When I was a youngster, Jersey had a Sewage Board Committee, which later changed its name (and some of its functions) and became the more euphemistic Public Works, and then Public Services, and now TTS.
All the recent talk about the incinerator has meant attention has been diverted from the Medical Officer of Health's recent report, which actually is giving us some facts and figures about sewage, which are rather worrying.
Liquid waste disposal
The sewage treatment plant at Bellozanne is ageing and has been in operation since 1959. Over the years, treatment processes have been updated as the population has grown and as more stringent effluent standards have been required. The plant was initially built to deal with a lower total volume of liquid waste than it does today. It currently receives on average 33,000 cubic metres per day - a 36% increase since 1977.
This increase has occurred despite the many surface water separation schemes undertaken during that time which should have reduced flows. The mains drainage systems work well in general, although in extended periods of inclement weather, the network becomes overburdened with surface water from combined drainage systems (where foul and surface waters are mixed together) and from ingress through leaking pipe work. The cavern under Fort Regent is designed to take up the excess from the town area and, when flows in the system return to normal, to pump back collected sewage into the works.
The report recommends:
the early formulation of an Islandwide liquid waste strategy to determine the appropriate level of improvement and extension to the mains drainage network, along with an appropriately sized and located replacement for the Bellozanne sewage treatment plant
What is missing from the report, and perhaps may become available from TTS, is the capacity of the sewage treatment plant in tons per day, and how close it is to reaching that capacity, and how much plant is needed per head of population to sustain that capacity.
This is what I call "real joined up thinking", and there seems to be precious little of it around. Population growth always looks at housing, roads, sometimes schools, but never at the distant end of the infrastructure needed to support it. Until, as with the incinerator, it has to be done hurriedly out of necessity, because when firefighting, it is the wrong time to stop and assess the merits of different engines.
In the University of London Study "Determining Sustainable Development Density using the Urban Carrying Capacity Assessment", the authors note that "The determination of the capacity of a system is fairly straightforward when managing suburban facilities as water supply, sewage treatment, and transportation."
There is also an energy cost to sewage treatment. The UK Parliamentary Office of Science and Technology, has produced a paper on "Energy and Sewage" in which they note:
Over 10 billion litres of sewage are produced every day in England and Wales. It takes approximately 6.34 gigawatt hours of energy to treat this volume of sewage, almost 1% of the average daily electricity consumption of England and Wales. The actual energy used will depend on the quality of sewage and intensity of treatment required. Typically, there are three stages of treatment:
. Primary. Solids are physically settled out.
. Secondary. Bacteria convert organic matter to a carbon-rich sludge.
. Tertiary. Further treatment may be used to remove more organic matter and/or disinfect the water.
Effluent is discharged to fresh, ground or coastal water.
Sludge is applied to agricultural land (62%), incinerated (19%), used for land reclamation (11%) or used for other purposes, such as composting or landfill (8%)
It would be interesting to note the statistics regarding Jersey's use of sludge.
The report also notes that:
There are mature, widely-practised technologies for generating fuels from sewage treatment and research has
identified future methods for exploiting sewage as an energy resource . In 2005 - 2006, the amount of
renewable energy generated on water industry sites was 493 gigawatt hours - 6.4% of the total energy used to
treat water and wastewater.
Regarding sustainable energy, it is also worth noting that biogas can be generated from the system, and this can offset against the energy consumption. Whether this would be viable in Jersey is another matter, considering the small size of the Island, but it is worth considering.
Biogas production from sewage sludge treatment, via a process called anaerobic digestion, is already a well established means of generating energy in the UK. Bacteria use organic matter in sludge to produce a mixture of methane (60 - 65%), CO2 (35 - 40%) and trace gases. Impurities, such as hydrogen sulphide and water, are removed and the resulting biogas is then commonly used in boilers or combined heat and power (CHP) systems. For example, anaerobic digestion facilities are being developed at United Utilities' Davyhulme sewage treatment plant that will provide 90% of the site's power via CHP. Biogas may also be used for other applications, such as vehicle fuel, if CO2 is also removed. In Linköping in Sweden, trains, buses,
taxis and some private cars run on biogas.
Links:
Report on Energy and Sewage
http://www.alphagalileo.org/images/pdf.pdf
Determining Sustainable Development Density using the Urban Carrying Capacity Assessment
http://eprints.ucl.ac.uk/208/1/paper78.pdf.
Medical Officer of Health report
http://www.gov.je/Health/public_health/OurIslandOurHealth2008.htm
Le Rocher
-
Le Rocher
- Du Jèrriais: page V
- Du Guernésiais: page IV
- Conseil scientifique des parlers normands en Jèrri: page VI
1 day ago
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4 comments:
On radio 4's Farming Today programme this mornign there was an interstign piece on how there isn't enough processed human sewage waste available to meet demand. Its a much cheaper alternative to oil based fertilizers, and high in phosphates that are also rising in price. There are rules on what crops can follow on land where solid waste has been applied, but generally theres an 18 month lag required.
Smallholders have been using the contents of compost toilets for centuries to mainting the fertility of their vegetable gardens. Ecologically its far more sensible than dumping it.
