RESUMO

In anaerobic digestion (AD), the choice of inoculum type seems to be relevant for methane production for complex substrates, such as lignocellulosic material. Previous work demonstrated that the addition of fresh manure and ruminal fluid to anaerobic sludge improved methane productivity and kinetics of AD of crude sugarcane bagasse (CSB). Considering that the improvement of methane production could be a result of a more adapted microbial community, the present study performed the Next Generation Sequencing analysis to identify changes in the microbiome of anaerobic sludge inoculum, resulting from fresh manure and ruminal fluid addition. In comparison with AD performed only with anaerobic sludge inoculum (50:50, U), accumulated methane production was 15% higher with anaerobic sludge plus ruminal fluid inoculum (50:50, UR) and even higher (68%) with anaerobic sludge with fresh bovine manure inoculum (50:50, UFM), reaching the value of 143 NmLCH4.gVS-1. Clostridium species were highly abundant in all inocula, playing an important role during the hydrolysis and fermentation of CSB, and detoxifying potential inhibitors. Microbial composition also revealed the occurrence of Pseudomonas and Anaerobaculum at UFM inoculum that seem to have contributed to the higher methane production rate, mainly due to their hydrolytic and fermentative ability on lignocellulosic substrates. On the other hand, the presence of Alcaligenes might have had a negative effect on methane production due to their ability to perform methane oxidation.

Assuntos

Microbiota, Saccharum, Animais, Bovinos, Anaerobiose, Celulose, Esgotos, Esterco, Metano, Reatores Biológicos

RESUMO

Dewatered sludges from twenty-two sewage treatment facilities were characterized to develop the quality control indices in India. This study used fertilizer index (FI) and clean index (CI) as a tool for categorizing sludge utilization into different classes (A, B, C and limited use classes LU-1, LU-2, LU-3) by their fertilizing potential, toxicity level, pathogen presence, and vector attraction reduction criteria. The findings revealed that total P (as P2O5), total N, and K (as K2O) in the sludge samples ranged from 0.9 to 5.7%, 1.2 to 3.8%, and 0.1 to 1.5%, respectively. Moreover, all sludges belong to Class C and lower category due to the presence of toxic metals and pathogens. The helminth eggs were found in the range of 25-1450 Numbers/4gTS in sludge samples. The highest number of helminth eggs of 1450/4 g of TS was found in the fecal sludge. The specific oxygen uptake rate (SOUR) values in the sludge samples varied from 0.3 to 4.9, with a median value of 1.3 and an RSD of 86% is way too high. It indicates that the sludge samples need further treatment to be less attractive as a food source for vectors and rodents. However, sludge samples have fertilizing potential and FI values ranges from 4.1 to 4.9, and CI value ranges from 2.5 to 5.0. It indicates that compost is best in quality and has high-fertilizer potential and low heavy-metal content, which is suitable for high-value crops such as organic farming. Further sludge treatment using typical composting, aerobic or anaerobic digestion, and solar or thermal drying could bring the sludges into the Class A and B categories.

Assuntos

Metais Pesados, Esgotos, Fertilizantes, Metais Pesados/análise, Controle de Qualidade, Índia

RESUMO

The microwave-enhanced advanced oxidation process (MW-AOP) was utilized for the treatment of liquid dairy manure, prior to anaerobic digestion (AD). A significant amount of soluble chemical oxygen demand (SCOD) was formed in the treated solution, but there was no or little increase in volatile fatty acid (VFA). In this study, up-flow anaerobic sludge blanket (UASB) reactors were used in both the conventional AD system and as the methane phase reactor in a two-phase anaerobic digestion (TPAD) system. Both AD systems were capable of operating at very short hydraulic retention times (HRTs) to as low as about 3 days, and very high methane production rates were achieved. However, much higher methane production was obtained in the TPAD system. The phase separation of the acidogenesis and the methanogenesis in the TPAD system not only increased methane production but also maintained reactor stability throughout the experimental period. Thus, the combination of MW-AOP treatment and TPAD appears to be an effective means of energy recovery from dairy manure.

