Monroe L. Weber-Shirk

School of Civil and

Environmental Engineering

NRP 3: Let’s get startedNRP 3: Let’s get started

AgendaAgenda

Project expectations Startup Checklist Organic Feed Lines Suspended solids targets, measurements SOP Research Ideas

Project expectations Startup Checklist Organic Feed Lines Suspended solids targets, measurements SOP Research Ideas

Project ExpectationsProject Expectations

6 weeks of plant operation For 3 weeks NRP is your only task 4 hours per week outside of class Data collection and data analysis used for plant

control (evidence of good engineering) Maintain good records of what you did and what

you learned Collaboration between teams is encouraged What is success?

6 weeks of plant operation For 3 weeks NRP is your only task 4 hours per week outside of class Data collection and data analysis used for plant

control (evidence of good engineering) Maintain good records of what you did and what

you learned Collaboration between teams is encouraged What is success?

Cite source!

Startup ChecklistStartup Checklist

Verify that all sensors are working Replace DO membrane Calibrate dissolved oxygen probe in saturated water Fill reactor with mixed liquor from IWWTP activated sludge

tank Fill organic waste bottle with organic waste Make sure that airflow calibration is complete before you

leave! Measure MLVSS (mixed liquor volatile suspended solids) Begin in settle phase (make sure time is long enough)

Verify that all sensors are working Replace DO membrane Calibrate dissolved oxygen probe in saturated water Fill reactor with mixed liquor from IWWTP activated sludge

tank Fill organic waste bottle with organic waste Make sure that airflow calibration is complete before you

leave! Measure MLVSS (mixed liquor volatile suspended solids) Begin in settle phase (make sure time is long enough)

Organic Feed LinesOrganic Feed Lines

What will happen if the organic feed line holds a high concentration of organics at room temperature for several weeks?

Why might this be a problem? _______________________

How can you solve this problem? _____________________________

What will happen if the organic feed line holds a high concentration of organics at room temperature for several weeks?

Why might this be a problem? _______________________

How can you solve this problem? _____________________________

Clog the screen in the valves

Purge organic feed line with tap water

Suspended Solids Targets and Measurements

Suspended Solids Targets and Measurements

Biggest problem last year was keeping adequate MLVSS in the reactor

Solids retention time is approximately 10 days

Target MLVSS of approximately 3 g/L If reactor volume is 4 L then waste ___

g/day Effluent concentration of solids needs to be

very low

Biggest problem last year was keeping adequate MLVSS in the reactor

Solids retention time is approximately 10 days

Target MLVSS of approximately 3 g/L If reactor volume is 4 L then waste ___

g/day Effluent concentration of solids needs to be

very low

1.2

Standard Operating Procedure (SOP)

Standard Operating Procedure (SOP)

How frequently do you check your plant? What do you need to check and/or record?

Organic waste volume MLVSS (by turbidity or by drying and ashing) BOD of effluent? Phosphorus concentrations?

How often must you add organic waste in the refrigerator?

Scrape sides of reactor to keep solids in suspension Verify that fill and drain times are reasonable (no

clogged valves)

How frequently do you check your plant? What do you need to check and/or record?

Organic waste volume MLVSS (by turbidity or by drying and ashing) BOD of effluent? Phosphorus concentrations?

How often must you add organic waste in the refrigerator?

Scrape sides of reactor to keep solids in suspension Verify that fill and drain times are reasonable (no

clogged valves)

Research Ideas (due next Wednesday in lab)

Research Ideas (due next Wednesday in lab)

Automate air flow calibration+

Automate the measurement of the oxygen uptake rate

Develop a better algorithm to control the DO+

Optimize biological phosphorus removal+

Automate measurement and wasting of MLVSS+

Measure BOD of reactor contents (or effluent) as function of time (use to optimize aeration time)

Automate air flow calibration+

Automate the measurement of the oxygen uptake rate

Develop a better algorithm to control the DO+

Optimize biological phosphorus removal+

Automate measurement and wasting of MLVSS+

Measure BOD of reactor contents (or effluent) as function of time (use to optimize aeration time)

