Search

The water industry as a whole consumes a considerable amount of energy in the treatment and distribution of water and wastewater. Like all sectors of society today, the industry is focusing efforts on reducing its CO2 emissions and improving the sustainability of its systems and practices. One way of achieving this is through the use of micro-hydropower (MHP) installations in water infrastructure for energy recovery purposes. This paper presents a review of energy use and CO2 emissions in the water industry as well as highlighting the opportunities and challenges for MHP energy recovery. The results indicate that significant potential exists for energy recovery in the water industry. However, many previous investigations have not considered key complexities such as variations in flows or turbine efficiency. Similarly, accurate costing and return on investment data are often absent or lacking sensitivity analysis. Further research is required to address the risks and long-term reliability of installations, alongside the development of firm policy to direct and incentivise sustainability gains in this area.

Soil is known to play an important role in the cycling of the human pathogen Escherichia coli O157 in the environment. Here we investigated whether residence time in soil influenced its ability to not only survive but subsequently reactivate after release into water during a simulated rainfall event. We inoculated an agricultural soil with chromosomally lux -marked E. coli O157 and then incubated it at 4 or 15 °C for up to 120 d, at which point the pathogen was recovered by extracting the soil with rainwater and its reactivation measured by monitoring bioluminescence over a 9 h period. We found that with increasing residence time in soil, E. coli O157 exhibited a reduction in both numbers and reactivation capacity as measured by cells' energy status (bioluminescence). As the degree of cell activity is linked to infectivity, this indicates that transmissibility may be reduced after a period within soil. This should be considered when assessing the degree of risk from environmental exposure to bacterial pathogens.

During the past 10 years, multidrug-resistant Gram-negative Enterobacteriaceae have become a substantial challenge to infection control. It has been suggested by clinicians that the effectiveness of antibiotics is in such rapid decline that, depending on the pathogen concerned, their future utility can be measured in decades or even years. Unless the rise in antibiotic resistance can be reversed, we can expect to see a substantial rise in incurable infection and fatality in both developed and developing regions. Antibiotic resistance develops through complex interactions, with resistance arising by de-novo mutation under clinical antibiotic selection or frequently by acquisition of mobile genes that have evolved over time in bacteria in the environment. The reservoir of resistance genes in the environment is due to a mix of naturally occurring resistance and those present in animal and human waste and the selective effects of pollutants, which can co-select for mobile genetic elements carrying multiple resistant genes. Less attention has been given to how anthropogenic activity might be causing evolution of antibiotic resistance in the environment. Although the economics of the pharmaceutical industry continue to restrict investment in novel biomedical responses, action must be taken to avoid the conjunction of factors that promote evolution and spread of antibiotic resistance.

We applied digestate generated from the anaerobic digestion of slurry, undigested slurry, or inorganic N (ammonium nitrate) or NPK compound fertilizer to pots of grass and a grass–clover mix grown in two soils. Crop yields were equal or enhanced with digestate, and analysis of soil water showed that there was less potential for loss of nutrients via leaching. Replacing inorganic fertilizer with digestate may therefore maintain grassland productivity but with less impact on the environment.

The antimicrobial action of chitosan and functionalized chitosan derivatives is well known; however, limited research has been undertaken on its use in meat environments. In this study, the antibacterial activity of a newly-developed arginine-functionalized chitosan was tested against pathogenic Escherichia coli O157 in chicken juice. The chicken juice was representative of the liquid which accumulates in food packaging and which is frequently implicated in food poisoning incidents. Aliquots of chicken juice (50 ml) were inoculated with a lux -marked strain of E. coli O157 to approximately 8.75 log 10 CFU ml −1 . Samples were subsequently mixed with chitosan-arginine of varying concentrations (0–500 mg l −1 ) and incubated at 4 or 20 °C to mimic refrigeration and room temperatures, respectively. Pathogen persistence and metabolic activity (indexed by bioluminescence measurements) were subsequently quantified in the liquor at 0 (immediately after mixing), 3, 12, 24, 48, and 72 h post-incubation. The presence of chitosan-arginine significantly reduced both the numbers and metabolic activity of the pathogen in a dose-dependent manner with greater inhibition seen at higher concentration. In addition, it also suppressed the growth of general food spoilage bacteria, reduced malodor and prevented pathogen re-growth up to 72 h. The results imply that incorporating water soluble chitosan-arginine into packaging may help maintain both product shelf life and freshness as well as minimize the risk of food poisoning in both retail outlets and domestic homes.