Assuntos

Esterco, Micro-Ondas, Anaerobiose, Esgotos, Metano, Reatores Biológicos

RESUMO

Wastewater with residual streptomycin sulphate usually contains high content of ammonia-nitrogen. However, the biological removal process of ammonia-nitrogen under streptomycin sulphate circumstance was unclear. In this study, short-term and long-term effects of streptomycin sulphate on biological nitrification systems, including AOB, NOB, SAOR, SNOR and SNPR, were evaluated comprehensively. The results indicated IC50 for AOB and NOB were 7.5 and 6.6 mg/L. SAOR and SNPR could be decreased to 3.43 ± 0.52 mg N/(g MLSS·h) and 0.24 ± 0.03 mg N/(g MLSS·h) while the addition of streptomycin sulphate was 10 mg/L. When streptomycin sulphate addition was stopped, nitrification ability recovered slightly, SAOR and SNPR increased to 9.37 ± 0.36 mg N/(g MLSS·h) and 1.66 ± 0.49 mg N/(g MLSS·h), respectively. The protein of EPS increased gradually during the acclimatization process, and the maximal protein value was 68.24 mg/g MLSS on the 100th day, however, no significant change of polysaccharose was observed during the acclimatization process. High abundance of ARGs and intI1 was detected in effluent and sludge of the biological treatment system. The maximal relative abundance of aadA1 in the sludge appeared on the 140th day, and increased by 0.99 orders of magnitude. Biological diversity decreased significantly during the acclimatization process, relative abundance of nitrosomonas was changed from 9.07% to 38.68% on the 61st day, while relative abundance of nitrobacter was changed from 1.30% to 0.64%. It should be noted that relative abundances of nitrosomonas and nitrobacter were reduced to 16.17% and 0.25% on the 140th day. This study would be helpful for nitrogen removal in wastewater with antibiotic.

Assuntos

Microbiota, Esgotos, Águas Residuárias, Antibacterianos, Estreptomicina/farmacologia, Estreptomicina/metabolismo, Nitrificação, Amônia/metabolismo, Nitritos/metabolismo, Reatores Biológicos, Resistência Microbiana a Medicamentos, Nitrobacter/metabolismo, Nitrogênio/metabolismo, Oxirredução

RESUMO

Increasing attention has been focused on the comprehensive utilisation of alkaline red mud (RM) derived from the aluminium industry. Phytoremediation serves as an effective strategy, but it is limited by the drawbacks of red mud. This study proposed 'co-hydrothermally treating red mud and sewage sludge (SS)' for producing a soil-like matrix, and explored the impacts of SS addition on the characteristics of hydrothermal solid and liquid products of RM. The results showed that the introduction of SS could improve the characteristics of hydrothermal products, including pH, the particle aggregation, and organic components. During hydrothermal treatment, the acid components released from SS could neutralise the alkalinity of RM, reducing the pH of hydrothermal product from 10.1 (without SS) to and 8.2 (80% SS), respectively. With the increase of addition ratio of SS, the main range of particle size distribution in hydrothermal solid products changed from 0.1∼1 µm to 10∼100 µm, suggesting the positive role of SS in improving the particle aggregation. XRD analysis showed that the addition of SS hindered the mineral crystallization of RM during hydrothermal treatment, while FTIR and XPS analysis confirmed that SS could serve as a 'supply source' of organic components, which created favourable conditions for hydrothermal solid products as soil-like matrix. The addition ratio of SS presented the negative correlation with the pH value and positive relative with chemical oxygen demand of hydrothermal liquid products. The hydrothermal liquid product modified by SS was beneficial to further improve soil-like matrix. The strategy of co-hydrothermal treating RM and SS to produce the soil-like matrix could massively consume solid wastes, which is a prospective approach to deal with the trouble of the aluminium industry and sewage treatment plants.