+ more on these topics coming up

Automate Airflow CalibrationAutomate Airflow Calibration

Identify what can cause the calibration to fail Change the code so the calibration always works Test the code under varied flow rates, valve

settings, and pressure ranges Eliminate the dialog box Save calibration equation to a file and retrieve it

when software begins running

Identify what can cause the calibration to fail Change the code so the calibration always works Test the code under varied flow rates, valve

settings, and pressure ranges Eliminate the dialog box Save calibration equation to a file and retrieve it

when software begins running

Develop a Better Algorithm to Control the DO

Develop a Better Algorithm to Control the DO

Compare different algorithms (perhaps two teams) Simulation Model Based Control PID

Log the relevant parameters to file (you will want this data for your final report)

Document problems getting either method to work

Compare different algorithms (perhaps two teams) Simulation Model Based Control PID

Log the relevant parameters to file (you will want this data for your final report)

Document problems getting either method to work

Empirical Aeration Model (based on aeration data)

Empirical Aeration Model (based on aeration data)

0

0.005

0.01

0.015

0.02

100 1000 10000

air flow rate (mol/s)

Kvl

(1/

s)

0

0.005

0.01

0.015

0 1000 2000 3000 4000 5000

air flow rate (mol/s)

Kvl

(1/

s)

, , ,min maxˆ ˆ ˆ air iv l v l v l

air halfi

nk k k

n n= +

+

( ), ,min

, , ,min max

ˆ ˆ

ˆ ˆ ˆv l v l half

airv l v l v l

k k nn

k k k

-=

- -

1, max

1, min

13511 /

ˆ 0.0426

ˆ 0.00099

half

v l

v l

n mol s

k s

k s

m-

-

=

=

=

Simulation Model Based ControlSimulation Model Based Control

( )( )

( )

i+1, 1

1

ˆiconsumption

v l ii

Dk

tk

D++

Dæ ö-è øD

=

( )

( ) ( )1

i

i iD DDt t

--Dæ ö =è øD D

( )( ) ( )

, ,1i 11

1ˆ ˆ+ v l v l ii iii

D Dk k D

D t t+++

é ùD Dæ ö æ ö= -ê úè ø è øD Dë û

,i

ˆ+ iconsumption v l ii

Dk k D

tDæ ö=è øD

change in storageconsumption input

Assume consumption is the same in next time step

( )

( )1

i+1

iiD DDt t

+ -Dæ ö =è øD D

= +

New transfer coefficient based on current and previous values

Eliminate Derivates(Alternative is Linear Regression)

Eliminate Derivates(Alternative is Linear Regression)

( )

( ) ( ) ( )1 1

i 1

2 i i i

i

D D DD Dt t t

- +

+

- -D Dæ ö æ ö- =è ø è øD D D

( )

( ) ( )1

i

i iD DDt t

--Dæ ö =è øD D

( )

( )1

i+1

iiD DDt t

+ -Dæ ö =è øD D

( )( )

( ) ( ) ( )1 1, ,1

1

21ˆ ˆ+ i i iv l v l ii i

i

D D Dk k D

D t- +

++

- -é ù= ê úDë û

( ), ,min

, , ,min max

ˆ ˆ

ˆ ˆ ˆv l v l half

airv l v l v l

k k nn

k k k

-=

- -

Calculate the new airflow given

the new transfer coefficient

( )( ) ( )

, ,1i 11

1ˆ ˆ+ v l v l ii iii

D Dk k D

D t t+++

é ùD Dæ ö æ ö= -ê úè ø è øD Dë û

Oxygen Transfer Coefficient Range

Oxygen Transfer Coefficient Range

Oxygen transfer coefficient should always be greater than the minimum transfer coefficient.

If the target transfer coefficient is less than the minimum then set air flow rate to _____

It may also be wise to code a maximum air flow rate (___________________________________)

Oxygen transfer coefficient should always be greater than the minimum transfer coefficient.

If the target transfer coefficient is less than the minimum then set air flow rate to _____

It may also be wise to code a maximum air flow rate (___________________________________)

2

17272.105* T

OC P eæ ö-ç ÷è ø=

zero

Based on the air flow calibration range

( )( )

( ) ( ) ( )1 1, ,1

1

21ˆ ˆ+ i i iv l v l ii i

i

D D Dk k D

D t- +

++

- -é ù= ê úDë û

Figure out how to initialize parameters

0

0.005

0.01

0.015

0.02

100 1000 10000

air flow rate (mol/s)

Kvl

(1/

s)

How might you choose t?How might you choose t?

