Comparative reductions of norovirus, echovirus, adenovirus, Campylobacter jejuni and process indicator organisms during water filtration in alluvial sand.

Sand filtration is a cost-effective means of reducing microbial pathogens in drinking-water treatment. Our understanding of pathogen removal by sand filtration relies largely on studies of process microbial indicators, and comparative data from pathogens are sparse. In this study, we examined the reductions of norovirus, echovirus, adenovirus, bacteriophage MS2 and PRD1, Campylobacter jejuni, and Escherichia coli during water filtration through alluvial sand. Duplicate experiments were conducted using 2 sand columns (50 cm long, 10 cm diameter) and municipal tap water sourced from chlorine-free untreated groundwater (pH 8.0, 1.47 mM) at filtration rates of 1.1-1.3 m/day. The results were analysed using colloid filtration theory and the HYDRUS-1D 2-site attachment-detachment model. The average log10 reduction values (LRVs) of the normalised dimensionless peak concentrations (Cmax/C0) over 0.5 m were: MS2: 0.28; E. coli: 0.76; C. jejuni: 0.78; PRD1: 2.00; echovirus: 2.20; norovirus: 2.35; and adenovirus: 2.79. The relative reductions largely corresponded to the organisms' isoelectric points rather than their particle sizes or hydrophobicities. MS2 underestimated virus reductions by 1.7-2.5 log, and the LRVs, mass recoveries relative to bromide, collision efficiencies, and attachment and detachment rates differed mostly by ∼1 order of magnitude. Conversely, PRD1 reductions were comparable with those of all 3 viruses tested, and its parameter values were mostly within the same orders of magnitude. E. coli seemed an adequate process indicator for C. jejuni with similar reductions. Comparative data describing pathogen and indicator reductions in alluvial sand have important implications for sand filter design, risk assessments of drinking-water supplies from riverbank filtration and the determination of safe setback distances for drinking-water supply wells.

Laboratory-scale waste stabilisation pond development.

The present study describes the development of a laboratory-scale waste stabilisation pond (WSP) system, undertaken in order to investigate the effects of hydraulic, physicochemical, microbial and physical parameters on wastewater treatment. Previous studies have focused predominantly on hydraulic characteristics. This system was engineered at a scale much smaller than had previously been seen in the literature. The scale of the model used here allows for improved optimisation at a shorter time scale that would be seen for larger pilot-scale systems. Additionally, with the addition of viruses, a smaller scale model allows for more control over viral concentration used. Once constructed, the system was dosed with wastewater from a wastewater treatment plant and both the influent and effluent were monitored using common testing methods as well as direct viral analysis. Successful wastewater treatment was seen in terms of reduction of indicator bacteria and virus, as determined by culture-based methods. This treatment and the associated stabilisation of physicochemical parameters such as dissolved oxygen and pH, indicates the successful development of a microbial community within the laboratory-scale WSP.

Comparison of faecal indicator and viral pathogen light and dark disinfection mechanisms in wastewater treatment pond mesocosms.

This study compared light and dark disinfection of faecal bacteria/viral indicator organisms (E. coli and MS2 (fRNA) bacteriophage) and human viruses (Echovirus and Norovirus) in Wastewater Treatment Pond (WTP) mesocosms. Stirred pond mesocosms were operated in either outdoor sunlight-exposed or laboratory dark conditions in two experiments during the austral summer. To investigate wavelength-dependence of sunlight disinfection, three optical filters were used: (1) polyethylene film (light control: transmitting all solar UV and visible wavelengths), (2) acrylic (removing most UVB <315 nm), and (3) polycarbonate (removing both UVB and UVA <400 nm). To assess different dark disinfection processes WTP effluent was treated before spiking with target microbes, by (a) 0.22 µm filtration to remove all but colloidal particles, (b) 0.22 µm filtration followed by heat treatment to destroy enzymes, and (c) addition of Cytochalasin B to supress protozoan grazing. Microbiological stocks containing E. coli, MS2 phage, Echovirus, and Norovirus were spiked into each mesocosm 10 min before the experiments commenced. The light control exposed to all sunlight wavelengths achieved >5-log E. coli and MS2 phage removal (from ~1.0 × 106 to <1 PFU/mL) within 3 h compared with up to 6 h in UV-filtered mesocosms. This result confirms that UVB contributes to inactivation of E. coli and viruses by direct sunlight inactivation. However, the very high attenuation with depth of UVB in WTP water (99% removal in the top 8 cm) suggests that UVB disinfection may be less important than other removal processes averaged over time and full-scale pond depth. Dark removal was appreciably slower than sunlight-mediated inactivation. The dark control typically achieved higher removal of E. coli and viruses than the 0.22 µm filtered (dark) mesocosms. This result suggests that adsorption of E. coli and viruses to WTP particles (e.g., algae and bacteria bio-flocs) is an important mechanism of dark disinfection, while bacteria and virus characteristics (e.g. surface charge) and environmental conditions can influence dark disinfection processes.

Use of Sonication for Enhanced Sampling of Attached Microbes from Groundwater Systems.

The vast majority of microorganisms in aquifers live as biofilms on sediment surfaces, which presents significant challenges for sampling as only the suspended microbes will be sampled through normal pumping. The use of a down-well low frequency sonicator has been suggested as a method of detaching microbes from the biofilm and allowing rapid sampling of this community. We developed a portable, easy to use, low-frequency electric sonicator and evaluated its performance for a range of well depths (tested up to 42 m below ground level) and casing types. Three sonicators were characterized in laboratory experiments using a 1 m long tank filled with pea gravel. These included a commercially available pneumatic sonicator, a rotating flexible shaft sonicator, and the prototype electric sonicator. The electric sonicator detached between 56 and 74% of microbes grown on gravel-containing biobags at distances ranging between 2 and 50 cm from the sonicator. The field testing comprises of a total of 55 sampling events from 48 wells located in 4 regions throughout New Zealand. Pre- and post-sonication samples showed an average 33 times increase in bacterial counts. Microbial sequence data showed that the same classes are present in pre- and post-sonicated samples and only slight differences were seen in the proportions present. The sampling process was rapid and the significant increases in bacterial counts mean that microbial samples can be quickly obtained from wells, which permits more detailed analysis than previously possible.

