Waste Water Test Prep

Front 1

BOD Formula

Back 1

lbs/day = concentration, ppm x Flow, mgd x 8.34 lbs/galexampleBOD5 = 200 ppmFlow = 25,000 gpd (0.025 mgd)lbs/day = 200 x 0.025 x 8.34 lbs/day = 41.7 lbs/day

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Removal Efficiency of BOD Formula

Back 2

% Removal = Influent - Effluent /Influent x 100example Influent BOD = 200 ppmEffluent BOD = 4 ppm% Removal = 200-4/200 x 100% Removal = 98%

Front 3

Temperature

Back 3

Temperature indicates thermal energy contained in waste water. Higher summer temp increase activity in the microorganisms, lower winter temp decrease activity in the bugs. Reaction rate double with 22°F (10°C) increase in temp.Increase in temp Industrial contributor, decrease in temp storm water.

Front 4

pH

Back 4

Measures acidity/alkalinity, actually measures concentration of hydrogen ions in a solution. pH scale is from 0-14, 7 neutral, 0-6 acidic, and 7.1-14 being basic.

Influent pH microorganisms remain most active between pH 6.5 to 8.0.

Influent waste water pH usually 6.8 - 7.2; significant change may indicate industrial or non-domestic discharge.

Septic waste water will have low pH, dark black color and H2S odors.

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Nutrients

Back 5

Common/Important nutrients in influent waste water are NITROGEN, PHOSPHORUS, and POTASSIUM....IRON

Front 6

Nitrogen

Back 6

occurs in 4 basic forms: AMMONIA, ORGANIC, NITRATE, and NITRITE. Total Kjeldahl Nitrogen (TKN) combination of ammonia and organic makes up majority of Nitrogen...mostly ammonia

Front 7

ATC

Back 7

Aeration Tank Concentration (MLSS Concentration)

Front 8

Methane

Back 8

CH4

Front 9

Alum Aluminum Sulfate

Back 9

AL2 (SO4)3

Front 10

Chlorine

Back 10

CL2(Greenish-Yellow 2 1/2 times heavier than air, 1 volume of liquid chlorine expands to 450 volumes of chlorine gas, cylinders filled 85% for gs expansion, max chlorine withdrawn from 100-150 lbs cylinder is 42 lbs per day against water pressure of 35 psi, max chlorine withdrawn from a ton container is 400 lbs per day against 35 psi or 8 lbs/day/degree Fahrenheit)

Front 11

Carbon Dioxide

Back 11

CO2

Front 12

Hydrogen Peroxide

Back 12

H2O2

Front 13

Hydrogen Sulfide

Back 13

H2S

Front 14

mg/l (milligrams per litter)

Back 14

ppm (parts per million)

Front 15

MLSS

Back 15

Mixed Liquor Suspended Solids (combination of Influent and RAS)

The concentration of suspended solids in the aeration tank of an activated sludge process. The MLSS concentration is expressed as mg/L (ppm). This term is also referred to as Mixed Liquor Total Suspended Solids (MLTSS).

Front 16

MLVSS

Back 16

Mixed Liquor Volatile Suspended Solids (active/volatile portion of MLSS)

Front 17

Nitrogen Gas

Back 17

N2

Front 18

Nitrate-Nitrogen

Back 18

NO3

Front 19

Nitrite-Nitrogen

Back 19

NO2

Front 20

NTU

Back 20

Nephelometric Turbidity Units

Front 21

Q

Back 21

Influent Flow in mgd: same as Plant Flow in mgd

Front 22

QR

QRAS

Back 22

Return Activated Sludge Flow (mgd)

Front 23

QWAS

Back 23

Waste Activated Sludge Flow (mgd)

Front 24

R to Q

Back 24

Return to Flow Ratio

Front 25

RR

Respiration Rate

Back 25

The measurement of oxygen utilization rate of sample in relationship to the weight of volatile microorganisms, as mg/hr/gm. The RR is considered to be a qualitative measurement.

Provides a direct indication of activity and viability of the microorganisms and is expressed as (mg) of oxygen utilized per hour by one gram (gm) of volatile mixed liquor (MLVSS), or mg/hr/gm.

