Water and Wastewater.com Help Forums - Coaggulation and flocculation

sfang85 Ex Member Company or Organization: Lotus scientific(M)	Coaggulation and flocculation Apr 22^nd, 2008, 7:17am i designing a wastewater treament equipment for labrotary use. i facing a problem to size the coagulant and flocculant tanks. first, i would like to ask how many aluminium sulphate i should put into the process ? is the soda ash neccesary in this treatment? how much of flocculant i should add into the process?
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DrHenry God Member Offline Ride, boldly ride, The shade replied... Posts: 788 Raleigh, NC Company or Organization: CESTAB (see bio)	Re: coaggulation and flocculation Reply #1 - Apr 22^nd, 2008, 2:31pm For wastewater, the alum could vary from 50 mg/L to 1000 mg/L depending on the wastewater. Floc may or may not be needed. I like caustic over soda ash. Can you give us more details about what your are doing? Wastewater source, flow, etc.
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sfang85

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Re: Coaggulation and flocculation
Reply #2 - Apr 23^rd, 2008, 12:28am

DR Henry and who may concern about this issue,

firt of all i would like to thanks DR Henry for the reply.

my work is actually to design a lab scale equipment which for student's labrotary work and understanding. the main purpose of this equipment is flotation. but i have to do some pretreatment before the flotation process in order to create a floc. which are coagulation and flocculation.
if my waste water amount is 50L, do u think 10L of coagulant tank is enough? if i insist to put flocculant, what is the limit?

thanks

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Ratnarin Narakhetudomsak Junior Member Offline Water and Wastewater.com is the best! Posts: 81 Thailand Gender: Company or Organization: Chemical Dynamics Co., Ltd.	Re: Coaggulation and flocculation Reply #3 - Apr 28^th, 2008, 3:38pm Dear Sir, Alum and Soda Ash is old fashion technology. Why don't you try PAC and Polyacrylamide? Try to study by reading the new technology and try to do the lab test by yourself. Goodluck.
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yuqing YaBB Newbies Offline leading manufacturer of water treatment chemical Posts: 19 Gender: Company or Organization: Gongyi Yuqing	Re: Coaggulation and flocculation Reply #4 - May 4^th, 2008, 7:14am i agree on the above one The polyaluminium chloride and polyacrylamide is the updated products,which is much superior to soda and sulfate salt. But regarding your prblem, i am sorry i can do nothing to help you.
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Shivaram K Full Member Offline WaterandWastewa ter.Com is the best! Posts: 169 bangalore Gender: Company or Organization: Cadbury Schweppes ltd	Re: Coaggulation and flocculation Reply #5 - May 19^th, 2008, 2:48pm PAC and lime are better compared to others.
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DrHenry

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Bottom line, doRe: Coaggulation and floccul
Reply #6 - May 19^th, 2008, 7:58pm

I just wanted to comment on the alum versus PAC question. Based on my experience over the last twenty years, we use alum for trials for a simple reason. We have found cases where alum will work, but PAC doesn't work very well. We have found that if PAC works, alum always works. I have theories about this but no hard facts and all I can give you is process history that could not be called complete. Bottom line, do not lump alum and PAC together in all cases.

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NorCal_Wastewater1

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Re: Coaggulation and flocculation
Reply #7 - May 19^th, 2008, 9:53pm

I would like to add to DrHenry's comment; Yes new is good, it is part of what we refer to as innovation, progress etc... but just because something is new doesn't mean it is always the better or best choice. One of the nice things about older is that we know what to expect out of it. There is a history of knowledge behind said product or process that may not neccessarily be there with the newer product or system. That's not to say that the newer product won't work, but to just say well that is old and this is new so this is what to use is the blind leading the blind so to speak. With time comes experience which leads to knowledge, which in turn allows us to make the better choice for said application.

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Have a great day,

Dallas

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Shivaram K

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Re: Coaggulation and flocculation
Reply #8 - May 22^nd, 2008, 5:12am

As per rmy experience

1) We have replaced Alum with PAC with less doasage. Also polymer dosage has become less with addition of PAC.
2) The combination of PAC+ Polumer, Alum+ polymer need to be worked out in lab befor etrying commercially.
3) Chekc if the dosages are less in given combinations and options as it will directly impact the operational cost.

It is better to do a labe test before we go for any confirmation. The retention times in the tank to be designed based on lab trials.Otherwise theer is high possibity of coming to a wring conclusion.

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