Rising PH??
I took a Ph reading of our effluent sample at 10:00pm and the PH was 7.76. I forgot about the sample and came in the next day and the PH was 8.89, what happened?? Just some more information. The water plant has R.O (reverse osmosis) as part of the treatment process. The wastewater plant is part activated sludge and part MBR.
29 
My Points
- You need to be logged in to view your points.
Redeem Points
Your shopping cart is empty
Visit the shop
I would suspect that atmospheric carbon dioxide dissolved in your sample and raised the pH.
We are unsure why, maybe due to the reject water from the R.O sytem at the water plant. But carbon dioxide goes away and the P.H slowly rises.
The pH increased because CO2 off-gassed from the sample. This is due to the equilibrium relationship between to amount of CO2 in the wastewater sample and the amount of CO2 in the air above the sample. (This relationship is known as Henry’s Law). When the pH of the wastewater is below the mid-8′s there is generally more CO2 in the wastewater than its natural equilibrium level with the atmosphere. Therefore CO2 will off-gass over time until it reaches equilibrium, and pH will rise.
CO2 off gassing is likely the cause. Temperature will also cause the pH to drift.
Since it is ASP and MBR plant prior to RO, it could be due to WAS have not been taken away from the system and this soluble microbial product (SMP) is passing through MBR permeate and enters in RO feed. This largly contains carbonaceous organic matter in the form of CO3, HCO3, hence the pH rises to alkaline side.
Several things could effect this. Was the sample sitting out and open? The temperture of the room, how many other chemicals had been opened with their fumes/particals in the air.
If proper pH methods were used it wouldn’t have happend. So, that is why.
Probably increased because of the increase of temperature and contamination exposure. The longer it stayed there the higher the temp and contaminates.
It could be several things: electrode drift, change in sample temperature, CO2 off gassing.
Check your meter. But C02 gasing off would be the likley cause.
Agree with bwendt
C02 gassing off would be my first place I would look.
Check your meter. But C02 gasing off would be the likley cause.
Could be a bad meter.But C02 gasing off is most likley.
C02 gassing off.
sounds like a CO2 issue
C02 gassing off would be my first place I would look.
Ph will usally increase with temp.
CO2 gasing off is likely
Very interesting
Dissolving atmospheric carbon dioxide probably raised the pH, but temperature differences could also play a role.
sounds like CO2
Sounds like the question has already been answered. I do know that it is in our permit that the pH reading must be taken within 15 minutes of sampling
Check your meter. But C02 gasing off would be the likley cause
need more info. was it the same sample from the night before? or was the probe left in the same spot but measuring a different sample? Temperature also affect pH
check for chemical leak in the R.O. ours uses sodium hydroxide.
C02 gasing off would be the most likley cause.
The sample will gain ions from the air and carbon dioxide gassing off raises the pH.
CO2 would be the likely cause by it gassing off