Can be used to determine health of activated sludge, can indicate presences of toxins.

Front 26

RSC

Back 26

Return Sludge Concentration

Front 27

Settleometer

Back 27

2 liter vessel to visually observe anticipated settling characteristics of secondary clarifier (settling of mixed liquor)

Front 28

SRT

Back 28

Sludge Retention Time (age of sludge)

Front 29

SS

Back 29

Suspended Solids

Front 30

SSC

Back 30

Settled Sludge Concentration

Front 31

SSV

Back 31

Settled Sludge Volume

Front 32

Supernatant

Back 32

Liquid removed from digester: returned to plant influent. Supernatant removal concentrates sludge in digester.

Front 33

SVI

Back 33

Sludge Volume Index (weight to volume ratio of mixed liquor)

(expresses the weight per volume of MLSS)

Front 34

TS

Back 34

Total Solids

Front 35

TSS

Back 35

Total Suspended Solids

Front 36

Volatile

Back 36

Material that burns in a muffle furnace at 55°C for 15 to 20 min

Front 37

VSS

Back 37

Volatile Suspended Solids (same as MLVSS when the sample is mixed liquor)

Front 38

WAS

Back 38

Waste Activated Sludge (excess sludge removed from activated sludge process)

The excess growth of microorganisms which must be removed to keep the activated sludge system in biological balance. Various control techniques can be used to estimate the amount of WAS that must be removed from the process on a daily basis.

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7.48

Back 39

gallons in 1 cubic foot of water

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8.34

Back 40

Weight of gallon of water

Front 41

Aeration System

Back 41

To provide mixing of influent waste water and activated sludge, and dissolve oxygen into the aeration tank contents (mixed liquor). diffused aeration systems

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3 types of Aeration Processes

Back 42

Conventional Aeration

Extended Aeration

Contact Stabilization

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Aeration Blowers

Back 43

provide air for dissolution and mixing in aeration tanks. Blowers can be centrifugal or positive displacement

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RAS System

Back 44

to collect sludge from the clarifier floor and return the RAS to the aeration system. RAS system can be air lift devices using air from the process blowers, or separate pums

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WAS System

Back 45

to remove a portion of RAS or mixed liquor to the digester. WAS is necessary to maintain the food to microorganism ratio in proper balance, which also controls the age and sludge quality.

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Digester Supernatant

Back 46

remove clear liquid from the aerobic digester after adequate settling. Supernatant should be removed to the aeration system. It can be pumped or air lifted.

Front 47

Chlorine Contact Chamber

Back 47

provide mixing and contact disinfection of the clarifier effluent and solution of chlorine. Disinfection is required to destroy pathogenic bacteria and low fecal coliform. Chlorine contact chambers are usually baffled to create an extended contact time.

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Effluent Disposal

Back 48

disposing the final, disinfected effluent.

Multiple Systems:

Percolation ponds

Leach Fields

Surface Water Discharge

Deep Well Injection

Spray Field

Reclaimed Utilization (must be filtered effluent for off-site reuse utilization)

Front 49

Activated Sludge Summary

Back 49

is maintained by proper environmental conditions in the process: DO, time, food balance, return of activated sludge temperature, nutrient balance and removal of excess activated sludge.

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High Rate Aeration

(young)

Back 50

Pure Oxygen

Aerobic Selector

Contact Tank of Contact Stabilization

DT = 1-4 hrs

Growth Rate = Log Growth

SRT 1-3 days (low)

F/M Ratio = 0.5 to 1.0 (high)

MLSS = 1,000 - 2,000

Volatile % (MLVSS) = 80-90%

MCRT = low decreasing

RR = more than 20 mg/hr/gm

OUR = higher than 1.0 ppm/min

SSV(5 min) = 800 or higher

SSC(end point) = 3-4 hrs

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Conventional Aeration

(normal)

Back 51

Complete Mix

Plug Flow

Step Feed

Contact Stabilization

DT = 6-12 hrs

Growth Rate = Declining Growth

SRT = 4-8 days (medium)

F/M Ratio = 0.2-0.5 (medium)

