Water Conservation

[Fett]

Hey everyone. It has been a long time since I posted here but I am in need of the mass intelligence again.

As I have posted a while ago about a PVC Pipe issue with my buildings Swamp Coolers. In the end all of the chat with the installers and the manufactuers and my bosses I ended up being the one who was right. The pipe size was inadequate for one section of the system. The installer ended up replacing that section with proper pipe size.

Now we have a new issue. Water conservation... here are the facts.

This building is a 340,000 square foot warehouse with a 32 foot cieling. It houses a liquid beverages and is cooled by 42 Evaporative Coolers(swamp). The coolers have 3 pads which are 5'H x 5'W x 4"Thick. A 5HP motor powers a 5 bladed propeller style fan. I'm not sure on the CFM. It should be around 30-40,000 CFM airflow.

We used last year 54,276 gallons of water PER day in August which is the hottest part of the year.

Here are the few idea's that I have been thinking about.

#1 Run half of the units that this building is equiped with. 21 units

#2 Turn up the continuity meter which measures how nasty the water is and dumps it when it reaches X amount of continuity. (downfall of this is more calcium will build up on the pads)

#3 run the units only at night and turn off the entire system in the morning. (hope that the mass of the building will hold the cold air in)

#4 increase the fan pulley size to slow the fan speed down.

I really want to try and conserve the pads for at least 5 years. This is year 2 and they are looking good so far, but if I have to change their water quality. Well... anyone know how heavy a 5'x5'x4" piece of concrete weighs?

Any ideas will help. Thanks

[Magoo]

Hi Fett,
that is one large amount of water evaporated every day. Like 205 metres cubed , a reasonable sized swimming pool.
Swamp boxes were fine when water was cheap.
Can you regenerate some air from control space, I would be inclined to raise the control point as well.
Is the warehouse insulated as such, that spray on foam stuff on the under side of ceiling could reduce heat loads as a one up cost.

[Fett]

Regenerate some air from the controlled space? Like recirculating the air in the building? It's a good thought but would require a retrofit of the building I think unless you are talking about an energy recovery system. There are open hoods in the roof(to many to count) and four double fan up-ducted hoods which serves as relief(not to mention all the overhead roll up doors that are open all day long for loading and unloading. The walls are 12" concrete and the roof is constructed of steel which is covered with five inches of spray on foam that has a glossy white finish(sunscreen and sunglasses required)...

The system does not have a control like a thermostat or anything like that. The units just run to replace the air in the building. The only control it has is the continuity controller which dumps water as the water gets a high concentration of minerals.

[lawrence1]

There are many commercial buildings here now using rainwater tanks to supply water for amenities(mandatory requirement for new residential buildings as well) ,,,worth a look as the water is free,,,,when it rains of course.

[Fett]

Unfortunately we get less than 6 inches of rain a year here in Phoenix. These coolers average 1300 gallons of water an hour of evaporation during the hight of our hot season when there is no rain. I wonder if reducing the water pressure somehow might help. Or reducing the nozzle size in the distributor pipe.

[Brian_UK]

Just trying to understand the contents of the warehouse.

You say liquid beverages, is this tanks of fluid or pallets of bottled drinks etc?

Are you trying to keep the product cool or the personal working inside the building?

[Fett]

The contents of this warehouse are beverages to be consumed by people. Most of them are not in danger of spoiling but there are some that will and we have a cold room which is refrigerated for those. Although during our summer months our average temperature is 43 degrees celcius and that will spoil any of our product in a short amount of time. The main objective for the swamp coolers is to keep personel from passing out from heat stroke while they are thumping cases. Last year we had quite a few days where it was 48 degrees celc.

[Magoo]

Hi Fett.
+48 'C is seriously hot. What about de-mineralizing the water to stop or reduce the spillage amount.
It would mean that a small water treatment plant would be required.

[Fett]

Hmm, like a water softening system?? Instead of dumping water down the drain?

