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1.
Environ Res ; 203: 111881, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34411547

RESUMO

In this study, waste cooking oil (WCO) co-fermentation with food waste by variable pH strategy was developed for microbial lipid production. Results showed that when WCO substitution rate within the range of 1.56-4.68% (corresponding to the WCO content in food waste), lipid production from Rhodosporidium toruloides 2.1389 could be increased by 7.2 g/kg food waste because of the better synergistic effect. Mechanism analysis revealed that the fatty acid salt produced from WCO under alkaline condition, as a surface active agent, could improve lipid production, but excessive WCO (29.2 g/L) would inhibit the lipid production due to its hindrance to the oxygen. The lipid composition analysis found that the produced lipid could be used as raw material for biodiesel production. It was estimated that 15.0 million tonnes of biodiesel could be produced from global food waste yearly by adopting the proposed WCO co-fermentation with variable pH strategy, together with reduction of about 0.31 million tonnes of CO2 equivalents and 1435 tonnes of SO2. It is expected that this study may lead to the paradigm shift in future biodiesel production from food waste.

2.
Sci Total Environ ; 807(Pt 1): 150860, 2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34626630

RESUMO

Antibiotic fermentation residue (AFR) is a form of bioavailable matter, that represents a typical category of hazardous waste associated with drug production in China. The disposal of these residues seriously restricts the sustainable development of the pharmaceutical industry. In this study, the steam explosion and aerobic composting (SEA-CBS) system was developed to thoroughly convert neomycin fermentation residue to organic fertilizer. The results implied that the ultimate removal rate of antibiotics was as high as 99.9% in all cases, including macrolide (kitasamycin and spiramycin), lincosamide (lincomycin), and beta-lactam (cephalosporin and penicillin) antibiotic biowastes. Pot experiments were also conducted to study the attenuation rule of antibiotic residues in the soil, and the distribution of antibiotic resistant genes from trace antibiotics. The produced fertilizer presented the better performance on mustard growth than conventional fertilizers. The average plant height and biomass were increased by 14.33%-55.83% and 136.71%-326.83%, respectively, after SEA-CBS pretreatment. Moreover, neomycin was the primary selective pressure, and six antibiotic resistance genes (ARGs) correlated with neomycin were screened. The acc(6')ib gene was identified as the target ARGs, the main resistance mechanism was antibiotic inactivation, and the absolute and relative abundances were 1.06 × 105 ± 3.80 × 104 copies/g and 6.23 × 10-4 ± 1.75 × 10-4 copies/16 s in the NFR-amended soils. The microbial community analysis showed that the variation of the soil microbial community was not dominated by neomycin fermentation residue (NFR) at initial concentrations below 0.42 µg/kg soil. This work demonstrated that the SEA-CBS system not only functioned as an efficient technology for concurrent neomycin sulfate removal and NFR composting, but also applied to a wide range of other antibiotic bio-wastes, which may benefit the recycling of AFR, as well as the data provide a theoretical basis for future agricultural utilization and safe evaluation.

3.
Biotechnol Biofuels ; 14(1): 162, 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301305

RESUMO

BACKGROUND: As one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays. RESULTS: In this study, a consortium of white rot fungi composed of Lenzites betulina and Trametes versicolor was employed to enhance the ligninolytic enzyme activity of laccase (Lac) and manganese peroxidase (MnP) under microbial synergism. The maximum enzymatic activity of Lac and MnP was individually 18.06 U mL-1 and 13.58 U mL-1 along with a lignin degradation rate of 50% (wt/wt), which were achieved from batch cultivation of the consortium. The activities of Lac and MnP obtained from the consortium were both improved more than 40%, as compared with monocultures of L. betulina or T. versicolor under the same culture condition. The enhanced biodegradation performance was in accordance with the results observed from scanning electron microscope (SEM) of lignin samples before and after biodegradation, and secondary-ion mass spectrometry (SIMS). Finally, the analysis of heteronuclear single quantum coherence (HSQC) NMR and gas chromatography-mass spectrometry (GC-MS) provided a comprehensive product mapping of the lignin biodegradation, suggesting that the lignin has undergone depolymerization of the macromolecules, side-chain cleavage, and aromatic ring-opening reactions. CONCLUSIONS: Our results revealed a considerable escalation on the enzymatic activity obtained in a short period from the cultivation of the L. betulina or T. versicolor due to the enhanced microbial synergistic effects, providing a potential bioconversion route for lignin utilization.