MLSS = 2,000 to 3,000

Volatile % (MLVSS) = 70-80%

MCRT = Good Range

RR = 12-20 mg/hr/gm

OUR = 0.5-1.0 ppm/min

SSV(5 min) = between 600-700

SSC(end point) = 1-2 hrs

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Extended Aeration

(old)

Back 52

Plug Flow

Oxidation Ditch

Carousel

Bardenpho

Orbal

DT = 18-24 hrs

Growth Rate = Endogenous Respiration

SRT = 10-30 Days (high)

F/M Ratio = 0.05-0.15 (low)

MLSS = 3,000-6,000

Volatile % (MLVSS) = 60-70%

MCRT = high or increasing

RR = less than 12 mg/hr/gm

OUR = less than 0.2 ppm/min

SSV(5 min) = less than 500

SSC(end point) = 1 hour or less

Front 53

F/M Ratio

Back 53

considered to be the diet of microorganisms: how many pounds of food are available for each pound of MLVSS. If too many microorganisms for amount of food, then microorganisms underfed. If not enough microorganisms for the amount of food then microorganisms overfed, would cause high BOD concentration in final effluent.

Front 54

Needed to calculate F/M Ratio

Back 54

1. Plant Flow rate in mgd

2. Volume of aeration system in mg

3. Influent BOD5 concentration in ppm

4.Aeration MLVSS in ppm

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F/M Ratio Formula

(F/M = BOD/VSS)

Back 55

F= Influent Flow (MGD) X Influent BOD Concentration (mg/l) X 8.34

M= Aeration System Volume (in Millions of Gallons) X MLVSS X 8.34

F/M = Flow(Influent BOD con) x (8.34) / Volume(Aeration MLVSS) x (8.34)

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Low F/M Ratio

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1. High oxygen consumption for aeration

2. Very rapid settleability with poor capture

3. Poor microbial web structure

4. Pin floc/ash in the clarifier effluent

5. Sludge pop-ups in the clarifier effluent

6. Denitrification in the clarifier

overall sludge production is much less and overall sludge wasting requirements are low

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High F/M Ratio

Back 57

1. Large microbial web (floc) structure

2. Very slow settleability with good capture

3. Hydraulic washout of high clarifier sludge blanket

4. Straggler floc in clarifier effluent.

5. Decreased RAS and WAS concentrations

6. Increased sludge production and wasting requirements

Blower energy is less due to improved oxygen utilization. The oxygen is utilized more by the microorganisms to breakdown the influent BOD (food) and is not tied-up or combined with other reactions.

Front 58

Gould Sludge Age (GSA)

Back 58

A measurement in days of the aeration system solids detention time. Compares the pounds of solids in the aeration tank, to the pounds of solids entering the aeration tank.Differes from the MCRT or SRT, which compare the pounds of solids in the aeration system to the total pounds of solids leaving the secondary system.

Front 59

Mean Cell Residence Time (MCRT)

Back 59

The average time in days a pound of volatile microorganism resides in the activated sludge process, including new cellular growth. MCRT can be interpreted as: Mean = Average, Cell = Bug, Resistance = living, and Time = average bug living time.

(Young Sludge): less than 5 days

(Old Sludge): greater than 12 days

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Solids Retention Time (SRT)

Back 60

The average residence time of suspended solids in a biological treatment system, equal to the total weight of suspened solids in the system divided by the total weight of suspended solids leaving the system per unit time.

Front 61

Sludge Volume Index (SVI)

Back 61

The SVI is a numerical indicator of the settling characteristics of activated sludge. It is the ratio of the volume (in milliliters per liter ml/L of settled sludge, from a settleometer in 30 mins, to the concentration of mixed liquor (milligrams per liter mg/L), multiplied by 1,000. In simpler terms, a volume to weight ratio of activated sludge.Used as a process indicator when compared against itself on a day-to-day basis.

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Subnatant

Back 62

Liquid that is removed from a tank between an upper blanket of sludge.

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Supernatant

Back 63

Liquid that is removed from a tank between an upper layer of scum and a lower blanket of sludge.

