sludge treatment method which provides several advantages such as enhanced biogas formation and fertilizer production. The main limitation to THP-AD is that hazardous odors, including NH3 and volatile sulfur compounds (VSCs), are emitted during the sludge treatment process. In order to develop strategies to eliminate odors, it is necessary to identify the key odors and emissions sites. This study identified production of NH3 (741.60 g·dry sludge t-1) and VSCs (277.27 g·dry sludge t-1) during sludge AD after THP, and measured emissions in each of the THP-AD sludge treatment sites. Odor intensity, odor active values, permissible concentration-time weighted average, and non-carcinogenic risks were also assessed in order to determine the sensory impact, odor contribution, and health impacts of NH3 and VSCs. The results revealed that odor pollution existed in all of the test sites, particularly in the sludge pump room and pre-dehydration workshop. NH3, H2S, and methyl mercaptan caused very strong odors, and levels of NH3 and H2S were enough to impact the health of on-site employees.


Asunto(s)
Aguas del Alcantarillado , Purificación del Agua , Anaerobiosis , Hidrólisis , Odorantes/análisis
6.
Ecotoxicol Environ Saf ; 211: 111912, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33493727

RESUMEN

The reuse of the sewage is an effective way to solve the shortage of water resources, but disinfection by-products (DBPs) caused by chlorination may bring potential ecological and health risks to the supplied water. In this study, the occurrence and potential ecological risk of DBPs in SH River in Beijing were evaluated. Four kinds of DBPs were detected in 84 samples by GC-MS, including THM, CH, CTC and TCAN, whose detection rates were 100%, 100%, 100% and 2.38%, respectively. Combining with the relevant standard limitation and corresponding threshold values in China, and the reported concentration in domestic and foreign literatures, the results showed that the number of samples which [THM], [CTC] and [CH] exceeded the threshold values in relevant standard for 23.81%, 100.00% and 89.29%, respectively. CTC showed the highest excess times than the threshold value with [CTC]max was 356.46 µg/L. In addition, the temporal and spatial characteristics of identified DBPs were studied. [THM], [CTC] and [CH] all exhibited the highest concentration in Aug., which was as the same as the variation trend of air and water temperature. With the increase of sampling distance, [THM] and [CTC] fluctuated greatly, and the background values in SH River were higher due to the supplement of the reclaimed water. [CH] and [TCAN] gradually decreased, which may be due to that they were more prone to volatilize in the channel and be degraded by aquatic microorganisms. In addition, the occurrence situation in S2 and S7, were in the order of CTC > CH > THM. Hence, the rank of the occurrence situation of identified DBPs was CTC > CH > THM > TCAN. Multivariate analysis showed that THM was significantly positively correlated with CTC and their sources were similar. Moreover, they were all affected by solution pH and DO. Potential ecological risk assessment indicated that the rank of identified DBPs ecological risk was CTC > THM > CH > TCAN. Among them, the risk level of CTC and THM were high in both daily and extreme situations. Therefore, the potential ecological risk caused by DBPs should be fully considered in the process of reclaimed water supplying landscape water, such as urban river. If a higher level of the ecological risk management is needed, THM, CTC and CH, especially CTC, should be considered firstly.


Asunto(s)
Desinfectantes/análisis , Monitoreo del Ambiente , Contaminantes Químicos del Agua/análisis , Beijing , China , Desinfectantes/química , Desinfección/métodos , Cromatografía de Gases y Espectrometría de Masas , Halogenación , Medición de Riesgo , Ríos , Eliminación de Residuos Líquidos , Aguas Residuales/análisis , Purificación del Agua/métodos , Abastecimiento de Agua
7.
J Hazard Mater ; 412: 125145, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33516109

RESUMEN

While ammonia (NH3) is one of the primary hazardous emissions from sludge aerobic composting plants, it has the potential to be recycled as an energy source or nitrogen fertilizer. Recently, an NH3 molecularly imprinted polymer (NH3-MIP) was developed that efficiently separated NH3 from other compounds, but its adsorption capacity required improvement. This study improved both NH3 adsorption capacity and separation of the NH3-MIP using acid hydrolysis optimization. NH3 adsorption capacity increased 13-fold and remained between 5.59 and 7.84 mmol·g-1 during simulated sludge aerobic composting. Separation factors for NH3/methyl sulfide (DMS) (i.e. NH3 adsorption capacity/DMS adsorption capacity) and NH3/dimethyl disulfide both increased more than 15-fold. Results showed that hydrolysis of the ester crosslinker, ethylene glycol dimethacrylate, on the NH3-MIPs produced chemical adsorption sites (‒COOH and epoxides) and increased hydrogen bonds (‒COOH and alcohol hydroxyl), which promoted NH3 adsorption and separation. It is expected that this will be a beneficial strategy for elimination of odors and NH3 recovery during sludge aerobic composting.

