• Replies 6 replies
  • Subscribers 29 subscribers
  • Views 96 views
  • Users 0 members are here
Options
Related
Hints and tips
  • To quote someone's message, first select/highlight the relevant text, and then use the Quote button that appears
  • To "mention" someone, type @ followed by the start of the forum name, and choose from the list; that person will get a notification of being mentioned

Flushing Toilets

ArchaeC

The age old problem of what to do and where to put human excreta is alive and kicking. People have dealt with it various ways over the years.

The earliest known sewage systems dating to c. 2600BCE, are those of the Indus people in Mohenjo-daro and Harappa in modern day Pakistan. Waste from toilets in houses flowed into brick drains, street side channels and into soak pits.

The Minoans in Crete had sophisticated drainage systems from around c. 2500. The Palace of Knossos had flushing systems in which the toilet was linked to a hole outside the toilet door by an under floor terracotta pipe. When it rained, the water from the roof would flush the loo, while in dry weather, it is likely an attendant would pour water into the hole and flush the waste through a system of stone built drains and terracotta pipes to a soak pit deep underground. Other Minoan palaces had similar systems.

The Romans were famous for their toilets but for them places like the River Tiber were handy exit points for waste disposal.

Today, much human excreta is processed in sewage plants, then dumped in the sea. Excreta from humans and animals that is washed from land into our seas, rivers and lakes contributes to water pollution. 

What to do?

_________________________________________________________________

AI has come up with the following:

Society could adopt several less polluting methods for handling human excreta:

  • Anaerobic digestion: Waste is processed in sealed digesters to produce biogas for energy and nutrient-rich slurry for fertiliser.
  • Urine diversion: Separating urine, which contains most nutrients, allows for nutrient recovery and reduces treatment loads.
  • Constructed wetlands: Natural reed bed systems filter and break down waste with minimal energy input.
  • Blackwater recycling: Closed-loop systems treat waste locally for reuse in irrigation or toilet flushing, avoiding discharge to the sea.
  • Composting toilets: Dry or waterless toilets convert waste into compost via controlled aerobic decomposition, producing soil amendments instead of effluent.

Each method focuses on resource recovery and minimises environmental contamination compared to conventional sewage plants and marine outfalls.

_______________________________________________________________

Could any of these AI suggestions realistically be implemented in all new homes, and eventually in all homes? Is the government likely to be thinking big on sewage matters?

The idea of anaerobic digestion producing biogas for energy sounds good, but would biogas have a bigger negative impact on the atmosphere than other methods?

Anybody got ideas for a better system than we currently have?

  • in reply to Fibonacci Squid

    You may have hit on a special interest. 

    Warning: any questions may be answered in great detail, but will be greatly appreciated 

  • I work with water and these work very well and are used frequently in small scale off the grid areas, but are difficult to scale up due to the housing infrastructure we currently have and also simply a matter of space.

    Sewage works do use anaerobic and aerobic decomposition, along with sediment collection (which later gets used for fertiliser). The treated effluent actually has very few harmful pathogens and these are easily diluted at the discharge points (most water treatment, including really nasty stuff like landfill leachate, is, at the end of the day, mostly dilution). This works great apart from as  says, when surface water entering the same system, and this is becoming increasingly worse as both the sewage being delivered to sewage works (increases in housing in previously sparse areas), and the number of intense storms or heavy rainfall periods (climate change) increase. It is this that leads to most episodes of untreated effluent being discharged.

    The problem with all of the ideas that AI has come up with is that it requires both completely separate waste systems for greywater and blackwater (talk to anyone who's had any pipework fixed in their house and imagine how putting that piping in would go) and either a location for executing this on or near the property (which both requires more space and is smellier than you think) or transport from many houses to a set location which would involve redoing all of the sewage lines, which is also way more than you think. Basically every road in the UK would need to be dug up. It's a massive challenge. This is absolutely not a country with infinite space.

    In terms of adding it to new homes, you are counting on developers to pay for it. More difficult than you'd think. Then there is the question of who would manage the maintenance and disposal/use of the eventual waste products. Would it be taken on by the water companies and paid for by the house owners or a new type of company? What would happen if that company went under?

