Research Funding cycle: 2016-21
Items of work carried out under the 2016-21 funding cycle
Review of wastewater monitoring applications for public health and novel aspects of environmental quality
Wastewater-based epidemiology (WBE) has received increasing attention over the past year across the world. In the UK, local, regional and national wastewater monitoring programmes were established in 2020 to detect severe acute respiratory syndrome coronavirus (SARS-CoVID-2) patterns in human sewage to monitor outbreaks. The establishment of these monitoring programmes has seen considerable investment into establishing the infrastructure, methodology and resources needed to sample, analyse, and interpret data from WBE. Whilst coronavirus has so far been the primary focus of these programmes, it is widely acknowledged that wastewater contains a diverse amount of chemical and biological information that can be used for wider public health purposes. The aim of this project was to review the literature on where else WBE could be utilised to inform public health.
The key findings indicate that there are only a very few technology ready applications of WBE. These include: (1) Estimation of community wide illicit drug usage; (2) Estimation of lifestyle chemical usage: alcohol, nicotine and caffeine; (3) Infectious disease tracking (e.g. polio, SARS-CoV-2); (4) Estimation of disease prevalence based on pharmaceutical usage.
The forementioned applications require significant infrastructure, including specialised staff to undertake sampling and sample preparation as well as an investment in analytical instrumentation. There is a clear potential to apply WBE in:
- Estimation of community-wide exposure to hazardous chemicals. Some initial work indicates that wastewater can provide information on community wide exposure to pesticides and industrial chemicals, which are linked with either occupational exposure or lifestyle choices.
- Prevalence of non-communicable disease (NCD). Current WBE approaches allow for estimation of pharmaceutical usage to treat, e.g. diabetics, cardiovascular disease or mental health conditions.
Lags in water quality response to diffuse pollution control measures: a review
A systematic review of evidence on lags in water quality response to diffuse pollution control measures implemented in Scotland is reported. The review focused on key pollutants in catchments smaller than 300 km2 in temperate regions. Findings were evaluated based on catchment typologies (e.g. catchment size, precipitation, land use, pollutant residence time, and soil /waterbody type) and data/analyses (e.g. monitoring design and record length). There was no evidence supporting fixed timeframes for a water quality response to measures or catchment typology -based lags. Observed lags varied: 1-25 years for river pollutants and potentially longer than 20 years for groundwater nitrate. Long-term water quality and catchment data are key to quantifying lags. It is recommended to keep monitoring and adjust expectations by planning for longer-term lags.
Natural sources of phenols and mitigation measures to reduce their release into the water environment
This study investigated the current state of knowledge reported in the literature on the sources of natural phenolic compounds; factors that trigger their release into the environment; their risks to water sources and potential mitigation measures to reduce these risks. A potential risk assessment methodology, which assesses the terrestrial sources of phenolic compounds and the potential risk to ground and surface waters was presented.
The main findings and recommendations from this study are:
- Changes in observed DOC concentrations may be used as an indicator of potential changes in the presence of phenolic compounds in surface and groundwaters.
- Restoring peatlands is one of the key factors of locking carbon in the soil and reducing the release of DOC and phenolic compounds to water sources.
- There are very few studies on the presence of phenolic compounds in the environment released from natural sources and their subsequent transfer to watercourses. A recommendation from this work would be to carry out a long-term study of the types of DOC and phenolic compounds in Scottish drinking water catchments. This would provide up to date data to validate the risk assessment developed in this project, and also to better understand the potential drivers of the release of phenolic compounds and their transfer in Scottish drinking water catchments.
Evaluating an upland NFM hydrometric network: implications for future monitoring
This project sought to assess the hydrometric network of the River Knaik catchment (37 km2) in Perthshire in terms of fitness for purpose and quality of the data collected to date for evaluating Natural Flood Management (NFM) measures. Rainfall and stream gauges were installed to measure the hydrological response to land use changes brought about by NFM. This evidence was needed to evaluate NFM in the catchment and inform future schemes.
The project found that the locations of the sensors to monitor hydrological change were appropriate given the planned NFM measures (peatland restoration, reduced sheep stocking density and tree planting). However, owing to technical problems and maintenance issues, the data quality was not sufficient to evaluate the effectiveness of measures for mitigating flood peaks.
Based on this assessment, options for redeploying the monitoring network elsewhere, alternative monitoring approaches and improving the current network were outlined. Of wider relevance to the practice of NFM hydrometric monitoring, this assessment highlighted the importance of long-term monitoring for reliable evaluation, the need for long term funding commitment (e.g. supporting staff to download and maintain the equipment) and technical input from a hydrologist. A research summary is provided below.