Assuntos

Esgotos, Solo, Esgotos/química, Solo/química, Alumínio, Biodegradação Ambiental

RESUMO

Anammox is one of the most innovative nitrogen removal technologies, while its functional bacteria-anaerobic ammonia-oxidizing bacteria (AAOB) is sensitive to the impurities in the wastewater. In this study, the long-term effects of sulfide at different concentrations (0, 5, 10, 20, 30, 50, 25 mg L-1) on low substrate Anammox process were studied. The results showed that when the sulfide was 25-30 mg L-1, AAOB was well coupled with sulfide-denitrifying bacteria and the total nitrogen removal efficiency (TNRE) reached a maximum of 91.0%. The hydroxylamine oxidoreductase activity and Heme-c reached 1.678 EU g-1 SS and 0.0023 mmol g-1 SS, respectively, with the hzo and nosZ gene concentrations as 2.52 × 108 and 4.45 × 107 copies mL-1. 50 mg L-1 sulfide inhibited the nitrogen removal by AAOB, resulting in the TNRE decreasing to 81.7%. The experimental results provide a reference for the practical application of Anammox in treating sulfur-containing wastewater.

Assuntos

Microbiota, Águas Residuárias, Desnitrificação, Nitrogênio/análise, Oxidação Anaeróbia da Amônia, Reatores Biológicos/microbiologia, Oxirredução, Bactérias/genética, Sulfetos, Esgotos

RESUMO

PURPOSE: Amniotic Fluid Sludge (AFS) has been theorized to be sonographic evidence of an underlying infection/inflammation and studies have concluded that approximately 10% of the patients who show signs of preterm labor with intact membranes have an underlying intraamniotic infection, mostly subclinical, carrying an increased risk for preterm birth with its subsequent neonatal and maternal complications. The purpose of the present systematic review is to evaluate the impact of antibiotic therapy on preterm birth rates of women diagnosed with AFS. METHODS: We searched Medline, Scopus, the Cochrane Central Register of Controlled Trials CENTRAL, Google Scholar, and Clinicaltrials.gov databases for relevant articles published until the 30th of September 2022. Observational studies (prospective and retrospective) that evaluated the impact of antibiotics on preterm delivery rates of patients with AFS were considered eligible for inclusion. Statistical meta-analysis was performed with RStudio and we calculated pooled risk ratios (OR) and 95% confidence intervals (CI). To evaluate the information size, we performed trial sequential analysis (TSA) and the methodological quality of the included studies was assessed using RoBINS tools. RESULTS: Overall, four retrospective cohort studies were included in the present systematic review and 369 women were enrolled. We demonstrated that preterm delivery prior to 34, 32 and 28 weeks of gestational age was comparable among the groups of women that had antibiotics and those that did not (OR: 0.34, 95% CI 0.05, 2.14, 0.40 [0.09, 1.66], 0.35 [0.08, 1.58], respectively) but the statistical heterogenicity of the studies included was high for every gestational period that was examined. CONCLUSIONS: According to our study, we cannot conclude that the use of antibiotics in women with amniotic fluid sludge benefit the prognostic risk to deliver prematurely. It is quite clear that data from larger sample sizes and more well adjusted and designed studies are needed.

Assuntos

Nascimento Prematuro, Humanos, Recém-Nascido, Feminino, Nascimento Prematuro/tratamento farmacológico, Estudos Retrospectivos, Esgotos, Líquido Amniótico, Estudos Prospectivos, Antibacterianos/uso terapêutico

