Browsing by Author "Zhang, Husen"
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- Anaerobic Co-Digestion of High Strength Food Waste with Municipal Sewage Sludge: An assessment of Digester Performance and gas productionPathak, Ankit Bidhan (Virginia Tech, 2014-06-06)Anaerobic digestion is perhaps the simplest and most widely accepted method for solids and residuals management in the field of wastewater treatment. An emerging trend with regard to anaerobic digestion is the addition of additional organic or industrial wastes rich in degradable material (COD) that can lead to increased methane production and reduce the energy demand of the facility. The objective of this research was to evaluate the effect of adding significant quantities (>20% of feed volume) of High Strength Food Wastes (HSW) to digesters treating conventional municipal sludge by monitoring key parameters such as pH, influent and effluent solids, ammonia, Volatile Fatty Acids (VFAs) and alkalinity. Daily gas production was also closely monitored. Four digesters were set up and exposed to different food waste loading rates. A comparison was drawn between the performance of these reactors, one of which was fed only with sewage sludge and served as the control. If the bacteria in the system are able to metabolize this additional COD, it should show up as an increase in gas production with little or no increase in effluent COD. Ammonia is another crucial parameter that needs to be closely watched as it can have an inhibitory effect on methane production. As part of this study, the impact of addition of free ammonium (simulating high ammonium concentration in the feed sludge or food waste) on digester performance was assessed. The digesters were closely monitored for signs of poor performance or failure.
- Comparison of Biological Aerated Filter (BAF) performance using two granular sunken media at low organic and hydraulic loadingsThomas, Ashly (Virginia Tech, 2015-09-24)Biological treatment forms an integral part of wastewater treatment. Biological aerated filters (BAFs) are submerged attached growth bioreactors which provide biological treatment as well as filtration in a single unit. The packing media used in BAFs plays an important role in the system performance and determines the ability of the system to meet treatment objectives. The performance of upflow BAFs was compared using North American clay media and Severn Trent monomedia at low organic and hydraulic loads (0.18 kg tCOD/m3d – 0.6 kg tCOD/m3d and 0.1 m/hr – 0.38 m/hr, respectively). Two identical, two stage, bench scale, upflow BAFs were constructed using PVC pipes with an internal diameter of 0.11 m. The system was operated at the Peppers Ferry Wastewater Treatment facility for two months and was fed with effluent from the primary clarifier. Grab samples of influent and effluent from the BAFs were collected thrice a week to evaluate carbon oxidation, solids removal and nitrification. In order to evaluate system recovery when BAFs are operated intermittently, a drying cycle of eleven days was introduced. Both media performed satisfactorily with respect to carbon oxidation and nitrification. On average, total COD and total suspended solids (TSS) removal rates were, respectively greater than 80% and 55%. Conversion of ammonia to nitrate was greater than 90% throughout the study. It was concluded that additional factors like media properties and economic factors need to be considered in selection of the media.
- Control of lupus nephritis by changes of gut microbiotaMu, Qinghui; Zhang, Husen; Liao, Xiaofeng; Lin, Kaisen; Liu, Hualan; Edwards, Michael R.; Ahmed, Sattar Ansar; Yuan, Ruoxi; Li, Liwu; Cecere, Thomas E.; Branson, David B.; Kirby, Jay L.; Goswami, Poorna; Leeth, Caroline M.; Read, Kaitlin A.; Oestreich, Kenneth J.; Vieson, Miranda D.; Reilly, Christopher M.; Luo, Xin M. (2017-07-11)Background: Systemic lupus erythematosus, characterized by persistent inflammation, is a complex autoimmune disorder with no known cure. Immunosuppressants used in treatment put patients at a higher risk of infections. New knowledge of disease modulators, such as symbiotic bacteria, can enable fine-tuning of parts of the immune system, rather than suppressing it altogether. Results: Dysbiosis of gut microbiota promotes autoimmune disorders that damage extraintestinal organs. Here we report a role of gut microbiota in the pathogenesis of renal dysfunction in lupus. Using a classical model of lupus nephritis, MRL/lpr, we found a marked depletion of Lactobacillales in the gut microbiota. Increasing Lactobacillales in the gut improved renal function of these mice and prolonged their survival. We used a mixture of 5 Lactobacillus strains (Lactobacillus oris, Lactobacillus rhamnosus, Lactobacillus reuteri, Lactobacillus johnsonii, and Lactobacillus gasseri), but L. reuteri and an uncultured Lactobacillus sp. accounted for most of the observed effects. Further studies revealed that MRL/lpr mice possessed a “leaky” gut, which was reversed by increased Lactobacillus colonization. Lactobacillus treatment contributed to an anti-inflammatory environment by decreasing IL-6 and increasing IL-10 production in the gut. In the circulation, Lactobacillus treatment increased IL-10 and decreased IgG2a that is considered to be a major immune deposit in the kidney of MRL/lpr mice. Inside the kidney, Lactobacillus treatment also skewed the Treg-Th17 balance towards a Treg phenotype. These beneficial effects were present in female and castrated male mice, but not in intact males, suggesting that the gut microbiota controls lupus nephritis in a sex hormone-dependent manner. Conclusions: This work demonstrates essential mechanisms on how changes of the gut microbiota regulate lupusassociated immune responses in mice. Future studies are warranted to determine if these results can be replicated in human subjects.