The EU Animal By-Products Regulations generated the need for novel methods of storage and disposal of dead livestock. Bioreduction prior to rendering or incineration has been proposed as a practical and potentially cost-effective method; however, its biosecurity characteristics need to be elucidated. To address this, Salmonella enterica (serovars Senftenberg and Poona), Enterococcus faecalis, Campylobacter jejuni, Campylobacter coli and a lux-marked strain of Escherichia coli O157 were inoculated into laboratory-scale bioreduction vessels containing sheep carcass constituents. Numbers of all pathogens and the metabolic activity of E. coli O157 decreased significantly within the liquor waste over time, and only E. faecalis remained detectable after 3 months. Only very low numbers of Salmonella spp. and E. faecalis were detected in bioaerosols, and only at initial stages of the trial. These results further indicate that bioreduction represents a suitable method of storing and reducing the volume of livestock carcasses prior to ultimate disposal.

How land-application of digestate sourced from anaerobic digestion (AD) of animal waste influences the functioning of a mixed pasture agroecosystem is not well characterised, particularly with regard to the response of the actively growing microbial community. We studied the impact of the liquid AD digestate on the decomposer community in two different soils, seeded with two different common grassland crops; a mixture of either grass or grass/clover in a greenhouse experiment. We studied bacterial (leucine incorporation into bacteria) and fungal (acetate incorporation into ergosterol) growth responses to AD cattle slurry digestate, undigested cattle slurry, mineral fertiliser (NPK and N) added at a rate equivalent to 150 kg N ha−1, and a no-fertiliser control treatment. Differences in fungal and bacterial growth were evident between the soil and sward types. However, the fertilisers consistently stimulated a higher bacterial growth than the no-fertiliser control, and liquid digestate resulted in a level of bacterial growth higher or equal to that of mineral fertiliser, whilst undigested slurry resulted in lower bacterial growth. These fertiliser effects on bacterial growth mirrored the effects on plant growth. In contrast, the fungal community responded only marginally to fertiliser treatments. We conclude that the application of digestate stimulates the bacterial decomposer community in a similar way to that of mineral fertilisers. Our results suggest that mineral fertiliser can be exchanged for liquid digestate with limited impact on the actively growing soil microbial community that, in turn, regulate important soil processes including nutrient cycling in agricultural soils.

Contamination of water with the zoonotic pathogen Escherichia coli O157 can have severe public health implications and has led to many large disease outbreaks. Although the gastrointestinal tract of ruminants is the recognised reservoir of this organism, E. coli O157 can persist for significant periods of time in animal manure and contaminated soil, from where it can be transferred to watercourses during periods of heavy rainfall. Freshwater ecosystems are often at the interface between agriculture and the wider environment and can play an important role in human exposure to E. coli O157, e.g. though contaminating drinking water, recreational surface waters and shellfish harvesting areas. To mitigate the risk of disease outbreaks, it is essential to have a rapid, robust and reproducible method for the detection of waterborne E. coli O157. Because of the very low infective dose and the high background levels of non-target microbes, detection methods need to be extremely sensitive, and display a high level of specificity. In this review, we briefly outline the environmental pathways for the movement of E. coli O157 into watercourses, and critically assess the methods that are currently used to detect E. coli O157 in freshwater systems. Finally, we determine the suitability of each method for the rapid, accurate and affordable detection of waterborne E. coli O157 and consider some future directions for detecting human pathogens in the environment.

The EU Animal By-Products Regulations forbid the burial of livestock carcasses on land. Farmers would benefit from the availability of biosecure and economically viable alternatives for storing and disposing of dead animals. We assessed the efficacy of bioreduction vessels as a mechanism of storing and reducing the volume of fallen livestock prior to ultimate disposal. Two experimental scenarios were tested: (1) a single input of 300 kg of dead sheep with no further inputs for 3 months, and (2) a continuous ‘on-farm’ addition of dead sheep over 12 months ( ca. 2–3 t animals vessel −1 ). The trials involved half-filling the vessels with water, addition of the dead sheep with subsequent heating (40 °C) and aeration of the liquor. Each trial was repeated three times. Our results showed a complete biodigestion and liquefaction of the animals alongside a significant bioreduction in the volume of the liquid. No pathogens could be detected in either the waste or the gaseous emissions. Calculations showed that bioreduction may offer significant long-term savings for farmers in terms of animal disposal costs. Our findings suggest that bioreduction may offer a practical, biosecure, and cost-effective method of storing fallen livestock prior to disposal via rendering or incineration.

