Research

20 pages, 1846 KiB

Open AccessArticle

Characterization and Dynamic Shift of Microbial Communities during Start-Up, Overloading and Steady-State in an Anaerobic Membrane Bioreactor

by Nsanzumukiza Martin Vincent, Yuansong Wei, Junya Zhang, Dawei Yu and Juan Tong

Int. J. Environ. Res. Public Health 2018, 15(7), 1399; https://doi.org/10.3390/ijerph15071399 - 03 Jul 2018

Cited by 21 | Viewed by 4811

Abstract

A lab-scale anaerobic membrane bioreactor (AnMBR) with a side stream tubular membrane was developed to treat synthetic domestic sewage to evaluate its performance and the dynamic shift of bacterial and archaeal communities during the start-up, steady-state, overloading and recovery periods of operation at [...] Read more.

A lab-scale anaerobic membrane bioreactor (AnMBR) with a side stream tubular membrane was developed to treat synthetic domestic sewage to evaluate its performance and the dynamic shift of bacterial and archaeal communities during the start-up, steady-state, overloading and recovery periods of operation at mesophilic temperatures. During the start-up period, the bacterial and archaeal communities changed drastically, and Proteobacteria and Bacteroidetes predominated. During the steady-state period, the AnMBR exhibited excellent COD removal above 91%, and COD of the effluent was below 50 mg/L. High-throughput sequencing analysis results revealed that bacterial and archaeal communities shifted significantly from the start-up to the steady-state period, and that the Proteobacteria phylum predominated on days 140, 162 and 190, and the archaea community hydrogenotrophic methanogen genus Methanolinea (1.5–6.64%) predominated over the aceticlastic methanogen genus Methanothrix (1.35–3.07%). During the overloading period, significant changes occurred in microbial community on day 210, e.g., the phyla Bacteroidetes (30%), Proteobacteria (23%) and Firmicutes (18%) predominated and the archaeal community was completely suppressed, and Methanobrevibacter (0.7%) was the only methanogen genus that emerged in the overloading period. After a shock loading period, the microbial communities exhibited significant changes within the ranks of methanogens and shifted to dominance of the aceticlastic methanogen pathway. In addition, the TVFAs to alkalinity ratio in this study was suitable as an indicator of monitoring performance in the AnMBR operation. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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14 pages, 2114 KiB

Open AccessArticle

Continuous Flow-Constructed Wetlands for the Treatment of Swine Waste Water

by Abasiofiok M. Ibekwe and Shelton E. Murinda

Int. J. Environ. Res. Public Health 2018, 15(7), 1369; https://doi.org/10.3390/ijerph15071369 - 29 Jun 2018

Cited by 9 | Viewed by 4425

Abstract

The microbiological quality of treated waste water is always a concern when waste water is disposed to the environment. However, when treated appropriately, such water can serve many purposes to the general population. Therefore, the treatment and removal of contaminants from swine waste [...] Read more.

The microbiological quality of treated waste water is always a concern when waste water is disposed to the environment. However, when treated appropriately, such water can serve many purposes to the general population. Therefore, the treatment and removal of contaminants from swine waste water by continuous flow-constructed wetlands involves complex biological, physical, and chemical processes that may produce better quality water with reduced levels of contaminants. Swine waste contains E. coli populations and other bacterial contaminants originating from swine houses through constructed wetlands, but little is known about E. coli population in swine waste water. To assess the impacts of seasonal variations and the effect of the wetland layout/operations on water quality, E. coli isolates were compared for genetic diversity using repetitive extragenic palindromic polymerase chain reaction (REP-PCR). None of the isolates was confirmed as Shiga toxin producing E. coli O157:H7 (STEC); however, other pathotypes, such as enterotoxigenic E. coli (ETEC) were identified. Using a 90% similarity index from REP-PCR, 69 genotypes out of 421 E. coli isolates were found. Our data showed that the E. coli population was significantly (p = 0.036) higher in November than in March and August in most of the wetland cells. Furthermore, there was a significant (p = 0.001) reduction in E. coli populations from wetland influent to the final effluent. Therefore, the use of continuous flow-constructed wetlands may be a good treatment approach for reducing contaminants from different waste water sources. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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14 pages, 502 KiB