How fast do significant DO changes happen? milliseconds, seconds, minutes, hours, days

How could you get a parameter with units of time? ___________

What would happen if you used a time interval based on the data acquisition rate? ________________________________

What other response time is important? __________________

How fast do significant DO changes happen? milliseconds, seconds, minutes, hours, days

How could you get a parameter with units of time? ___________

What would happen if you used a time interval based on the data acquisition rate? ________________________________

What other response time is important? __________________

Inverse of kv,l

Noisy data rapidly changing air flow rate

Air accumulator cycle time

Code SuggestionsCode Suggestions

Place the code inside the Set Airflow.VI Design the code so although it is called as

frequently as the Plant Control SubVI that it only calculates a new airflow rate at a time interval that you set (____)

The code will need to remember previous oxygen transfer coefficients and previous oxygen deficits (____________)

Oxygen deficits might be based on an average measurement over a time period that is small relative to t.

Place the code inside the Set Airflow.VI Design the code so although it is called as

frequently as the Plant Control SubVI that it only calculates a new airflow rate at a time interval that you set (____)

The code will need to remember previous oxygen transfer coefficients and previous oxygen deficits (____________)

Oxygen deficits might be based on an average measurement over a time period that is small relative to t.

Shift Registers

t

Improve the Simulation Model Based Control

Improve the Simulation Model Based Control

Measure oxygen transfer coefficient with your wastewater

Plot (and log to file) the transfer coefficient and the deficit

Note that is the rate of oxygen transfer (per liter) into the reactor

Integrate starting from the addition of waste to determine the total amount of BOD consumed

Measure oxygen transfer coefficient with your wastewater

Plot (and log to file) the transfer coefficient and the deficit

Note that is the rate of oxygen transfer (per liter) into the reactor

Integrate starting from the addition of waste to determine the total amount of BOD consumed

,v̂ lDk

,v̂ lDk

Proportional Integral Derivative Control

Proportional Integral Derivative Control

( ) 1c D

I

u t K t TT t

ee eæ öD

= + ×D +ç ÷è øDåKc is controller gain (tuning parameter)

TI is the integral time (tuning parameter)

TD is the derivative time (tuning parameter)

/t is the error rate of change (Note that this is the same as the dissolved oxygen concentration rate of change) is the area under the curve of the error as a function of time.u(t) is the airflow rate that the controller sets

te×Då

The Error () is the difference between the Process Variable and the

desired Setpoint. The controller uses the proportional gain, Kc, the

integral time constant, Ti, and the derivative time constant, Td, to

determine an Output which drives the Error to zero.

P I D

Optimize Biological Phosphorus Removal

Optimize Biological Phosphorus Removal

1 hour of anaerobic operation after the addition of organic waste Stored energy (Poly P) is used to sequester

organic carbon Cellular phosphorus is released in this phase

Main reactor (aerated) Inorganic phosphorus is sequestered in a

phosphorus rich energy storage (Poly P)

1 hour of anaerobic operation after the addition of organic waste Stored energy (Poly P) is used to sequester

organic carbon Cellular phosphorus is released in this phase

Main reactor (aerated) Inorganic phosphorus is sequestered in a

phosphorus rich energy storage (Poly P)

Automate Measurement and Wasting of MLVSS

Automate Measurement and Wasting of MLVSS

Use the Honeywell turbidity sensors to measure the turbidity of the mixed liquor

Develop a calibration between sensor voltage and MLVSS

Investigate the possibility of mounting the sensor in the side of the tank (at what elevation and orientation for dual purpose?)

Or use a pump to circulate mixed liquor through the turbidity sensor

Use the Honeywell turbidity sensors to measure the turbidity of the mixed liquor

Develop a calibration between sensor voltage and MLVSS

Investigate the possibility of mounting the sensor in the side of the tank (at what elevation and orientation for dual purpose?)

Or use a pump to circulate mixed liquor through the turbidity sensor

[ ] [ ]//

mg LTSS mg L C Turbidity NTU

NTUé ù= ×ê úë û

Where C is approximately 2.3 (mg/L)/NTU

Class ActivityClass Activity

Go to the boards in your double teams Split board in half Write your research project titles List what is required to make the project

successful List the most likely reasons for failure

Go to the boards in your double teams Split board in half Write your research project titles List what is required to make the project

successful List the most likely reasons for failure