Runoff from agricultural land into watercourses may transport and deposit animal-derived waste contaminated with Escherichia coli O157:H7 onto beaches, which may in turn lead to human infection. To simulate contamination, freshwater mixed with cattle slurry containing E. coli O157:H7 was added to sand from three recreational beaches. The sand was then maintained in a dry state (nontidal) or subjected to a repeated seawater tidal simulation. The pathogen could still be recovered from all sands by day 5. Although survival of the pathogen did not statistically vary between sands of different origin under nontidal conditions, significant differences in numbers occurred between sands when subject to tidal simulation. In the tidal simulations, a considerable proportion of the E. coli O157:H7 rapidly dissipated from sand into the seawater. In a separate experiment, the activity of bioluminescent (lux-marked) E. coli O157:H7 cells was monitored in various mixtures of contaminated runoff water and seawater over 5 days. Pathogen activity declined with increasing seawater concentration; however, cells remained viable in all treatments over the 5-day period. The addition of nutrients to water rapidly increased pathogen activity in all treatments. Our findings highlight the resilience of E. coli O157:H7 in aquatic and marine environments.

Globally, the hydropower (HP) sector has significant potential to increase its capacity by 2050. This study quantifies the energy and resource demands of small-scale HP projects and presents methods to reduce associated environmental impacts based on potential growth in the sector. The environmental burdens of three (50-650 kW) run-of-river HP projects were calculated using life cycle assessment (LCA). The global warming potential (GWP) for the projects to generate electricity ranged from 5.5-8.9 g CO2 eq/kWh, compared with 403 g CO2 eq/kWh for UK marginal grid electricity. A sensitivity analysis accounted for alternative manufacturing processes, transportation, ecodesign considerations, and extended project lifespan. These findings were extrapolated for technically viable HP sites in Europe, with the potential to generate 7.35 TWh and offset over 2.96 Mt of CO2 from grid electricity per annum. Incorporation of ecodesign could provide resource savings for these HP projects: avoiding 800 000 tonnes of concrete, 10 000 tonnes of steel, and 65 million vehicle miles. Small additional material and energy contributions can double a HP system lifespan, providing 39-47% reductions for all environmental impact categories. In a world of finite resources, this paper highlights the importance of HP as a resource-efficient, renewable energy system.

Survival and movement of Escherichia coli O157:H7 in both soil and vermicompost is of concern with regards to human health. Whilst it is accepted that E. coli O157:H7 can persist for considerable periods in soils, it is not expected to survive thermophilic composting processes. However, the natural behavior of earthworms is increasingly utilized for composting (vermicomposting), and the extent to which earthworms promote the survival and dispersal of the bacterium within such systems is unknown. The faecal material produced by earthworms provides a ready supply of labile organic substrates to surrounding microbes within soil and compost, thus promoting microbial activity. Earthworms can also cause significant movement of organisms through the channels they form. Survival and dispersal of E. coli O157:H7 were monitored in contaminated soil and farmyard manure subjected to earthworm digestion over 21 days. Our findings lead to the conclusion that anecic earthworms such as Lumbricus terrestris may significantly aid vertical movement of E. coli O157 in soil, whereas epigeic earthworms such as Dendrobaena veneta significantly aid lateral movement within compost. Although the presence of earthworms in soil and compost may aid proliferation of E. coli O157 in early stages of contamination, long-term persistence of the pathogen appears to be unaffected.

