Dear Uwe Bruenjes

I apologise for the delays in responding to your private messages, the same
apology goes to Vivienne Hallman. In the past week(s) or so, there were a
number of things that called for my immediate attention and so I had to
reset priorities and in the process I had to temporary put aside other
things to be done later, unfortunately.  One of the occupational hazard of
a consultant is having to do too much within too little time by oneself.

Your situation now reminds me of a poster which I still keep from the days
when I was working in the research laboratory and the poster says
"We, the unwilling, led by the unqualified, have been doing the
unbelievable for so long with so little, that we now attempt the impossible
with nothing".

I feel I can share your feelings when you wrote:
>in my spare time I'm in charge of the construction of a church,
>pastorial house and orphanage for about 50 children. We have
>a lot of land of about 2ha at the feet of a mountain, and I would
>like to arrange everything as self-sustainable as possible.

On Oct 29, you expressed your interests in certain parts of the UNU
Integrated Bio-system at Montfort Boys' Town as well as the potential of
"enhanced cassava" (protein-enrichment using cassava roots) to Walter
Vermeulen (W Samoa).

I wrote:
> I recommend that people who are interesting in designing
>integrated bio-systems should look seriously at your local resources. The
>system at UTA as described in Lylian Rodriguez's paper is basically founded
>on the use of cassava and duckweed. Again, I echo the message of Thomas
>Preston on the importance of the use of local resources in livestock feeds.
>If you cant get this into a viable operation, the whole system will
>collapse. Therefore it is important to have an operating base before you
>think of designing a system.

I like to add further to say that the basic resources is that you need a
source of water or wastewater, then you need organic biomass (plant crop
residues, kitchen wastes, manure etc). With unlimited creativity, you can
then design and choose options and make your choices for your particular
situation. I dont know your local situation fully yet, so my suggestions
should be considered as just ideas. You need to make the hard decisions.

You have 50 children (at the orphanage - of course!), 2 ha church property
land plus access to public land, lots of sun. I guess water is a precious
item and therefore even wastewater needs to be contained and re-used.

>I would like to know if under the given circumstance it would be a good
>idea to lead the waste waters to a biodigestor, so to recover nutrients
>in a usable form (low pathogen count) and to obtain biogas, which could
>be used in the kitchen. To enhance the digestion, we are able to count
>on an extra supply of cow manure.

if you couple it with cow manure, I would certainly say yes.

Q how much wastewater do you have per day and how much cow manure ?

Using biogas technology:
if you use a polyethylene tube digester, you need to protect it from the
burning sun. How cold are the nights ?

If you have not done any digestion before, this is what I would suggest.

Find yourself two large plastic bags (transparent garbage bags are useful
and more exciting for beginners). Fill it less than half with wastewater or
grey water that has as little detergent as possible and add cow manure so
that it makes a  thin "soup", mix it gently without too much agitation
(careful not to tear the bag in the process).....to a consistency of a
light blended vegetable soup (not a thick heavy veg soup). Using cut long
strips from the inner tubing of rubber tyre, carefully tie the open end of
the bag to one end of a 1 or 2 metre long tubing (water hose is fine). Make
sure it is airtight (to test - close the other end of the hose and apply
some pressure on the bag and with some soap solution on the bag-hose joint
- you should not see bubbles). Then sink the open end of the hose into tall
(half meter if available) container with water. If you can get a thin metal
or glass tube (or a thick hypodermic syringe) to serve as a "jet" for the
gas and burner point later, then close the open end of the hose with a cork
or rubber stopper with the jet in it.  You can check for gas production
daily by taking it out of the tall container of water and putting the
needle part into a glass of tap water to see bubbles.  After a few days,
you can light the needle end. (caution: first gently maintain some pressure
on the bag, check the flow of gas in the glass of tap water and then light
it at the needle end).

The gas production will slow down with time, and after about 30 or 40 days,
you can dilute the bag material with grey water and use it on the soil for
your plants.

This is the basic experiment. You could also use glass or plastic water
bottles instead of plastic bags.
(I have put a photo in http://home2.swipnet.se/~w-25860/jacky/b-14.JPG)

Then you can let your imagination fly. You can use a 10 meter long
polythelene bag/tube - 2 meter diameter and make yourself a polyethylene
tube digester like the one used by Lylian Rodriguez. You can have many
garbage bags and run a batch system linking them to a large plastic gas
collector.  You can move slowly and choose from a variety of designs
depending on your need, choice, funds, comfort, etc.etc.. This is an
important process of learning and experience which I believe is needed
before reaching a productive system.

What is your source of cooking fuel ?

>I would like to know if it is a good idea to separate the so-called
>"grey waters" from the shower, etc., treat them somehow and
>reuse them, as water is very scarce in our state. And if the effluent
>water from the biodigestor could be used for something more than
>just irrigating land, that would be really great!

what do you do now with the grey water and sewage ?

regards
Jacky Foo
UNESCO Microbial Resources Centre