8.
J Colloid Interface Sci ; 581(Pt A): 314-322, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32771741

RESUMEN

Three-dimensional polyaniline (PANI) hydrogel was used as the conductive medium to improve the methane (CH4) production from the anaerobic degradation of organics in wastewater. The porous structure and hydrophilic surface of the PANI hydrogel promoted the adhesion of the anaerobes. The PANI hydrogel existed as a conductive emeraldine base (EB) form with a conductivity of 0.42 S/cm, and had a good biocompatibility with the microorganisms in the anaerobic system. The conductive PANI hydrogel was added into the anaerobic sludge as the conductive medium of the direct interspecies electron transfer (DIET) between bacteria and archaea, accelerating CH4 production during the biodegradation of organic pollutants. The results indicated that the CH4 production rate was increased by 10.50%, 14.21%, 28.77% and 19.30% from the anaerobic system with adding 1000, 2000, 3000 and 4000 mg/L of PANI hydrogel. The proportion of Methanosaeta in the anaerobic sludge with the ability of DIET was increased to 64.74% after adding the PANI hydrogel. The conductive PANI hydrogel served as an electronic channel to enrich the microorganism with the DIET ability, which was responsible for PANI hydrogel improved CH4 production.

9.
Environ Res ; 189: 109884, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32678736

RESUMEN

Biological treatment of high salinity organic wastewater is a significant challenge because many microorganisms involved in the anaerobic digestion process cannot survive high osmotic pressures. In order to alleviate some of the stresses associated with the treatment of high salinity wastewater, two lab-scale up-flow anaerobic sludge bed reactors with or without magnetite (100 g/L) were used to treat high salinity organic wastewater. This study showed that the bioreactor amended with magnetite had higher chemical oxygen demand removal efficiencies (90.2% ± 0.54% vs 73.1% ± 1.9%) and methane production rates (4082 ± 334 ml (standard temperature and atmospheric pressure, STP)/d vs 2640 ± 120 ml (STP)/d) than the non-amended control reactor. In addition, the consumption of volatile fatty acids (20.9 ± 3.4 mM vs 61.7 ± 2.0 mM) was accelerated. Microbial community analysis revealed that the addition of magnetite caused the enrichment of many bacterial genera known to form robust biofilms (i.e. Pseudomonas) that are also capable of extracellular electron transfer and methanogens from the genus Methanosarcina which have been shown to participate in direct interspecies electron transfer. These results show that magnetite addition could enhance the performance of anaerobic digesters treating high salinity wastewater.

10.
IET Nanobiotechnol ; 14(4): 308-313, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32463021

RESUMEN

The binding reaction of reduced graphene oxide-silver nanocomposites (rGO-AgNCs) with calf thymus single-stranded DNA (ssDNA) was studied by ultraviolet-visible absorption, fluorescence spectroscopy and circular dichroism (CD), using berberine hemisulphate (BR) dye as a fluorescence probe. The absorbance of ssDNA increases, but the fluorescence intensity is quenched with the addition of rGO-AgNCs. The binding of rGO-AgNCs with ssDNA was able to increase the quenching effects of BR and ssDNA, and induce the changes in CD spectra. All of the evidence indicated that there was a relatively strong interaction between ssDNA and rGO-AgNCs. The data obtained from fluorescence experiments revealed that the quenching process of ssDNA caused by rGO-AgNCs is primarily due to complex formation, i.e. static quenching. The increasing trend of the binding equilibrium constant (Ka) with rising temperature indicated that the binding process was an endothermic reaction. The calculated thermodynamic parameters showed that the binding process was thermodynamically spontaneous, and hydrophobic association played predominant roles in the binding of ssDNA to the surface of rGO-AgNCs.

