energy saving and process optimization with liquiline control

02/13/2017

Products Solutions Services

Energy Saving & Process Optimization with Liquiline Control

Efficiency Up, Costs Down in WWTP with Liquiline Control

Slide 1 Jeff Low

02/13/2017


Content

• Introduction of WWTP process • Biological treatment• Nitrification & De-Nitrification process• Design of modern biological treatment • Energy Consumption of typical WWTP• Control Strategies • Endress+Hauser Instrumentation offering• Application reference

Slide 2 Jeff Low

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Treatment technologies


Wastewater components

Biological processesMechanical/physical processes

Non soluble soluble

deposable floated suspended organic inorganic

Flotation,Filtration

Sedimentation,Filtration

Flocculation,Filtration

anaerobe aerobe Physical/Chemical-physical/ thermal processes

Biological degradable

Non or difficult biological degradable

Common in municipal WWTP Not common in municipal WWTP

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Biological treatment - Pollutants removal

Most modern WWTPs have to reduce • C: organic matter (molecules with organic carbon) • N: Nitrogen compounds (ammonium, nitrate, nitrite) • P: Phosphate


Biological treatment by using

• aeration basins (to reduce organics and

ammonium),

• anoxic basins (to reduce nitrate), and by

• adding flocculants (to reduce phosphate).

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Wastewater pollutants

E+H ConductaSlide 5 / 114

• Gross pollutants, floating material, screenings, …• Sand, wood, plastics, … • Removal by screens, sieves, grit chamber

• Oxygen consuming substances (COD, BOD5)• Causes: Oxygen depletion in rivers, lakes (aerobic to anaerobic)• All degradable organic substances and ammonia• Removal by sedimentation and biological degradation

• Nutrients (N, P)• Causes: Growth of algae (eutrophication), oxygen depletion, toxicity• Nitrogen (ammonia, nitrate), phosphorus• Removal by biological conversion and/or chemical methods

• Pathogens (E.coli, Enterococci, … )• Risk when bathing and eating seafood• Removal by disinfection or membrane filtration

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C - Carbon Removal


Aeration process

C + O2 + Bacteria --> CO2 + Bacteria

• Basin with bacteria (so called activated sludge) “consume” the organic carbon compounds and oxidize them into CO2.

• Large amount of oxygen (O2) is put into the basin by large air blowers.

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N - Nitrogen Removal


Nitrification NH4 + O2 + Bacteria ----> NO2 + O2 ----> NO3

• Most of the Nitrogen comes in as Ammonium (NH4). • First step, bacteria convert (NH4) into Nitrite(NO2) and other

bacteria in the same basin convert Nitrite into Nitrate(NO3).

De-NitrificationNO3 + C + Bacteria ----> N2 gas

• Second step, bacteria convert Nitrate(NO3) into Nitrogen gas (N2). • Nitrogen gas then goes out of the water. • This process does not require oxygen.

Slide 7 Jeff Low

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DE-NITRIFICATION

NITRIFICATION


Oxygen – Ammonia - Nitrate

Organic Carbon + Oxygen Carbon Dioxide + Water + BacteriaCn + O2 CO2 + H2O + new Bacteria

Ammonia + Oxygen Nitrate

NH4 + O2 NO2 NO3

Nitrate + organic Carbon Nitrogen ()

NO3 + Corg N2

“Aerobic conditions”

Aeration ON

Aeration OFF

“Anoxic Conditions”

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Methods of biological wastewater treatment


Activated sludge Trickle filters Immersion trickle filters Bio-Filtration

Working principle

Through extensive mixing and aeration in a tank filled with wastewater, there is an aerobic metabolism of microorganisms. The resulting sludge is fed to a sedimentation tank and, after sedimentation, partially returned to the biological reactor.

Coarse-grained fill material (gravel, lava slag or stone) in containers is irrigated with desilted wastewater. Microorganisms living on the trickle filters perform the biological degradation of organic wastewater constituents. The required aeration is provided by ambient air.

Immersion trickle filters consist of a horizontal axis, about which cylindrical bodies are mounted. The cylinders dip halfway into the wastewater, so that the microorganisms, which are living on them, are alternately brought into contact with air and “food”.

Biofilters are biocatalysts or bioreactors in which harmful substances and odors are removed from exhaust air and wastewater streams by the metabolic activity of microorganisms. The filter material (peat, bark or wood fiber) absorbs degraded pollutants from the feed stream.

Advantages

Comprehensive cleaning ofwastewater substances containing C,N and P.

Low energy consumption Low energy consumption Degradation of nitrogenLow solids content

Disadvantages

High operating costs due to compressor and pump activities

Not suitable for comprehensive nitrogen oxidation

High construction costsOnly small quantities of wastewater cleanable

Cleaning capacity 75 - 80%. A post-stage is needed.

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Activated Sludge Processes


Slide 10 / 114 E+H Conducta

Continuous Activated Sludge (CAS) Sequence Batch Reactor (SBR) Membrane Reactor (MBR)

Principle Principle PrincipleBeside mechanical cleaning, disinfection and sludgemanagement, the main treatment in a continuoussystem takes place in anoxic, aerobic andsettlement zones.

