How to dose coagulant? 2

[BTJCM]

Hi I have a problem with coagulant-flocculant-sorbent dosing. We are using CFS(coagulant-flocculant-sorbent(PACL)) who have 10-11% Al[sub]2[/sub]O[sub]3[/sub] or 20-23% w/w PACL, SG = 1.18 50% basicity and 10,5% w/w Cl. The amount of waste water that passes for 4 hours is 18000 liters. I have to calculate CFS dosing for 4h (ml / min) and what will be the amount of CFS used for all 18000 liters.

Thank you in advance.

 

[ashtree]

You need to do a series of jar tests to work out what dose is required to achieve the water quality desired. From there you can calculate how much coagulant is required to treat the 18000 litres.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[BTJCM]

Hi ashtree, I already made the jar test but the amount of coagulant used was of the order of 2 milliliters per liter. That's why I'm interested how to calculate the theoretical amount of coagulant. Because this amount of coagulant it seems too much for me.

Best Regards

 

[bimr]

There is no theoretical calculation, but there are typical dosages for various applications. It is more of an art to find the correct dosage.

Your best option is to have the chemical sales people visit your facility. They have more experience doing the dosing calculations, and it is in their interests to make the dosing correct. They will probably do the dosing calculations for free.

 

[BTJCM]

Hi bimr, I'm interested in guideline doses for the coagulant, specifically for waste water from thread dyeing. For example some similar guidelines, links or information about the amount of coagulant used in thread dyeing, so that I can get an idea of the quantity used in similar processes, even though any waste water itself is different.

Best Regards.

 

[bimr]

It will be hard to find practical experience for such a specific application.

The attached paper may provide some guidelines.

 

[ashtree]

What can you tell us generally about the water?
Do you know parameters such as pH, solids content, conductivity, etc?
Some of those parameters may help to guide you with what you want to know.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[BTJCM]

Hi ashtree, parameters of the waste water are: ph is between 9.5-11.0, we are using CO[sub]2[/sub] for neutralize the ph environment. COD = 800-1200 mg/l, BOD[sub]5[/sub] = 200-600 mg/l, Suspended solids = 80.4 mg/l, SO[sub]4[/sub] = 300-600 mg/l, Sulphides = 0.2 mg/l, PO[sub]4[/sub] = 6.6 mg/l, P = 2.15[sup]a[/sup] mg/l, Petroleum products = 1.51 mg/l. We are using a lot of Hydrosulfide and NaOH.

Best Regards

 

[ashtree]

The suspended solids are significant and i assume that is why you are trying to settle them out. However what are you intending to do with the effluent, because perhaps you might be bettrer to look at the whole treatment path than just to focus on settling the solids.

Are you intending to dose thecoagulants before or after the CO2 injection?

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[bimr]

You should expect to use a significant amount of coagulant with the waste stream that you have.

The use of hydrosulfide is hazardous as there is a potential to generate deadly hydrogen sulfide.

 

[BTJCM]

Hi, here is a brief description of waste water treatment.
Step 1: to reduce the temperature of the waste water goes through a heat exchanger until it reaches a temperature of about 40-45 degrees.
Step 2: after the heat exchanger, the waste water enters the mediator, where the waste water is aerated.

https://files.engineering.com/getfi...675&file=Lenovo_A1000_IMG_20181008_090835.jpg

Step 3: after the mediator, waste water passes through the tube where the carbon dioxide and the coagulant are dosed. After that they are mixed in mixing tube and ph controller(the controller is set to support ph = 8) regulate the amount of CO[sub]2[/sub], which has to be dosed.

https://files.engineering.com/getfi...41ef-aac3-b3e28b68e330&file=Dosing_system.png

Step 4: the waste water goes into the vertical precipitator.

I want to reduce mainly the quantity of SO[sub]4[/sub], Sulphides, COD and BOD[sub]5[/sub].

Best Regards

 

[ashtree]

Unfortunately the photos do not tell me that much about the process that you are using. Is it possible to get a schematic or a P and ID or even a sketch of the process flow path?
Do you a MSDS or an application sheet for your CFS so that we can see what the active ingredients are? It may or may not be the right cioagulant for what you are trying to do.





Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[BTJCM]

Thank you for all your advices, but my boss take decision that we will use other coagulant MSDS(

https://files.engineering.com/getfi...44-48a3-9a7c-963d4df86425&file=cfsSheet.pdf),

because it's more cheap. Ashtree, I wasn't able to find the original scheme of purification plant, but here is simple block diagram

https://files.engineering.com/getfi...b21f-4ca2-86a3-460c2c6ab937&file=Scheme_of_PC

].png, feel free to ask if you have other questions. I will try to give the best answer I could. About chemical process in production area, I can't tell anything because information its classified and even I don't have permission about consistency of dyes. I just can tell you that we are using a lot of NaOH, opticid, Hydrosulfide and dyes. Dyes are organic and do not contain hazardous substances(they are not classified as hazardous, harmful, toxic etc....).


Best Regards

 

[ashtree]

It may be cheap to buy but unless it works it will be exzpensive.

Once again you need to go back and do jar tests to determine a dose rate and and an optimum pH.
However i doubt that this coagulant will remove sulphates, or sulphides but it might reduce the BOD and COD if in particulate form and you can form a floc that settles.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"