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

THE PROJECT Microalgae for the treatment and valorization of wastewater and by-products from farming and dairy industry www.disat.unimib.it

VALORIZATION Animal feed Nutraceutics Cosmetics Bioenergy Regulatory and public acceptance constraints VALORIZATION Animal feed Nutraceutics Cosmetics www.disat.unimib.it Bioenergy Pharmaceutics

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 www.disat.unimib.it

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. www.disat.unimib.it EQUALIZED FLOW OF PROCESS WASHING WATERS

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 www.disat.unimib.it K [ppm] Cr µg/L Ni Pb Cu Cd 1.0 5.7 0.0 23 0.1 AAS N/P molar ratio = 4

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) www.disat.unimib.it

RESULTS: PAM measurements www.disat.unimib.it

RESULTS: Nutrient and COD removal www.disat.unimib.it 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

ALGAE/BACTERIA INTERACTIONS www.disat.unimib.it ~1.88 g CO2/g microalgae ~ 1.5 g O2/g microalgae O2

RESULTS: Quality of the effluent Parameter Algae treated effluent Italian Limits surface waters (152/2006) Italian limits sewerage (152/2006) pH 7.5 5.5-9.5 - 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 www.disat.unimib.it

RESULTS: Harvesting SETTLING TIME T0 1’ 2’ 3’ 6’ 10’ www.disat.unimib.it SETTLING TIME T0 1’ 2’ 3’ 6’ 10’

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 www.disat.unimib.it

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 www.disat.unimib.it

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 www.disat.unimib.it

THANKS FOR YOUR ATTENTION www.disat.unimib.it