- Effect of Addition of High Strength Food Wastes on Anaerobic Digestion of Sewage SludgeVaidya, Ramola Vinay (Virginia Tech, 2015-06-11)Anaerobic co-digestion of municipal sludge and food wastes high in chemical oxygen demand (COD) has been an area of interest for waste water treatment facilities looking to increase methane production, and at the same time, dispose of the wastes and increase the revenue. However, addition of food wastes containing fats, oils and grease (FOG) to the conventional anaerobic digestion process can be difficult and pose challenges to utilities. Incorporating these wastes into the treatment plants can potentially inhibit the digestion process. In this study four lab-scale, anaerobic digesters were operated under mesophilic conditions and fed municipal sludge. One of them served as the control, while the other three digesters were fed with different volumetric loadings of juice processing waste, cheese processing waste (whey), dissolved air flotation waste (DAF) from a food processor, and grease trap waste (GTW), in addition to the municipal sludge. The impact of these high strength wastes (HSWs) on digester performance was analyzed for a total period of 150 days. Among the parameters analyzed were pH, total and soluble COD (tCOD and sCOD), Total and Total Volatile Solids (TS and TVS), Total Ammonia Nitrogen (TAN), Total Kjeldahl Nitrogen (TKN), Volatile Fatty Acids (VFA), Long Chain Fatty Acids (LCFA), and alkalinity. Biogas was collected and analyzed for methane content. The dewatering characteristics of digested sludge were also studied. Volatile organic sulfur compounds were analyzed on the dewatered sludge in order to monitor odors. This study showed that different high strength wastes have different impacts on digester performance. HSWs have the ability to degrade along with municipal sludge and to increase biogas production. However, anaerobic digestion can be inhibited by the presence of FOG, and addition of these wastes might not always be cost effective. Careful selection of these wastes is necessary to ensure stable digester operation, while bringing about increases in gas production. Utilities need to be cautious before adding any high strength wastes to their digesters.
- Modeling human enteric dysbiosis and rotavirus immunity in gnotobiotic pigsTwitchell, Erica; Tin, Christine; Wen, Ke; Zhang, Husen; Becker-Dreps, Sylvia; Azcarate-Peril, M. Andrea; Vilchez, Samuel; Li, Guohua; Ramesh, Ashwin; Weiss, Mariah; Lei, Shaohua; Bui, Tammy; Yang, Xingdong; Schultz-Cherry, Stacey L.; Yuan, Lijuan (2016)BACKGROUND: Rotavirus vaccines have poor efficacy in infants from low- and middle-income countries. Gut microbiota is thought to influence the immune response to oral vaccines. Thus, we developed a gnotobiotic (Gn) pig model of enteric dysbiosis to study the effects of human gut microbiota (HGM) on immune responses to rotavirus vaccination, and the effects of rotavirus challenge on the HGM by colonizing Gn pigs with healthy HGM (HHGM) or unhealthy HGM (UHGM). The UHGM was from a Nicaraguan infant with a high enteropathy score (ES) and no seroconversion following administration of oral rotavirus vaccine, while the converse was characteristic of the HHGM. Pigs were vaccinated, a subset was challenged, and immune responses and gut microbiota were evaluated. RESULTS: Significantly more rotavirus-specific IFN-γ producing T cells were in the ileum, spleen, and blood of HHGM than those in UHGM pigs after three vaccine doses, suggesting HHGM induces stronger cell-mediated immunity than UHGM. There were significant correlations between multiple Operational Taxonomic Units (OTUs) and frequencies of IFN-γ producing T cells at the time of challenge. There were significant positive correlations between Collinsella and CD8+ T cells in blood and ileum, as well as CD4+ T cells in blood, whereas significant negative correlations between Clostridium and Anaerococcus, and ileal CD8+ and CD4+ T cells. Differences in alpha diversity and relative abundances of OTUs were detected between the groups both before and after rotavirus challenge. CONCLUSION: Alterations in microbiome diversity and composition along with correlations between certain microbial taxa and T cell responses warrant further investigation into the role of the gut microbiota and certain microbial species on enteric immunity. Our results support the use of HGM transplanted Gn pigs as a model of human dysbiosis during enteric infection, and oral vaccine responses.