Front 64

Total Solids (TS)

Back 64

The sum of the constituents in a wastewater sample, usually stated in milligrams per liter. The solids content of a sample including both dissolved and settleable solids. The analysis is performed by evaporating a 100 ml sample (in an evaporation dish) in a dying oven at 103°C, and then comparing the weight reading of the empty dish and the dried dish.

Front 65

Total Suspended Solids (TSS)

Back 65

Solids in a wastewater solution which will not total settle by gravity. Solids that will be caught on a filter (collodial and setteable solids). Approx. 50% of the suspended solids will settle out in a primary clarifier after about one hour detention time.

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Turbidity

Back 66

A cloudiness of a liquid due to finely divided material in suspension which may not be of sufficient size to be seen sd individual particles by the naked eye, but which scatters the light in passage through the liquid.Can be measured in Jackson Turbidity Units (JTU), or NTU.

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Weir Overflow Rate

Back 67

A hydraulic loading criteria for the design of a clarifier. Defined as the gallons per day of flow through the tank divided by the total linear footage of weir length.

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Volatile Solids

Back 68

Roughly defined as combustible solids. The quanity of solids in a wastewater sample lost upon ignition of the dry solids in a muffle furnace at 500°C for about 20 to 30 mins. The VS fraction is representative of the active microorganism population. In activated sludge system, the concentration is considered to be about 75%-80% of the total solids value (which may change depending on the age of the microorganism)

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Sludge Settling Rate (SSR)

Back 69

A parameter commonly used to measure the hydraulic loading rate of a clarifier, expressed as gallons per day per square foot of surface area. (gpd/sq.ft)

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Return Activated Sludge (RAS)

Back 70

That portion of settles solids from a secondary clarifier that is returned to an aeration tank, and mixed with incoming wastewater. An optimum RAS ratio should supply an adequate quantity of microorganisms to the aeration tank in order to stabilize the incoming BOD.

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Plug Flow Activated Sludge

Back 71

A flow pattern where the contents of the aeration thank flow along the length of the tank. Mixed liquor enters the beginning of the tank and exits at the end of the tank.

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Pin Floc (OLD)

Back 72

Very fine floc particles that do not precipitated during the settling process. An activated sludge process operating in an old sludge state may have pin floc overflowing the weirs of the final clarifiers.May be the result of dead microbial mass due to biological deflocculation.

Front 73

Oxygen, Saturation

Back 73

Oxygen saturation changes as the temperature of the liquid changes. Colder waters can maintain a higher dissolved oxygen saturation level opposed to warmer waters.

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Nitrosamonas

Back 74

A type of bacteria associated with the nitrification process. This type of bacteria converts ammonia to nitrite through oxidation.

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Nitrobacteria

Back 75

A type of bacteria associated with the nitrification process. This type of bacteria converts nitrite to nitrate through oxidation.

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Nitrite

Back 76

An intermediate oxidation state between ammonia nitrogen and nitrite nitrogen. Nitrite concentration can be used to monitor how well nitrification is progressing in a treatment process. High nitrite concentration indicate incomplete nitrification, and could lead to problems such as high chlorine and oxygen demands. Too high of a nitrite concentration in an activated sludge system can also lead to a low pH condition in the aeration tank.

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Nitrification

Back 77

Biochemical conversion of unoxidized ammonia and organic nitrogen to oxidized nitrogen (nitrite and nitrate). First stage BOD is when carbonaceaous compounds are oxidized to carbon dioxide. Second stage is reffered to as nitrification stage: ammonia to nitrite and then nitrate.

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Mixed Liquor

Back 78

A mixture of return activated sludge and wastewater (primary effluent or raw wastewater). Oxygen is added to the mixed liquor to support the life processes of the microorganisms.

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Microorganisms

Back 79

The combination of various types of bacteria and indicator organisms which require a microscope to be seen. Bacterial microorganisms are responsible for the stabilization of organic matter in wastewater

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Log growth phase

Back 80

The period of time when the mass of microorganisms is doubling at regular intervals. A growth phase in which new cell production is maximum (high rate loading)

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Diurnal

Back 81

Having a daily cycle; recurring every day. A diurnal flow patter through a wastewater treatment plant would be determined by evaluating the plant's flow charts over various 24 hour periods.

