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Clogging constructed wetlands

Clogging constructed wetlands

(OP)
I own and run a private 150,000 gpd WWTP and a septic pumping business. Our volume is very irregular and sometimes unpredictable between camp that were connected to, a cheese plant (lots of whey), and the septic business. From now till early fall we will have our heaver flow rates.

Our setup is dewatering (3/8”) dual 30,000 gallon surge tanks, 8,000 gallon septic tank (dual chamber), dewatering (500 micron cloth), and a constructed wetlands. For all of our dewatering we use roll off dewatering tanks.

Our original planes did not include the second set of dewatering tanks. They were added because of clogging where the water enters the wetlands. At the time of the issue the county agreed to let us add the box. Tons of paperwork, pay the county more money, and all was great.

Last week the county inspector came out and because the second dewatering tank is not on a set of engineered stamped planes I'm now paying a fine. After talking to others with in the county he is only going after private WWTP and not any of them run by the county. We are working on getting new stamped planes and all the new paper work.

Is clogging normally an issue constructed wetlands?

Is there anything I can do besides recirculate more through the wetland beds?

RE: Clogging constructed wetlands

The cheese wastewater will eventually clog the soils.

The remedy is to remove more of the fats prior to the wetlands treatment.

RE: Clogging constructed wetlands

(OP)
I thought the cheese maker was sending us mostly protean. I'll get who ever picks up there load to get a sample before and after they mix there tank.

If I do have a fat issue than I think it would be from scum layers of the septic tanks were pumping.

I have grabbed a few samples from different places that a friend will test tomorrow for me.

I would of never thought I would of needed more primary treatment. We pump from the surge tanks at 40 gpm and there is hardly any sludge in them. The scum layer in the septic tank grows about 1/4” a day and suck it off every week or 2. I can see how 80 gpm would keep the keep the scum layer from foruming.

RE: Clogging constructed wetlands

It is difficult to know what is in the wastewater. The cheese manufacturing plant will dump to waste what is not needed or rejected.

You may have CIP cleaning products, salts, fats, proteins, phosphorus, etc.

I know of one cheese manufacturing plant that had a ridge and furrow system where the soil clogged up.

RE: Clogging constructed wetlands

(OP)
I don't know what cleaning products there using now. Last time I checked with them they were cleaning with bleach. We should only be getting what they drain from the vats and drain table. Everything else goes into there septic system.

I know it's high in salt, protean, phosphates, and a ph between 5 and 5.5. We pick up around 18,000 gallons a week. If that’s where the fats were coming from I would think it would take a longer than 6 months to clog the gravel intake beds.

RE: Clogging constructed wetlands

(OP)
I had a colleague run some tests for me and then he wanted to come out and have a tour / look see. From the test it looks like the oils are coming from the septic tanks were pumping.

We were also looking at the build out / upgrade planes for the plant. The wetlands were built out for the 150,000 gpd and everything else was to be built out in 4 stages. At the beginning we built out all of stage 1 and part of stage 2. Were missing the septic tank from stage 2 sending double the amount of water into septic tank not letting the liquids separate.

What I need to do is to just build out to stage 3. It would give us 3 30,000 surge tanks and 3 8,000 gallon septic tanks. With having the WWTP ready to go it would help us to find the investors to build out the housing development that was planed.

He suggest that we install a pipe to lower the height of the discharge from the primary filters to under the water line in the surge tank. It will cut down on the mixing that is happening and should let more separation with in the surge tank.

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