4.
Environ Res ; 202: 111638, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34273368

RESUMO

The disposal and reuse of cephalosporin mycelia dregs (CMDs) pose a great challenge to the biopharma industry, but it acts as the new source of antibiotic resistome, although agriculture intensification remains uncertain. Herein, two common cash crops (maize and soybean) were planted in the actual field, and the effects of the application of treated CMDs, chicken manure and chemical fertilizer served as control groups were both investigated according to comparison experiment. Amplicon-targeted 16S rRNA and high-throughput sequencing was analyzed for rhizosphere antibiotic resistome. Results showed that hydrothermal and spray-dried (HT + SD) CMDs could promote nutrients uptake and stabilize soil fertility indicator, and finally improved the crop yield (maximum, 119.68%). The numbers and relative abundances of total ARGs in soils were not significantly different from that of conventional fertilizer (p > 0.05), but crop type marked the differences in distribution. The overall economic benefits are predicted to be around $373-745 million annually, considering its application to the whole country. HT + SD-treated CMDs can be therefore used as a high-quality and safe alternative fertilizer for agriculture use. These findings are expected to offer a fresh perspective on the application of antibiotic fermentation residue (AFR) in the future.


Assuntos
Antibacterianos , Solo , Antibacterianos/farmacologia , Cefalosporinas , Resistência Microbiana a Medicamentos , Genes Bacterianos , Esterco , Nutrientes , RNA Ribossômico 16S/genética , Microbiologia do Solo
5.
Bioresour Technol ; 337: 125400, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34139562

RESUMO

To compare the effects of low- and high-temperature thermal-alkaline pretreatments (LTTAP, 60 ± 1 °C, pH 12.0 ± 0.1, 30 min and HTTAP, 160 ± 1 °C, pH 12.0 ± 0.1, 30 min, respectively) on anaerobic digestion (AD) of waste activated sludge, long-term and semi-continuous experiments were conducted in three laboratory continuous stirred tank reactors. The experimental results showed that the two pretreatments increased the methane yield of sludge from 89.20 ± 2.41 mL/g added volatile solids (VS) to 117.50 ± 5.27 mL/g added VS (LTTAP) and 156.40 ± 2.99 mL/g added VS (HTTAP). After AD, the reduction of sludge (volatile solid) increased from 32.91 ± 0.27% to 44.17 ± 1.53% (LTTAP), and 50.86 ± 1.18% (HTTAP), and the abundance of pathogenic bacteria decreased from 6.53% to 0.38% (LTTAP) and 0.14% (HTTAP). LTTAP enhanced both hydrogentrophic and acetoclastic methanogenis and HTTAP only enhanced acetoclastic methanogenis. Additionally, the energy efficiency of HTTAP and its subsequent AD was lower than that of LTTAP and its subsequent AD.


Assuntos
Metano , Esgotos , Anaerobiose , Temperatura Alta , Temperatura , Eliminação de Resíduos Líquidos
6.
Environ Res ; 197: 111095, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33811864

RESUMO

Tetracycline has been frequently detected in municipal wastewater due to its extended use for various purposes. This study investigated the influence of tetracycline on non-aerated microalgal-bacterial granular sludge cultivated for municipal wastewater treatment. It was found that ammonia-N removal rate decreased at the tetracycline concentrations of 1 and 10 mg/L. A mass balance on nitrogen further revealed that the observed ammonia-N removal could be mainly attributed to microalgal assimilation which was inhibited by tetracycline at the concentrations studied. In fact, reduced production of chlorophyll in microalgae was observed in the presence of tetracycline, leading to decreased ammonia-N removal rate. Meanwhile, decreased dissolved oxygen (DO) concentration at high tetracycline concentration also indicated inhibition of microalgae. Furthermore, the relative abundances of microalgae containing green algae and cyanobacteria were inhibited by tetracycline. The results gathered in this study indicated the tetracycline-induced decoupling of symbiosis in microalgal-bacterial granular sludge. It is expected that this study can shed lights on the behaviors of non-aerated microalgal-bacterial granules in response to the presence of tetracycline during municipal wastewater treatment.


