Recent research efforts demonstrated an increase in fecal coliform counts in anaerobically digested biosolids after dewatering. Variety of bacteria enters viable but nonculturable (VNC) state as a survival response when exposed to environmental stress. Increase in coliform concentration after digestion and dewatering processes have been attributed to cells going into a viable but non-culturable state implying that traditional coliform enumeration methods are not sufficient to determine number of viable cells. Therefore, this research has been undertaken to develop a method for rapid and accurate quantification of viable but non-culturable pathogens in biosolids via monitoring and quantifying stress-related genes in Salmonella sp. The proposed method has the potential to allow accurate detection of pathogens in biosolids even when the cells are non-culturable due to environmental stress. The research proposed identification of stress related genes in Salmonella when cells are exposed to heat for different durations by using available Salmonella microarrays. In the context of this study the identified stress genes can be quantified through reverse transcription, complementary DNA (cDNA) synthesis, and amplification of cDNA via quantitative reverse transcription polymerase chain reaction (qRT-PCR). Then quantity of mRNA can be correlated to cell viability and cells ability to grow, i.e., their culturability. Development of a novel approach to understand the pathogen behaviour in biosolids is key to ensure low public health risks from biosolids. Nevertheless, the initial results suggest that intact RNA isolation from biosolids is still challenging task.
The ethanol industry has grown rapidly during the past ten years, mainly due to increasing oil prices. However, efficient and cost-effective solutions for treating thin stillage wastewater have still to be developed. The anaerobic membrane bioreactor (AnMBR) technology combines classical anaerobic treatment in a completely-stirred tank reactor (CSTR) with membrane separation. The combination of these two technologies can achieve a superior effluent quality and also increase biogas production compared to conventional anaerobic solutions. A pilot-scale AnMBR treating thin stillage achieved very high treatment efficiencies in terms of chemical oxygen demand (COD) and total suspended solids (TSS) removal (>98%). An average permeate flux of 4.3 L/m2 x h was achieved at relatively low transmembrane pressure (TMP) values (0.1-0.2 bars) with flat-sheet membranes. Experience gained during the pilot-scale studies provides valuable information for scaling up of AnMBRs treating complex and high-strength wastewaters.
This paper describes the ongoing operations of a 12 m 3 pilot-scale AnMBR treating thin stillage from a corn-to-ethanol wet mill facility. The main objective was to evaluate the performance of the anaerobic CSTR system coupled with an ultrafiltration (0.08 μm) flat-sheet membrane unit. Following an initial start-up stage the system ran steadily at a flux in the 4-6 LMH range, with MLSS concentrations of 22-26 g/L. The observed trans-membrane pressure (TMP) rarely exceeded 20 kPa when pushed to the higher end flux and always recovered after an overnight relaxation. A simple mass balance revealed excellent COD removal (over 98%), at the loading rate of 6-8 kg TCOD/m 3 /day. This study is ongoing and the data will be analyzed as it is collected.
The primary objective of this study was to investigate the effects of choice of the indicator organisms on the accuracy of classifying the fatty acid methyl ester (FAME) profiles of the known-source library isolates. First, a known-source library containing the FAME profiles of Enterococcus isolates cultured from six different possible sources of microbial pollution was developed. A total of 511 Enterococcus isolates were profiled: 120 isolates from sewage samples representing humans; 69 from dairy and cattle cow; 74 from chicken; 76 from swine; 94 from deer; and 78 from waterfowl. Classification of known-source Enterococcus isolates into their respective host categories resulted with a 66% average rate of correct classification (ARCC) in a six-way discriminant analysis (DA). The ARCC increased to 75% when the individual hosts were pooled into larger categories of human, livestock, and wildlife. The accuracy was 80% when isolates of human origin were discriminated against those of non-human origins. Recently, several studies reported the ARCCs for various classification schemes associated with total coliform (TC), fecal coliform (FC), and Escherichia coli of the known-source isolates. When the accuracy of classification of Enterococcus isolates was compared to those reported for TC, FC, and E. coli isolates, the lowest ARCCs were associated with classification of E. coli isolates, the only species level indicator organism among the four compared. It was found that the degree of discrimination increases as the indicator becomes more inclusive of bacteria from different genus. In addition, random cluster formation analysis indicates that known-source libraries with isolate numbers between 300 and 500 might be sufficient for MST by FAME.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.