Open AccessArticle

Characterization of Bacterial Communities and Their Antibiotic Resistance Profiles in Wastewaters Obtained from Pharmaceutical Facilities in Lagos and Ogun States, Nigeria

by Amarachukwu Obayiuwana, Adeniyi Ogunjobi, Min Yang and Mark Ibekwe

Int. J. Environ. Res. Public Health 2018, 15(7), 1365; https://doi.org/10.3390/ijerph15071365 - 29 Jun 2018

Cited by 45 | Viewed by 5098

Abstract

In Nigeria, pharmaceutical wastewaters are routinely disseminated in river waters; this could be associated with public health risk to humans and animals. In this study, we characterized antibiotic resistant bacteria (ARB) and their antibiotic resistance profile as well as screening for sul1 [...] Read more.

In Nigeria, pharmaceutical wastewaters are routinely disseminated in river waters; this could be associated with public health risk to humans and animals. In this study, we characterized antibiotic resistant bacteria (ARB) and their antibiotic resistance profile as well as screening for sul1 and sul2 genes in pharmaceutical wastewater effluents. Bacterial composition of the wastewater sources was isolated on non-selective media and characterized by the polymerase chain reaction (PCR) amplification of the 16S rRNA genes, with subsequent grouping using restriction fragment length polymorphism (RFLP) and sequencing. The antibiotics sensitivity profiles were investigated using the standard disk diffusion plate method and the minimum inhibitory concentrations (MICs) of selected antibiotics on the bacterial isolates. A total of 254 bacterial strains were isolated, and majority of the isolates were identified as Acinetobacter sp., Klebsiella pneumonia, Proteus mirabilis, Enterobacter sp. and Bacillus sp. A total of 218 (85.8%) of the bacterial isolates were multidrug resistant. High MICs values were observed for all antibiotics used in the study. The result showed that 31.7%, 21.7% and 43.3% of the bacterial isolates harbored sul1, sul2, and Intl1 genes, respectively. Pharmaceuticals wastewaters are potential reservoirs of ARBs which may harbor resistance genes with possible risk to public health. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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13 pages, 3402 KiB

Open AccessFeature PaperArticle

Impact of Vegetative Treatment Systems on Multiple Measures of Antibiotic Resistance in Agricultural Wastewater

by Lisa M. Durso, Daniel N. Miller and Christopher G. Henry

Int. J. Environ. Res. Public Health 2018, 15(7), 1295; https://doi.org/10.3390/ijerph15071295 - 21 Jun 2018

Cited by 5 | Viewed by 3401

Abstract

Wastewater is an important vector of antibiotic resistant bacteria and antibiotic resistance genes (ARB/G). While there is broad agreement that ARB/G from agricultural (ag) wastewaters can be transported through the environment and may contribute to untreatable infectious disease in humans and animals, there [...] Read more.

Wastewater is an important vector of antibiotic resistant bacteria and antibiotic resistance genes (ARB/G). While there is broad agreement that ARB/G from agricultural (ag) wastewaters can be transported through the environment and may contribute to untreatable infectious disease in humans and animals, there remain large knowledge gaps surrounding applied details on the types and amounts of ARB/G associated with different agricultural wastewater treatment options and different ag production systems. This study evaluates a vegetative treatment system (VTS) built to treat the wastewater from a beef cattle feedlot. Samples were collected for three years, and plated on multiple media types to enumerate tetracycline and cefotaxime-resistant bacteria. Enterobacteriaceae isolates (n = 822) were characterized for carriage of tetracycline resistance genes, and E. coli isolates (n = 673) were phenotyped to determine multi-drug resistance (MDR) profiles. Tetracycline resistance in feedlot runoff wastewater was 2-to-3 orders of magnitude higher compared to rainfall runoff from the VTS fields, indicating efficacy of the VTA for reducing ARB over time following wastewater application. Clear differences in MDR profiles were observed based on the specific media on which a sample was plated. This result highlights the importance of method, especially in the context of isolate-based surveillance and monitoring of ARB in agricultural wastewaters. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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13 pages, 1690 KiB

