4 replies to this topic

[siretb]

Helo

I have a waste water stream (600l/hour, pH 7.5, containing N and S. Temprature 25°C.)
major components are Na2SO4, NaCl (6g/l) ... So it's a brine, I do not think it is a very favorable media for bacterial growth.

We wish to add bleach (NaCl0) to inhibit bacterial or algae growth, but I have no idea of the amount needed.

The COD is 130 mg/l but my feeling is that I need much less NaClO than what would be required for the complete oxidation. I just want to control "life".

I'd appreciate if someone could give me an idea of the quantity needed.

[ankur2061]

Siretb,

Nalco Chemicals is one of the leading companies in supply of biocides for wastewater treatment. Have a look at the link below for further details:

http://www.nalco.com...t-integrity.htm

They should be able to provide you a tailor-made solution for your waste water treatment problem.

Regards,
Ankur.

[siretb]

Thank you Ankur.

[kkala]

I have a waste water stream (600l/hour, pH 7.5, containing N and S. Temprature 25°C.)
major components are Na2SO4, NaCl (6g/l) ... So it's a brine, I do not think it is a very favorable media for bacterial growth.
We wish to add bleach (NaCl0) to inhibit bacterial or algae growth, but I have no idea of the amount needed.
The COD is 130 mg/l but my feeling is that I need much less NaClO than what would be required for the complete oxidation. I just want to control "life".
I'd appreciate if someone could give me an idea of the quantity needed.

This wastewater looks similar to seawater (NaCl content is lower in the latter). Once seawater was treated by injecting NaClO solution into it, to be used in heat exchangers. Equivalent Cl2 dosage was specified to 10 ppm Cl2 (10 mg/l) for shock chlorination and 1-2 ppm Cl2 for continuous chlorination. This was residual Cl2, which can control algae growth*. After use and before sending back to sea, this wastewater was treated with Na2SO3 solution to eliminate residual Cl2 (chlorine).
What is purpose of mentioned wastewater treatment, reuse or disposal? Despite the small flow rate (600 l/h) reuse is assumed (otherwise why control algae?), and then above text may be of some help. Some organic compounds are rapidly oxidized by chlorine, some others are slowly oxidized*. This makes "residual" Cl2 unclear (after how much time?). Mentioned COD may require 130/32*74.5 ~ 300 mg NaClO /l for complete oxidation. Probably Cl2 (that is NaClO) consumption after a definite time can be specified through experiments; or estimated after knowing the organic compounds specifically.

* From Betz "Handbook of Industrial Water Conditioning" (Chapter 4, Chlorination), 1976.

[siretb]

Thank you Kkala, that was really helpful.
Yes this is for re-use, and this chlorination will just be a precaution against uncontrolled (and severe) algae development.