4 replies to this topic

Hii

I am considering getting an natural evaporation to reduce my waste water volume (pre hydrated liquor i,e effluent from pulp mill digesters). There is very little information available on evaporation rate reduction versus humidity. I am located in south INDIA and summer time the humidity can be high for long periods of time. I would like know from people who use atmospheric evaporators how much does outside humidity impact the evaporation rate? What kind waste water volume reduction is gained by atmospheric evaporator? Also, what are the other pit falls of atmospheric evaporators? Is their any technology to make the evaporation rate high even in high humid condition?

Regards,
Bharath
bharathkumar.v@adityabirla.com

[kkala]

I am considering getting an natural evaporation to reduce my waste water volume (pre hydrated liquor i,e effluent from pulp mill digesters). There is very little information available on evaporation rate reduction versus humidity. I am located in south INDIA and summer time the humidity can be high for long periods of time. I would like know from people who use atmospheric evaporators how much does outside humidity impact the evaporation rate? What kind waste water volume reduction is gained by atmospheric evaporator? Also, what are the other pit falls of atmospheric evaporators? Is their any technology to make the evaporation rate high even in high humid condition?

I dare say an opinion, even though I do not fully understand the issue. Waste water is supposed to be in lagoon(s), evaporated by solar radiation.
Incident solar radiation will increase water temperature, hence water vapor pressure. The question is whether we can assume that (like an evaporator) practically all ingoing solar heat is converted into water vapor through evaporation. The answer may be "yes" for a rough estimate, but this has to be investigated.
Let us suppose that we can proceed, based on this assumption. Local ground level radiation can be calculated for any hour of the day, and statistical "corrections" can be made according to local meteorological data, e.g. cloudiness, humidity.
For Greece max ground solar radiation is taken as 1 kW/m2 (in safety studies),apparently conservative and on the high side. "Transmisivity" of atmosphere (not well understood by me) depends on humidity and reduces ground radiation. Similar figures can be found for your place in South India to base your estimates.
But apart from above, local meteorological stations may record not only precipitation, but also evaporation. If found, you will have a statistical solution to the issue. I remember these two parameters were recorded for a new site in Greece, using simple equipment for meteorology. But I have a doubt whether evaporation considered solar radiation, it was probably considered for places under shade. In this case a combination of the two (evaporation under shade plus due to solar radiation) has to be taken into account.
Hopefully a more experienced member can advise specifically on this matter.

Edited by kkala, 05 June 2011 - 04:08 AM.

[breizh]

In addition to Kostas's comments , I let you consider this resource :

[breizh]

Here the resource.
Hope this helps

Breizh

[kkala]

Here the resource.
Hope this helps Breizh

Interesting presentation, indeed, suggesting (among other useful info) PenPal equation for evaporation & spray heads (resulting water drop size -50 μm) to increase evaporation.