mixing wastewaters

[485627]

Is mixing of the old, anaerobic wastewater with the same ammount of fresh wastewater going to decrease or increase generation of the hydrogen sulfide that already began within the sewer line? Will new amounts of dissolved oxygen terminate anaerobic bacteria activity or is it to late for that after the generation of H2S already started?

 

[LHA]

Theoretically, diluting septic WW should decrease anaerobic activity, and doing so may raise pH slightly. But if you have odor problems, I don't think you will notice a difference by dilution, unless the "fresh" WW has a very good DO concentration.

Adding DO will not remove H2S, but it will (fairly rapidly) decrease its additional formation, as the oxidation processes will preferentially utilize the O2.

 

[485627]

Thanks for your reply.
This part intrigued me: unless the "fresh" WW has a very good DO concentration.
Since we are dealing with households, i'd like to know are there any cleaning products or detergents that increase DO concentration?
What are the chemicals we should look for in these cleaning products that will increase DO concentration?
If it is possible to achieve this with everyday household activites it would be a big step toward solution of the problem for the people living in that street. At least untill other apartments are build there (in about two years) which will add enough power to the stream to insure selfcleansing of the sewer.

 

[LHA]

I don't know of anything domestic WW sources can add to their WW to increase DO; I misunderstood your previous question, it sounded like you were adding activated sludge (or some other process WW) to the stream.

Just adding new anoxic WW to the stream might dilute the H2S to a slightly lower concentration, but it won't remove it.

I think you need a way to flush the lines periodically until the inflows are high enough to scour them. I am interested to hear of any suggestions anyone else might have...

 

[semo]

I don't think household chemicals are going to increase the DO and doubt the homeowners will want to routinely dump a jug of something ($$$) down the drain to solve a problem they probably feel the district/city should handle.

I'm assuming right now that this is an odor problem more so than damage to the infrastructure. If so, is the problem in the gravity mains, the lift station, or where. A little more info on the system and problem will help with answers.

 

[orenda1168]

485627:

As another option, contact ECP International, LLC at 514-577-4108, or water@infoecp.com, for information on an environmentally friendly sulfide neutralizer that will eliminate the H2S problem.

Orenda

 

[485627]

Here are additional information:
The problem is bad odour in only one of streets from this part of the city. The cause is in combination of factors. First part of the street (and sewer) long about 100m is ocupied with ten households. They produce more or less constant output of wastewater that has to go through 300m of gravity sewer line until it reaches main pipe line. Since this 300m is not inhabited, the stream becomes slow and solids become septic. The slope of the gravity sewer is the same as in surrounding streets that have no odour problems. However, the topografy of the surface in this street is parallel with the slope which keeps sewer constantly deep about one meter exposing it more to surface temeperature than sewers in surrounding streets whose depth is constantly rising.

Small building with 8 appartements is about to be build in the middle of empty 300m section. It will add new WW to already septic WW (created by those 10 households). Will their wastewater help solving the odours? I am aware of benefits of the flushing but that is not a permanent solution. In next two years few more buildings will be built creating stream powerful enough to ensure selfcleaning of the sewer. However my concern is with this building beeing finished soon in the midlle of the bad odour 300m section where it has to stand alone for the next 2 years. Will bad odours continue after the people start living in that building? I wonder will their WW increase or decrease bad odour until the completion of the building project in two years.

 

[dicksewerrat]

The new building should help the odor situation. The addition of more flow should help cut down the amount of solids laying in the pipe.

 

[semo]

I agree, the additional flow should help. It might not solve it; but, it will probably help.

Another thing that might help is the addition of manhole vent piping on a few manholes. They need to be routed to a high point where the wind can carry the odor away. When there is no wind and the air is heavy, the odors can still settle in the neighborhood.

Getting watertight manhole lids might also help to keep the odor contained in the line.

Adequate flow is the best solution.

 

[kchayfie]

Have you considered dosing something like calcium nitrate into the sewer? I've used this when low flows are being pumped over long distances. The nitrate provides the oxygen to prevent H2S build up.

 

[485627]

I've come across this product that claims cleaning of sewage systems without the use of dangerous toxic chemicals. It's produced by Unitor, it's called Gamazyme 700FN and it uses specialised bacteria to digest grease, fats, sewage, starch and other organic compounds. Do you have any experience with this product?

I've copied this from Gamazyne site: Ineffective or septic sewage treatment can be reactivated and maintained in peak operating efficiency by dosing Gamazyme 700FN direct in the tank or via the nearest toilet. The bacteria in Gamazyme 700FN will colonise the waste organic material which lines the pipework/tank system and degrade the waste until the system is clean. The biological activity in the sewage treatment plant is greatly increased, so the plant can thus handle more waste. The obnoxious smells in toilet areas and scuppers are reduced.

 

[dicksewerrat]

Unfortunately stirring up old 'anerobic sludge will release a lot of H2S.. I suggest you clean this line on a regular basis until flow increases.

 

[rak74]

Any idea the slope on the pipe? Sounds to me like solids are settling out causing the odor. There is no way (unless there is a pump station involved here) that the sewage is turning septic in 300m with a propoerly designed trunk line. Pipe should be inspected via CCTV to search for blockages in the pipe.

 

[Icanfix]

Is there a fire hydrant in the area that could be a source of water to flush the system every few days? That would wash the solids out of the sewer to the main. The flushing should, at least, minimize the production of H2S. Unless the sewage plant can't handle the lower solids that would result from the flushing.