Tracking SARS-CoV-2 via Municipal Wastewater
Sampling wastewater from a community can be a relatively straightforward way to determine if specific agents are being excreted by that population. As SARSCoV-2, the causative agent of COVID19, can be present in the faeces of infected people, then it may be possible to determine if a community has infected individuals by monitoring the wastewater or other sewage samples for the presence of the virus. The most sensitive method for detection of the virus is to amplify sections of its RNA genome, a practice that is now applied to respiratory tract swabs worldwide to determine whether people are infected. This three-month project had two main objectives: (1) to test methods to concentrate, extract and amplify viral RNA from different wastewater samples to work out whether the virus can be detected; (2) to add a safe ‘control’ virus into wastewater samples to compare the efficiency of methods between different laboratories and to account for losses during processing to help determine exactly how many SARS-CoV-2 viral particles were in the wastewater sample. A key point is that this project was not assessing whether any detected SARS-CoV-2 RNA represented the presence of infectious viral particles. The focus was to develop a detection tool for the virus in communities that could help to identify infected populations. The project compared several published methods for viral extraction from wastewater and then looked at other sewage plant samples such as ‘sludge’ and ‘cake’ as well as some of the outflow water that is released into the environment. The main results were as follows: (1) A safe control virus was compared against SARS-CoV-2 as a way to measure detection efficiency from different types of samples. This control virus behaved in a very similar way to the pandemic virus and is now being supplied to other laboratories as a safe way to test any concentration and extraction methods. We used both this virus and SARS-CoV-2 to measure the efficiency of the methods trialled. (2) SARS-CoV-2 virus was detected in certain wastewater samples collected during the initial wave of the pandemic in Scotland. The different methods tested offer different pros and cons. The two main methods, spin filter columns and PEG precipitation can both work, but both can have high losses of virus. Columns are quite expensive and may be subject to supply problems, whereas precipitation can more easily handle larger volumes, but requires a high-speed spin step needing more specialised equipment. (3) Direct extraction from more solid samples such as ‘sludge’ and ‘cake’ does not require a concentration step and while this was more sensitive, it was only possible to test a small number of samples, so further work is needed to confirm this. (4) No SARS-CoV-2 RNA was detected in the outflow water during the tests, whilst given that primary sludge is treated (e.g. pasteurized, heat-dried, alkali-lime treated), as per legislative requirements, concentration of viral RNA in the solid phase should pose no further risk to human health. In summary, wastewater and other samples from wastewater plants can be used to determine the presence of SARS-CoV-2 in the local population. The sensitivity of this approach needs to be evaluated, but it offers the potential to monitor populations with much lower levels of sample processing than testing of individuals. More work is required to translate levels of viral RNA in wastewater to the level of infection within the community. While more samples need to be evaluated, SARS-CoV-2 virus was not detected in outflow water released from a wastewater plant receiving wastewater containing the virus. Infectivity was not assessed, but the low levels of SARS-CoV-2 RNA detected are unlikely to represent an additional threat to the health of individuals that work with wastewater taking standard precautions in their work environment.
Private water supplies and the potential implications of climate change
The aim of this study was to better understand the likely impacts of climate change (amount, frequency, and distribution of precipitation) on Private Water Supplies (PWS) in Scotland. In particular, the consequences on PWS resilience to water shortages in order to assess changes in vulnerability due to reduced quantity of water as a result of climate change.
Scotland has abundant water resources as a result of its mostly temperate and oceanic climate, but with a highly variable spatial and temporal distribution of precipitation. The west is generally wetter whilst the east is dryer, giving a distinct west to east gradient due to the ‘rain shadow’ influence of the western and northern uplands. Annual and decadal variability in precipitation can be large. Drought can be an issue with very low river and spring flows and low reservoir and loch levels known to occur in both west and east Scotland in connection with periods of prolonged (i.e. lasting for one season or longer) dry weather. The 2015-2021 River Basin Management Plan (RBMP) report compiled by the Scottish Environment Protection Agency (SEPA) points to a greater risk of water flows being worse than the good status required by the Water Framework Directive (“Directive 2000/60/EC) in rivers used for irrigating cropland but only during dry weather. It is essential to address resilience to drought given the latest climate projections for the UK (UKCP18) indicating increasingly variable weather, including: altered spatial and temporal precipitation patterns and variable amounts across Scotland (West becoming increasingly wetter, East becoming drier); higher probability of drier and warmer summers; and increased rates of loss of surface water through greater evapotranspiration (from plants and ground surfaces) and evaporation from water bodies.
generally serve approximately 4% of the resident population in Scotland and potentially many thousands of tourists, primarily in rural areas. In 2018, there were 21,980 PWS and the largest population relying on PWS reaching approximately 30,000 and 40,000 people in Aberdeenshire and Highland, respectively. PWS use a variety of sources such as boreholes, wells, springs, riverintakes, lochs or rainfall and may serve a single house, rural communities up to 5000 people, schools, hospitals
Slender Naiad (Najas flexilis) is a rare aquatic plant species of European conservation importance.The species is believed to be under increasing threat in its Scottish stronghold. However, the factors that affect the health of N. flexilis populations in Scotland are not fully understood, such as, why does the species disappear, and where and why it fares well in some sites. In addition, more needs to be known about what actions can be taken to ensure that the habitat quality needed to support populations of the plant is either maintained or restored. Thus, this project was commissioned by CREW to review the existing knowledge and available information on the habitat requirements of N. flexilis from Scotland and other countries where the species is native. The aim is also to identify what data are already available, where they are, and how to access them.
