1. New solutions to treat dairy wastewater
Valeria Mezzanotte, Tania Fantasia, Francesca Marazzi, Micol Bellucci, Elena Ficara

2. THE PROJECT
Microalgae for the treatment and valorization of wastewater and by-products from farming and dairy industry

3. VALORIZATION Animal feed Nutraceutics Cosmetics Bioenergy
Regulatory and public acceptance constraints
VALORIZATION
Animal feed
Nutraceutics
Cosmetics
Bioenergy
Pharmaceutics

4. AIM OF THE WORK
Testing the possibility of a low cost microalgal/bacteria process to treat washing waters from a milk whey factory to remove nitrogen, phosphorus and COD
Assessing the possible paths for biomass valorization

5. Where does our tested sample come from?
Whey processing site in Cazzago S. Martino
(BS) (1660 t storage capacity):
Recovery of whey’s noble constituents (lactose and whey proteins) by:
reverse osmosis,
Ultrafiltration
concentration by MVR evaporator.
EQUALIZED FLOW OF PROCESS WASHING WATERS

6. Physico-chemical characterization
K mg/L
Mg mg/L
Ca mg/L
Si mg/L
Fe mg/L
Na mg/L
Zn mg/L
Mn mg/L
Mo mg/L
Al mg/L 83 20
275
0.0 5
583
ICP
K [ppm] Cr
µg/L Ni Pb Cu Cd
1.0
5.7
0.0 23
0.1
AAS
N/P molar ratio = 4

7. Scenedesmus acuminatus (SA), mixed population (MP)
EXPERIMENTAL SETUP
Strain selection: tested strains and populations:
Chlorella sp.,
Scenedesmus acuminatus,
Scenedesmus obliquus,
Arthrospira platensis
mixed population made of Chlorella, Chlamydomonas and Scenedesmus spp. previously grown on dairy wastewater
Scenedesmus acuminatus (SA), mixed population (MP)
2. Semicontinuous lab-test (70 dd) 2.5 L culture volume 12 hours light/dark cycles (≈ 130 µmol m-2 s-1) HRT 7 days CO2 supply controlled by pH (fixed at 7.5)

9. RESULTS: PAM measurements

10. RESULTS: Nutrient and COD removal
SA % Removal:
Tot N 81
NH4- N 88
Tot P 57
COD 90
PM % Removal:
Tot N 89
NH4- N 99
Tot P 74
COD 91

11. ALGAE/BACTERIA INTERACTIONS
~1.88 g CO2/g microalgae
~ 1.5 g O2/g microalgae O2

12. RESULTS: Quality of the effluent
Parameter
Algae treated effluent
Italian Limits
surface waters (152/2006)
Italian limits sewerage (152/2006) pH
7.5 -
COD (mg/L)
78-84
160
500
NH4-N (mg/L)
5-6 15 30
NO3-N (mg/L) 20
NO2-N (mg/L)
0.6
Tot P (mg/L)
4-6 10

13. RESULTS: Harvesting SETTLING TIME T0 1’ 2’ 3’ 6’ 10’
SETTLING TIME
T ’ ’ ’ ’ ’

14. Work in progress
Characterization of algal biomass for protein, carbohydrate and lipid content in view of its possible use for animal feed and agriculture
Analysis of the potential use of algal biomass as substrate for extracting valuable molecules
Analysis of biogas
production potential

15. FINAL REMARKS
Washing water from milk serum processing is suitable as algae substrate and does not contain potentially harmful substances
The algae based process allows to produce an effluent which can be discharged in surface water complying with the quality standards set by the Italian law
The efficient removal of COD (including organic nitrogen) by bacteria is made possible by the production of oxygen by microalgae
The removal of nutrients is net, due to algal uptake

16. SCALING UP CONSIDERATIONS
The use of algal/bacteria consortium seems to be a practicable and economic alternative for the treatment of the tested kind of wastewater
In the experiment CO2 was provided but this could probably be avoided: the release of CO2 from the oxidation of organic molecules seems largely enough to sustain algal growth and the oxygen release from photosynthesis for COD oxidation
The developed algal biomass is easily harvested by settling
Process washing water can be held as a by-product and not as a true wastewater and this would be a positive factor in view of the valorization of algal biomass

17. THANKS FOR YOUR ATTENTION