Assuntos
Microalgas , Esgotos , Biomassa , Reatores Biológicos , Nitrogênio , Simbiose , Tetraciclina/toxicidade , Águas Residuárias
7.
Sci Total Environ ; 765: 144397, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33385817

RESUMO

Rural sewers are applied widely to collect rural sewage and biofilm characteristics in rural sewers may be different with municipal sewers. The succession of bacteria communities, sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) need to be studied since rural sewers have a potential risk of sulfide and methane accumulation. In this study, lab-scale rural sewer facilities were established to analyze the characteristics of sewer biofilm and the generation of sulfide and methane. The results indicate that the variation tendency of biofilm thickness in rural sewers was different with municipal sewers. Time-based bacterial succession existed in rural sewer biofilms and the predominant genus was changed from Acinetobacter (approximately 19.10%) to Pseudomonas (approximately 12.61%). SRB (mean 1.49 × 106dsrA copies/cm2) were abundant than MA (mean 2.57 × 105mcrA copies/cm2) while MA were eliminated gradually in rural sewer biofilms. The tendency of sulfide and methane generation was similar with the number variation of SRB and MA, indicating sulfide accumulation might be more serious trouble than methane accumulation in a long-run rural sewer. Overall, this study deeply analyzed the succession of rural sewer biofilms and found that MA and methane were automatically inhibited in rural sewers.


Assuntos
Archaea , Metano , Bactérias , Biofilmes , Características da Família , Esgotos , Sulfatos , Sulfetos
8.
J Environ Manage ; 281: 111925, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33422912

RESUMO

High cost of sewer systems usually restricts the sewage collection in rural areas. Many rural areas take traditional sewer scheme whose private-secondary-main sewer diameter is 110-200-300 mm without hydraulic calculation and increased the total cost of sewers. The rational utilization of small diameter sewers might contribute to sewer cost reduction. In this study, rural sewer length and cost models were established taking sewer diameter, household number, and length/width ratio of village as parameters to evaluate the cost benefits of using small diameter sewers. Hydraulic calculation of sewers was applied by Storm Water Management Model to ensure the small diameter sewers were feasible. The results indicate that household number and length/width ratio cause obvious impact on sewer length and cost. Main sewer with 200 mm diameter is suitable for the village with less than 1000 households. Using small diameter sewers can reduce the sewer cost by 6-15% compared with traditional sewer scheme and 110-110-200 might be the better scheme to rural areas because of the low cost (including construction cost and operation and maintenance cost) and high tolerance of sewage flow fluctuation. This study provided the suitable diameter of rural sewers based on cost model and hydraulic calculation which might be helpful for the application of rural sewers.


Assuntos
Esgotos , Águas Residuárias , Água
9.
Bioresour Technol ; 318: 123953, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32927314

RESUMO

This study reported a "treating waste by waste" strategy to dispose waste activated sludge (WAS), i.e. reverse osmosis (RO) brine-enhanced anaerobic fermentation. RO brine was hazardous by-product from seawater desalination process, which contains numerous Na+. After 4-day RO brine-enhanced anaerobic fermentation at Na+ concentration of 0.33 mol/L, 5.0 g/L VSS reduction (37.9% of VSS) was achievable, leading to considerable soluble chemical oxygen demand (SCOD) release of 349.6 mg/g VSS. Acetic acid was predominant component in SCOD (31.1%), followed by propionic, butyric, valeric acids and proteins (14.0-17.6%). Sludge solubilization and SCOD composition in the enhanced anaerobic fermentation with RO brine and NaCl agent were similar, whereas less nutrient release and extracellular polymeric substance (EPS) disruption were achieved by RO brine, attributing to the Ca2+&Mg2+-caused skeleton strengthening on EPS matrix. Such RO brine-based strategy provided environmental and economic benefits, e.g. none chemical consumption, synchronous disposal of WAS and RO brine.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Esgotos , Anaerobiose , Fermentação , Concentração de Íons de Hidrogênio , Osmose , Sais
10.
Bioresour Technol ; 313: 123656, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32561106

RESUMO

Straw as an agricultural byproduct has been recognized as a potential resource. However, open-field straw burning is still the main mean in many regions of the world, which causes the wasting of resource and air pollution. Recently, many technologies have been developed for energy and resource recovery from straw, of which the biological approach has attracted growing interests because of its economically viable and eco-friendly nature. However, pretreatment of straw prior to biological processes is essential, and largely determines the process feasibility, economic viability and environmental sustainability. Thus, this review attempts to offer a critical and holistic analysis of current straw pretreatment technologies and management practices. Specifically, an integrated biological processes coupled with microbial degradation and enzymatic hydrolysis was proposed, and its potential benefits, limitations and challenges associated with future large-scale straw treatment were also elaborated, together with the perspectives and directions forward.


