14 replies to this topic

Hi!

I'm looking for some help here. Currently I have a project where my batch process produces 10m^3 of waste water for every batch. Temperature is 30C and concentration of phenol in my waste water is 20g/l. I am required to reduce this concentration of phenol by at least 90%. The plant produces 600 batches in a year. Basically I'm supposed to suggest 4 methods of achieving this and choosing the best one as a recommendation.

I've googled this and looked at some books as well, however most of them give very general information. Eventually I will need to do extractor sizing, costs, efficiency etc etc and so I will need quite a lot of specific information. Do you have any idea as to which processes I should look at and if information such as costs are easily obtained for the recommended processes?

The few that I have on my list are Membrane Aromatic Recovery System (MARS), using supercritical CO2 and electrochemical oxidation. Any help is very much appreciated!

[Austro]

I am by no means qualified to speak on the matter but what about:

1: UV light degradation (cheapest??)

2: Filtering with activated carbon

[breizh]

Hi ,
I'm thinking FENTON reaction to eliminate the phenol ( H2O2 + FeSO4 s catalyst) .
Breizh

I am by no means qualified to speak on the matter but what about:

1: UV light degradation (cheapest??)

2: Filtering with activated carbon

Dear Austro,

Thank you for your reply. I'll definitely look at filtering with activated carbon more and hopefully it'll be a feasible option. As for UV light degradation, it may be possible but do you think the process will be too slow to be implemented on an industrial scale? (keeping in mind we will need 90% removal)

[siretb]

20 g/l is a lot. I think that acticated carbon will be quickly saturated, and anyway, the activated carbon only traps the phenol and you have to either regenerate, or dispose of the spent carbon. I have not studied the economics, but AC would not be my favored option.
Chemical treatment (Fenton, ...), I like more.

Supercritical oxidation will call for expensive equipment, and your overall flow rate is not that large.

Liquid liquid extraction, technically, would work for 90% removal. However, for a batch process it's not my favored.

Hi everyone,

Thanks for all your suggestions. I'm now looking at the Fenton Reaction because a few of you suggested this method and I've done some research regarding this reaction. The problem that I now face is in deciding 2 things:

1) What should the proportion of H202 and FeSO4 be compared to the amount of phenol in my waste water? There does not seem to be any guide as to how I should calculate a value for this and most of the studies that have been done into this reaction obtained it through experimenting.

2) Should the catalyst be added into the waste water directly to carry out the reaction and then be precipitated out at the next stage? (The current limit of iron in water discharge I have found is 1mg/l) Or can we embed the iron in some kind of zeolite or polymer such that we do not need to carry out any precipitation in the next stage?

Thanks so much!

[Qalander (Chem)]

Although not Certain,

but do explore dilute KMnO4(potassium per Manganate) solution use;

if this is easily/economically viable and proves chemically useful!

[riven]

Hi everyone,

Thanks for all your suggestions. I'm now looking at the Fenton Reaction because a few of you suggested this method and I've done some research regarding this reaction. The problem that I now face is in deciding 2 things:

1) What should the proportion of H202 and FeSO4 be compared to the amount of phenol in my waste water?

2) Should the catalyst be added into the waste water directly to carry out the reaction and then be precipitated out at the next stage? (The current limit of iron in water discharge I have found is 1mg/l) Or can we embed the iron in some kind of zeolite or polymer such that we do not need to carry out any precipitation in the next stage?

Thanks so much!

For question 1 an experiment will probably be necessary unless you have data for this particular reaction. But the first question is what is actually going to happen. It is likely that your target reaction will be to knock off phenol OH with a H+. However that will still leave you with circa 20g/l of CxHx. Also the OH addition may also occur. The point is what is going to happen and even after whatever that is happens you may still be left with organic pollutants and may require additional cleanup along with the need for iron removal.
For question 2: I cannot see how you could embed the Fe catalyst into a polymer/zeolite/silica in a useful. howevcer would catalyst pebbles work in the form of a bed reactor?

A number of other questions:
1. Have you considered a membrane operation such as Nanofiltration/reverse osmosis etc. The US EPA did a lot of work on removing phenol from waste water using pervaporation in the 90's with zenon. While ultimately it may not be economical it is worth considering.
2. Is it possible to remove it at an earlier stage? This is probably beyond your scope.
3. What about biological treatment? I would guess that this is the easiest as long as the phenol does not posion your bugs.

[Qalander (Chem)]

Dear All,
Actually Phenol C5OH is less poisonous/objectionable/hazardous.
If Compared with C6H6 Benzene in all respects ;I believe.
Please correct if I am wrong.

Hey,

Just to give you guys a heads up regarding this topic in case you are interested. Did an analysis on the Fenton's Reaction and did some economic calculations.

Aldrich sells 50 wt% of Hydrogen Peroxide in water (4 litres) at £149.00
50 wt% amounts to 590.16g/l of hydrogen peroxide.
In Fenton's reaction, the norm is to use stoichiometric amounts of H202 which is 5 times that of phenol.

20g/l phenol = 0.2127 mol/l
Required H202 = 5*0.2127 = 1.064 mol/l = 36.17 g/l
Volume of H202 required per batch of waste water =(361.7/0.59016) = 612.89 litres
total yearly cost from H202 = (612.89/4)*£149*600 (batches in a year) = £13.7 million

£13.7 million just from H202 alone, it looks like this process is not going to be feasible. I think 20g/l of phenol is just way too high and I'll probably explore membrane separation to remove the phenol and then I can probably recycle this phenol into the process.

[Qalander (Chem)]

What about KMnO4 dilute solution Lab scale/ Feasibility/ Any other issues?

[riven]

£13.7 million just from H202 alone, it looks like this process is not going to be feasible. I think 20g/l of phenol is just way too high and I'll probably explore membrane separation to remove the phenol and then I can probably recycle this phenol into the process.

The costs are quite high but you should use
http://www.icisprici...s/SubPage52.asp
as scaling up lab costing is not going to be accurate. Buying phenol in bulk is much cheaper.

For membrane operation use the search "VOC separation membrane" which will give you separation s mainly involving removing volatile organics from waste water applications.

I still think that activated carbon as previously suggested and biological treatment are probably the most effective. While 20g/L is a lot in terms of environmental impact, it is still a low concentration. Chances are that any process you try will be expensive.

[breizh]

For cost estimate , let you consider 1800 - 2000 yuans / ton H2O2 35% ( bulk) .
breizh

[JLMONTREAL]

Maybe you can consider vacuum distillation first and carbon filter phenol from the distilled water. the concentrated phenol may be recycled or sold.

Hi!

I'm looking for some help here. Currently I have a project where my batch process produces 10m^3 of waste water for every batch. Temperature is 30C and concentration of phenol in my waste water is 20g/l. I am required to reduce this concentration of phenol by at least 90%. The plant produces 600 batches in a year. Basically I'm supposed to suggest 4 methods of achieving this and choosing the best one as a recommendation.

I've googled this and looked at some books as well, however most of them give very general information. Eventually I will need to do extractor sizing, costs, efficiency etc etc and so I will need quite a lot of specific information. Do you have any idea as to which processes I should look at and if information such as costs are easily obtained for the recommended processes?

The few that I have on my list are Membrane Aromatic Recovery System (MARS), using supercritical CO2 and electrochemical oxidation. Any help is very much appreciated!

[Qalander (Chem)]

Definitely subject to ;If other impurities,Contaminants and Bi cyclic aromatics etc. compounds are not part of the stream.