Novel approach enables high resolution microbial source ... · PROKARYA 42 instituteofwater.org.uk...
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PROKARYA instituteofwater.org.uk 42 instituteofwater.org.uk 43 This resulted in the instigation of potable water treatment processes designed to remove 99.99% of bacteria. As public health continued to improve, the proportion of disease burden arising from contact with bacteria began to shift from potable water to a broad range of environments. In the 1970s the European Economic Community began to focus on the quality of the water in which we swim, after it was established that gastrointestinal disease was common after bathing (Brown 1964). In 1976 the Bathing Water Directive was introduced in order to further protect public health. During the subsequent decades many improvements were made to water company assets, introducing primary and secondary treatment of sewage as well as disinfection in some cases. Bathing water quality is significantly improved today, with the proverbial “low hanging fruit” having been picked. In order to further reduce exposure to faecal bacteria it has become necessary to gain a greater understanding of their source. When the Bathing Water Directive came in to force, the primary source of faecal contamination in bathing waters was the discharge of insufficiently treated sewage. By 1998, of the 9.5 million people whose sewage discharged directly to sea 11 percent was untreated, 68 percent primary or secondary treated and 21 percent tertiary treated (Water Services Association 1998). It is now becoming clear that a significant proportion of the faecal bacteria currently found in bathing waters arise from agricultural runoff. Microbial source tracking attempts to elucidate these sources and their relative contribution to faecal bacteria in the bathing water. At present the assumption is that sewage is the primary source of faecal bacteria in bathing water, and thus the wastewater industry is expected to invest millions of pounds in asset improvement programs which are generally targeted at reducing the frequency and impact of combined sewer overflows, or disinfecting treated sewage before final discharge. Many of these programs are based on hydraulic models which attempt to simulate the behaviour of the sewerage network and use assumptions for bacterial load and source. Whilst these models are invaluable in understanding the operation of the network, they cannot give an accurate reflection of the impact of diffuse and point source faecal contamination since they do not directly measure the faecal communities in the source or the bathing water. Due to the need to better understand the impact of point and diffuse contamination on bathing waters, many novel approaches have been developed which attempt to differentiate between the faecal host animal (e.g. human vs cow). Some approaches are based on chemistry, such as sterol ratios. It is suggested that each host animal has a unique ratio of sterol compounds in their faeces, and this can be used to differentiate the contamination source. However the analysis of these ratios swiftly becomes difficult when multiple faecal sources are present so it’s utility is limited. Most the In 1854 John Snow tracked the spread of cholera and established that the source of the outbreak was a water pump in Broad Street, Soho. By doing so he invented the field of epidemiology and established the link between faecal contamination of drinking water and the spread of gastrointestinal disease. remaining approaches are biological, targeting either the regulated bacteria themselves or proxies for faecal contamination. Quantitative polymerase chain reaction (qPCR) experiments have moved the field forward immensely, with many new faecal source host markers having been identified. For example, the bacterium Catellicoccus marimammalium lives only in the guts of birds, and therefore its presence indicates faecal contamination from birds. These presence/absence markers can help narrow down the potential sources involved, but still don’t give an indication of relative contribution to contamination from each source since their abundance is not thought to be stable within the gut. qPCR is also somewhat sensitive to various chemicals that persist in the environment such as humic acids, and is limited to one marker per run. Recent developments in DNA sequencing have reduced costs significantly, to the point where it can be used routinely in biological investigations. This can include profiling the bacteria in bioreactors such as activated sludge and anaerobic digestors or investigating the biology underlying the removal of micropollutants in potable water systems, and most recently in microbial source tracking. This approach can be used to