Assuntos
Agricultura , Hidrólise
11.
Bioresour Technol ; 312: 123397, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32526667

RESUMO

This study reported a novel pretreatment approach with combination of alkaline protease (AP) and pH 10 for enhancing short-chain fatty acids (SCFAs) production from waste activated sludge (WAS). Through the AP-based pretreatment, WAS flocs were disintegrated with cell lysis, leading to release of biodegradable organic matters. At the external AP dosage of 5%, SCOD of 5363.7 mg/L (SCOD/TCOD = 32.5%) was achievable after 2-h pretreatment. More than 66% of SCOD was composed of proteins and carbohydrates. Considerable SCFAs of 607 mg COD/g VSS was produced over a short-term anaerobic fermentation of 3 days, which was 5.4 times higher than that in the control. Acetic and propionic acids accounted for 74.1% of the SCFAs. The AP-based approach increased endogenous protease and α-glucosidase activities, facilitating biodegradation of dissolved organic matters and SCFAs production. Such approach is promising for WAS disposal and carbon recovery, the produced SCFAs might supply 60% of carbon gap in wastewater.


Assuntos
Ácidos Graxos Voláteis , Esgotos , Anaerobiose , Proteínas de Bactérias , Endopeptidases , Fermentação , Concentração de Íons de Hidrogênio
12.
Bioresour Technol ; 313: 123659, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32554151

RESUMO

This study reported the NaCl-enhanced anaerobic fermentation with cation-exchange resin regeneration waste liquid (CRWL) as alternative NaCl source for waste activated sludge (WAS) disposal and carbon recovery. Through 4-day CRWL-enhanced anaerobic fermentation at Na+ concentration of 0.34 mol/L, the Na+-caused sludge disintegration triggered numerous release of dissolved organic matters (DOMs), i.e. 371.6 mg/g VSS, with composition distribution: acetic acid (28.2%) > butyric acid (16.1%) ≈ valeric acid (17.8%) ≈ proteins (16.4%) > propionic acid (14.4%) > unknown (3.2%) > carbohydrates (3.9%). Satisfying chemical conditioning performance for the fermented sludge was observed at the FeCl3 dosage of 0.3 g/g DS, attributing to the roles of double-layer compression and electric neutralization. The capillary suction time (CST) and sludge cake moisture content were decreased to 60.3 s and 75.1%, against those of 607 s and 93.5% before conditioning, respectively. Such "treating waste by waste" strategy could provide numerous environmental and economic benefits.


Assuntos
Esgotos , Cloreto de Sódio , Anaerobiose , Cátions , Ácidos Graxos Voláteis , Fermentação , Eliminação de Resíduos Líquidos
13.
Bioresour Technol ; 312: 123605, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32504951

RESUMO

Nowadays, tetracycline has been frequently detected in municipal wastewater, posing a pressing threat for wastewater treatment. This study investigated the defensive responses of microalgal-bacterial granules to tetracycline. It was found that the physical structure of microalgal-bacterial granules tended to shift from individual granules to loosely inter-connected agglomerates. In response to tetracycline, microalgae instead of bacteria in granules were found to produce more low molecular weight polysaccharides in extracellular polymeric substances (EPS), which increased from 0.26 mg C/g VSS in the control to 17.81 and 25.15 mg C/g VSS after being exposed to 1 and 10 mg/L of tetracycline, respectively. It was further revealed that tetracycline could bind to tryptophan in EPS proteins, and this action in turn could help to alleviate the direct toxicity of tetracycline to microorganisms in granules. Moreover, it appeared that the abundance of Pseudomonas-carrying tetracycline resistant genes increased substantially, together with gradual disappearance of Cyanobacteria.