Groundwater biofilm dynamics grown in situ along a nutrient gradient.

This paper describes the in situ response of groundwater biofilms in an alluvial gravel aquifer system on the Canterbury Plains, New Zealand. Biofilms were developed on aquifer gravel, encased in fine mesh bags and suspended in protective columns in monitoring wells for at least 20 weeks. Four sites were selected in the same groundwater system where previous analyses indicated a gradient of increasing nitrate down the hydraulic gradient from Sites 1 to 4. Measurements during the current study classified the groundwater as oligotrophic. Biofilm responses to the nutrient gradients were assessed using bioassays, with biomass determined using protein and cellular and nucleic acid staining and biofilm activity using enzyme assays for lipid, carbohydrate, phosphate metabolism, and cell viability. In general, biofilm activity decreased as nitrate levels increased from Sites 1 to 4, with the opposite relationship for carbon and phosphorus concentrations. These results showed that the groundwater system supported biofilm growth and that the upper catchment supported efficient and productive biofilms (high ratio of activity per unit biomass).

Appraising bacterial strains for rapid BOD sensing--an empirical test to identify bacterial strains capable of reliably predicting real effluent BODs.

The measured response of rapid biochemical oxygen demand (BOD) biosensors is often not identical to those measured using the conventional 5-day BOD assay. This paper highlights the efficacy of using both glucose-glutamic acid (GGA) and Organisation for Economic Cooperation and Development (OECD) BOD standards as a rapid screen for microorganisms most likely to reliably predict real effluent BODs when used in rapid BOD devices. Using these two synthetic BOD standards, a microorganism was identified that produced comparable BOD response profiles for two assays, the MICREDOX® assay and the conventional 5-day BOD(5) test. A factorial experimental design systematically evaluated the impact of four factors (microbial strain, growth media composition, media strength, and microbial growth phase) on the BOD response profiles using GGA and OECD synthetic standard substrates. An outlier was identified that showed an improved correlation between the MICREDOX® BOD (BOD(sens)) and BOD(5) assays for both the synthetic standards and for real wastewater samples. Microbial strain was the dominant factor influencing BOD(sens) values, with Arthrobacter globiformis single cultures clearly demonstrating superior rapid BOD(sens) response profiles for both synthetic and real waste samples. It was the only microorganism to approach the BOD(5) response for the OECD substrate (171 mg O(2)L(-1)), and also reported BOD values for real waste samples that were comparable to those produced by the BOD(5) test, including discriminating between filtered and unfiltered samples.

Tacklinq chronic disease.

Chronic disease management is being given top priority by the Government through a number of policy documents and initiatives. Judith Chamberlain-Webber describes recent changes and the opportunities they are opening up, particularly for nurses working with patients with long-term conditions.

Seven steps to patient safety.

Nurses have a fundamental role in ensuring the safety of patients in their care. Judith Chamberlain-Webber outlines current policy measures aimed at removing the blame culture and encouraging the reporting of incidents and near misses without fear of reprimand, so that lessons can be learned.

MICREDOX--development of a ferricyanide-mediated rapid biochemical oxygen demand method using an immobilised Proteus vulgaris biocomponent.

Biochemical oxygen demand (BOD) is an international regulatory environmental index for monitoring organic pollutants in wastewater and the current legislated standard test for BOD monitoring requires 5 days to complete (BOD5 test). We are developing a rapid microbial technique, MICREDOX, for measuring BOD by eliminating oxygen and, instead, quantifying an equivalent biochemical co-substrate demand, the co-substrate being a redox mediator. Elevated concentrations of Proteus vulgaris, either as free cells or immobilised in Lentikat disks, were incubated with an excess of redox mediator (potassium hexacyanoferrate(III)) and organic substrate for 1h at 37 degrees C without oxygen. The addition of substrate increased the catabolic activity of the microorganisms and the accumulation of reduced mediator, which was subsequently re-oxidised at a working electrode generating a current quantifiable by a coulometric transducer. The recorded currents were converted to their BOD5 equivalent with the only assumption being a fixed conversion of substrate and known stoichiometry. Measurements are reported both for the BOD5 calibration standard solution (150 mg l(-1) glucose, 150 mg l(-1) glutamic acid) and for filtered effluent sampled from a wastewater treatment plant. The inclusion of a highly soluble mediator in place of oxygen facilitated a high ferricyanide concentration in the incubation, which in turn permitted increased concentrations of microorganisms to be used. This substantially reduced the incubation time, from 5 days to 1h, for the biological oxidation of substrates equivalent to those observed using the standard BOD5 test. Stoichiometric conversion efficiencies for the oxidation of the standard substrate by P. vulgaris were typically 60% for free cells and 35-50% for immobilised cells.

What does the GMS contract mean?

The changes in primary care help tailor services to local needs, with benefits to patients. Nurses will play a key part in managing improved access to services, especially in chronic disease management. Strategically, the nurse's role has the potential to change and expand, offering the option of becoming partners with GPs or even grouping together to form a limited company and seek contracts with the PCT. Last but not least organisational standards in the quality framework for CPD and good human resources practice should result in improving nurses' employment conditions.