11.
Water Environ Res ; 92(11): 1888-1898, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32306479

RESUMEN

Heavy metals in reclaimed water are a global problem that leads to ecological risks for the replenishment water body. This study investigated concentrations and ecological risks posed by heavy metals in SH River, Beijing, which is supplied by reclaimed water. Results showed that Cr was not detected in the sample, Cd and Pb exceeded threshold values according to regulations by 1.19% and 25.00%, respectively. The characterization of temporal and spatial of heavy metals was studied. The potential ecological risks posed by heavy metals in SH River were found to be low and safe. The risk decreased in the order Pb > Cu > Zn > Ni > Cd > As by comprehensive index assessment; this changed to Pb > Cd > As > Ni > Cu > Zn according to potential ecological risk assessment. Pb posed the greatest ecological risks and was identified as most contaminated metal. According to discussion of sampling sites and water quality, it was proposed that reclaimed water and exogenous discharges were the main sources of the heavy metals identified. This should be considered when developing catchment management strategies for heavy metals elimination and protection of the aquatic environment. If a higher level of ecological risk management is required, Pb, Cd, and Cu should be considered first and should be removed in situ through ecological remediation methods. PRACTITIONER POINTS: Reclaimed water and exogenous discharges were the main sources of the heavy metals identified. The potential ecological risks posed by heavy metals in SH River were found to be low and safe. The risk decreased in the order Pb > Cu > Zn > Ni > Cd > As by comprehensive index assessment. Potential ecological risk assessment showed Pb > Cd > As > Ni > Cu > Zn. Pb posed the greatest ecological risks and was identified as most contaminated metal.


Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Beijing , China , Monitoreo del Ambiente , Sedimentos Geológicos , Metales Pesados/análisis , Medición de Riesgo , Ríos , Aguas Residuales , Contaminantes Químicos del Agua/análisis
12.
Chemosphere ; 249: 126449, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32208217

RESUMEN

Influence of floc breakage and re-growth on the release of natural dissolved organic matter (DOM) and dissolved Al was explored. Results indicated that Al species including monomeric species (Ala), medium polymer species (Alb), and colloidal or solid species (Alc) in polyaluminum chlorides (PACls) played significant role. At lower doses ranged from 5 to 20 mg/L, floc breakage damaged Ala-NOM bonds for AlCl3, causing obvious release of DOM and dissolved Al. After re-growth, dissolved Al mainly connected with broken flocs, rather than released DOM. Thus, after re-growth, DOM release was still remarkable, but additional removal of dissolved Al was observed. At higher doses above 20 mg/L, more Ala transformed to Alb and Alc. Due to the enmeshment effect induced by Alc coagulation, fewer DOM and dissolved Al were released after breakage, and additional removal of DOM and dissolved Al were attained after re-growth. For PAClAl13 which mainly contained Alb, at optimal dose, floc breakage generated the most severe release of DOM and dissolved Al, while the result after re-growth was just reverse. This was ascribed to stronger charge neutralization ability of Alb. Furthermore, the influence of floc breakage and re-growth on DOM and dissolved Al for PAClC was similar to that for AlCl3. The reason was fully analyzed in this research. This study may give further indication regarding reaction mechanisms of floc breakage and re-growth for PACls.


Asunto(s)
Aluminio/toxicidad , Eliminación de Residuos Líquidos/métodos , Hidróxido de Aluminio/toxicidad , Cloruros , Floculación , Polímeros/química
13.
Chemosphere ; 249: 126077, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32045752

RESUMEN

Aerobic composting and anaerobic digestion with hydrolysis pretreatment are two mainstream methods used to recycle and reclaim sewage sludge. However, during these sludge treatment processes, many odors are emitted that may cause severe emotional disturbance and health risks to those exposed. This study identified odor pollution (i.e. sensory influence, odor contribution, and human risks) from samples collected during sludge aerobic composting throughout different seasons as well as during anaerobic digestion with hydrolysis pretreatment. Odor intensity, odor active values, and permissible concentration-time weighted averages for ammonia and five volatile sulfur compounds were assessed. The results revealed serious odor pollution from all sampling sites during aerobic composting, especially in winter. Excessively strong odors were identified in the composting workshop, with total odor active values between 997 and 8980 which accounted for 78.45%-96.18% of the total sludge aerobic composting plant. Levels of ammonia and dimethyl disulfide in the ambient air were high enough to harm employees' health. During anaerobic digestion, excessively strong odors were identified in dehydration workshop 2, and the total odor active values of six odors reached 32,268, with ammonia and hydrogen sulfide levels significant enough to harm human health.