Assuntos
Microalgas , Águas Residuárias , Antibacterianos , Bactérias , Tetraciclina
14.
Bioresour Technol ; 312: 123303, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32521466

RESUMO

This study developed an economical approach for enhancing short-chain fatty acids (SCFAs) production from waste activated sludge (WAS) by NaCl assistant anaerobic fermentation. With NaCl addition at 20 g/L, sludge disintegration with extracellular polymeric substance (EPS) disruption and cell lysis were induced owing to the attack of osmotic pressure, which facilitated WAS solubilization with release of biodegradable organic matters. The SCOD sharply increased to 4092 mg/L (SCOD/TCOD = 23.9%) after 2-day hydrolysis, against 1462 mg/L in the control. After 4-day anaerobic fermentation, considerable SCFAs production of 288.2 mg COD/g VSS was achievable. More than 60% of the SCFAs was composed of acetic and propionic acids. The feasibility of bio-electrogenesis in microbial fuel cell (MFC) utilizing fermentative liquid was assessed. As such, the produced SCFAs could be consumed with energy recovery, thereby the used NaCl was reusable, which created environmental and economic benefits, e.g. reduced NaCl consumption and cost, negligible residual NaCl.


Assuntos
Esgotos , Cloreto de Sódio , Anaerobiose , Matriz Extracelular de Substâncias Poliméricas , Ácidos Graxos Voláteis , Estudos de Viabilidade , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise
15.
J Hazard Mater ; 398: 122930, 2020 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-32464562

RESUMO

The correlation of the lack in multivalent cations with hydrolase activity and microbial community in anaerobic fermentation of waste activated sludge was investigated in this study. It was demonstrated that considerable solid phase reduction of 41 % (7.87 g/L) was achievable through a cation exchange resin-enhanced anaerobic fermentation of 4 days. The protease and α-glucosidase, especially α-glucosidase, were easily influenced by a lack in multivalent cations. Furthermore, species abundance and diversity of microbial community gradually decreased. Meanwhile, the bacteria community structure presented obvious dynamic shifts. Ruminococcaceae_UCG_009, Bacteroides and Macellibacteroides responsible for organic matter biodegradation and SCFAs production became dominant bacteria in cation exchange resin-enhanced anaerobic fermentation, which was less influenced by the lack in multivalent cations, while the SCFA consumers (e.g. methanogens) were inhibited with reduced abundances due to their susceptibility to the lack in multivalent cations. Redundancy analysis revealed that the lack in multivalent cations were responsible for the microbial community evolution, which was proved by the high Grey relational coefficients (0.747-0.820) and significant negative Spearman coefficients (-0.5798 to -0.9429) between multivalent cation and microbial community. Obviously, the cation exchange resin-induced removal of multivalent cations reduced enzyme activity and modified microbial community structure, which created a beneficial environment for enhancing anaerobic fermentation.


Assuntos
Microbiota , Esgotos , Anaerobiose , Resinas de Troca de Cátion , Cátions , Ácidos Graxos Voláteis , Fermentação , Hidrolases
16.
Water Res ; 179: 115884, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32388049

RESUMO

Globally increasing concerns have been raised on the high energy consumption and greenhouse gas emissions in conventional municipal wastewater treatment processes over the past decades. In this study, a self-sustaining synergetic microalgal-bacterial granular sludge process was thus developed to address these challenges. The results showed that the microalgal-bacterial granular sludge process was capable of removing 92.69%, 96.84% and 87.16% of influent organics, ammonia and phosphorus under non-aeration conditions over a short time of 6 h. The effluent could meet the increasingly stringent discharge standards in many countries worldwide. A tight synergetic interrelationship effect between microalgae and bacteria in granules was essential for such excellent process performance. The stoichiometric and functional genes analyses further revealed that most of organic matter and nutrients were removed through microalgal and bacterial assimilations. Moreover, it was found that there existed a desirable distribution of functional species of microalgae and bacteria in microalgal-bacterial granules, which appeared to be essential for the self-sustaining synergetic reactions and stability of microalgal-bacterial granules. Consequently, this work may offer a promising engineering alternative with great potential to achieve energy-efficient and environmentally sustainable municipal wastewater treatment.