RESUMO

Antibiotic resistance genes (ARGs) have been widely detected in the environment. Anaerobic digestion (AD) has the potential ability to remove ARGs, and a comprehensive study is needed on the variations in ARGs during AD. In this study, variations in antibiotic resistance genes (ARGs) and microbial communities were investigated during the long-term operation of an upflow anaerobic sludge blanket (UASB) reactor. An antibiotic mixture of erythromycin, sulfamethoxazole and tetracycline was added to the UASB influent and the operation period was 360 days. The abundances of 11 ARGs and class 1 integron-integrase gene were detected in the UASB reactor, and the correlation between the ARGs and the microbial community was analyzed. The composition of ARGs indicated that the main ARGs in the effluent were sul1, sul2, and sul3, whereas the main ARG in the sludge was tetW. Correlation analysis indicated a negative correlation between microorganisms and ARGs in the UASB. In addition, most of ARGs showed a positive correlation with norank_f_Propionibacteriaceae and Clostridum_sensu_stricto_6, which were identified as potential hosts. These findings may help develop a feasible strategy for removing ARGs from aquatic environments during anaerobic digestion.

Assuntos

Antibacterianos, Esgotos, Antibacterianos/farmacologia, Anaerobiose, Tetraciclina, Resistência Microbiana a Medicamentos/genética, Eliminação de Resíduos Líquidos

RESUMO

A needle-solid-phase microextraction (SPME) method based on hybrid monolithic column (HMC) was proposed for simultaneous separation and extraction of seven amphetamine-type stimulants (ATSs) (amphetamine, methamphetamine, cathinone, methcathinone, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and 3,4-methylenedioxyethylamphetamine), combining with ultra-performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometer (UPLC-QTRAP MS/MS). Thiol functionalized HMC (T-HMC) showed high extraction efficiency and excellent elution results towards target analytes, among three kinds of single/bi-functionalized HMCs. Various parameters of SPME operation and analytical performance were investigated systematically. The adsorption mechanism of T-HMC to ATSs was also discussed and explained as a mixed mode of electrostatic and hydrophobic interactions. Under the optimum experimental conditions, the proposed T-HMC needle-SPME-UPLC-QTRAP MS/MS method was rapid and convenient with good accuracy, low sample consumption, high sensitivity and strong anti-interference ability. This method was successfully applied to quantitative determination of seven trace ATSs in complex sewage and urine samples. In view of abundant types of HMCs, the needle-SPME based on functional HMC also had the potential to selectively separating and enriching other tract new psychoactive substances in complex matrices, and could provide a reliable tool for drug monitoring, especially in applications for forensic analysis and drug abuse.

Assuntos

Anfetamina, Estimulantes do Sistema Nervoso Central, Esgotos, Microextração em Fase Sólida, Cromatografia Líquida de Alta Pressão/métodos, Espectrometria de Massas em Tandem/métodos

RESUMO

The start-up and stable operation of partial nitritation-anammox (PN/A) treatment of mature landfill leachate (MLL) still face challenges. This study developed an innovative staged pilot-scale PN/A system to enhance nitrogen removal from MLL. The staged process included a PN unit, an anammox upflow enhanced internal circulation biofilm (UEICB) reactor, and a post-biofilm unit. Rapid start-up of the continuous flow PN process (full-concentration MLL) was achieved within 35 days by controlling dissolved oxygen and leveraging free ammonia and free nitrous acid to selectively suppress nitrite-oxidizing bacteria (NOB). The UEICB was equipped with an annular flow agitator combined with the enhanced internal circulation device of the guide tube, which achieved an efficient enrichment of Candidatus Kuenenia in the biofilm (relative abundance of 33.4 %). The nitrogen removal alliance formed by the salt-tolerant anammox bacterium (Candidatus Kuenenia) and denitrifying bacteria (unclassified SBR1031 and Denitratisoma) achieved efficient nitrogen removal of UEICB (total nitrogen removal percentage: 90.8 %) and at the same time effective treatment of the refractory organic matter (ROM). The dual membrane process of UEICB fixed biofilm combined with post-biofilm is effective in sludge retention, and can stably control the effluent suspended solids (SS) at a level of less than 5 mg/L. The post-biofilm unit ensured that effluent total nitrogen (TN) remained below the 40 mg/L discharge standard (98.5 % removal efficiency). Compared with conventional nitrification-denitrification systems, the staged PN/A process substantially reduced oxygen consumption, sludge production, CO2 emissions and carbon consumption by 22.8 %, 67.1 %, 87.1 % and 87.1 %, respectively. The 195-day stable operation marks the effective implementation of the innovative pilot-scale PN/A process in treating actual MLL. This study provides insights into strategies for rapid start-up, robust NOB suppression, and anammox biomass retention to advance the application of PN/A in high-ammonia low-carbon wastewater.

