Bio Tower Effluent BOD = 90 Mg/L

CASE STUDIES

Case #1

The Glymphville Wastewater Treatment Plant is a 2 MGD activated sludge treatment facility. Compliance problems prompted the village to hire a Slick Rick Consulting firm to evaluate the system performance. The firm concluded that the plant was overloaded and a recommendation was made to install Bio Towers prior to the aeration basin to reduce the BOD loading to the aeration basins. Slick Rick’s installed the Bio Tower, received payment and was never heard of again. Several months later, the treatment system began to experience severe bulking problems. Based on the following process information please help Glymphville’s operator before the Village founding father fires him. (Note: Slick Rick is the founding father’s nephew).

Plant Data:

· Raw Influent BOD = 200 mg/L

· Bio Tower Effluent BOD = 90 mg/L

· Bio Tower Effluent ammonia nitrate nitrogen = 2 mg/L

· Bio Tower Effluent phosphorus = 0.6 mg/L

· Aeration basin MLSS = 2660 mg/L

· Aeration basin MLVSS = 2450 mg/L

Microscopic observations:

· Excess amount of a large filament with heavy attached growth. The filament stains Gram-variable and Neisser negative.

· Positive India Ink test

· Protozoan count:

ORGANISM / Slide #1 / Slide #2 / Slide #3 / Average / Percent
Amoebae / 0 / 0 / 1 / .3 / 0.3% / 2.4%
Flagellate / 0 / 6 / 0 / 2 / 2.1%
Free-swimming Ciliates / 1 / 6 / 0 / 2 / 2.1% / 79.1%
Crawling ciliates / 26 / 15 / 20 / 21 / 22%
Stalked ciliates / 67 / 32 / 58 / 52 / 55%
Metazoa
(Rotifers, nematodes etc.) / 13 / 20 / 17 / 17 / 18% / 18%
Total / 107 / 79 / 96 / 95

Case #2

Toni Town USA operates a small activated sludge treatment system in rural Idaho. Influent enters a small primary clarifier prior to aeration and then on to a single secondary clarifier. Sludge is removed and treated in a small aerobic digester prior to land spreading. The facility has submitted facility plans to add additional sludge storage because the current digester does not have the capacity to hold sludge for the required 180 days. Additional sludge is currently being stored in the primary clarifier. Over the last several months this facility has begun experiencing severe bulking in the clarifier and foaming in the aeration basin. Use the following information to help Toni Town before they go up in “foam”.

Plant Data:

· Primary effluent BOD = 105 mg/L

· Primary effluent Ammonia nitrate nitrogen = 14

· Primary effluent phosphorus = 1 mg/L

· MLSS = 1800 mg/L

· MLVSS = 1690 mg/L

Microscopic Observations:

· An insignificant number of filaments were observed in the mixed liquor

· Little to no filaments observed in the foam

· Positive India Ink test

· Protozoan Count:

ORGANISM / Slide #1 / Slide #2 / Slide #3 / Average / Percent
Amoebae / 6 / 3 / 1 / 3 / 4% / 14.5%
Flagellate / 13 / 6 / 6 / 8 / 10.5%
Free-swimming Ciliates / 15 / 12 / 7 / 11 / 14.5% / 81.6%
Crawling ciliates / 22 / 15 / 20 / 19 / 25%
Stalked ciliates / 40 / 32 / 23 / 32 / 42%
Metazoa
(Rotifers, nematodes etc.) / 5 / 1 / 2 / 3 / 4% / 3.9%
Total / 101 / 69 / 59 / 76

Case #3

The operator at the Bennington WWTP performs routine microscopic evaluations of the plant mixed liquor. The plant was running well. However, he began to notice a change in the microscopic observations. Last week when he looked at the sample he saw the following:

The sludge was compact and the fluid surrounding the floc was quite clear of dispersed bacteria. But, today when he looked at the sample it was quite different. He noticed that the fluid surrounding the floc looked quite different.

What do you suspect is going on? The plant data is as follows:

· Primary effluent BOD = 350 mg/L

· MLVSS = 1200 mg/L

· Aeration tank dimensions = 25 ft long, 15 ft wide, 12 ft deep.

· Flow = 300,000 gallons/day

· pH = 6.9

· Influent BOD = 500 mg/L

· Final effluent BOD = 75 mg/L

What calculation will you perform to prove what you suspect is the problem?

Case #4

The Dayton WWTP is started experiencing foaming and bulking in the activated sludge treatment plant shortly after heavy rains pounded the city over the past few days. Since the community has combined sewers a heavy load of storm water entered the plant. Jerry, the Electrical Supervisor, took one Wastewater Microbiology class and decided he knew enough to fix the problem (even though he did not do too well in the class). He instructed the operator to decrease the return and increase the number of microorganisms in the aeration basin. Please help the operator get out of this foamy mess!!!

The Microscopic evaluation revealed the following:

· An significant number of filaments were observed in the mixed liquor

· Little to no filaments observed in the foam

· Positive India Ink test

· Protozoan Count: