Kinda OT:- COD Probe ?

i have been assigned a project where the COD levels (Chemical Oxygen Demand)in the effluent is to be monitored. I have done some research on the internet but the most i could find is like a sampling system complete in a control cabinet.

Ideally because the probe would be installed in an effluent drain, some form of wireless communications would be ideal as these will be in a remote location.

Has anyone had any dealings with COD probes or wireless effluent monitoring systems.

Thanks

LH

Remote no problem use a battery and power supply.
Wireless in a single package is the kicker. Check with your local sewer districts. See what they do and do it with.

Dan Bentler

Cod

I Believe you can use a Turbidity meter to measure the COD levels in the effluent.

You will have to google it though as dont have all the details


Jules

Turbidity is not a good a indicator for COD, as things other than organics can be suspended and cause turbidity.

COD is usually not a true real time measurement. It can't be measured directly like pressure or temperature. COD is almost always measured with some kind of sample pumped to a device, the oxygen uptake measured over a period of time, and then the COD calculated. Depending on the waste stream they can be maintenance intensive, as the sample lines plug easily. For some types you also need to replenish titration chemicals.

Arthur Technologies, ChemScan, and Hach are, or at least used to be, suppliers of these instruments. I suggest you go to wef.org and look at their supplier data base for possibilities.

Thanks for the replies Tom, after researching COD meters online, the best i could find was the endress + hauser COD meter which has a sampling delay of 5 mins minimum. Looks like this delay is to measure the oxygen depletion or such like.

The only reason i wanted to measure COD is that our effluent goes offsite and we are billed by COD levels.

Alternatively i could measure the conductivity of the fluid which would tell me what material was going to drain and a flow meter of some sort to measure the totals. The problem with flow meters in drains is that the flow would never be at full bore and would require some sort of accumulator.

Thanks for the info anyway i will continue looking.

LH

For flow measurements in a drain line / channel, a standard way is to install a flume and a weir, and read the depth of effluent going over the weir.

I am also looking for sensors for COD/BOD for my digester system...and a sensor for reading total % of solids in the feed and effluent tanks...right now the USDA is manually sampling these things, but we want to automate it on the next system we build.

David

Conductivity may not give you what you are looking for unless you have a very steady waste stream and can determine a good correlation between COD and conductivity - unlikely in my opinion.

Your best bet is to have a three step program:

1) measure and totalize flow as David suggests
2) use a sampler like ISCO or similar to do a composite sample
3) use a lab test to measure COD of the sampled waste

I'd suggest you talk to the guy that handles collections and industrial monitoring at your municipal treatment facility. Find out the methodology they are using to bill your company, and run your proposed scheme past them. It will save hassles in the future.

David - look at Insite IG http://www.insiteig.com/ - they have TSS meters, but I'm not sure if they can handle the very nasty environment in an anaerobic digester. Aerobic digester should be OK.

thanks tom, i am currently looking into the way they monitor and analyzse our effluent.

many thanks for all the replies

LH