LOW COST NON THERMAL PLASMA TREATMENT OF DISTILLERY WASTEWATER FOR - - PowerPoint PPT Presentation

• A. DJUKIĆ-VUKOVIĆ1, D. MLADENOVIĆ1, S. LAZOVIĆ2, S. KOCIĆ-TANACKOV3, J.

PEJIN3, L. MOJOVIĆ1

1FACULTY OF TECHNOLOGY AND METALLURGY, UNIVERSITY OF BELGRADE, KARNEGIJEVA 4, 11120 BELGRADE,

SERBIA

2INSTITUTE OF PHYSICS BELGRADE, UNIVERSITY OF BELGRADE, PREGREVICA 118, 11080 ZEMUN, SERBIA 3 FACULTY OF TECHNOLOGY, UNIVERSITY OF NOVI SAD, CARA LAZARA 1, 21000 NOVI SAD, SERBIA

LOW COST NON‐THERMAL PLASMA TREATMENT OF DISTILLERY WASTEWATER FOR LACTIC ACID FERMENTATION

1 L of bioethanol produced 20 L of stillage are remaining!

Distillery wastewater from bioethanol production - stillage

Pollution: ↑ COD ↑ BOD5

► Has to be treated

prior to disposal

Mojović, L., Pejin, D., Rakin, M., Pejin, J., Nikolić, S., & Djukić-Vuković, A. (2012). Renewable and Sustainable Energy Reviews, 16(8), 6040-6047.

Stillage composition

Dry matter (%) 12.79 ± 0.31 Protein (g/L) 63.91 ± 2.81 Reducing sugar (g/L) 11.19 ± 0.83 Free –amino nitrogen (mg/L) 295.6 ± 1.5 Ash (g/L) 31.2 ± 0.1

Stillage microbiota – susceptibility to contamination ...

AIM: Opportunities for application of non-thermal plasma in LA biorefinery processes

STILLAGE CLOSED FERMENTATION

Lactobacillus rhamnosus ATCC 7469

– high

stereoselective L- lactic acid strain

• probiotic strain

LACTIC ACID

Fermentation media

SPENT FERMENTATION MEDIA ANIMAL FEED

WITH PROBIOTIC BIOMASS STERILIZATION

PLA

Stillage – by-product from bioethanol production on different feedstocks

“OPEN” FERMENTATION

NON-THERMAL PLASMA

“OPEN” FERMENTATION

ULTRASOUND

 ↑ Energy  Maillard reaction Non convenient for large volumes

Non-thermal plasma generates:

• reactive species
• UV radiation
• electroporation of cells to lower extent

Non-thermal or cold plasmas: ●lower pressures ●lower temperatures ●less energy intensive

Nitric oxide NO Peroxynitrite ONOO- Dinitrogen trioxide N2O3 Superoxide anion O2

• Hydrogen peroxide H2O2

Hydroxyl radical •OH Secondary generated active species Media subjected to plasma treatment → “etching” surfaces → ↓ pH value of media (H3O+)

• To inactivate undesired microbiota in substrate?

Applications:

In stillage microbiota: Gram (+) bacteria – lactic acid bacteria - desired Gram (-) bacteria – undesired

Materials and methods

High-power ultrasound Ultrasound sonotrode (TT 13 mm , Bandelin, Germany), 20 kHz, 200 W Volume of sample 60 ml

• Plasma needle operating at 25 kHz in ambient

air.

• Argon was used as a feed gas (2 slm flow rate)

in order to reduce the breakdown voltage through Penning ionization.

• The operating power was 2 W.
• The distance between the jet and substrate

was 1 cm.

Non-thermal plasma Non-thermal plasma Non-thermal plasma generated UV

UV + reactive species UV

NON-THERMALPLASMA TREATMENT IN BIOREFINERY PROCESSES

Two model microorganisms treated by non-thermal plasma in sterilized water and stillage: Lactobacillus acidophilus – Gram (+) bacteria – representative of LAB Escherichia coli – Gram (-) bacteria

• 5
• 4
• 3
• 2
• 1
• L. acidophilus
• E. coli

Water

LogN/N0 reduction

• L. acidophilus
• E. coli

Stillage

UV Total inactivation by plasma

• E. coli
• E. coli
• L. acidophilus
• L. acidophilus
• E. coli is more susceptible to plasma

treatment than L. acidophilus ...

ROS, RNS

Results

1 2 20 21 22 23 24 25 4 6 8

logN (CFU/ml) Time (h)

NON-THERMALPLASMA TREATMENT IN BIOREFINERY PROCESSES

Number of viable cells of stillage microbiota in time after different treatments

untreated ultrasound plasma

• 24h after treatment no significant

increase in the number of bacteria

• 3 log unit lower number of viable

cells than in untreated sample Longer storage time for stillage Versatility in utilization – for different revalorization strategies

4 6 8 10

Untreated, LAB Sterile, LAB P 30min, LAB US 10 min, LAB 24

logN (CFU/ml) Time (h)

1

NON-THERMALPLASMA TREATMENT IN BIOREFINERY PROCESSES

Effect of treatments on growth of LA producing microorganisms and LA production

Lactobacillus rhamnosus ATCC 7469 – high L (+) LA strain The growth of microorganisms was not affected by previous plasma treatment.

12 24 36 48 5 10 15 20 25 30 35

Ultrasound Sterilization Plasma L1 Untreated

Lactic acid concentration (g/L) Time (h)

Stereoselectivity? closed LAF - 97.2% of produced LA was L (+) isomer Plasma treated, open LAF - 95.5% L (+) isomer

NON-THERMALPLASMA TREATMENT IN BIOREFINERY PROCESSES

Estimate of required energy for different processes at laboratory level and mass of LA produced

• Highest in LA production
• Lowest in energy consumption

36 kJ 90 kJ 315 kJ Sterilization 20min UT 10min PT 30min

20 40 60 80 100

Relative %

Conclusions

• Non-thermal plasma treatment could decrease the

number of microorganisms in media and improve

• verall performance of LAF on stillage
• Plasma treatment has shown selectivity towards G (-)

bacteria.

• Plasma treatment resulted in the highest LA

productivity (20% higher than with ultrasound treatment) and lowest energy consumption - in “open” fermentation.

• Stereoselectivity of L(+) LA was maintained.

NON-THERMALPLASMA TREATMENT IN BIOREFINERY PROCESSES

CONTACT Aleksandra Djukić-Vuković Faculty of Technology and Metallurgy, University of Belgrade Serbia

adjukic@tmf.bg.ac.rs

ACKNOWLEDGMENT

This work presented here was funded by the Serbian Ministry of Education, Science and Technological development (TR 31017).

Thank you for your attention!