Asunto(s)
Compostaje , Odorantes/análisis , Medición de Riesgo , Estaciones del Año , Aguas del Alcantarillado , Aerobiosis , Amoníaco/análisis , Anaerobiosis , Humanos , Hidrólisis , Compuestos de Azufre/análisis
14.
Bioresour Technol ; 300: 122670, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31901512

RESUMEN

Ammonia (NH3) is the predominant harmful odor emitted from sludge aerobic composting plants, however, this NH3 could be recycled and used as energy or nitrogen fertilizer. Therefore, the aim of this study was to use molecular imprinting technology to prepare an adsorbent that could separate NH3 from mixed gases. An NH3 molecular imprinted polymer (NH3-MIP) was prepared by precipitation polymerization and optimal synthesis was determined by testing several different ratios of reaction components. NH3 adsorption capacity of the optimal NH3-MIP was 1.62 times that of non-imprinted material. NH3 separation factors increased from 154 (dimethyl sulfides) and 217 (dimethyl disulfides) for non-imprinted material, to 213 (dimethyl sulfides) and 302 (dimethyl disulfides) for the NH3-MIP. The adsorption mechanism was identified as physical adsorption and hydrogen bonding between H-O on the -COOH in NH3-MIP and the nitrogen in NH3. Effective desorption at 150 °C with vacuum maintained over 95% of the NH3 adsorption capacity.


Asunto(s)
Compostaje , Impresión Molecular , Adsorción , Amoníaco , Aguas del Alcantarillado
15.
Bioresour Technol ; 297: 122422, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31767427

RESUMEN

In order to illustrate the impact that application of positive or negative potential to conductive materials can have on direct interspecies electron transfer (DIET) and reactor performance under high organic loading rates, three continuous laboratory-scale reactors with carbon-cloth electrodes poised at +0.7 V, -0.7 V (vs. Ag/AgCl) and no-potential were fed high concentrations of ethanol wastewater. While exoelectrogens and methanogens that are capable of DIET were significantly enriched in poised reactors, they performed worse than the non-current control. Volatile fatty acids (VFAs) accumulated more rapidly in the positively then negatively poised reactor, but neither could withstand high-loading rates. These results demonstrate that applying potential to conductive materials had a negative effect on anaerobic digestion under high-loading conditions.


Asunto(s)
Reactores Biológicos , Metano , Anaerobiosis , Transporte de Electrón , Electrones
16.
Bioresour Technol ; 297: 122371, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31753601

RESUMEN

In this study, nitrous oxide was recovered from a lab-scale moving-bed biofilm reactor (MBBR) treating partial nitrification-treated leachate supplemented with a nosZ-deficient strain of Pseudomonas aeruginosa. Batch culture tests with the nosZ-deficient strain determined that the threshold for free nitrous acid (FNA) inhibition was 0.016 mg/L and that FNA concentrations above this threshold severely inhibited denitrification and transcription of genes from the dissimilatory nitrate reduction pathway (narG, nirS, and norB). High nitrite removal and N2O conversion efficiencies (>95%) were achieved with long-term operation of this MBBR. N2O accounted for the majority of biogas (80%) produced when the MBBR was fed partial nitrification-treated leachate with high nitrite concentrations and the drainage ratio was adjusted to 30%. Bacterial community analysis revealed that the nosZ-deficient Pseudomonas strain remained metabolically active and was primarily responsible for denitrification processes in the reactor. This study presents a promising method for N2O recovery from incineration leachate.


Asunto(s)
Óxido Nitroso , Pseudomonas aeruginosa , Biopelículas , Reactores Biológicos , Desnitrificación , Incineración
17.
Bioresour Technol ; 298: 122547, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31837579

RESUMEN

Anaerobic dynamic membrane bioreactors (AnDMBRs) can improve the efficiency of organic matter removal during wastewater treatment at a low cost. However, application of AnDMBRs for treatment of high-strength wastewater is usually unsuccessful. This study investigated whether use of conductive carbon cloth as the supporting material in an AnDMBR permits higher organic loading rates for treatment of brewery wastewater than non-conductive polyester cloth. The AnDMBR with carbon cloth operated stably with a COD removal efficiency of 98% even when high concentrations of influent COD (10,000 mg/L) were provided, while the polyester cloth reactor deteriorated when reactors were fed only 5000 mg/L influent COD. Microorganisms capable of direct interspecies electron transfer (DIET), including Geobacter and Methanothrix species, dominated the surface of the carbon cloth. These results demonstrate that carbon cloth provides an excellent supporting material for AnDMBRs by stimulating growth of microorganisms that can directly transport electrons to and from conductive materials.