Assuntos

Desnitrificação, Poluentes Químicos da Água, Amônia, Nitritos, Nitrogênio, Esgotos, Biomassa, Oxidação Anaeróbia da Amônia, Reatores Biológicos/microbiologia, Oxirredução, Nitrificação, Bactérias, Carbono

RESUMO

The aim of the study was to investigate the effect of the biochar (BC) dose on solvent extractable (Ctot) and freely dissolved (Cfree) polycyclic aromatic hydrocarbons (PAHs) content during co-composting. A significantly better reduction of Σ16 Ctot PAHs after 98 days occurred during composting with BC (for 1% of BC - 44% and for 5% of BC - 23%) than in the control (15%). Despite the relatively high reduction of Ctot PAHs in the experiment with 5% BC rate, the content of the PAHs was still the highest compared to other variants. Regarding Cfree PAHs, 5% rate of BC resulted in the best reduction of PAHs, while the 1% BC dose resulted in a lower reduction of Cfree than the control. For 1% BC, PAHs losses was more effective, and sequestration processes played a less significant role than in the experiment with 5% dose of BC. The total and dissolved organic carbon, and ash were predominantly responsible for Ctot and Cfree losses, and additionally pH for Cfree. The results of the experiment indicate that BC performs a crucial role in composting, affecting the Ctot and Cfree PAHs in the compost but the final effect strictly depends on the BC dose.

Assuntos

Compostagem, Hidrocarbonetos Policíclicos Aromáticos, Poluentes do Solo, Esgotos/química, Triticum, Hidrocarbonetos Policíclicos Aromáticos/química, Poluentes do Solo/química, Carvão Vegetal/química, Solo/química

RESUMO

Disposal of waste glass and incinerated sewage sludge ash (ISSA) in landfills is a waste of resources and poses significant environmental risks. This work aims to recycle waste glass and ISSA together to form value-added glass-ceramics. The physical and mechanical properties, leaching behaviour, and microstructure of the glass-ceramics produced with different proportions of waste glass powder (WGP) and ISSA were investigated. Thermodynamic calculations were performed to predict the formation of crystalline phases and the phase transformation involved. The results showed the potential of WGP and ISSA as raw materials in glass-ceramics production. WGP effectively densified the microstructure of the glass-ceramics by forming a viscous phase. As WGP content increased, the total porosity of glass-ceramics decreased whereas the density increased, accompanied by the formed anorthite transforming into wollastonite. The incorporation of WGP densified and refined the pore structure of the glass-ceramics, thereby improving the mechanical properties and reducing the water absorption. The glass-ceramics produced with a 50:50 blend of WGP and ISSA exhibited the highest compressive strength of 43.7 MPa and the lowest water absorption of 0.3 %. All fabricated glass-ceramics exhibited innocuous heavy metal leaching. The co-sintering of ISSA and WGP can produce additive-free glass-ceramics, characterized by reduced energy consumption and notable heavy metal immobilization capacity. These materials hold promise for utilization in construction as building materials.