Assuntos
Microalgas , Águas Residuárias , Biomassa , Fósforo , Esgotos
17.
Environ Res ; 187: 109651, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32422485

RESUMO

Most rural wastewater treatment facilities require aeration equipment to ensure sufficient dissolved oxygen (DO) during processing. Operation and maintenance are costly, and cannot be met in many areas with poor economic levels. This has led to further deterioration of the rural water environment and aroused much attention. This work reports a plug-flow step feed system utilizing wind and solar hybrid energy for rural wastewater treatment. Under certain climatic conditions, the wind energy and solar energy provided complimentary power generation, and an automatic control system (without batteries) was constructed. The corresponding control logic for multi-energy level operation was developed. Furthermore, the power generation efficiency of the system, the pollutant removal, and its mechanism on the bioreactor were also analyzed. According to the monitoring of meteorological conditions, wind and solar resources at the test site were abundant, and the electricity generated by the power generation was sufficient to meet the operational needs of the equipment. Energy efficiency can reach 80.0%. The characteristics of pollutant removal in each process section were studied on spatial and temporal dimensions. Results showed that the wastewater treatment process reached mean removal efficiencies of chemical oxygen demand (CODcr), NH4+-N, total nitrogen (TN) and total phosphorus (TP) were 90.2%, 94.3%, 61.4% and 63.1%, respectively. Analyses of microbial community richness and group changes in each anoxic/aerobic reaction chamber in the biofilm reactor showed that the population structure was relatively stable and that there were abundant functional bacteria capable of degrading pollutants in each aerobic and anoxic unit. This system can thus be a more sustainable treatment process than traditional techniques used for rural wastewater treatment, providing a new design approach for low-energy consumption and unattended rural wastewater treatment.


Assuntos
Energia Solar , Águas Residuárias , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Nitrogênio/análise , Eliminação de Resíduos Líquidos , Vento
18.
Environ Res ; 187: 109628, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32438098

RESUMO

Sewers may affect the characteristics and bacterial communities of wastewater, and need be studied as they may impact treatment facilities and recycling operations. In this study, the wastewater characteristics and bacterial communities from the inflow and outflow of two sewers (sewage and greywater) were analyzed. The chemical oxygen demand was significantly reduced in the sewage and greywater sewer and the greywater sewer generated less sulfide and methane. Proteobacteria, Bacteroidetes, and Firmicutes as the major phyla in sewage and greywater and sewer biofilms. Sewer conveyance caused changes in the distribution and community interaction of suspended bacteria. Greywater contained abundant water-related pathogenic bacteria (WPB) and some WPB (e.g. Aeromonas, Klebsiella and Shigella) number in greywater were not lower than sewage. Sewers could increase the number of Shigella in sewage and decrease the number of Acinetobacter in greywater. Further treatment or disinfection of greywater collected by sewers was necessary and directly reuse of greywater without treatment should be avoided.


Assuntos
Esgotos , Águas Residuárias , Bactérias/genética , Análise da Demanda Biológica de Oxigênio , Metano/análise
20.
Environ Res ; 183: 109289, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32113173

RESUMO

Small diameter gravity sewers (SDGS) have been applied in rural areas to collect sewage or greywater. Flow conditions in rural SDGS are variable and their influences on bacteria in sewer biofilms are still not clear. To investigate the effect of flow conditions on sewage and greywater SDGS biofilms, six sewage SDGS and six greywater SDGS were operated and Illumina HiSeq sequencing was subsequently performed on sewer biofilms. The results indicate that the predominant bacterial phyla in both sewage and greywater SDGS biofilms were Proteobacteria (63.0% ± 9.3%) and Actinobacteria (26.5% ± 8.8%) and co-presence relationship was the main interaction in SDGS biofilm bacterial communities. Compared with stable flow conditions, variable flow conditions altered the bacterial community of SDGS biofilms from the aspect of bacteria compositions and community interactions and the relative abundance of many bacteria showed significant distinctions between stable and variable flow conditions. In sewage SDGS biofilm, the relative abundance of denitrifying, nitrite-oxidizing, and sulfate-reducing bacteria decreased significantly in variable flow conditions while in greywater SDGS biofilms, nitrite-oxidizing and water-related pathogenic bacteria decreased significantly in variable flow conditions. Influences of flow conditions on predicted bacterial functions were also significant in sewage and greywater SDGS biofilms. Variable flow conditions might be conducive to the reduction of H2S generation and water-related pathogenic bacteria in rural SDGS biofilms.


Assuntos
Bactérias , Biofilmes , Esgotos , Eliminação de Resíduos Líquidos , Movimentos da Água
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