identify the sources of contamination in a bathing water, enabling a focussed approach to improving water quality. The most significant impact of DNA sequencing on microbial source tracking is the ability to produce a “microbial fingerprint” by analysing the entire bacterial community. It has recently been shown that each point source has a unique “fingerprint” including individual CSOs, meaning for the first time the impact of point sources can be quantified. This is significant, since we can now pin point exactly which assets are having the most impact on water quality in terms of the percentage of bacteria in the bathing water originating from that asset. This can also be set in the context of diffuse pollution which can also now be quantified. This enables the targeting of asset investment where it will be most cost effective, but also gives an indication of how that investment will impact the bathing water. For example, if a CSO is contributing 5% of the bacteria in a bathing water during storm conditions, but agricultural runoff is contributing 40% the case can be made for disproportionate cost. Equally where CSOs are clearly the main source of faecal bacteria, investment can be directed to those outfalls which most impact water quality. Another interesting use of this technology is identifying crossed connections, where a toilet is incorrectly plumbed in to the surface water system. These crossed connections may have a disproportionate impact on water quality due to direct discharge to the water course. A single sample can show whether human faecal bacteria are present. Microbial source tracking can also be of use in reducing coliform failures in potable water. The bacteria in raw water entering water treatment plants could be apportioned to source, enabling proactive work to reduce the microbial load on a treatment works and thus reduction of the risk of failure. In the face of climate change and more intense storms, the risk to potable water will increase, making this kind of investigation vital. Microbial source tracking is on the cusp of becoming a main stream tool, ready to assist in asset investment planning and reduction of the environmental impact of the wastewater industry. Gregg Iceton, Managing Director of Prokarya Limited Prokarya provides high resolution microbial source tracking and community profiling to the wastewater industry Novel approach enables high resolution microbial source tracking BacTrack: High resolution microbial source tracking Quantify the impact of diffuse and point sources on bathing water quality Differentiate between individual CSOs and WWTP outfalls Detect cross connections in surface water systems Identify the source of coliforms in raw water BacPro: Microbial community profiling Troubleshoot and optimise activated sludge, trickling filters, anaerobic digestion Link the performance of bioreactors to the underlying biology Research reactor design, filter media and biological removal of micropollutants sales@prokarya.com www.prokarya.com 07492 089596 0191 662 2117
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instituteofwater.org.uk42 instituteofwater.org.uk 43
This resulted in the instigation of potable water treatment processes designed to remove 99.99% of bacteria. As public health continued to improve, the proportion of disease burden arising from contact with bacteria began to shift from potable water to a broad range of environments. In the 1970s the European Economic Community began to focus on the quality of the water in which we swim, after it was established that gastrointestinal disease was common after bathing (Brown 1964). In 1976 the Bathing Water Directive was introduced in order to further protect public health. During the subsequent decades many improvements were made to water company assets, introducing primary and secondary treatment of sewage as well as disinfection in some cases.
Bathing water quality is significantly improved today, with the proverbial “low hanging fruit” having been picked. In order to further reduce exposure to faecal bacteria it has become necessary to gain a greater understanding of
their source. When the Bathing Water Directive came in to force, the primary source of faecal contamination in bathing waters was the discharge of insufficiently treated sewage. By 1998, of the 9.5 million people whose sewage discharged directly to sea 11 percent was untreated, 68 percent primary or secondary treated and 21 percent tertiary treated (Water Services Association 1998). It is now becoming clear that a significant proportion of the faecal bacteria currently found in bathing waters arise from agricultural runoff. Microbial source tracking attempts to elucidate these sources and their relative contribution to faecal bacteria in the bathing water.