Assuntos

Metais Pesados, Esgotos, Reciclagem/métodos, Vidro, Cerâmica, Água, Cinza de Carvão, Incineração

RESUMO

The fate and behavior of antibiotic resistance genes (ARGs) in decentralized household wastewater treatment facilities (DHWWTFs) are unclear. In this study, targeting on a representative DHWWTF that receive all wastewater from a residential complex having 150 households, the transfer, elimination and accumulation of tetG, tetM, sul1, sul2 and intl1 were quantitively studied through real-time PCR-based quantification, mass balance evaluation and the existing state analysis based on size fractionation. Significant abundance changes of the genes were observed in involved biological reactions and the sedimentation process due to microbial growth and decomposition as well as the accumulation of the genes to sludge. tetG and sul1 increased in their fluxes against respective input in the influent. Although substantial portions of the increased genes were found in excess sludge compared to the flux of genes in the influent, those remaining in the discharge were still high, with an average about 3.4 × 1014 copies/d. The abundance of all four genes (tetG, tetM, sul1and sul2) in both water and sludge phases showed a general trend of reduction as sludge accumulated gradually in its storage tank within two months after desludging. Classification of ARGs based on particle sizes (>250 µm, 125-250 µm, 75-125 µm, 25-75 µm, 3-25 µm, <3 µm) indicated that while the major part of ARGs were distributed in particles with larger sizes (125-250 µm), ARGs in smaller particles (3-25 µm) and free ARGs (<3 µm) still existed, which may pose a greater threat to water environment due to their poor settleability. The results of this study can benefit the optimization of on-site maintenance and operation of decentralized wastewater treatment facility for elimination of the transfer of ARGs.

Assuntos

Águas Residuárias, Purificação da Água, Antibacterianos/farmacologia, Esgotos, Genes Bacterianos, Resistência Microbiana a Medicamentos/genética, Água

RESUMO

Reported ethanol titres from hydrolysis-fermentation of the degraded fibres in paper sludge (PS) waste, generally obtained under fed-batch submerged conditions, can be improved through fermentation processes at high solids loadings, as demonstrated in the present study with two industrial PS wastes at enzyme dosages appropriate for solids loadings up to 40% (w/w). The industrial yeast,Saccharomyces cerevisiaestrain Ethanol Red®, was compared to two genetically engineeredS. cerevisiaestrains, namely Cellusec® 1.0 and Cellusec® 2.0, capable of xylose utilisation, and xylose utilisation and cellulase production, respectively. High-solids batch fermentations were conducted in 3 L horizontal rotating reactors and ethanol titres of 100.8 and 73.3 g/L were obtained for virgin pulp and corrugated recycle PS, respectively, at 40% (w/w) solids loading using Ethanol Red®. Xylose utilisation by Cellusec® 1.0 improved ethanol titres by up to 10.3%, while exogenous cellulolytic enzyme requirements were reduced by up to 50% using cellulase-producing Cellusec® 2.0.

Assuntos

Celulase, Saccharomyces cerevisiae, Saccharomyces cerevisiae/metabolismo, Esgotos, Xilose/metabolismo, Etanol/metabolismo, Celulase/metabolismo, Fermentação, Hidrólise, Resíduos Industriais

RESUMO

Chlorination is a commonly used disinfection method in sewage treatment process. However, resistant bacteria may survive chlorination and enter the receiving aquatic environment upon effluent discharge. There has been limited research on the effects of chlorination on bacterial survival in seawater. To address this knowledge gap, microcosm experiments were conducted to simulate the discharge of chlorinated effluents into coastal seawater. The results revealed that bacterial communities in seawater-based effluents survived better in seawater than those in freshwater-based effluents. High chlorine dosages could significantly reduce the viable bacterial populations and their chance of regrowth in seawater. Additionally, faecal indicator bacteria (FIB) that entered the viable but non-culturable (VBNC) state under chlorination tended to persist in the VBNC state without resuscitation during seawater incubation. Because of the prevalence of VBNC indicator bacteria, qPCR quantification of FIB was more effective than conventional culture-based methods in tracing viable pathogenic chlorine-resistant bacteria, although the correlation strength varied depending on the type of effluent. This study sheds light on how chlorine dosages and the intrinsic properties of effluents affect bacterial survival in seawater and highlights the potential and limitations of using FIB in monitoring the health risks associated with the discharge of chlorinated effluents.

