Water Environment Federation (WEF) Discussion Forums / WEF Discussion Forums / Operation & Maintenance / Treatment difficulties / Latest Posts

RE: Treatment difficulties

RichRoberts — Fri, 28 Mar 2008 15:37:28 GMT

WIthout pulling out a MOP or Sacramento those sure sound like classic signs of old sludge. Increase wasting to get younger. Rich

RE: Treatment difficulties

wastewater girl — Thu, 20 Mar 2008 12:45:04 GMT

Thanks for your help on the sludge question!

RE: Treatment difficulties

Mikel — Wed, 27 Feb 2008 08:21:45 GMT

Rotifers indicate your sludge is "old". Increase wasting to reduce the sludge age. We use MCRT and run at about 9 days. This keeps us dominated by stalked ciliates that settle well but provide very good effluent quality. Wasting must be increased in steps in order to not upset the system. General rule is no more than a 10% change per adjustment. Also it usually takes 1-2 sludge ages to complete the change with out detrimental effects. For us thats 9-18 days. Monitor OUR's and do microscopic observations regularly so you don't go the other way and get young..

RE: Treatment difficulties

Jerry — Fri, 22 Feb 2008 20:11:03 GMT

Hi WW Gal. Don't pay any attention to that mean old man. He's is probably an Engineer.

I used to be a member of a question and answer committe that made up, you guessed it, questions and answers. This was before ABC, and horse drawn honey wagons. Anyway there was a lot of arguing in those meetings. Nobody could agree on anything, so we, with all of our brilliance, made the proctors say, "Select the most correct answer". I told you we were brilliant, or was it "Cop outs"?

Your first answer is probably "Old Sludge" . Your second one, about Anaerobic Digesters, is up in the air. "Phewy"

RE: Treatment difficulties

wastewater girl — Thu, 21 Feb 2008 11:46:12 GMT

I wish I could research this kind of information. I have tons of books but this stuff cannot be taught through books alone. I also tried google but that didn't work either. I used this site as a last effort. Who better to learn from than the people that work with these situations everyday. I dont work in a plant so I have no one to learn from. Any help you could give me would be benfical.

RE: Treatment difficulties

Deerfield Wastewater — Wed, 20 Feb 2008 16:55:27 GMT

I must say that I got a chuckle when Wastewater Girl admitted her question was a homework assignment. It sounded like a question right off of a wastewater licensing exam. I think that the fact that it elicited a response from industry elders that it can't be answered without more information is telling. How many of us have had to memorize pat answers to inane wastewater exam questions in order to pass the test, and then spend our careers taking book knowledge with a grain of salt.

RE: Treatment difficulties

El Centro — Tue, 19 Feb 2008 18:35:57 GMT

I do have another question that maybe someone could answer.

An anaerobic digester has a pH balance of 7.0. For the last few days it has been producing less gas, and the quality of the gas is not as good (as methane). The amount of feed sludge has not changed, and the amount of sludge withdrawn is the same. What could the problem be? What tests could be done to verify your assumption? What steps should be taken to correct the situation?

----------------------------------------------------------------------------------------

"Wastewater Girl" with all due respect, the purpose of any homework assignment given by an instructor is so that you perform your own research and by doing it you will be exposed to more information than what is being asked for; consequently the acquisition of knowledge and your abilities to become a professional in this endeavor will greatly increase.

There is no wrongdoing in asking for help, I believe that all in this discussion forum will agree that it would work more to your benefit to perform your own research and be able to call it your own.

Just an observation, please don’t take it personal…smile!

RE: Treatment difficulties

wastewater girl — Tue, 19 Feb 2008 16:22:29 GMT

I do have another question that maybe someone could answer.

RE: Treatment difficulties

wastewater girl — Tue, 19 Feb 2008 16:21:06 GMT

Unfortunately I cannot give anymore information. This is a homework question. I am studying to be an operator.

RE: Treatment difficulties

Victor — Tue, 19 Feb 2008 14:49:42 GMT

Wastewater Girl:

I think that you need to provide much more information than just the types of higher level organisms that are or not present in your treatment system. What type of wastewater plant are you operating, MLSS concentrations, SRT, F/M, flow...

It sounds like you may have a long detention time. Again, I've seen cases where the solids drop like a rock but leave a murky supernatant. I've also seen toxicity affecting it in much the same manner. I could go on and on about instances where this might occur. I think you need to tell us more.

RE: Treatment difficulties

Jerry — Tue, 19 Feb 2008 13:52:43 GMT

5 to 9 mg/l BOD and 6 to 12 mg/l TSS is not much of a problem. These tests have a margin of error that would explain the small difference. However the fast settling and residual pin floc may indicate something. What is your MLSS and settleability after 30 minutes?

Treatment difficulties

wastewater girl — Tue, 19 Feb 2008 13:08:08 GMT

Here is my problem. The effluent BOD has increased from 5 mg/l to 9 mg/l. The effluent TSS has increased from 6 mg/l to 12 mg/l. The 30 minute settling test reveals that the activated sludge settles fast, but leaves behind some pin floc. A microscopic examination revealed that there is an overabundance of rotifers, but few amoeboids and flagellates. What is the problem? What can I do to correct it? Which tests should be run to see if the corrective action helped?