Prelim elimin inary ary ev eval aluati uation on of of - - PowerPoint PPT Presentation

Prelim elimin inary ary ev eval aluati uation

• n of
• f Scenedesmus obliquus

gr growth th on

• n or
• rganic

nic solid

• lid waste diges

estate, wi with di differ eren ent mechani echanical pretr trea eatm tmen ent

• P. Scarponi, A. Costa Devoti, A. Volpi Ghirardini, C. Cavinato

Department of Environmental Science, Informatics and Statistic, Unversity Ca’ Foscari of Venice, Italy

Anaerobic digestion (AD) is a widespread biotechnology for organic fraction of municipal solid waste (OFMSW) or industrial food waste treatment to produce energy (biogas). AD system is an efficient methodology to treat this type of waste but at the same time AD effluent had substantial nitrogen, phosphorus and other pollutants load, that avoid its environmental release.

We tested S. obliquus growth on OFMSW‐AD effluent in order to evaluate microalgae strain growth capacity and effect on AD digestate.

PROBLEM RESEARCH CARRIED OUT STATE OF ART

OFMSW+waste activated sludge Biogas Biomass Effluent cleaned Microalgae treatment AD effluent AD Lipid Protein PHA Cha, b and carotenoid

OFM OFMSW di digestate char characteriz rizatio tion The anaerobic digestate was collected in a wastewater treatment plant (WWTP) in north‐east of Italy

Value pH 7,6 Total alkalinity (g CaCO3/l) 1,69 Partial alkalinity (g CaCO3/l) 2,84 N‐NH4

+ (mg N/l)

573 VFA (mg/l) 80 sCOD (mg/l) 300

It was tested on S. obliquus with three pretreatment conditions:

• Without pretreatment (no PT);
• Centrifugation (AC)
• Filtration (AUF)

Experimental set up

• S. obliquus growth was tested in:
• mixotrophic and heterotrophic conditions;
• Inoculum and digestate dilution was 1:10;
• Bubbling and mixed in continuous;
• Light irradiation (2010 LUX).

20 40 60 80 100 120 140 160 1 2 3 4 5 6 7 8 9

Cell milion * ml Day

Autotrophic Mixotrophic 1 g/l Glu Heterotrophic 1g/l Glu 1 2 3 4 5 6 7 8 9

Day

MIxotrophic Digestate no PT Heterotrophic Digestate no PT Mixotrophic Digestate AC Heterotrophic Digestate AC Mixotrophic Digestate AUF Heterotrophic Digestate AUF

• S. obliquus could growth on OFMSW digestate with or without pretretment, using ammonia and organic compounds.

Illumination is a fundamental factor for microalgae growth on this substrate.

Cellular count

Max value in control condition

Dry weight (g/l)

• St. dev.

Phototrophic 0,12 ± 0,01 Mixotrophic (1 gl‐1 glu) 0,15 ± 0,002 Mixotrophic no PT 0,3 ± 0,1 Mixotrophic AC 0,42 ± 0,08 Mixotrophic AUF 0,5 ± 0,04 Productivity (g/l*d)

• St. dev.

Mixotrophic (1 gl‐1 glu) 0,018 ± 0,0003 Mixotrophic no PT 0,033 ± 0,02 Mixotrophic AC 0,053 ± 0,01 Mixotrophic AUF 0,063 ± 0,005 Digestate pretreatment gave best results for microalgae growth, the difference on dry weight and productivty between AC and AUF was small, so we deduced aswell that just one AC cycle will be enough like pretreatment.

In all test condition, initial ammonia concentration was 50 Nl‐1. At the end of test an ammonia reduction of 95,3 % (± 3,5) was observed. Probably this result was not correlated only to microalgae growth but it was also caused by ammonia stripping by bubbling and pH increased by photosynthetic activity. Ammonia reduction

10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9

% NH3 removal Day

% Ammonia removal

Mixotrophic Digestate no PT Mixotrophic Digestate AC Mixotrophic Digestate AUF

Chlor Chloroph phyll yll a, a, b and and tot total ca caroten tenoid accum accumula latio tion

Mixotrophic control

(µg ml‐1 *cell)

Media

• St. dev.

Ch a 6,11 ± 1,8 Ch b 7,4 ± 2,4 Carotenoid tot ‐ ‐

0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08 Cha Chb Carotenoid tot

Chlorophyll a, b anc Carotenoid tot µg/ml *cell

Mixotrophic Digestate no PT Mixotrophic Digestate AC Mixotrophic Digestate AUF

Conclusion

AC and AUF pretreatment on OFMSW gave best growth results in mixotrophic conditions. Pretreatment and illumination permit S.

• bliquus growth on this

wastewater with ammonia reduction of about 95%. Next studies:

Scale up in countinuous mixotrophic condition

• nly with AC
• pretreatment. Evaluate

nutrient removal and by‐ products production and accumulation.

Thank Thank yo you fo for the the atte attent ntion