Assuntos

Halogenação, Esgotos, Cloro/farmacologia, Bactérias/genética, Água do Mar

RESUMO

The release of antibiotics has attracted wide attention due to their abuse and discharge. How to remove these emerging contaminants is an urgent need to be solved. In the present study, sludge-based biochar combining chitosan and iron oxide was prepared via municipal sewage sludge. The novel biochar modified with chitosan and iron oxide exhibited satisfying performance in eliminating antibiotics from water. The application of modified biochar combined with activated persulfate (PS) showed a remarkable removal efficiency of 96.98% for tetracycline (TC). Analysis of the surface characteristics of the modified biochar showed the presence of structural defects, dispersed iron oxides, abundant functional groups, a porous structure, and a relatively stable crystal structure. These characteristics attributed significant importance to facilitating the degradation of TC. A series of experimental conditions including preparation temperature (600-900 ℃), reaction temperature (15-45 ℃), contaminant concentration (30-180 mg/L), adsorbent usage (0.1-1 g/L), pH (2-10), and persulfate addition concentration (1-5 mmol) were conducted. The results revealed that the highest removal efficiency was achieved at 96.98% under the conditions of TC concentration at 30 mg/L, reaction temperature at 35 ℃, pH of 4, adsorbent addition amount of 0.6 g/L, and PS concentration of 2 mmol, respectively. Three degradation pathways and seven intermediate products of TC were proposed. Therefore, our study provides a promising approach for developing effective removal of antibiotic pollutants.

Assuntos

Quitosana, Compostos Férricos, Poluentes Químicos da Água, Esgotos/química, Água, Poluentes Químicos da Água/análise, Tetraciclina/química, Antibacterianos/análise, Carvão Vegetal/química, Adsorção

RESUMO

Although flavins are known as effective electron mediators, the binding capacity of exogenous flavins by anaerobic granular sludge (AGS) and their role in interspecies electron transfer (IET) remains unknown. In this study, AGS was mediated by using three exogenous flavins of riboflavin (RF), flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD). Results showed that the total amounts of flavins associated with extracellular polymeric substance (EPS) of AGS increased by 2.03-2.42 and 3.83-4.94 folds, after exposure to 50 and 200 µM of exogenous flavins, respectively. A large portion of FMN and FAD was transformed into RF by AGS. Exogenous flavin mediation also stimulated the production of EPS and cytochrome c (c-Cyts) as well as cytochrome-bound flavins. The increased abundance of these electron mediators led to a reduced electrochemical impedance of EPS and improved extracellular electron transfer capacity. The methane production of AGS after mediation with exogenous RF, FMN, and FAD increased by 19.03-31.71%, 22.86-26.04%, and 28.51-33.44%, respectively. This study sheds new light on the role of exogenous flavins in promoting the IET process of a complex microbial aggregate of AGS.

Assuntos

Dinitrocresóis, Flavina-Adenina Dinucleotídeo, Esgotos, Flavina-Adenina Dinucleotídeo/metabolismo, Mononucleotídeo de Flavina/metabolismo, Elétrons, Anaerobiose, Matriz Extracelular de Substâncias Poliméricas/metabolismo, Riboflavina/metabolismo, Suplementos Nutricionais, Metano