At present the assumption is that sewage is the primary source of faecal bacteria in bathing water, and thus the wastewater industry is expected to invest millions of pounds in asset improvement programs which are generally targeted at reducing the frequency and impact of combined sewer overflows, or disinfecting
treated sewage before final discharge. Many of these programs are based on hydraulic models which attempt to simulate the behaviour of the sewerage network and use assumptions for bacterial load and source. Whilst these models are invaluable in understanding the operation of the network, they cannot give an accurate reflection of the impact of diffuse and point source faecal contamination since they do not directly measure the faecal communities in the source or the bathing water. Due to the need to better understand the impact of point and diffuse contamination on bathing waters, many novel approaches have been developed which attempt to differentiate between the faecal host animal (e.g. human vs cow). Some approaches are based on chemistry, such as sterol ratios. It is suggested that each host animal has a unique ratio of sterol compounds in their faeces, and this can be used to differentiate the contamination source. However the analysis of these ratios swiftly becomes difficult when multiple faecal sources are present so it’s utility is limited. Most the
In 1854 John Snow tracked the spread of cholera and established that the source of the outbreak was a water pump in Broad Street, Soho. By doing so he invented the field of epidemiology and established the link between faecal contamination of drinking water and the spread of gastrointestinal disease.
remaining approaches are biological, targeting either the regulated bacteria themselves or proxies for faecal contamination. Quantitative polymerase chain reaction (qPCR) experiments have moved the field forward immensely, with many new faecal source host markers having been identified. For example, the bacterium Catellicoccus marimammalium lives only in the guts of birds, and therefore its presence indicates faecal contamination from birds. These presence/absence markers can help narrow down the potential sources involved, but still don’t give an indication of relative contribution to contamination from each source since their abundance is not thought to be stable within the gut. qPCR is also somewhat sensitive to various chemicals that persist in the environment such as humic acids, and is limited to one marker per run.
Recent developments in DNA sequencing have reduced costs significantly, to the point where it can be used routinely in biological investigations. This can include profiling the bacteria in bioreactors such as activated sludge and anaerobic digestors or investigating the biology underlying the removal of micropollutants in potable water systems, and most recently in microbial source tracking. This approach can be used to identify the sources of contamination in a bathing water, enabling a focussed approach to improving water quality. The most significant impact of DNA sequencing on microbial source
tracking is the ability to produce a “microbial fingerprint” by analysing the entire bacterial community. It has recently been shown that each point source has a unique “fingerprint” including individual CSOs, meaning for the first time the impact of point sources can be quantified. This is significant, since we can now pin point exactly which assets are having the most impact on water quality in terms of the percentage of bacteria in the bathing water originating from that asset. This can also be set in the context of diffuse pollution which can also now be quantified. This enables the targeting of asset investment where it will be most cost effective, but also gives an indication of how that investment will impact the bathing water. For example, if a CSO is contributing 5% of the bacteria in a bathing water during storm conditions, but agricultural runoff is contributing 40% the case can be made for disproportionate cost. Equally where CSOs are clearly the main source of faecal bacteria, investment can be directed to those outfalls which most impact water quality.
Another interesting use of this technology is identifying crossed connections, where a toilet is incorrectly plumbed in to the surface water system. These crossed connections may have a disproportionate impact on water quality due to direct discharge to the water course. A single sample can show whether human faecal bacteria are present.
Microbial source tracking can also be of use in reducing coliform failures in potable water. The bacteria in raw water entering water treatment plants could be apportioned to source, enabling proactive work to reduce the microbial load on a treatment works and thus reduction of the risk of failure. In the face of climate change and more intense storms, the risk to potable water will increase, making this kind of investigation vital. Microbial source tracking is on the cusp of becoming a main stream tool, ready to assist in asset investment planning and reduction of the environmental impact of the wastewater industry.
Gregg Iceton,
Managing Director of Prokarya Limited
Prokarya provides high resolution microbial source tracking and community profiling to the wastewater industry
Novel approach enables high resolution microbial source tracking
BacTrack: High resolution microbial source tracking
Quantify the impact of diffuse and point sources on bathing water quality
Differentiate between individual CSOs and WWTP outfalls
Detect cross connections in surface water systems
Identify the source of coliforms in raw water
BacPro: Microbial community profiling
Troubleshoot and optimise activated sludge, trickling filters, anaerobic digestion
Link the performance of bioreactors to the underlying biology
Research reactor design, filter media and biological removal of micropollutants
07492 089596
0191 662 2117