Open AccessArticle

Persistence of Salmonella Typhimurium in Well Waters from a Rural Area of Changchun City, China

by Jiahang Li, Meiyue Ding, Ziming Han and Jincai Ma

Int. J. Environ. Res. Public Health 2018, 15(6), 1090; https://doi.org/10.3390/ijerph15061090 - 28 May 2018

Cited by 9 | Viewed by 3352

Abstract

Salmonella-contaminated well water could cause major infection outbreaks worldwide, thus, it is crucial to understand their persistence in those waters. In this study, we investigated the persistence of Salmonella enterica serovar Typhimurium in 15 well waters from a rural area of Changchun [...] Read more.

Salmonella-contaminated well water could cause major infection outbreaks worldwide, thus, it is crucial to understand their persistence in those waters. In this study, we investigated the persistence of Salmonella enterica serovar Typhimurium in 15 well waters from a rural area of Changchun City, China. Results illustrated that the time to reach detection limit (ttd), first decimal reduction time (δ), and the shape parameter (p) ranged from 15 to 80 days, from 5.6 to 66.9 days, and from 0.6 to 6.6, respectively. Principal component analysis showed that ttds of S. Typhimurium were positively correlated with total organic carbon, pH, NH₄⁺–N, and total phosphate. Multiple stepwise regression analysis revealed that ttds could be best predicted by NH₄⁺–N and pH. Canonical correspondence analysis and variation partition analysis revealed that NH₄⁺–N and pH, and the rest of the water parameters, could explain 27.60% and 28.15% of overall variation of the survival behavior, respectively. In addition, ttds were found to be correlated (p < 0.01) with δ and p. Our results showed that the longer survival (>2.5 months) S. Typhimurium could constitute an increased health risk to the local communities, and provided insights into the close linkage between well water quality and survival of S. Typhimurium. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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6715 KiB

Open AccessArticle

Selection of a Very Active Microbial Community for the Coupled Treatment of Tetramethylammonium Hydroxide and Photoresist in Aqueous Solutions

by Giulio Moretti, Federica Matteucci, Matteo Saraullo, Francesco Vegliò and Maddalena Del Gallo

Int. J. Environ. Res. Public Health 2018, 15(1), 41; https://doi.org/10.3390/ijerph15010041 - 27 Dec 2017

Cited by 5 | Viewed by 3761

Abstract

Aerobic treatment of wastewater containing Tetramethylammonium hydroxide (TMAH) and photoresist was investigated using a lab scale reactor inoculated with activated sludge coming from urban wastewater treatment that never received TMAH before. The consumption of TMAH was monitored by liquid ion chromatography. Biodiversity indices [...] Read more.

Aerobic treatment of wastewater containing Tetramethylammonium hydroxide (TMAH) and photoresist was investigated using a lab scale reactor inoculated with activated sludge coming from urban wastewater treatment that never received TMAH before. The consumption of TMAH was monitored by liquid ion chromatography. Biodiversity indices were calculated from Denaturing Gradient Gel Electrophoresis (DGGE) bands distribution and used to estimate changes in community composition related to adaptation to the new feeding compound. The first week of adaptation was crucial, and it was analyzed in detail: many organisms died, and the microbial community suffered a great shock. TMAH levels remained constant through the first four days, and then suddenly dropped to undetectable, and at the same time NH₄⁺ increased. When the community showed complete adaptation, predominant groups of bacteria were obtained by the Illumina sequencing of 16s rDNA amplicons, to provide insights on ecology of the adapted community, focusing on the main actors of TMAH abatement. Richness of species (Rr) peaks suggest that the development of TMAH-consuming bacteria leads to persistent consortia that maintain toxicity resistance over time. This showed adaptation and changes of the population to the different feeding conditions, and it opens new perspectives in the in situ treatment of these important residues of industrial processes without relying on external processing plants. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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3791 KiB