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Digestion

Back 82

The biological decomposition of organic matter in sludge, resulting in partial gasification, liquefaction and mineralization. Digestion can be accomplished aerobically or anaerobically, largely depending on the volume and type of sludge to be digested. The proper operation of a digestion is a function of time, temperature, sludge feed and withdrawal characteristics.

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Diffuser

Back 83

A porous plate, tube, or other device through which air is forced and divided into bubbles for a diffusion in liquids. There are various types of diffusers available which can produce bubbles of various sizes (ranging form vary fine to very coarse) depending on the application. In the operation of an aerated grit chamber, the diffusers (with the addition of air) allow the organic solids to remain in suspension, while the heavier inorganic solids to remain in suspension, while the heavier inorganic solids settle below the diffusers. However, in the operation of an aeration tank, the diffusers prevent any settling of mixed liquor.

Front 84

Density

Back 84

The weight per unit volume of a substance. The density of water (at 4° C) is 1.0 gram per cubic centimeter, or about 62.4 pounds per cubic foot.

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Detention Time (DT)

Back 85

The theoretically required duration period for a known volume of flow to be detained in a tank. Detention time is gennerally calculated in units of minutes of hours.

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Denitrification

Back 86

The removal of conversion of nitrogen compounds through biological action. Denitrification is the conversion of nitrate to free nitrogen gas by nitrified bacteria (usually due to depletion of oxygen). In an activated sludge process, denitrification can be detected by the presence of many fine bubbles on the surface of the final clarifier.

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Conventional Loading

Back 87

Refers to the process loading of 0.2 to 0.5 lbs/day BOD applied/lb MLVSS. Microorganism growth curve is usually in the declining growth phase.

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Conventional Activated Sludge Process

Back 88

An activated sludge process utilizing a plug-flow, complete mix, or step feed configuration through the aeration tank. Primary effluent (or raw wastewater) and return activated sludge are introduced at the beginning of the aeration tank depending on the flow pattern.

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Coliform

Back 89

A group of non-pathogenic organisms that are considered to be indicators of the presence of pathogenic bacteria. Coliform bacteria primarily inhabit the intestinal tract of human beings and other warm-blooded animals. Coliform group bacteria are destroyed by the application of chlorine. Wastewater treatment effluents must comply with a specific coliform count.

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Chemical Oxygen Demand (COD)

Back 90

A measure of the oxygen-consuming capacity of the inorganic matter present in wastewater. It is expressed as an indicator of the amount of oxygen consumed from chemical oxidation in a specified test.

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BUGS

Back 91

A slang term for the active and volatile microorganisms in the activated sludge process.

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Assimilation (Eat)

Back 92

The process by which food is converted to cell protoplasm. Assimilation is commonly referred to when discussing the biological activity of microorganisms. As an example, BOD (food) is assimilated by the microorganisms (bugs) in an activated sludge process.

Front 93

MCRT

days (Mean Cell Residence Time)

Back 93

Pounds MLVSS Under Aeration / WAS, lbs/day VSS + Final Effluent, lbs/day VSS

Front 94

SRT

days (Solids Retention Time)

Back 94

Pounds MLSS Under Aeration / WAS, lbs/day TSS + Final Effluent, lbs/day TSS

Front 95

GSA

days (Gould Sludge Age)

Back 95

Pounds MLSS Under Aeration / Aeration Influent, lbs/day TSS

Front 96

Dissolved Oxygen (DO)

1-3 ppm or mg/L

Back 96

measurement of free oxygen present in the waste water or mixed liquor expressed in milligrams per liter (mg/L). Most important process control parameters in keeping a healthy aerobic biological environment.

Front 97

D.O.

defined

Back 97

Oxygen, either atmospheric or pure, dissolved in the water or waste water. DO is the residual concentration of oxygen available for the BUGS after the oxygen demand has been satisfied. An aeration tank must maintain a sufficient DO level to support biological life activities, and provide an adequate buffer for additional oxygen-consuming loading.