Bioreduction is a novel method for the on-farm storage of fallen stock in a vessel containing water that is heated and aerated, prior to disposal. The combination of a mesophilic temperature and high bacterial population leads to rapid degradation of carcasses due to microbial and enzymatic breakdown of protein material; and ultimately the reduction in volume of waste to be disposed. The system could, however, be improved if more was known about the changes that occur during a bioreduction cycle. Pig carcasses were placed within two commercial-scale bioreduction vessels (BVs) (6.5 m3 capacity) and the changes in physicochemical parameters, enzymatic activity, gas emissions and microbial communities were analysed over 56 days. Analyses showed that each vessel displayed different physicochemical parameters. The microbial communities within both vessels were also distinct, though they converged between days 28 and 42 before again diverging. Of the enzymes assayed, acetylesterases showed the highest activity during initial stages, with a subsequent increase in lipase towards the end. All other enzymes showed little activity in comparison. Despite active aeration of the vessels, conditions were redox-constrained, leading to the emission of gases associated with anaerobic conditions, namely NH3 and H2S. It was concluded that no single parameter governed the biochemical processes and that each BV will have its own unique microbial population and hence rate of decomposition. Further work is needed to increase the rate of bioreduction through bioaugmentation or developing enzyme additives.

SUMMARYAsymptomatic carriage of gastrointestinal zoonoses is more common in people whose profession involves them working directly with domesticated animals. Subclinical infections (defined as an infection in which symptoms are either asymptomatic or sufficiently mild to escape diagnosis) are important within a community as unknowing (asymptomatic) carriers of pathogens do not change their behaviour to prevent the spread of disease; therefore the public health significance of asymptomatic human excretion of zoonoses should not be underestimated. However, optimal strategies for managing diseases where asymptomatic carriage instigates further infection remain unresolved, and the impact on disease management is unclear. In this review we consider the environmental pathways associated with prolonged antigenic exposure and critically assess the significance of asymptomatic carriage in disease outbreaks Although screening high-risk groups for occupationally acquired diseases would be logistically problematical, there may be an economic case for identifying and treating asymptomatic carriage if the costs of screening and treatment are less than the costs of identifying and treating those individuals infected by asymptomatic hosts.

Livestock mortalities represent a major waste stream within agriculture. Many different methods are used throughout the world to dispose of these mortalities; however within the European Union (EU) disposal options are limited by stringent legislation. The legal disposal options currently available to EU farmers (primarily rendering and incineration) are frequently negatively perceived on both practical and economic grounds. In this review, we assess the potential environment impacts and biosecurity risks associated with each of the main options used for disposal of livestock mortalities in the world and critically evaluate the justification for current EU regulations. Overall, we conclude that while current legislation intends to minimise the potential for on-farm pollution and the spread of infectious diseases (e.g. transmissible spongiform encephalopathies, bacterial pathogens), alternative technologies (e.g. bioreduction, anaerobic digestion) may provide a more cost-effective, practical and biosecure mechanism for carcass disposal as well as having a lower environmental footprint. Further social, environmental and economic research is therefore warranted to assess the holistic benefits of alternative approaches for carcass disposal in Europe, with an aim to provide policy-makers with robust knowledge to make informed decisions on future legislation.

In order for policy-makers to formulate effective disease control measures they require accurate estimates of the extent and prevalence of the disease. On occasion, obtaining these data can be difficult, as farmers may perceive relevant information as being sensitive to divulge. Consequently, underestimation of disease prevalence may occur due to farmer reticence about admitting to behaviours and outcomes that are considered professionally transgressive. To overcome such weaknesses, this study used a novel social science survey method known as the Randomized Response Technique in order to obtain population level estimations of transgressionary behavior and disease prevalence for the case of sheep scab in Wales. Since deregulation in 1992, sheep scab has become widespread throughout the UK. Previous estimates of sheep scab in the UK have employed survey techniques which do not adequately protect the anonymity of the farmers' answers other than via verbal or institution backed promise. In this study, farmers at several agricultural shows in Wales were asked to complete questionnaires according to the Randomized Response Technique during the summer of 2009. The survey results suggest that 30% of farmers did not routinely treat their sheep for scab. A further 36.5% of the surveyed farmers admitted to having sheep scab in their flocks in the past 5 years. These estimates are both higher than obtained by previous surveys which used more traditional questionnaire structures. Survey responses revealed a strong willingness to reintroduce compulsory treatment measures to control or eradicate the disease. This is the first study to demonstrate the value of the Randomized Response Technique in the context of animal health.

