Dual Media filter vs Pressure sand filter

[kwisatz_haderach]

Hi guys, please help a novice learner understand which is best. We have a requirement for filtering surface water that is high in TSS (around 100 PPM and trubidity (30 NTU). We contacted three suppliers and one has given pressure sand filter (PSF) followed by activated carbon filter (ACF), while the 2nd supplier suggested to go with Multi grade filter filled by ACF, while the third one has suggested Dual Media filter followed by ACF. Three suppliers are telling me that theirs is the best solution for our requirement. I can't able to choose between them. Please help. Based on your experience which you will choose?

 

[pierreick]

Get a chemical engineer involved!
Sand filter is for raw water, coarse filtration, AC filter is a polishing filter.
Note: AC technology is good for Hydrocarbon removal, but you need to be able to regenerate/dispose them
Good luck
Pierre

 

[swazimatt]

is this for stormwater runoff?

 

[kwisatz_haderach]

No, this is just for our factory usage. First we are using ground water that has less TSS and turbidity, but due to local govt restrictions we have to use canal water now, which is high in these values.

 

[swazimatt]

ok, for reuse in the factory?
I suppose it depends on what your final requirements are, we use silt stopper aka "lamellas" for our site sediment control during wet season, basically a flocculation system (and i think dosing is an option). This may be all you need
https://www.trenchmate.co.nz/wp-content/uploads/Trenchmate-Siltmate-SM50-spec-sheet-2023-V3c.pdf

There are numerous stormwater devices that we use as well that use filters, but those would be via gravity flow (google Spel filters, stormwater360)

 

[bimr]

Almost all filters presently sold are multimedia filters. Either multimedia or dual media. The advantage of a multimedia filter is that it provides some depth filtration that allows longer filter run times. In sand filters, the filtration occurs right at the surface of the media which limits the filter run cycle.

A TSS level of 100 mg/L is generally considered too high for direct filtration. With that high of a solids loading, the conventional approach will be sedimentation followed by filtration. 100 mg/L TSS will allow very short filtration cycles.

You probably don't need carbon filtration. Carbon is used for taste and odor removal as well as for removal of trace amounts of organics (TOC).

 

[LittleInch]

So what is your requirement in terms of solids and removal of other contaminants?

"Factory usage" could be anything. Just washing and cooling out actually used in the process?

I would be concerned about filter usage and you might be better off for looking at backwash filters or even cyclone?

 

[kwisatz_haderach]

bimr, thanks for your input. So that means i have to give frequent backwashing if i choose only sand filter right? Also what about backwash flow rate? Different suppliers have given different backwash flow rates. 40 vs 60 vs 90 while our feed flow rate is 40 m3/hr. I read that slightly higher backwash flow is better since it seperates the media particles and clean between these? How can i know how much is best?
We are planning to install the sedimentation and flocculation system later due to budget constraints.

 

[kwisatz_haderach]

@LittleInch, We already have all the water treatment systems (Dual Media Filtration, Membrane filtration) before but until now we are using ground water as raw water so the existing system is working good, but due to the shift to canal / irrigation water we can't feed this water directly to our existing system since the existing system is designed for less TSS load and more TDS load and this canal water has more TSS and less TDS. So we are planning to treat this before sending it to our primary treatment.