Greywater pasteurisation, is that possible?

[vkl02]

Hi guys,

I've been looking for the articles about greywater pasteurisation but...unsuccessful to find one. As far as I know greywater pasteurisation is the process using the solar engergy to heat up the greywater up to (65-85oC) to kill bacteria. I reckon the technology is alright for treatment of rainwater but not for greywater as greywater contains a lot more contaminants.
Please provide me some more information on greywater pasteurisation if any of you guys have experienced or read something about it.

Cheers

vkl02

[mgopilot]

In the Book Earthship 4, and avilable with search, there are ultraviolet water sterilization systems used in solar houses with water recycling systems. Energy use is 65 watts when the water flows. This unit is last in line after a sand filter, then micron filters and activated charcoal. Heating water is too much energy, except in the hot water tank, where it is needed.

[Richard]

vkl02,

I studied rainwater harvesting/greywater system use in the UK quite extensively as part of my postgraduate degree. I don't think I ever came across an example (in the UK) where pasteurisation was used as a method of sterlisiation. In fact, most water re-use systems are designed to keep the water as cool as possible, since the warmer the water the more likely bacteria and pathogens are likely to increase in number.

For greywater systems, we would normally use a series of particle filters followed by disinfectant to kill any unwanted bugs. Rainwater harvesting systems often come equipped with UV filters.

Pasteurisation is not a method we would commonly use.

[MarkuisMellvile]

Originally Posted by TheRobster

For greywater systems, we would normally use a series of particle filters followed by disinfectant to kill any unwanted bugs. Rainwater harvesting systems often come equipped with UV filters.

Pasteurisation is not a method we would commonly use.

What disinfectants do you commonly specify Rob? Have you chosen biodegradable ones, or does the system contribute small levels of synthesised chemical compounds to the waterflow?

MM

[Richard]

Originally Posted by MarkuisMellvile

What disinfectants do you commonly specify Rob? Have you chosen biodegradable ones, or does the system contribute small levels of synthesised chemical compounds to the waterflow?

MM

Often they are bromine based, sometimes chlorine. As far as I'm aware, environmental friendlyness isn't an issue that is taken into account, it's more to do with effectiveness and cost (i.e. which is the most effective disinfectant that will cost us the least amount of money?)

[vkl02]

So you would say that greywater pasteurisation itself is not good enough to achieve well treated greywater, wouldn't you, mgopilot?
Looks like we're all going back to filtration process for greywater/wastewater treatment.

[mgopilot]

Originally Posted by vkl02

So you would say that greywater pasteurisation itself is not good enough to achieve well treated greywater, wouldn't you, mgopilot?
Looks like we're all going back to filtration process for greywater/wastewater treatment.

Filtration isn't necessary for re-use for watering indoor plants (as per Earthship 1-4). Sand filtration before micron filtration, helps keep filter cleaning/replacement down. The activated charcoal filter is for any bad tastes, and UV sterilizes without addition of chemicals.
There are now Y valves to put rinse water from washing into the grey water system, and soapy-dirty water into the black water system. In Earthship 4, Mike Reynolds goes on to self treat blackwater with an interior wetlands. In my experience, humidity is a mold problem, so it is best to return black water to the ground filtration after treatment in a septic tank.
With greywater systems, and water free compost toilets, a small septic tank is still required for overflow. Dirty dish and clothes washing soapy water take a septic system to treat without filter clogging being a big problem, and overcoming the charcoal, too. Two plumbing systems, grey and black.
Instead of using the 65 watts of UV per household, chemical anti-viral/bacterial agents such as chlorine in the right concentration may be added. They do impart a taste, and can interfere with septic systems. In one experiment in biology, I used the old pioneer filter--gravel graduated to sand. Poured micro-organism filled swamp water through it (a coffee can with small hole in the bottom), added a drop of tincture of iodine to a glass of it. Waited a couple minutes and drank it. Not bad, but not great. In backpacking we use tablets which impart taste. In periodic maintenance of my well, I add chlorine bleach at 32 oz to 400 gallons (every 5-7 years). This requires I add RidX micro-organism mix to the septic system afterward (in fact, this is used monthly to bi-monthly for a better system performance).

[Richard]

Current UK best-practice manuals for rainwater & greywater reuse are published by CIRIA (Construction Industry Research & Information Association).

http://www.ciria.org/acatalog/C539.html

http://www.ciria.org/acatalog/PR080.html

[vkl02]

Thanks for your help, guys.

I have another question for you guys but not quite sure if I'm in the right room to ask. Has anyone ever come across developing an equation for contaminants removal rate for Biological aerated filter using mathematical method intead of experimental method? Any sort of information will be useful.

Regards,

vkl02

[Richard]

There might be some useful information in this:

http://homepages.nildram.co.uk/~proe...PhD_Thesis.pdf

-Rob