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Sunday, April 30, 2017

Water Purification

Posted by steve on November 28, 2007

Tapescript – Drinking water

PREAMBLE

I am in my tenth year of image streaming. In the earliest sessions I was requesting to closely study a settlement with ecological and sustainable living arrangements. I started concentrating on the social organization rather than the technological infrastructure. After having completing a few writing assignments in the water industry I realized that in none of my streams did I understand how good, clean, healthy drinking water was supplied.

This is a bit of an oversight on my part – I got transport, manufacturing, organization of work, energy – most of the essentials. I need to go and look at water.

REQUEST

To visit a place, PORENA or similar, that in the framework of a sustainable way of living, provides good quality drinking water for residents.

On the bench in the departure area. Everything is so familiar I notice many of the lifts, trains and other departure possibilities from earlier streams.

I wander up to a train station. A fast train attracts my attention; it is aerodynamically formed, pointed at both ends and painted in white with red stripes. A large wide door opens,

I get in and sit down. The door closes and we are off.

It’s a train to Porena. It shakes and rattles as we go over the points, picking its way out over the multitude of tracks that lead from the station. Next it travels over a river bridge and into an old fashioned tunnel.

We start to pick up speed and are quickly into the countryside. I see the unmistakable white walls of Porena and we glide into the tunnel that goes under the city. The train stops at the underground station.

I walk up the stairs and into the corridor of the work section of the central building. The sign Water Board on the door beckons me in. As I enter I see several people busily working at their desks. One looks up and comes over to me.

‘Hi – you are here to visit us?’

‘Yes,’ I say. ‘I need to know about drinking water’.

He takes me over to a tap and pours out a glass of water.

‘Taste it!’

It tastes good, and I detect no trace of chlorine.

‘How do you do it?’

I start to pick up key words. Rain – Sand – Collector.

They have a big sand bed, the rain falls on it and it runs through the sand and is collected into one pipe, by gravity. Questions pop up rapidly. How deep is the sand? And how wide is the bed? How many people use it?

The system supplies one million residents. The beds are separated and localized to provide the immediate neighbourhood. They show me a picture of how the sand beds are spread around the city, between the houses.

‘Not surface water?’ I ask.

‘No, rain water,’ they reply.

They collect the rainfall. And as they never pollute it, the rain is always a good source. Furthermore, they explained that theirs was not a universal solution. It depends on climate. Their climate is temperate and enough falls as rain for their needs. They do not seem to collect water off the roofs so much, just that which falls onto the sand bed.

‘Can I see one,’ I ask?

They show me on the map where the sand beds are, between the housing areas. You are not allowed to walk on them, or dirty them in any way. We decide to go and look at the ones in the central area.

We walk out through the back and down some steps. We arrive in the park area, and quite close we see the circular sand bed, about 20m in diameter – 2 or 4 meters of sand deep. I get a rush of disbelief but I shall carry on anyway.

This one is inside the circle in the clean area, the park. It’s as high as me – higher almost. A set of steps lead up to the edge so you can look over the bed.

I climb up and look over. I ask if I can touch the sand – they say no but I can look at it. The sand looks fairly clean except for some small plants growing on top of it. They rake these off now and again. This makes it look like a Zen garden – with rake marks in various patterns over the whole surface. I can imagine raking these beds can be a bit of a meditative exercise. The rain water drains through the sand and runs into a collector at its base.

Because it is rainwater there are no organic pollutants in it. Other particles are removed as it drains though the sand….

I ask; ‘How did you get the sand here?

‘We went and got it. It took a lot of work but it was worth it. This is a – build once use forever – system.’

‘How do you clean it?’

‘We’ll tell you later.’

We go back up to the Water Board offices. I get to see a model – there is a drain at the bottom, a plastic tray, like a leaf. It is UV resistant, light and trough shaped. The water drains though to the bottom where it runs into a collecting point, an underground well or storage tank.

It was built cut and cover. They dug out a pit. In the base they built the tank with watertight bricks. Then they laid the collector plates and over that they filled the bed with sand. A pump pumps water up to a tank in the roof. From the tank the water runs under gravity to feed the taps in the household.

