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In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

Hi all, hope you are all well. First time posting here, so please excuse any mistakes I've made.

I'm on a project where we're designing a rainwater storage and pumping system that ties into the overall processing plant. In one area, we have a sump pump which discharges into a storage tank, and the discharge from this tank ties into the process plant. The sump pump is in a vehicular traffic area and the client wants any potential diesel / hydrocarbons in the rainwater going through the sump pump to be filtered out prior to the water going into the tank, and then into the downstream process.

I've been searching for in-line filters, diesel filters, oil separators etc. and the majority of what I'm seeing seems to be stand-alone skid-mounted equipment. We're hoping to source something that is more "in-line", similar in concept to a Y-strainer or basket strainer, that could be supported on a small frame if need be. We're trying to stay away from skid-mounted equipment if possible.
I've attached a screenshot of the area I'm talking about.
Max duty for the sump pump has been specified as 46m3/h and 7.6m head, so we're looking for a filter that can perform at this duty as a minimum.

I'm hoping someone might have come across something similar to what I'm talking about and can point me in the right direction, please.

Thanks for your time.

RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

Google oily water separator.

It's relatively easy to separate water from diesel but separating diesel from water is much more challenging. The process is slow and difficult to do in line. Basically, you need to let it settle out. Oily water separators are very large relative to capacity let the water to meander around baffles or plastic pellets that the oil can cling to. They're not perfect, either as 15ppm is all that marine units achieve.

Anywhoo, you have the benefit of storing your water in a tank so I suggest you do the bulk of your separation there. Skimmers installed in the storage tank could handle a lot of the work.

RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line


46 m3/hr is a considerable flow.

I understand the desire, but without actually stating what the oil content is coming in and what you need out, you won't get very far.

Trace elements of oil on water are actually very difficult to remove below say 5-15ppm.

Normally rainwater contaminated with oil / diesel etc needs to run through an interceptor before being pumped anywhere.

Garage (Gas station) forecourts are similar.
Something like this https://marshindustries.co.uk/products/hydroil-for...

I don't know of any inline filtration system other than maybe an inline cyclone, but then you need a continuous out flow of oily water.

Anything you do you then need to think about how to remove any oil you do capture.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

There are no designs of oil/water separators that are in-line.

You will have to do the oil/water separation in a separate tank.

RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

You can't even steam-distill the water to purify it, as the oil/diesel/gas products have overlaps in their distillation curves with water.

You can, however, use freeze-"distillation" (https://en.wikipedia.org/wiki/Fractional_freezing) to purify the water (extract solid, very pure water ice and wash that with pure water, reject unfrozen gunk), but I've only seen that used in a batch process.

RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

Settling tanks with skimmers are the only way to do this. The system can be made more compact if you use a series of settling tanks with the oiliest water spilling over into the next tank each time. Then you only have to skim the last one.
But in any case they need to be large enough that the flow is quiescent.

There are some absorption filters that will absorb hydrocarbons in water, but hte life is short and the ones that I have seen cannot be regenerated, only replaced.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

If there is "free product", you must remove it with either an oil/water separator or a hydrophobic coalescing filter.

If there is dissolved phase material, activated carbon will work. But you'll need a huge bed for such a large flow.


RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line

There are sensors that can be located in your sump which will detect the oil on the top and shut off the pump before it pumps the oil. There is an alarm system that will indicate there is too much oil in the sump.

They may not be large enough for what you are doing, but it is a shot.


RE: In-Line Hydrocarbon / Diesel Filter in Rainwater Sump Pump Line


Is there any way you can disconnect the drain from that location to the sump tank, add a new tank of appropriate capacity to take the contaminated water and use a mobile equipment either to transport it to the plant WWTP or dump into a nearby plant open/oily water drain?


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