- Modeling human enteric dysbiosis and rotavirus immunity in gnotobiotic pigs. [poster]Twitchell, Erica; Tin, Christine; Wen, Ke; Zhang, Husen; Becker-Dreps, Sylvia; Azcarate-Peril, M. Andrea; Vilchez, Samuel; Li, Guohua; Ramesh, Ashwin; Weiss, Mariah; Lei, Shaohua; Bui, Tammy; Yang, Xingdong; Schultz-Cherry, Stacey L.; Yuan, Lijuan (2016-12)Background Oral vaccines, such as those for rotavirus are less efficacious in children from underdeveloped regions, where most severe disease occurs, than in children from more affluent areas. This disparity may be due to altered gut microbiota composition (dysbiosis), environmental enteropathy (EE), high maternal antibody titers, malnutrition, or influence of concurrent enteropathogens. Composition of gut microbiota in children is influenced by method of delivery, environmental hygiene and nutritional status. Studies have shown composition of gut microbiota to be significantly different between African and northern European infants and between malnourished and well-nourished children. A recent study has shown that EE was associated with failure of the oral rotavirus vaccine Rotarix, and underperformance of the oral polio vaccine. An animal model to study the effects of enteric dysbiosis on oral vaccine immunity is needed to evaluate potential treatments to reverse the dysbiosis and/or improve vaccine efficacy. Pigs and humans have similar immune systems, high genomic and protein sequence homology, omnivorous diet, and colonic fermentation, making pigs valuable models in biomedical research. The neonatal gnotobiotic (Gn) pig is a well-established model of human rotavirus disease and immunity.
- Phylogenetic and Metagenomic Analyses of Substrate-Dependent Bacterial Temporal Dynamics in Microbial Fuel CellsZhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen (PLOS, 2014-09-09)
- Probiotics and virulent human rotavirus modulate the transplanted human gut microbiota in gnotobiotic pigsZhang, Husen; Wang, Haifeng; Shepherd, Megan L.; Wen, Ke; Li, Guohua; Yang, Xingdong; Kocher, Jacob; Giri-Rachman, Ernawati; Dickerman, Allan W.; Settlage, Robert E.; Yuan, Lijuan (2014-09-09)We generated a neonatal pig model with human infant gut microbiota (HGM) to study the effect of a probiotic on the composition of the transplanted microbiota following rotavirus vaccination and challenge. All the HGM-transplanted pigs received two doses of an oral attenuated rotavirus vaccine. The gut microbiota of vaccinated pigs were investigated for effects of Lactobacillus rhamnosus GG (LGG) supplement and homotypic virulent human rotavirus (HRV) challenge. High-throughput sequencing of V4 region of 16S rRNA genes demonstrated that HGM-transplanted pigs carried microbiota similar to that of the C-section delivered baby. Firmicutes and Proteobacteria represented over 98% of total bacteria in the human donor and the recipient pigs. HRV challenge caused a phylum-level shift from Firmicutes to Proteobacteria. LGG supplement prevented the changes in microbial communities caused by HRV challenge. In particular, members of Enterococcus in LGG-supplemented pigs were kept at the baseline level, while they were enriched in HRV challenged pigs. Taken together, our results suggested that HGM pigs are valuable for testing the microbiota’s response to probiotic interventions for treating infantile HRV infection.