Wastewater Lagoon Systems

Front 1

1 In general, most permit violations in lagoon systems are related to problems with

lack of dissolved oxygen
excess algae blooms
excessive nitrification
excessive dissolved oxygen
low influent loadings

Back 1

excess algae blooms

Front 2

2 During daylight hours (due to photosynthesis) algae in a lagoon

produce dissolved oxygen while consuming carbon dioxide.
consume dissolved oxygen while giving off carbon dioxide.
consume dissolved oxygen and consume carbon dioxide as well.
produce carbon dioxide that lowers pH values thus decreasing oxygen demand.
have no impact on dissolved oxygen levels.

Back 2

produce dissolved oxygen while consuming carbon dioxide

Front 3

3 During the summer months, A lagoon system is experiencing BOD & TSS violations, the plant operator determines that the soluble BOD in the effluent is within permit limits while particulate values exceed the limits. In fact, the values of particulate BOD increase in each of the 3 cells in series while most soluble BOD is removed in the first cell.

This is most likely due to excessive nitrification taking place.
This is most likely a sign of inadequate aeration.
This is most likely a problem with short-circuiting and inadequate treatment.
This is most likely a problem with

Back 3

This is most likely a problem with excess algae in the effluent.

Front 4

4 Lagoon systems accumulate sludge over time, the sludge accumulation rate is

almost nothing, sludge accumulation in a lagoon system is insignificant and is not a operational concern.
lower in facilities with high algae counts, the algae consumes the sludge.
only a concern when lagoons accept septic tank wastes.
only a problem in combined sewer systems.
approximately 0.2 lbs of sludge produced per pound of BOD removed, but can be higher if there are excessive algae blooms.

Back 4

approximately 0.2 lbs of sludge produced per pound of BOD removed, but can be higher if there are excessive algae blooms.

Front 5

Lagoon systems experience diurnal (Day & Night) differences with alternating periods of photosynthesis and respiration.

TRUE
FALSE

Back 5

TRUE

Front 6

6 Due to diurnal differences in operation, a lagoon system is likely to experience the lowest dissolved oxygen readings

at any time since diurnal differences have no bearing on dissolved oxygen readings.
during mid day, when water temperature is up and biological activity is at its highest rate.
during nighttime, just before dawn.
when pH values change more than 0.2 on the pH scale.
influent BOD loadings are at their lowest.

Back 6

during nighttime, just before dawn

Front 7

7 During the daylight hours pH values are likely

to be the same as night-time operations (barring any drastic changes)
to be lower, due to the release of carbon dioxide.
higher due to the consumption of carbon dioxide during photosynthesis
lower due to higher influent flow.

Back 7

higher due to the consumption of carbon dioxide during photosynthesis

Front 8

8 During nighttime lagoon operations,

pH values are likely to be lower while the demand for dissolved oxygen is likely to be higher due to respiration.
pH values are likely to be constant while the demand for dissolved oxygen is likely to be lower due to respiration.
pH values are likely to be higher while the demand for dissolved oxygen is likely to be lower due to respiration.
pH and DO values should be approximately the same as daytime operations (barring any drastic changes in incoming waste).
pH values are likely to be slightly higher while the demand for dissolved oxygen is likely to be constant (compared to daytime) due to respiration.

Back 8

pH values are likely to be lower while the demand for dissolved oxygen is likely to be higher due to respiration

Front 9

9 The difference between a filtered (0.45 microns) BOD sample and a non-filtered BOD sample is known as particulate BOD.

TRUE
FALSE

Back 9

TRUE

Front 10

10 Excessive algae growth in a lagoon system can be controlled by

limiting sunlight into the lagoon
removing excess solids from the lagoon
filtering
ALL OF THE ANSWERS ARE CORRECT

Back 10

ALL OF THE ANSWERS ARE CORRECT

Front 11

12 During the nighttime hours (due to respiration), algae consume dissolved oxygen while giving off carbon dioxide.

TRUE
FALSE

Back 11

TRUE

Front 12

13 In a lagoon system, An effluent TSS to BOD ratio of 3.0 indicates

excess aeration.
normal operation.
low influent TSS.
lack of sludge in the lagoon system.
algae overgrowth or loss of old sludge.

Back 12

algae overgrowth or loss of old sludge.

Front 13

14 Lagoon systems are considered ideal for nitrification.

TRUE
FALSE

Back 13

FALSE

Front 14

15 Facultative bacteria

operate completely without air
function with or without elemental oxygen, in the lack of elemental oxygen, the organisms will find another electron acceptor using nitrate, sulfate or carbonate in that order.
need a constant supply of elemental oxygen.
are not present in lagoon systems.
are found only in the top six inches of a lagoon system.

Back 14

function with or without elemental oxygen, in the lack of elemental oxygen, the organisms will find another electron acceptor using nitrate, sulfate or carbonate in that order.

Front 15

16 In a 3 cell series lagoon system, most of the CBOD will be removed

in the last lagoon cell
in the second lagoon cell
equally in all cells
in the first lagoon cell
only after all the ammonia is converted to nitrate.

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in the first lagoon cell

Front 16

17 Approximately 10-25% of ammonia present in a lagoon system is removed by algae and microorganisms via cell uptake, however, most of this is given back as the algae and microorganisms die and decompose.

TRUE
FALSE

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TRUE

Front 17

18 During the summer months, An operator of a 3 cell lagoon system works 5 days a week (08:00 to 16:00). He takes a DO profile around noon with readings of about 6.0 mg/l to 6.5 mg/l in all three cells. He has shut off all the aerators in cell one and the readings are still about the same. After a few days, he is receiving odor complaints and notices a foul odor (rotten egg smell) in the morning when he first arrives. What is most likely taking place?

The DO reading is too high and the water is shedding excess dissolved oxygen creating bubbles that bring up stink with them. Aerators need to be shut down (or choked back) in other cells as well.
High influent BOD in the morning, he should run the aerators for a few hours in the morning then shut them down.
At night (during periods of respiration) facultative bacteria are finding their electron acceptor through sulfates (creating the rotten egg smell) due to the lack of elemental oxygen during the night hours. Aerator should be running during nighttime hours and a DO profile preformed during nighttime operation, preferably just before dawn.
Excess flow in the mornings is causing a bit of an overload, this can be corrected by storing flow in the collection system for later periods in the day.
Low F/M Ratio, the flow through the lagoons is unbalanced.

Back 17

At night (during periods of respiration) facultative bacteria are finding their electron acceptor through sulfates (creating the rotten egg smell) due to the lack of elemental oxygen during the night hours. Aerator should be running during nighttime hours and a DO profile preformed during nighttime operation, preferably just before dawn.

Front 18

19 Excessive algae growth will cause an increase in the sludge accumulation rate.

TRUE
FALSE

Back 18

TRUE

Front 19

20 During cloudy days, the amount of dissolved oxygen produced by algae in a lagoon system

will be the same regardless.
will be less than compared to a bright sunny day
will increase after dark
will be much higher than compared to a bright sunny day.

Back 19

will be less than compared to a bright sunny day