The now published report highlights that much of the sensitivity of N. flexilis to the known threats of, eutrophication, competition with other plants and the mild acidification of circumneutral lakes can be related to its physiology as an obligate user of CO2; N. flexilis plants being unable to metabolise bicarbonate for photosynthesis. This physiological restriction puts limits on its distribution, particularly with respect to the pH and alkalinity of the lake, and is the reason that N. flexilis is typically found in circumneutral waters, with C-limitation of growth likely to be present at pH <5.5 and pH>8. This physiological requirement may be the reason for the favourable habitat being associated with machair and with anecdotal evidence of populations in lakes around groundwater springs – which are normally high sources of free CO (Falkowski and Raven, 2007). In terms of acidification, lower pH levels below 6.5 may be detrimental to reproductive performance of N. flexilis, before lower pH levels <5 start impacting growth rates through CO2-limitation. In relation to eutrophication, nutrient enrichment leads to increases in phytoplankton, epiphyte and aquatic plant growth. This has the potential to lead o C-limitation for obligate CO2 users during daytime if pH levels rise above 8. This is likely to be exacerbated by grassland or forestry improvements if liming of the land leads to increased pH of circumneutral lakes (but beneficial in acid lakes). The result of both eutrophication and alkalisation is a strong competitive advantage for aquatic plants that use bicarbonate. This is especially true for plant species that can tolerate and survive the combination of low light and increased ratio of bicarbonate to CO2 such as Elodea spp. Whether or not invasive nonnative species, such as Elodea, have impacted N.flexilis populations indirectly, through reducing CO2 availability, or directly, through competition for deeper, low-light habitat is unknown; a combination of both direct and indirect impacts may be involved. This report is the output of the first phase of the project, and a second report will be published in early 2021, including information on which lochs in Scotland provide the most favourable conditions for Slender Naiad, and possible sites for potential re-introduction in the future.
Understanding the link between phosphorus and ecological impact
Factoring ecological significance of sources into phosphorus source apportionment: Phase 2
Phosphorus (P) source apportionment is an important tool for prioritising mitigation strategies and assessing compliance as part of River Basin Management Planning process within the EU Water Framework Directive. However, the methodology for P source apportionment in rivers is subject to significant errors and uncertainty as annual total P loads are assumed to correlate with ecological impact, despite a wealth of evidence to demonstrate other factors such as seasonality and P bioavailability that affect the processes and mechanisms responsible for the transport of P from source to river systems (Stutter et al., 2014).
In 2014 CREW delivered a descriptive methodology of how modelled Total Phosphorus (TP) loads could be modified to take account of their impact on ecology (Phase 1). This project (Phase 2), evaluated the relevance of the method developed in Phase 1 to derive ‘ecologically significant source apportionment’ and examined potential factors affecting ecological status based on the regulatory data. Data from 45 Scottish streams were examined to identify a relationship between diatom response (a key ecological indicator for water body status) and other factors including: nutrients, soluble reactive phosphorus (SRP) loads from different sources, land cover proportions and hydrological catchment characteristics. The main findings and recommendations of Phase 2 are available below in the Executive Summary and Main Report.
Retrofitting Sustainable Urban Drainage Systems to industrial estates
Industrial estates are a well-recognised cause of pollution and Sustainable Urban Drainage Systems (SUDS) have been identified as an important option to address the pollution risk. This study aimed to investigate the potential for retrofitting SUDS on industrial estates to try to reduce pollution of watercourses. The project focused primarily on source control SUDS, or SUDS on an individual property bassis, as well as conveyance types of SUDS.
The principal research site was Houston Industrial Estate, Livingston, which has over 100 businesses and includes major, extensive factory premises, as well as intermediate-size factory premises and many small industrial units typically managed by a landlord or agent. In addition, one sector of the estate has been redeveloped since the statutory requirement to use SUDS technology was established in Scotland. This allowed the project to assess the maintenance of the SUDS installed at that time as well as the SUDS awareness of those businesses.
Research methods included an initial SUDS awareness survey, verification visits and detailed follow-up with several premises to explore opportunities and barriers to retrofitting SUDS in their specific circumstances, and a breakfast seminar and focus group for participating businesses.
The study identified three broad classes of barriers to retrofits: cost, time and space. A number of opportunities were identified, including a need for education and engagement with businesses, including support to grasp opportunities as well as understand requirements. An Executive Summary and Summary report are available below.
Private Water Supplies and the local economic impacts in Scotland
There are approximately 22,000 private water supplies in Scotland serving a population of nearly 197,000 people
Many of these are also micro- and other businesses which rely on these supplies for their existence: frequently
providing services to a broader public as visitors and tourists particularly in remote rural areas of the country.
This study provides evidence of the impact private water supply reliance has upon social and economic
infrastructure; business development; costs of clean water; land management and stewardship and support needs.
It also highlights indicative issues within three sectors (tourism, dairy farming and forestry) that are likely to be
more widely pertinent.
The findings reveal the complexity of private-supply arrangements and infrastructure, and the considerable
gaps to be bridged to ensure future rural social and economic sustainability, system effectiveness, and to
reduce localities’ vulnerabilities.
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