They show me a diagram. A pressurized submerged pump is controlled from a pump-house. They also show me how there are two systems: white water for drinking and grey water for other uses.

I comment: ‘This seems fairly clear. What about cleaning?’

‘You just drink it.’

They are saying it’s clean there is never any bacteria that can get into it as long as the network is kept clean. I ask about samples and stuff.

‘They take regular samples. There is no point of use cleaning.’

All seems very simple. One of my guides is an expert. I ask to borrow his eyes.

I get the feeling of a water reservoir –

I will ask questions first.

Q. How is it taken from the artificial well to the roof tanks?

A. A pump in the pump house pumps it round and keeps it under pressure.


Q. How many of these beds are in use and where are they situated?

A. They are situated in the green area, between the houses around the outer part of PORENA city. They get some roof run-off from the roof it seems out here. In the central park area they just collected rainfall.

I explore the way they clean the top of the sand. The rake needs to be long enough to reach the centre from both sides of the bed wall. Depending on where it is situated and how much run off is diverted through it, one bed can supply 20 to 100 people with 10 to 20 litres a day.

I ask to visit the residential area. We leave the office and start off towards the canal. We walk through rather charming narrow cobbled streets. Between the rows of houses there are growing areas. The housing is quite dense and full of variety.

‘We like variety,’ my guide says.

The placement of the beds has something to do with the train. They locate the sand beds at the furthest points from the train. Two beds are located together, and they do not allow trees to grow around them. They look like swimming pools.

I walk around to inspect these installations. I see they get some water from the roof which is led via a gutter through the air. I ask about the history of these installations. They must have put a lot of effort into making them.

I gather that after work was abolished, sustainable drinking water was among their top priorities. They came up with the sand bed ideas and started to try it out. They came up with the ideas of building the well in waterproof brick.

To ensure no contamination, the beds were located between the stations, and an integral part of radiality thinking. I glean that the sand bed in the centre of the park is a fountain as well – a combined fountain water feature and water purification installation.

My next question: what about cleaning the sand?

The top layer is taken away and it is replenished now and again. Rain brings with it particles and bacteria. This aerial plankton and stuff only gets in the top layer.

‘We rake it off the water board looks after it with volunteers. The sand is taken away for compost. We get the sand from the sand pit – there are plenty of places to get it.’

My guides start winding up: ‘Have you seen everything – any last questions?’

I ask about grey water.

‘Grey water is another story – come back to see how we do that connected to biogas and etc. A whole new ballgame.’

I understand from my hosts that the important thing is to stop polluting the air. Then rainwater becomes the best water solution. If you are going to have a city with people living close together you need on work on creating infrastructure. This is needed from the beginning and planned from the beginning. You need to work out the areas rainfall etc. Once you decide on the mathematics and the planning constraints it’s easy to do.

They welcome me back with other questions. I take my leave back to the station and the train which is already waiting.

Facilitators still trying to do it by yourself?

Clue for you? Facilitation that is needed.

What surprised me

I was surprised by the simplicity in just filtering through sand. I would be thinking they need to disinfect or use UV light or all kinds of industry standard solutions.

I was also surprised I missed it earlier visits – you can really see here you get what you ask for.

The attitude that each area has its own micro climate and its own conditions to work under should not have surprised me. A one size fits all solution does not work when you are re-localising.

Verifications.

Internet search of Water purification methods show that sand beds are common and well known –but not for rain.

http://www.oasisdesign.net/water/treatment/slowsandfilter.htm

A few rainwater purifying experiments turn up on search.

http://www.uoregon.edu/~hof/S01havestingrain/index.html

I can ask industry experts if this could work. Otherwise a simple model could be built

What could you use TODAY and what could be done TODAY?

This exercise has made it painfully obvious that NO EMISSIONS should be permitted into the air that can pollute rainwater. Lobbying for stricter regulations is one thing to do.

Remaining questions.

Grey water purification hangs together with this but how?