[lowcool]

water recycling is the go,but your evaporation rate is very high leaving you with a high mineral content,as magoo says.i would be inclined to treat the water before usage and recycle your drainage/run off,lessening component corrosion and increasing the life of the unit and components.dont know about comparable costs in the long run it may benefit from loss of down time repairs etc

[Magoo]

Hi Fett
I would be weiry of recycling water from swamp boxes, legionnella [ spell check ] you don't want everyone dropping dead on you.
I am wondering if you chilled the feed water to each swamp box, that evaporation rate would be reduced. What is the temp of water now.
On the hottest day you using on average 2.3 litres per sec., and by dropping temp 10'C, equates to a 100 KwR chiller. 28 ton. Would crank up the power bill but will save water.
magoo

[Fett]

Lowcool - Recycling the water is a good idea. I am afraid though that the company would say no to installing such a system that would soften the water, but my counter offer would be telling them it would save them on the water bill. I would have to do the math to show them numbers. Just for a mental note. There is a very limited amount of space where the water tank and the pump is at. So if such a system were to be installed it would have to be small.

Magoo - Today it was 36.5 'C. I did happen to stick my hand under the incoming water supply and then move to the return water supply from the coolers. The return supply was much cooler than the incoming fresh water. I did not have a thermometer on hand though. I would guess that the fresh water coming in is around 15 'C.

Right now I am only operating 8 of 42 coolers. They are only running at night between 8pm and 8am. The building stays cool during the day, but when we start hitting 37 'C the building won't retain that cool.

Oh and wouldn't a little bit of Chlorine be enough to kill any Legionnella? I will run this thought past my supervisor.

[lowcool]

could you run your water through one of those ultra violet thingys for bacteria treatment ? or theres water treatment as in whats already being used on cooling towers etc.
im not specific on legionela breeding conditions but am sure it wouldnt be as much of a concern looking at your rainfall assuming you have a low humidity range

[Fett]

Hmm, I think chlorine would be strong enough to kill off any bacteria of any kind. Legionnella is the same as Legionair's Disease correct?

[lowcool]

yeah mate,legionella causes legionaires disease

[Magoo]

H Fett.
I am not sure what the ideal conditions are for legionella. I think you may be OK with the lower water and basin temps. Would pay to find out though, what the ideal conditions are.
Running over night is good option so as to use the concrete walls and floor to store cooling effect.

[Fett]

Here is some interesting information on Legionella.

http://www.pepfilters.com/pdf/Legion...%20Article.pdf

http://www.pepfilters.com/pdf/MIN%20...ELLA%20EXP.pdf

http://www.pepfilters.com/pdf/AWT%20...y%20Update.pdf

[Fett]

The search for water filtration is difficult. Water softening is out of the question because it adds salt to the water.

[Fett]

Alright. Here are some of the steps I have taken to save some water.

#1 I bumped the continuity meter up from 2100 to 4000(fresh water coming in is at 800-1000 microfarad). The manufacturer recommends the meter be set at 2000 which is a 30% bleed off rate. I ran into a problem with this. Since it dumps water less often. Algae has been growing in the water. So I am in the process of constructing some basic water filters to combat this. Also from what I have read. The water temperature is too low for legionnella to grow.

#2 We purchased and installed larger pulleys on the fan to slow the fan speed down. Less air flow results in less evaporation.

#3 I cut back on the amount of evaporative coolers that will actually operate. Only 20 of 41 are operating. So far this year it has been a very mild summer.

#4 I took the screens out of the drains up in the cooler pans so that more water will drain back down to the main tank and not sit in the cooler.

#5 Only running the coolers between 6pm and 9am.

Any other idea's that anyone can think of? I'll see if I can get together some photos.

[Magoo]

Hi Fett.
you seem to be on the right track, saving water etc., consider an ozonator to pre treat the feed water. They come as a box and 3 pin plug, but they sanitise the feed water.
magoo

[Fett]

I was actually looking at ultra-violet light water purifiers. I read that the water has to be clear for them to work effectively though which also brings about water filtration.

[Magoo]

Hi Fett.
An ozonator will treat water irrespective of water quality, but I would recommend at least a primary lump removal filter system. It is scary what is actually in the water supply.