Sterilization of lagoon water for reuse

[ChE51]

Hello,

Onsite we have a lagoon and we are trying to find a way of recycling it back into the plant. Basically we have decided that it would be best to recycle back to our tote cleaning area. Due to operating requirements we have to provide hot water that can be used as a wash and a rinse. The 'bugs' that would be in this water would affect some of our products. If the water is kept at 85C for at least 10 mins the 'bugs' would not survive. Does anyone have any suggestions of a hot water tank design that could assure this residence time?....I am thinking a baffled design

CHE51

 

[BRT549]

Could you fry the bugs with sodium hypochlorate? Chemical injection of a biocide might be a more cost effective method than heating water if your process can stand it.

 

[ChE51]

It's a possibility but I think sodium hypochlorate would affect at least one of our products. The operators have cases where they hot water rinse and some when they cold water rinse. If they always cold water rinsed this wouldnt be a big problem. Do you know approximately how much sodium hypochlorate/lagoon water you would have to add? how long does it take to be effective? and if possible a cost estimate?..thanks for your help

 

[EMKWR]

Hi ChE51,

in what way do the bugs effect your process. Is the problem the bugs itself or the biofouling caused by the bugs. If the latter is the case you could do with discontinuous biocide dosage.
We had some nice experience with a bioprobe, the so-called biogeorge. It's a probe which measueres on line currents caused by microbiological activity. The moment one gets in the "danger-zone" the signal increases. I have maybe some info about it as a pdf, somewhere on my pc. If you're interested I'll see if I can find it. Edwin Muller
KEMA Power Generation & Sustainables
Arnhem, The Netherlands
E-mail e.f.muller@kema.nl
Internet:

http://www.kema-water.nl

 

[ChE51]

We are using the lagoon water on product tote cleaning. There are some products that if we were to add to a bug contaminated tote they would provide the right environment for these bugs to grow and therefore contaminate the product....the main question I have is if raising the temperature of the water will kill all the bugs...arent there alot of microorganisms that can withstand high temperatures?

 

[BRT549]

We treat a cooling pond with the hypochlorate, mainly to keep the algae growth down. We use the cooling water as makeup in the plant, so the water doesn't cycle up too far.

We use 50 ppm addition rate in the summer, and drop down to about 15 ppm in the winter. We buy the hypochlorate for about $0.18/lb, so we spend about $500 a month in the summer to treat about 130 gpm. That $ number is for a bulk rate, and we keep refilling a 300 gallon tote. To inject the chemical we have a little LMI diaphragm pump that goes for about $800. So capex is about $1500 to get rolling; operating cost is based on your gpm. Hope this helps.

 

[ChE51]

Thanks BRT, those numbers are very helpful. Just want to make sure that the numbers are based on 130USGPM that runs continously. If not how many USG do you treat per month?

CHE51

 

[ChE51]

BRT,

Are your $ figures US or Canadian?

 

[ChE51]

I have recently (actually today) come up with another idea on how to reuse the lagoon water: Use it as cooling tower makeup. I have confirmed the capacities and they are similar and currently the cooling tower water is already treated for bugs. Does this seem like a good idea?