Microorganisms suspended in the activated sludge(activated sludge flocs) react under oxygen inlet anddegradate pollutant substances. Settling isolates sludge and clarified water. Toensure stable biomass values in the system settledsludge is recycled.

The aeration is done by surface aerators or finebubble diffusor hardware and compressors.

The processes of equalization, aeration andclarification are all done in one basin.

SBR systems consist of five common steps: 1) Fill2) React (aeration)3) Settle (sedimentation/clarification)4) Draw (decanted)5) Idle

The SBR acts as an equalization system when fillingthe tank which tolerates peak flows or huge loads.

The aeration is mainly done by fine bubble diffusorsand compressors.

Membrane bioreactors (MBR) combine activatedsludge processing with a membrane liquid-solid seperation process. There is no need of clarificationand tertiary filtration due to membrane micro- orultrafiltration.

The system allows to drive at high sludge valuesbetween 8 – 12g/l. Limitations due to bad settlingcharacteristics of sludge are avoided and thereforehigher loading rates can be driven.

The aeration is done by fine bubble diffusors andcompressors mainly.

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Biological treatment


Slide 11 Jeff Low

Aeration basin and Second clarifier

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What is the energy consumption and How to reduce cost

Jeff LowSlide 12

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Energy: 15%

Maintenance: 14%Non

personneland other

costs: 13%

Sludge disposal and treatment:

31%

Personnel: 27%

Share of total operating costs

Op-Ex in a middle sized German WWTP (50,000-100,000 PE)


50,000 – 100,000 inhabitants; Bode, Grünbaum

Slide 13 Jeff Low

Biological treatment

and secondary

clarification: 67%

Flocculation filtration:

8%

Sludge treatment:

11%

Infrastructure and other: 6%

Sewage lift station: 5%

Primary treatment: 3%

Energy consumption in detail Aeration (blowers) and sludge handling (pumps) are the main energy consumers in WWTP

Biggest Savings potential

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Control Strategies in aeration

• Main target Minimum energy consumption at maximum plant safety

• 1st priority -Process stability and reliable limits of the outlet even in situations with changing inlet loads

• 2nd priority –Optimization of energy consumption


Slide 14 Jeff Low

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Biological treatment – energy consumption

• Aeration require blowers


Slide 15 Jeff Low

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How much Oxygen is really needed?

Below 1 mg/l DO the bacteria activity is decreasing significantly limits and process in danger!


100 100

Oxygen concentration mg/l

Rel.

perf

orm

ance

of

nitr

ified

bac

teria

[%

]

0 1 2 3 4

50

0

50

0

12

To optimize the aeration process, the Oxygen concentration range between 1.2 … 2 mg/l has the ideal cost efficiency ratio!

DO-concentration above 2,5 … 3,0 mg/l don´t result in higher bacteria activity and better results but increase the energy demand waste of energy!

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12

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E+H instrumentation offering

Jeff LowSlide 17

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Measured parameters

• Most modern WWTPs for process control it makes great sense to measure online :

• Dissolved oxygen (DO)• Ammonium (NH4)• Nitrate (NO3)

Sometimes also• Ortho-phosphate (PO4) • Total organic carbon (TOC)• Chemical Oxygen Demand (COD)


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Full instrumentation of a biological process with Deni/Nitri (1)


Slide 19 / 33

Example simultaneous aeration

pH/Temp

Monitored, important parameter for bacterial activity

Susp. Solids

Controlled, indicates bacteria concentration

Oxygen Controlled, guarantee air supply for bacteria

NH4 Monitored, indicates the success of Nitrification

NO3 Monitored, indicates success of Denitrification

(ORP) Especially in SBR and intermitted process to monitor the aeration/non aeration periods Waste activated sludge (WAS)

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Full instrumentation of a biological process with Deni/Nitri (2)


Example simultaneous aeration

Sludge Level

2nd clarifier control (sludge discharge; quality of water discharge outlet!)

Pressure Air pipe

Monitor the blower performance, indicates blockages

Flow Air pipe

Monitor the blower performance, indicates blockages

Flow RAS Hydraulic balance of the system

Pressure RAS

Pump safety

SuspendedSolids & Flow in WAS

Controls the bacteria concentration and sludge age in the basins Waste activated sludge (WAS)

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Aeration control with Ammonia and Oxygen

• Standard control:Oxygen measurement for oxygen concentration control (min… max)

• Enhanced control:The comparison of Ammonia value and Ammonia set-point defines the O2-set point of the Oxygen control.

• In both cases the actuating variable is the O2- feed (blower)


Industry ManagementSlide 21 / 33

Waste activated sludge (WAS)

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Intermitted aeration – ISE two-parameter version creates benefit!


