OPTIMISATION OF ASSETS BY ULTRASOUND TO ACHIEVE LOWEST OPERATIONAL COSTS 6 th European Waste Water...

OPTIMISATION OF ASSETS BY ULTRASOUND TO ACHIEVE LOWEST

OPERATIONAL COSTS

6th European Waste Water Management Conference & Exhibition

9 - 10th October 2012, Manchester


INDEX

1. Ultrasound engineering

2. Anaerobic digestion application

3. Bulking and foaming application

4. Excess sludge reduction application

5. Nitrogen removal application

Optimisation of assets by ultrasound to achieve lowest operational costs


1. ULTRASOUND ENGINEERING

• A wave is a disturbance travelling through a medium

• Sound is a wave where excited magnitude is pressure

• Ultrasound (US) is a sound wave where the frequency is beyond 20 kHz

• With adequate frequencies and intensities strong ultrasonic cavitation is produced


What is ultrasound?


• Cavitation bubbles cannot survive in the medium (water)

• Forceful implosion takes place and high energy is delivered



Ultrasonic cavitation




Effect on the sludge


• 5 oscillators (1 kW each)

• Reactor volume 30 l

• Frequency 20 kHz

• Intensity 25 to 50 W/cm2

• Sonication dose 1 to 9 kWh/m3

• Sizes 1.5 x 1.1 x 0.35 m



The reactor

Neue Sonotrode

Sonotrode nach dem Dauereinsatz


New sonotrode

Sonotrode after 1.5 to 2 years



Transferring energy to the sludge


• Preconditioning sludge

• Easily adapted to existing facilities

• Fixed, skid or mobile availability

• Local & remote control

• GiMACS

• Predictive analysis (Mass balance)

• Start up & commissioning

• Consulting service & support



Engineering package & consulting service




Applications in WWTPs


2. ANAEROBIC DIGESTION APPLICATION


Process • Sludge to be treated is between 30

and 50% of the Thickened Waste Activated Sludge (TWAS)

• US dose ≈ 4 kWh/m3 to reach cell breakdown

• CODs and enzymes are released

• Hydrolysis step is highly intensified

• The organic fraction is further degraded


• Increase in Volatile Solids degradation: 20 - 30%

• Increase in biogas production: 20 - 30%

• Digested sludge reduction: 15 - 25%

• Increase in dewatering 10 - 20%

• Complete elimination of the problems associated with bulking and foaming inside the digester



Results

It is only necessary a 5 kW US unit for each 200 m3/d of mixed sludge




Case study: Bamberg WWTP

• VSdeg increased from 34 to 50%

• Biogas enhanced 45%

• New digester construction avoided


• Sludge treated is approx. 1% of the Returned Activated Sludge (RAS)

• Low US dose is applied (≈ 1 kWh/m3)

• Only filamentous microorganisms are affected (ΔCOD ≈ 0)

3. BULKING & FOAMING APPLICATION


Process

Not treated Sonicated


• A selective sonication to remove only filamentous microorganisms for the activated sludge system takes place

• Associated problems with Bulking & Foaming complete disappear

• Up to 65% in SVI reduction

• Chemical solutions are not necessary

• WWTP processes have not to be modified (sludge age, etc.)



Process




Case study: Seevetal WWTP

Conventional activated sludge tank

Activated sludge tank after sonication


• TWAS is disintegrated with an US dose ≈ 4 kWh/m3

• CODb is produced which is recycled back to the biological reactor

• Cell lysis and cryptic growth process takes place meaning a significant excess sludge reduction

• New flocs are formed when cell content is released into the medium

4. EXCESS SLUDGE REDUCTION APPLICATION


Process


• Depending of the biological reactor characterization a reduction around 30% in excess sludge production is reached

• After the sonication a new floc-matrix is formed due to a new re-aggregation which results in a more suitable structure to be dewatered. 2 points more in dewatering is achieved

• With high US dose filamentous microorganisms are killed meaning an elimination of Bulking & Foaming problems



Results

One 5 kW US unit can remove 500 to 750 kg/d of WAS produced


• Excess sludge production reduced in nearly 30%

• Dewatering increased 2 points

• No Bulking & Foaming in the biological reactor



Case study: Leinetal WWTP

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• TWAS is disintegrated at ≥ 4 kWh/m3

• CODb is produced which is recycled back to the anoxic zone

• A new autochthonous carbon source readily biodegradable for denitrification is available

• Hydrolysis rate of the WAS endogen particulate COD is enhanced meaning lower HRT and lower volume

5. NITROGEN REMOVAL APPLICATION


Process


• Total inorganic nitrogen in the final effluent can be reduced up to reach optimum levels

• WWTP is self-sufficient in carbon source for denitrification

• Excess sludge production is reduced around 25 to 30%

• Dewatering of the sludge for disposal in increased in 2 points

• Bulking & Foaming problems are completely eliminated



Results

One 5 kW US unit can remove 60 to 100 kg/d of inorganic nitrogen


• Ninorg reduced up to less than 5 mg/l in the final effluent

• WAS production reduced in 25%

• Sludge dewatering increased 2 points

• No bulking & Foaming problems



Case study: Bünde WWTP

… more details can be found in our paper submitted for this event


Any questions?

Contact:

Luis VergaraTechnical Director

[email protected]


OPTIMISATION OF ASSETS BY ULTRASOUND TO ACHIEVE LOWEST OPERATIONAL COSTS 6 th European Waste Water...

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