Open AccessArticle

A Novel and Native Microcystin-Degrading Bacterium of Sphingopyxis sp. Isolated from Lake Taihu

by Juan Zhang, Qingqing Lu, Qin Ding, Lihong Yin and Yuepu Pu

Int. J. Environ. Res. Public Health 2017, 14(10), 1187; https://doi.org/10.3390/ijerph14101187 - 06 Oct 2017

Cited by 29 | Viewed by 4427

Abstract

A native, highly efficient microcystin-LR (MC-LR)-degrading bacterium named a7 was isolated from Lake Taihu and identified as Sphingopyxis sp. by 16S rDNA sequence analysis. The strain a7 could totally degrade MC-LR at a rate of 3.33 mg/(L•h), as detected by high-performance liquid chromatography [...] Read more.

A native, highly efficient microcystin-LR (MC-LR)-degrading bacterium named a7 was isolated from Lake Taihu and identified as Sphingopyxis sp. by 16S rDNA sequence analysis. The strain a7 could totally degrade MC-LR at a rate of 3.33 mg/(L•h), as detected by high-performance liquid chromatography (HPLC). The mlrA, mlrC, and mlrD genes were detected in the strain a7 by sequence analysis. Tetrapeptide and Adda—which are the middle metabolites of MC-LR—were analyzed via liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) during degradation. These metabolites were degraded completely, which suggested that the native Sphingopyxis sp. a7 was highly efficient in MC-LR degradation under bench conditions. Thus, strain a7 exhibited a significant potential application for bioremediation in water bodies contaminated by MC-LR produced by harmful cyanobacterial blooms. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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1181 KiB

Open AccessArticle

A Marine Bacterium, Bacillus sp. Isolated from the Sediment Samples of Algoa Bay in South Africa Produces a Polysaccharide-Bioflocculant

by Ncedo Ntozonke, Kunle Okaiyeto, Arinze S. Okoli, Ademola O. Olaniran, Uchechukwu U. Nwodo and Anthony I. Okoh

Int. J. Environ. Res. Public Health 2017, 14(10), 1149; https://doi.org/10.3390/ijerph14101149 - 29 Sep 2017

Cited by 12 | Viewed by 4238

Abstract

Bioflocculants mediate the removal of suspended particles from solution and the efficiency of flocculation is dependent on the characteristics of the flocculant. Apart from the merits of biodegradability and harmlessness, bioflocculants could be viable as industrially relevant flocculants as they are a renewable [...] Read more.

Bioflocculants mediate the removal of suspended particles from solution and the efficiency of flocculation is dependent on the characteristics of the flocculant. Apart from the merits of biodegradability and harmlessness, bioflocculants could be viable as industrially relevant flocculants as they are a renewable resource. Additionally, the shortcomings associated with the conventionally used flocculants such as aluminium salts and acrylamide polymers, which include dementia and cancer, highlight more the need to use bioflocculants as an alternative. Consequently, in this study a marine sediment bacterial isolate was screened for bioflocculant production. Basic local alignment search tools (BLAST) analysis of 16S ribosomal deoxyribonucleic acid (rDNA) sequence of the bacterial isolate showed 98% similarity to Bacillus thuringiensis MR-R1. The bacteria produced bioflocculant optimally with inoculum size (4% v/v) (85%), glucose (85.65%) and mixed nitrogen source (urea, ammonium chloride and yeast extract) (75.9%) and the divalent cation (Ca²⁺) (62.3%). Under optimal conditions, a maximum flocculating activity of over 85% was attained after 60 h of cultivation. The purified polysaccharide-bioflocculant flocculated optimally at alkaline pH 12 (81%), in the presence of Mn²⁺ (73%) and Ca²⁺ (72.8%). The high flocculation activity shown indicates that the bioflocculant may contend favourably as an alternative to the conventionally used flocculants in water treatment. Full article

(This article belongs to the Special Issue Microbiological Evaluation of Wastewater Treatment)

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