    I think the biggest task right now is getting the sewerage separated from road drainage (and improving road drainage while we're at it, our drain system is not designed for these more intense rainstorm style weather patterns, climate change is very much a thing)

    Eventually world wide we will need to look at reducing our water use (I mainly work with the sourcing of freshwater to drink, it's more of a problem than you'd think, even in this country, especially as we're getting more periods of drought, I refer you once again to climate change). A really good technique to build into new builds is the recycling of greywater to be used for things like flushing toilets. This reduces total waste water and preserves super high quality drinking water for the actual drinking bit. You may be able to drink from a toilet bowl, but you do not need to. 

    Overall: 

    Nice ideas, much harder to implement with limited space and an enormous undertaking for integration into existing infrastructure

    It is absolutely essential to review how we're using freshwater and disposing of various different types of surface water

    The current sewage treatment already does aerobic and anaerobic digestion very effectively, the issue is that they're largely at or over capacity so are struggling to process it all

    Removal of surface runoff from this system will help with the point above and is probably the biggest priority and easiest to tackle currently. If done correctly, it will also help tackle flooding

    All of these problems are being made worse by anthropogenic climate change. They will continue to be made worse by anthropogenic climate change. Limiting global warming worldwide will limit how much worse they will be made. 

  • I think a lot of the problem is caused by surface water (rain) entering the same sewer as the foul water, which overwhelms the system and causes raw sewage to be dumped in rivers.

    Fortunately for new developments you almost always have to keep surface water separate.

    Anaerobic digestion is cool, I didn't realise it was an option for this. The plants might not be very popular because of the smell, though.

    Wetlands are already being used in nutrient neutrality areas to reduce eutrophication from wastewater!

    You can get greywater and rainwater harvesting systems, but they don't seem very popular. Possibly because you have to have separate storage for surface water in addition to the harvesting tank, which is expensive.

    The system is definitely not very efficient as it is, now there's so many people and more extreme rain.

    The Thames Tideway super sewer is a really cool drainage project which relates to this  

  • I think the first two could be done, I don't know about the atmospheric effects of biogas use would be, but it shouldn't be beyond the bounds of human ingenuity to male it less poluting.

    As things like ammonia and other products that could be made from urine are made in other countres many tanker containing these products have been held up in the Straits of Hormuz, it seems a bit of a no brainer to make our own, it's not likely to be something we'd run out of.

    If we were going to use reed beds for waste management then we'd have to give up on toilet paper, or have another system for it's removal.

    Iains right many of our sewerage systems are Victorian, they do need maintainance and replacement and the more we build new homes the more pressure these aging systems are under. I hope it dosen't take something like The Great Stink again to persaude politicians to invest, or force the foreign owned water companies to stop giving all the money made out in dividends and bonus's back into the system.

  • Honestly, no idea. Sewage water is gonna end up in the sea somehow, even in rain form. I don't think anything we try will change that.

  • ArchaeC said:
    Could any of these AI suggestions realistically be implemented in all new homes, and eventually in all homes? Is the government likely to be thinking big on sewage matters?

    I think many new homes already have some of this integrated by law but the real issue is what happens once it has left the home / estate and is into the larger sewer system that is run by the local authorities.

    Most of the big cities where most people live or spend a lot of time each day are build on Victorian era sewage systems that are struggling with the sheet volume as well as crumbling infrastructure and significant limitations on access for maintenance.

    Add to this the fact they were privatised and most of the companies are scrimping on maintenance and often find it cheaper to pay the fines for "accidental" discharge into the sea - then you start to see that it is not the design but the management that is the issue.

    If we can solve the underlying infrastructure issue then the other plans can be implemented but it will be at massive cost when you consider how many of these plants need to be built around the country and at significant disruption while the work is carried out - and of course there is the small matter of who has to pay for this multi trillion pound project.

    For now I suspect the best solution is for new builds to need to have local systems that can do end-to-end processing even though this will add a lot to the cost of such developments.We have to start somewhere.