Ruminants, and to a lesser extent monogastric farm animals, are known to be natural reservoirs of Escherichia coli O157:H7, and contact with contaminated faeces has been linked to human infection. This study used a nontoxigenic, chromosomally marked, lux reporter strain to compare the persistence and activity (bioluminescence) of E. coli O157:H7 over 21 days in the faecal liquor of five farm animals: horse, sheep, cow, pig and piglet. Samples were inoculated with the lux E. coli O157:H7 (7.82 log CFU mL(-1)) and stored at 20 +/- 1 degrees C. The organism was recovered from all samples throughout the experimental period, although lower numbers were recovered from horse faecal liquor relative to all other types (P0.001). The organisms' activity declined in all samples over time and no luminescence could be detected in any sample 21 days postinoculation. However, activity did increase greatly within pig and piglet faeces during initial stages of monitoring and overall luminescence was greater in piglet samples compared with all other samples (P0.001). This is the first study to demonstrate how both the persistence and metabolic activity of E. coli O157:H7 notably varies within a range of ruminant and nonruminant animal faeces. Further research is needed to elucidate the factors that govern differential persistence and metabolic activity of E. coli O157:H7 within such matrices.

Runoff from agricultural land into watercourses may transport and deposit animal-derived waste contaminated with Escherichia coli O157:H7 onto beaches, which may in turn lead to human infection. To simulate contamination, freshwater mixed with cattle slurry containing E. coli O157:H7 was added to sand from three recreational beaches. The sand was then maintained in a dry state (nontidal) or subjected to a repeated seawater tidal simulation. The pathogen could still be recovered from all sands by day 5. Although survival of the pathogen did not statistically vary between sands of different origin under nontidal conditions, significant differences in numbers occurred between sands when subject to tidal simulation. In the tidal simulations, a considerable proportion of the E. coli O157:H7 rapidly dissipated from sand into the seawater. In a separate experiment, the activity of bioluminescent (lux-marked) E. coli O157:H7 cells was monitored in various mixtures of contaminated runoff water and seawater over 5 days. Pathogen activity declined with increasing seawater concentration; however, cells remained viable in all treatments over the 5-day period. The addition of nutrients to water rapidly increased pathogen activity in all treatments. Our findings highlight the resilience of E. coli O157:H7 in aquatic and marine environments.

Survival and movement of Escherichia coli O157:H7 in both soil and vermicompost is of concern with regards to human health. Whilst it is accepted that E. coli O157:H7 can persist for considerable periods in soils, it is not expected to survive thermophilic composting processes. However, the natural behavior of earthworms is increasingly utilized for composting (vermicomposting), and the extent to which earthworms promote the survival and dispersal of the bacterium within such systems is unknown. The faecal material produced by earthworms provides a ready supply of labile organic substrates to surrounding microbes within soil and compost, thus promoting microbial activity. Earthworms can also cause significant movement of organisms through the channels they form. Survival and dispersal of E. coli O157:H7 were monitored in contaminated soil and farmyard manure subjected to earthworm digestion over 21 days. Our findings lead to the conclusion that anecic earthworms such as Lumbricus terrestris may significantly aid vertical movement of E. coli O157 in soil, whereas epigeic earthworms such as Dendrobaena veneta significantly aid lateral movement within compost. Although the presence of earthworms in soil and compost may aid proliferation of E. coli O157 in early stages of contamination, long-term persistence of the pathogen appears to be unaffected.

Implications The Global Farm Platform was conceived and established to explore multidisciplinary strategies for optimising the sustainability of ruminant livestock systems around the world. International sustainability issues are common, but the solutions are often region-specific; therefore, our farms, situated across all major agroclimatic zones, are a unique resource worldwide. Each farm is following ?steps to sustainable livestock? to improve their production system(s), thereby developing robust metrics to progress economic, environmental and social viability. The consortium works collaboratively to improve the sustainability of ruminants, which we argue are a vital component of global food systems, delivering both human and planetary health. Made available in DSpace on 2021-11-05T19:00:24Z (GMT). No. of bitstreams: 1 TakingSteps.pdf: 21431595 bytes, checksum: 032590d403d7e48f19472a6ad4fb2337 (MD5) Previous issue date: 2021