Front 98

D.O. formula

Back 98

Oxygen Supply - Oxygen Demand = Dissolved Oxygen (Oxygen Residual) = 0 left over

Actual Formula:

Initial D.O. - Final D.O. / Test Time, min X 60 min/hr

Front 99

D.O. formula

example

Back 99

Data:

8.5 ppm Initial D.O.

2.0 ppm Final D.O.

7 Minutes OUR Test Time

What is the OUR in mg/L/hr?

8.5 ppm - 2.0 ppm / 7 minutes X 60 min/hr

= 55.7 mg/L/hr

OUR at the inlet end should be about 50 to 100 mg/L/hr, OUR at the outlet end should be about 20 to 30 mg/L/hr.

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D.O.

Facts

Back 100

Higher DO, higher driving force, means bugs work more because more oxygen is available for assimilation (eat). Lower DO, lower driving force, same bugs will work less with same amount of food.

D.O. should stay between 1-3 ppm, if too low then not enough residual oxygen to accommodate a sudden increase in biological loading rate; too high then wasted energy in the form of unnecessary aeration horsepower.

Front 101

D.O

Reading

Back 101

taken with D.O. meter and Probe.

Probe's gold cathode must be cleaned periodically to remove foreign materials. Gently rub the gold cathode with a pencil eraser.

Front 102

Oxygen Uptake Rate (OUR)

Back 102

is a quantitative measure of the weight of oxygen consumed per unit of time. The OUR is expressed as milligrams per liter per hour (mg/L/hr), and the OUR test is a direct indication of how active the microorganism are in the activated sludge process.

Front 103

OUR formula

(mg O2/l/hr)

Back 103

(DO) 0 min - (DO) 10 min / 10 min reading X 60 min/hr

High OUR, high activity level or high live organism

Low OUR, low activity level or low live organism level

Trend from a day to day extremely important

Front 104

(OUR)

explained

(inlet end)

Back 104

The demand for oxygen is highest at the inlet end of the aeration tank, the OUR reading and microorganism activity rate should be the highest here. Oxygen demand should decrease toward the outlet end of the tank, which would reduce the activity rate of microorganisms and result in lower OUR reading.

If OUR higher than 100 mg/L/hr at inlet end indicates large amount of food, low DO environment can cause filamentous over-growth. If OUR at the inlet of the aeration tank is lower than 50 mg/L/hr, indicates low food available, and/or inactive microorganisms. This condition may exist with an old sludge enviornment.

High OUR levels at the end of the outlet of the aeration tank indicates too much BOD (food). In order to produce a high OUR, the microorganisms must be subjected to a good supply of oxygen along with good supply of available food.

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(OUR)

explained

(outlet end)

Back 105

If OUR at the outlet end of the aeration tank is higher than 30 mg/L/hr, indicates:

1. Too much food is still available

2. Bugs are still active

3. High F/M Ratio

4. Low MCRT/SRT- bugs very young

5. RAS rates maybe too high

6 WAS rates maybe too high

7. Aeration detention time too short

Front 106

MLVSS formula grams/L

Back 106

MLVSS in mg/L /1000

Front 107

RR formula

(RR, mg/hr/gm)

Back 107

OUR, mg/L/hr / MLVSS, gm/L

Front 108

RR formula

example

Back 108

Data:

55.7 mg/L/hr OUR

3,000 mg/L divided by 1,000 = 3 gm/L MLVSS

What is the RR in mg/L/hr?

55.7 mg/L/hr / 3 gm/L = 18.6 mg/hr/gm

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RR formula 2

(RR, mg/hr/gm)

Back 109

(DO at 0 min - DO at x min) (1000) (60) / (MLSS, mg/l) (x min)

example

DO at 0 min = 8 mg/l

DO at 6 min = 2 mg/l

MLSS = 2000 mg/l

RR = (8-2) (1000) (60) / (2000) (6) = 30 mg/hr/gm

Typical Ranges:

5-15 low food (BOD) concentration, low activity, low F/M

30-50 high food (BOD) concentration, high activity, high F/M

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SSC Formula

Back 110

1000 ATC / SSV

Aeration Tank Mixed Liquor Concentration (ATC)

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Normal Settling Sludge

Back 111

A normal settling good quality activated sludge will concentrate to an SSC range from about 12 to 18 percent in 1 hour and will reach ultimate compaction( wont settle anymore) somewhere between 1 and 2 hours

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Rapid Settling Sludge

Back 112

A rapid settling sludge, concentrating to an SSC of more than 20 percent in 1 hour and reaching endpoint concentration in less than an hour is usually an old over oxidized sludge.

