A review of practical tools for rapid monitoring of membrane bioreactors
- Authors: Scholes, Emily , Verheyen, Vincent , Brook-Carter, Phillip
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Water Research Vol. 102, no. (2016), p. 252-262
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- Description: The production of high quality effluent from membrane bioreactors (MBRs) arguably requires less supervision than conventional activated sludge (CAS) processes. Nevertheless, the use of membranes brings additional issues of activated sludge filterability, cake layer formation and membrane fouling. From a practical standpoint, process engineers and operators require simple tools which offer timely information about the biological health and filterability of the mixed liquor as well as risks of membrane fouling. To this end, a range of analytical tools and biological assays are critically reviewed from this perspective. This review recommends that Capillary Suction Time (CST) analysis along with Total Suspended and Volatile Solids (TSS/VSS) analysis is used daily. For broad characterisation, total carbon and nitrogen analysis offer significant advantages over the commonly used chemical and biological oxygen demand (COD/BOD) analyses. Of the technologies for determining the vitality of the microbial biomass the most robust and reproducible, are the second generation adenosine-5'-triphosphate (ATP) test kits. Extracellular polymer concentrations are best monitored by measurement of turbidity after centrifugation. Taken collectively these tools can be used routinely to ensure timely intervention and smoother operation of MBR systems. © 2016 Elsevier Ltd.
The composition and stability of the faecal microbiota of merino sheep
- Authors: Mamun, Mohammed , Sandeman, Mark , Rayment, Philip , Brook-Carter, Phillip , Scholes, Emily , Kasinadhuni, Naga , Piedrafita, David , Greenhill, Andrew
- Date: 2020
- Type: Text , Journal article
- Relation: Journal of Applied Microbiology Vol. 128, no. 1 (2020), p. 280-291
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- Description: Aims: To determine the composition and temporal stability of the gut (faecal) microbiota of sheep (Ovis aries). Methods and Results: Microbial population dynamics was conducted using ARISA (28 sheep) and 16S rRNA sequencing (11 sheep). Firmicutes and Bacteroidetes were the predominant bacterial phyla, constituting ~80% of the total population. The core faecal bacterial microbiota of sheep consisted of 67 of 136 detected families and 91 of 215 detected species. Predominant microbial taxa included Ruminococcaceae, unassigned families in Bacteroidales and Clostridiales, Verrucomicrobiaceae and Paraprevotellaceae. Diversity indices and core microbiota composition demonstrated the stability of the core microbiota over 2–4 weeks. The core microbiota remained similar over ~5 months. Conclusions: Temporal stability of the sheep microbiota is high over 2–4 weeks in the absence of experimental variables. The core microbiota of Merino sheep shares taxa found in other breeds of sheep and other ruminants. Significance and Impact of the Study: Numerous studies seek to investigate the impact of experimental variables on gut microbiota composition. To do so, knowledge of the innate stability (or instability) of the microbiota over an experimental time course is required, independent of other variables. We have demonstrated high stability of the gut microbiota in sheep over 3–4 weeks, with moderate stability over ~5 months. © 2019 The Society for Applied Microbiology
Colloidal carbon interference in the treatability of pulp and paper wastewater by MBR
- Authors: Scholes, Emily , Brook-Carter, Phillip , Verheyen, Vincent
- Date: 2019
- Type: Text , Journal article
- Relation: Journal of Environmental Chemical Engineering Vol. 7, no. 5 (2019), p. 1-9
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- Description: Pulp and paper wastewaters are challenging to treat due to their variability, complexity and toxicity. Membrane Bioreactor’s (MBR’s) provide high-quality filtrates but are subject to periods of low filterability / high capillary suction time (CST) which potentially limit their use in this application. There is a paucity of published literature concerning long-term operational issues in full-scale, industrial MBR’s. We hypothesised that either changes of bacterial population, alteration/reduction of bacterial metabolism or bacterial production of extra-cellular polymers (ESPs) increased CST and reduced filterability. This study, conducted over two years at the 16.4MLD Gippsland Water Factory, was structured to inform this bacterial centric hypothesis. However, no shifts in bacterial population were seen as causative of high CST and microbial stress levels and biological activity were observed to be low during high CST and no sign of toxicity was found. The strongest correlator with CST was the concentration of colloidal Total Organic Carbon of the mixed liquor suspended solids (MLSS) supernatant (following centrifugation). The carbonaceous colloids accumulated in the supernatant were named ‘Non-Centrifugable Total Organic Carbon’ (NCTOC). Their accumulation in the MLSS was found be due to their biologically refractory nature and their retention by the MBR membrane. The accumulation of NCTOC typically followed a period where the influent had a high colour and a high sodium to calcium ratio, which is consistent with a pulping by-product called ‘Black Liquor’. Additional experiments with Black Liquor allowed us to conclude that high CST can be produced by addition of Black Liquor.