Asunto(s)
Carbono , Aguas Residuales , Anaerobiosis , Reactores Biológicos , Textiles , Eliminación de Residuos Líquidos
18.
Bioresour Technol ; 291: 121877, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31376672

RESUMEN

Bioelectrochemical conversion of CO2 to CH4 is a promising way to increase the calorific value of biogas produced during anaerobic digestion. There are two groups of methanogens enriched in these systems, hydrogenotrophs and acetoclastic methanogens that can also directly accept electrons from an electrode or another microorganism. In this study, a microbial electrolysis cell (MEC) poised at -500 mV (vs. SHE) was operated for biogas upgrading. Methane content in the biogas increased from 71% to >90%, and 8.2% of the CO2 was converted to methane. Methanothrix, an acetoclastic methanogen that can participate in direct electron transfer (DET), and Azonexus, an acetate-oxidizing electrogen, were enriched on the cathode. Transcriptomics revealed that Methanothrix on the cathode were using the CO2 reduction pathway, while Methanothrix in the bulk sludge were using the acetate decarboxylation pathway for production of methane. These results show that stimulation of DET in MEC enhances biogas-upgrading processes.


Asunto(s)
Biocombustibles , Methanosarcinaceae , Electrodos , Electrólisis , Transporte de Electrón , Electrones , Metano/metabolismo , Aguas del Alcantarillado
19.
Ecotoxicol Environ Saf ; 181: 499-507, 2019 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-31229840

RESUMEN

In recent years, increasing eutrophication in large freshwater lakes, which are an important drinking water source for cities in China, have been resulted in substantial cyanobacteria blooms that could cause serious taste and odor (T&O) problems. In this investigation, three typical lakes (Songhua Lake, Chaohu Lake and Taihu Lake) as drinking water sources located in different geographical areas in China, were selected to study the problems of cyanobacteria-derived T&O (i.e., 2-methylisobornoel, geosmin, ß-ionone, 2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine, and 2-methylbenzofuran). The occurrence of T&O in target lakes was compared across various nutrition states and geographic locations, to get more information for early warning for algal bloom and T&O occurrence, being useful lake water management and purification. Results show that the occurrence of T&O in Songhua Lake was the poorest for the lowest nutrient state, as a first report in T&O research field in China. This is a lake located in Northeast China at high latitude, with lower water temperatures. The occurrence of T&O in Chaohu Lake was ranked in the middle. That in Taihu Lake was the most intensive. Finally, the relationship between water quality, T&O and its origin was analyzed by multivariate statistical methods (correlation analysis, principal component, and cluster analyses).


Asunto(s)
Cianobacterias/metabolismo , Lagos/microbiología , Odorantes/análisis , Gusto , China , Monitoreo del Ambiente , Eutrofización , Lagos/química , Nutrientes/análisis , Nutrientes/normas , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/normas , Calidad del Agua
20.
Water Res ; 161: 570-580, 2019 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-31238222

RESUMEN

The raw fresh leachate from municipal solid waste (MSW) incineration plants contains high concentrations of volatile fatty acids (VFAs), ammonia and metals, all compounds that severely limit anaerobic digestion treatment efficiencies. These inhibitory compounds make reactor systems unstable, causing reactor start-up periods to take more than 100 days, even when the leachate is diluted significantly. In this study, granular activated carbon (GAC) was incorporated into a bioreactor fed with raw incineration leachate. Addition of GAC allowed direct treatment of raw incineration leachate without any start-up acclimation period, while the non-amended control reactor soured immediately and collapsed within 17 days. When hydraulic retention time (HRT) of the GAC-amended reactor was stepwise decreased to increase organic loading rates (OLR) to 25.0 kgCOD/(m3·d), COD removal efficiencies remained stable at >90%. Metagenomic analysis of the GAC-amended reactor revealed that Geobacter and Methanosarcina, species known to participate in direct interspecies electron transfer (DIET), were more abundant in the GAC-amended reactor than the seed sludge. In addition, the abundance of genes coding for proteins thought to be involved in DIET such as electrically conductive pili and the outer membrane c-type cytochrome, OmcS, increased significantly, while genes involved in fermentation, and nitrate (narG) and sulfate (dsrA) reduction dropped significantly as the experiment progressed. These results are significant because this is the first detailed investigation into the metabolic capabilities of microbial communities involved in efficient treatment of raw incineration leachate within biomethanogenic reactors that did not require a long start-up period.


Asunto(s)
Carbón Orgánico , Incineración , Anaerobiosis , Reactores Biológicos , Electrones , Metano , Aguas del Alcantarillado
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