Interstingly I think the Soil Association doesn't permitt this practice since bringing in treated human waste could theoreticlly carry contaminants. I'll have to check on that.
You might be able to hear the programme again on the BBC site's listen again facility.
Thanks. It is available on Radio 4 listen again(what I pay my licence fee for, the best Radio station in the world!). Will listen to it later today.
There's a transcript of an Australian discussion on the same subject at:
http://www.abc.net.au/pm/content/2008/s2274419.htm
MARK COLVIN: You could call it the bottom end of the food cycle: using treated human waste to fertilise food crops.
Bio-solids is the euphemism the industry uses and Australian farmers are being urged to consider using them instead of expensive synthetic fertilisers.
Researchers from the CSIRO say nutrients from treated sewage can help improve the quality of the soil, increase plant growth and make significant cost-savings for farmers.
Other researchers are even looking at using the by-products to build roads.
Jennifer Macey reports.
(Sound of toilet flushing)
JENNIFER MACY: Half of the waste flushed from Melbourne's toilets ends up at the Werribee sewage treatment plant.
Once the sewage has been treated the left over sludge is dried and stored on-site. But this waste stockpile has grown to more than 2 million cubic metres.
Professor Mike McLaughlin from the CSIRO's Land and Water says it's a wasted resource
MIKE MCLAUGHLIN: If you think about our food supply, what were doing is harvesting all these nutrients from agricultural land and bringing it into cities and our choice is then well: do we pump it into ocean and cause problems; or do we put it in a landfill which is a bit of a waste; do we burn it and cause other problems; or do we re-use it back where nutrients have come from and that's really what the recycling schemes are about.
JENNIFER MACY: A nationwide study by the CSIRO has found bio-solids can improve soil quality by returning nutrients to the ground. It can also boost growth and yields in grain crops.
The results have been presented this week at the Australian Water Association's Bio-solids Conference in Adelaide.
Professor Mike McLaughlin says farmers could save thousands by making the switch.
MIKE MCLAUGHLIN: We had trials on sugar cane, on trees, and on cotton, sorghum and peanuts, wheat in Queensland and the returns of $1,800 per hectare were a combination of increased crop growth, and returns from the extra productivity and also the savings on fertiliser costs which can be quite significant.
JENNIFER MACY: And the grains policy director with Agforce Queensland Lindsay Krieg says there's growing interest among farmers.
LINDSAY KRIEG: I think we have to consider options like this, they're already using a lot of feed lot manure out of the cattle feed lots, as well as obviously manure from piggeries, they probably need to consider using human bio-solids as well.
The price of fertilisers where they are at the moment is making grain production almost unsustainable, with the fertiliser use that we've had - so we really need to consider some other options.
JENNIFER MACY: One of the big worries many people have about using sewage sludge on farming crops is that it could lead to the spread of diseases.
But Dr Stephen Smith from the Imperial College in London says bio-solids are more rigorously tested than manure from livestock.
STEPHEN SMITH: Under the controlled management of bio-solids for agricultural land there's no one reported case of any disease outbreak associated with its use. So we're, you know very confident that it's a safe and reliable material that can be used as a fertiliser replacement and soil conditioner for agricultural use.
JENNIFER MACY: In New South Wales there's a waiting list for bio-solids, whereas in Queensland much of the leftover sewage ends up in landfill.
Melbourne Water says its bio-solids stockpile isn't suitable for agricultural use, so it's looking at creative alternatives.
Julia Lamborn is from Swinburne University's engineering faculty and is testing the viability of using treated poo to make roads.
JULIA LAMBORN: Should be looking at either putting it in an embankment or putting a layer of it as part of those foundation layers in the road.
JENNIFER MACY: And is it as strong as normal soils?
JULIA LAMBORN: When you add cement to it as a stabiliser, yes it is. And we've found from our tests so far that if we add about 3 per cent cement to it then it actually meets some of the Vic roads standards and would be able to be used in the same position as that kind of grade of fill would be.
JENNIFER MACY: Driving on top of recycled effluent may eliminate the "yuck" factor - but it may still be a problem when fertilising food crops.
Yet the CSIRO's Professor Mike McLaughlin says farmers are less worried.
MIKE MCLAUGHLIN: Because by the time the material's processed, it comes out almost of a compost type quality - if it's well processed and ready for agricultural use. So quite often when sewage bio-solids go to a farm, the first thing a farmer does is stick his hands it is rub it and smell it and give it the seal of approval.
MARK COLVIN: Rather them than me, Professor Mike McLaughlin from the CSIRO ending that report by Jennifer Macey.
Thanks for that Australian link, and apologies for for forgetting to correct the typing before sending that last item - I can spell reasonably, but I type truly badly.
According to United Utilities agricultural services site "The use of Biosolids in organic farming schemes is currently not recognised by the Soil Association" Biosolids is the industry term for processed sewage.
There is a great book for anyone interested in composting human waste: The Humanure Handbook, by Joseph Jenkins ISBN 0-9644258-9-0. It is American in origin, but full of facts, history, and graphics. I may even get round to doing a review someday.
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