From
http://www.newmars.com/desert/

15th December (Sunday)

Back to work today. Everyone got up later than usual, which seems to be
developing into a trend here. Nikki, Ella and Eric went out on an EVA
while Duncan, Mike and I stayed behind to do some cleaning up of the
Hab, and I did more work on the ever-present Ops Manual. The suiting up
took place in record time, and that left Duncan and Mike to clean up
and later discover that the outside waste storage tanks were
overflowing onto the ground. They were not happy, as you might imagine.

The overflow occurred, we guess, because of a blockage in the pipe
between two tanks. Duncan and Mike had to do some very messy and nasty
work trying to figure out the problem and a solution. By manually
pumping back water through the pipes, they managed to get a trickle of
liquid flowing, but it didn't seem like enough. Basically, the grey
water recycling system is shot to hell. It's just fundamentally wrong.

Firstly, it's wrong in theory. The GreenHab is supposed to recycle and
clean, to an acceptable standard, the urine and waste water of six
people. That's a lot of waste. However, the GreenHab only has five
tanks of plants, and the total surface area of those tanks is probably
less than 10 square metres. That's not even enough to clean the waste
produced by one person. Maybe if you had some really high tech stuff -
advanced filters, constant chemical monitoring and treatment,
specialised microbes, you might be able to get towards it, but
something the size of the GreenHab just can't work for six people.

Secondly, it's wrong in practice. The pipes are all too small, there's
no pumping, things get clogged up too easily. The flow rates of the
system haven't been considered properly, which means that we have
occasional overflows of tanks as there are spikes in water usage.

If the Mars Society really wants to consider using a greenhouse to
recycle the entire waste water of the hab, they need to spend a lot
more money, maybe on computerised telemetry, and get better expertise
in.

So, everyone was a bit depressed (apart from the people who went on the
EVA and had a great time). I made some soup and bread, and then we just
moped around for the afternoon trying to get in contact with Mission
Support about the whole GreenHab issue. Mission Support have thankfully
agreed with us in the assessment that it just doesn't work and is a
potential health hazard, so we're going to cut it out of the system and
flush the waste water to a leachfield. The GreenHab is probably going
to be on a separate water circuit and used for growing food.