|
| | | Forum Newbie
Group: Forum Members
Last Login: 2/4/2008 2:45:48 PM
Posts: 2, Visits: 8 |
| | We work with a small town that has had very erratic organic loadings to their existing aerated lagoon. The influent BOD is typically less than 400 mg/l but samples exceeding 1000 mg/l are occasionally measured. This is from a community that is mostly residential with a growing commercial/institutional sector, including several restaurants, schools, an rv park, and a microbrewery. They use a flow-proportioned composite sampler at the head of their treatment plant, so we are fairly confident in the results. The town has instituted a pre-treatment program, consisting of large settling tanks, for significant commercial/institutional users, but continues to get the sporadic results. The results are frequent enough that the organic loading has been consistently exceeding the design capacity of the lagoons, although the effluent BOD continues to be within discharge limits. When the influent is high strength, it tends to be very dark and have a high solids content. The town has been unable to find any evidence of illegal dumping and they have a strong educational program to minimize discharge of organic material to the sewer. A recent suggestion was the buildup and periodic sloughing of "black algae" from the collection system piping, particularly clay pipe. My first thought was that algae are photosynthetic and would not be present in the collection system piping, but maybe "algae" is not the correct term. Has anyone encountered "black algae" in the collection system and a resulting impact on the influent BOD at the treatment plant? Thanks for any assistance. |
| |
| | | 
Supreme Being
Group: Forum Members
Last Login: Yesterday @ 3:47:34 PM
Posts: 335, Visits: 435 |
| | Brent: I can only speculate as to what the black mass might be unless it is viewed under the microscope. My vote would be for mycelial mass from fungi. Would be curious to take a look at it.
E. coli happens! Database Central |
| |
| | | Supreme Being
Group: Forum Members
Last Login: Today @ 12:06:24 AM
Posts: 282, Visits: 3,508 |
| How small is small in terms of the town and its flow to the treatment system. I'm a bit suspicious of the RV park as a possible source of dark influent. Is the RV park fairly large compared with the non-transient population? RVs have "black water" storage tanks that collect the toilet wastes only (usually). Often, RV owners will dump the tanks only when they are filled. So, each tank dumping would be of say 40 to 80 gallons of very concentrated waste. If the Rv park is a fairly large one (compared with the rest of the town's population), this could lead to a bit of a slug if (for example) 50 RV's come to the park on a given day, and all dump the "black tank" within a few hours.
Jeff Naumann
(310) 540-0045
FAX (310) 540-0337
http://www.jeffnaumannassociates.com/ |
| |
| | | Forum Newbie
Group: Forum Members
Last Login: 2/4/2008 2:45:48 PM
Posts: 2, Visits: 8 |
| | Jeff and Victor, I have recommended examination by a microbiologist the next time a slug comes through to see if the material is biological in nature. The Town has a population of about 1800 (0.3 to 0.4 MGD) and the RV park is sizeable - possibly 100+ units in the summer and now kept open year-round with probably 20 +/- units in the winter. I agree that the RV park is a potential source of high loading, but the park tends to have long-term residents (temporary workers in oil and gas or construction), so I think the loading from this source would be relatively constant. The Town has required installation of sampling manholes on the services of all suspected high loading commercial/institutional sources, but it is difficult to determine the source when the loading is sporadic. Thanks for the input - we'll keep looking. Brent |
| |
|
|