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Slow Settling Sludge

Back 113

An extremely slow settling sludge, concentrating to an SSC of less than 10 percent is usually a young sludge. Such a sludge may not settle at all during the first 5 or 10 min and may only reach between 700 and 900 cc/l during the first hour of the settleometer test. Settling and compaction continues, though at a slow rate, for 3 to 4 hours or longer.

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SVI Formula

Back 114

30 min settleometer reading, ml / MLSS, mg/l X 1000

Typical Range: 50-150

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SVI

(settling)

Back 115

Low SVI: normally good settling , poor capture (<50) (old)

High SVI: Normally good capture, poor settling (>150) (young)

Front 116

Sludge Age (SA) Formula

days

Back 116

VAT, mg X MLSS mg/l X 8.34 lbs/ gal /

Q mgd X primary effluent SS, mg/l X 8.34 lbs/gal

Ranges: 2.5 - 6.0 days

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Total Solids (TS)

mg/L

Back 117

weight of TS in sample (g) X 1,000 / volume of sample (L)

Front 118

What is Hydraulics?

Back 118

the study of the behavior of fluids.

Uses the following basic units of volume, area, and velocity.

1.length is in feet (ft)

2.Area is in square feet (sq ft)

3.Flow rate is in volume per unit time, such as

a.gallons per minute (gpm)

b.million gallons per day (mgd), or

c.Cubic feet per second (cfs)

4.Speed or velocity

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Basic Facts About Water

Back 119

1. one gallon of water weighs 8.34 pounds

2. one cubic foot of water weighs 62.4 pounds

3. one cubic foot of water is = 7.48 gallons of water

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Sludge Wasting Rates, affect the following

Back 120

1.Stability of the Activated Sludge

2.Growth Rate of the Bugs

3.Mixed liquor settleability

4.Occurrence of Foaming/Frothing

5.Possibility of Nitrification

6.Nutrient Quantities Needed

7.Quality of Final Effluent

Front 121

Formula for BOD entering/leaving the Plant

Back 121

(BOD, mg/l) (Flow, mgd) (8.34) =lbs BOD/day

Front 122

Producing Good Quality Effluent with proper settling characteristics

Back 122

1.Dissolved Oxygen available to the bacteria

2.Sludge Mass, the number of bacteria in the system

3.Returns, the flow rate of sludge from the secondary clarifier back to the aeration basin

Front 123

SRT Formula

Back 123

lbs of Solids in Aeration Basin/ lbs/day of Solids lost in Wasted Sludge

(MLSS, mg/l) (Volume, MG) (8.34)/ Waste TSS, mg/l) (Flow, MGD) (8.34)

Front 124

Operational Item

Hydraulic Retention Time

Back 124

20 to 30 days

Front 125

Operational Item

Volatile Solids Loading

Back 125

0.1 to 0.2 lbs VS/day/cu.ft.

Front 126

Operational Item

Gas Production Rate

Back 126

11 to 20 cu.ft./lb VS reduction (depending on temperature)

Front 127

Operational Item

Volatile Acid to Alkalinity Ratio

Back 127

0.1 to 0.25

Front 128

Operational Item

Digester Temperature

Back 128

about 95°F (+/- 1°F per day)

Front 129

Operational Item

pH

Back 129

6.8 to 7.2

Front 130

Operational Item

Volatile Solids Reduction

Back 130

40% to 60%

Front 131

Operational Item

Digested Sludge

Back 131

Odorless

Black

Readily Dewaterable

Front 132

Operational Item

Supernatant

Back 132

50 to 500 ppm TSS

500 to 1000 ppm BOD

200 to 300 ppm NH3

Front 133

Reduction of Volatile Solids %(must be 38% volatile reduction or higher)

Back 133

in - out x 100 / in - (in x out)

cheat (if in - out >= 38%)