• Outlet quality depends on the duration of Aeration On/Off cycles

• Ammonia detects end of nitrification (NH4-N 0) and influences Oxygen Set-Point

• Nitrate detects end of denitrification (NO3 0)

• Both parameter can be measured at one point

• Backup control strategy is a time controller (if instrumentation fails)


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Control of Waste Activated Sludge


• The sludge concentration in the aeration basin is controlled by the sludge amount which is taken off the biological system (waste activated sludge WAS)

Task• Adjustment of sludge concentration in the

basin (SS) by QWAS

• Adjustment of sludge age by QWAS and SSWAS

• Avoidance of overloading the 2nd clarifier


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Liquiline Control : Applications

E+H ConductaSlide 24 / 114

Aeration controlcontinuously

Aeration controlintermittent

Precipitant dosing controlOrtho-phosphate

The following processes can be optimised by the use of Liquiline Control.


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Liquiline Control

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Intermitent Aeration Control


Slide 26 Jeff Low

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Continuous Aeration Control Energy Saving & Process Optimization with Liquiline Control

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Key Message

By monitoring the concentration of Oxygen(DO), Ammonium(NH4)and Nitrate (NO3), we can control the efficiency of aeration process thus optimize in energy consumption

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Application Reference

Slide 29 Jeff Low

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Results from the process - intermittent


E+H ControlCustomer Control

NH4-NNO3-N

Pressure in PipeValve activity

O2

Total nitrogen values above limit

Safe total nitrogen values

Effluent limit: Total nitrogen 12 mg/l

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Results from the process - continuous


E+H control Inflow NH4-NCustomer control

Customer control: High valve activity -> High energy use

E+H control: Less valve activity -> 20 % energy savings

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Endress+Hauser ConductaSlide 32 / 114

References“I was amazed by how fast and smoothly it went. Within a few hours, the controller was up and running. After just a few weeks, we saw that we were able to operate the system at a very stable level while almost halving aeration times. Obviously, this saves energy.“Michael Szegedi, Operating Manager of Waldhausen Wastewater Treatment Plant

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Case studies from R+E (Middle sized plant)


Christoph HerbSlide 33 / 114

Plant details : • 80 000 PE • 12 Ml/d

R+E projects:• Energy monitoring • Continuous aeration control • Phopshate precipitant dosing (in preparation)

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Results from plant (80 000 PE) – ROI analysis


Energy costs (1 kWh) € 0,12 Sum of power blower 80 kWSavings by optimization: 20 %

Energy consumption before E+H: € 82 000,- / p. a. (average)Energy consumption with E+H: € 66 355,- / p. a. (average)

Annual energy savings: € 15 644,- (20 %)

Energy savings per day: € 45,-

Return on invest: appr. 1 year

Calculation based on real customer data.

Slide 34 Jeff Low

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Customer benefit in a nutshell

• Meet total nitrogen and NH4-N effluent directives

• Optimize your process and increase plant efficiency.

• Save energy, thus operating costs (Op-Ex).

• Have less investments and a fast ROI

• Less actuators use demand less MRO for blower.


Slide 35 Jeff Low

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3-years story together with a customerWWTP Faellanden – Bachwis in Switzerland45,000 PE

2008energy costs of 110,000 - CHF per yearintermitted aeration with time controlnew blower was necessary

2009Investment into Oxygen instrumentation and implementation of an oxygen based control strategy-> yearly energy costs: 79,000 - CHF

2010Investment into ISE sensor for NH4 and NO3 to improve the control strategy-> yearly energy costs: 63,000 - CHF

-39 % energy costs

-25 % energy costs


Slide 36 Jeff Low

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Municipal WWTP Tomaszow Mazowiecki


• Project: 4 intermittent aeration controller + 4 phosphate elimination controller in bio-reactors

• Plant size: 150 000 PE (22,5 Mld)• 2xCDC81, 4xCAS40D, 4xCOS61D, 4xCM44X,

4xCA80PH, 4xCAT820• Process consulting, commissioning &

optimization of instrumentation + control• First installation in Poland regarding

automation solutions in wastewater

Slide 37 Jeff Low

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WWTP Danjang (Jiangsu Province)


• Project: 1 continuous aeration controller with predictive function

• Comfortable visualization and documentation of measuring data

• Plant size: ~ 200 000 PE (30 Mld)

Slide 38 Jeff Low

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WWTP Danjang (Jiangsu Province)


• CDC81, CAS40D, COS61D, CM44X, RSG40 • Process consulting • Commissioning & optimization of new aeration control

system including instrumentation • First installation in China regarding automation solutions in

wastewater

Slide 39 Jeff Low

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Impressions



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Plant layout



Hydaulical loadPE 79 000 Ml/d (m³/d) 12

Biological loadBOD5 load 5000 kg/d N load 620 kg/d P load 134 kg/d

C:N:P ratio 37:4,6:1

PartsMechanical-biological purification includingnitrification, denitrification and phosphoruselimination.

Anaerobic sludge digestion including sludge dewatering.

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Technical information



BasinsPre-clarifier 2 x 567 m³Anoxic zone (Bio-P) 3 x 502 m³

2 biological zones 4932 m³35 % Denitrification 1726 m³ Daily Ø ret. Time 5

Compressor 3 x 2300 m³/hFine bubble diffusors

Post-clarifier 2 x 3250 m³

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Instrumentation



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Thank you very much for your attention

Slide 46 Jeff Low

energy saving and process optimization with liquiline control

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