RESUMO

Algae have great application prospects in excess sludge reclamation and recovery of high-value biomass. Chlorococcum humicola was cultivated in this research, using sludge extract (mixed with SE medium) with additions of 10%, 20%, and 30% CO2 (v/v). Results showed that under 20% CO2, the dry weight and polysaccharide yield reached 1.389 ± 0.070 g/L and 313.49 ± 10.77 mg/L, respectively. 10% and 20% CO2 promoted the production of cellular antioxidant molecules to resist the toxic stress and the toxicity of 20% CO2 group decreased from 62.16 ± 3.11% to 33.02 ± 3.76%. 10% and 20% CO2 accelerated the electron transfer, enhanced carbon assimilation, and promoted the photosynthetic efficiency, while 30% CO2 led to photosystem damage and disorder of antioxidant system. Proteomic analysis showed that 20% CO2 mainly affected energy metabolism and the oxidative stress level on the early stage (10 d), while affected photosynthesis and organic substance metabolism on the stable stage (30 d). The up-regulation of PSII photosynthetic protein subunit 8 (PsbA, PsbO), A0A383W1S5 and A0A383VRI4 promoted the efficiency of PSII and chlorophyll synthesis, and the up-regulation of A0A383WH74 and A0A2Z4THB7 led to the accumulation of polysaccharides. The up-regulation of A0A383VDH1, A0A383VX37 and A0A383VA86 promoted respiration. Collectively, this work discloses the regulatory mechanism of high-concentration CO2 on Chlorococcum humicola to overcome toxicity and accumulate polysaccharides.

Assuntos

Dióxido de Carbono, Clorofila, Clorofila/metabolismo, Dióxido de Carbono/toxicidade, Antioxidantes, Proteômica, Esgotos

RESUMO

With the rise of the concept of carbon neutrality, the current wastewater treatment process of industrial organic wastewater is moving towards the goal of energy conservation and carbon emission reduction. The advantages of anaerobic digestion (AD) processes in industrial organic wastewater treatment for bio-energy recovery, which is in line with the concept of carbon neutrality. This study summarized the significance and advantages of the state-of-the-art AD processes were reviewed in detail. The application of expanded granular sludge bed (EGSB) reactors and anaerobic membrane bioreactor (AnMBR) were particularly introduced for the effective treatment of industrial organic wastewater treatment due to its remarkable prospect of engineering application for the high-strength wastewater. This study also looks forward to the optimization of the AD processes through the enhancement strategies of micro-aeration pretreatment, acidic-alkaline pretreatment, co-digestion, and biochar addition to improve the stability of the AD system and energy recovery from of industrial organic wastewater. The integration of anaerobic ammonia oxidation (Anammox) with the AD processes for the post-treatment of nitrogenous pollutants for the industrial organic wastewater is also introduced as a feasible carbon-neutral process. The combination of AnMBR and Anammox is highly recommended as a promising carbon-neutral process for the removal of both organic and inorganic pollutants from the industrial organic wastewater for future perspective. It is also suggested that the AD processes combined with biological hydrogen production, microalgae culture, bioelectrochemical technology and other bio-processes are suitable for the low-carbon treatment of industrial organic wastewater with the concept of carbon neutrality in future.

Assuntos

Poluentes Ambientais, Águas Residuárias, Carbono, Esgotos, Anaerobiose, Reatores Biológicos, Nitrogênio/análise, Eliminação de Resíduos Líquidos/métodos

RESUMO

In anaerobic/aerobic/anoxic (A/O/A) process, endogenous denitrification (ED) is critically important, and achieving steady endogenous partial denitrification (EdPD) is crucial to carbon saving and anammox application. In this study, EdPD was rapidly realized from conventional activated sludge by expelling phosphorus accumulating organisms (PAOs) in anaerobic/anoxic (A/A) mode during 40 days, with nitrite transformation rate (NTR) surging to 82.8 % from 29.4 %. Competibacter was the prime EdPD-fulfilling bacterium, soaring to 28.9 % from 0.5 % in phase II. Afterwards, balance of high NTR and phosphorus removal efficiency (PRE) were attained by well regulating competition and cooperation between PAOs and glycogen accumulating organisms (GAOs) in A/O/A mode, when the Competibacter (21.7 %) and Accumulibacter (7.3 %, mainly Acc_IIC and Acc_IIF) were in dominant position with balance. The PRE recovered to 88.6 % and NTR remained 67.7 %. Great balance of GAOs and PAOs contributed to advanced nitrogen removal by anammox.

Assuntos

Fósforo, Esgotos, Esgotos/microbiologia, Desnitrificação, Glicogênio, Reatores Biológicos/microbiologia, Nitritos, Nitrogênio