Impact of Microalgae/Cyanobacteria Co-culture on Sugar Mill Effluents:

Transcription

1 Impact of Microalgae/Cyanobacteria Co-culture on Sugar Mill Effluents: Water and Added Value Assessment Jacob Foy Advisors: M.T. Gutierrez-Wing and Ronald Malone 9 th Annual Louisiana Groundwater, Water Resources & Environmental Symposia, 4/16/15

2 Research Objectives Characterize water effluents of a biomass processing facility (sugar mill used as surrogate) Determine suitability of effluents for algal cultivation Determine biomass production, nutrient uptake, and organic consumption Develop water quality model for biomass processing facility 1

3 Background 11 sugar mills in LA Milling season (Oct-Dec) Water and solid waste products Wash water Evaporator water Ash slurry Filter mud Bagasse Fertilizer Energy to mill Alma Image: American Sugar Cane League 2

4 Wash water 1-15 gal/ton cane processed Rinse incoming cane and milling equipment Retention ponds Evaporator water 23 gal/ton cane processed High sugar content High temperature Aerated and discharged daily Incoming raw cane Wash water retention ponds during milling season Aeration of evaporator effluents during milling season 3

5 Water Requirements Louisiana sugar mill regulations for facilities that impound all wastewaters for discharge after the milling season (State Guidelines LAC 33:IX.77.D.2.c). Parameter Daily Average (mg/l) Daily Maximum (mg/l) BOD TSS Dissolved oxygen (minimum) ph * * *Treated water must have ph between

6 Case Study: Alma Plantation Sugar Mill Surrogate for multi-feedstock biomass processing facility Evaporator water pond and raceway 8 wash water retention ponds 1 month sampling plan Water quality N, P, COD Bayou Fusilier and Discharge Bayou 1.56 million tons cane (213) 5

7 35 Conductivity Comparison 16 D.O. Comparison 3 25 During milling Post milling During milling Post milling S 2 15 mg-o 2 /L EEO EEO Pond Water Quality Pond 1 9 ph Comparison During Milling Post Milling ORP Comparison 5 During milling Post milling ph mv EEO EEO Pond Pond 6

8 mg-n/l Nitrogen and Phosphorus Characteristics Total Nitrogen Evap mg-n/l NH 4 -N 2 2 1/13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 Month/Year 1/13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 Month/Year 6 Total Phosphorus 6 PO 4 -P mg-p/l 3 mg-p/l /13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 1/13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 Month/Year Month/Year 7

9 Chemical Oxygen Demand 12 Pond 4 COD 1 Evaporator Pond COD mg-cod/l filtered 4 unfiltered Evap filtered Evap unfiltered /13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 1/13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 Month/Year Month/Year 8

10 Dual role of algae in wastewater Dalrymple et. al, Water treatment of effluents a) Remove N, P b) Reduce COD c) Oxygenate water 2. Accumulate valuable biomass a) Biofuels b) Bioproducts 9

11 Algal growth experiments Co-culture of microalgae/cyanobacteria (Chlorella vulgaris/leptolyngbya sp.) Native to Louisiana Mixotrophic growth 1. Differing ratios of wash water and evap. water :1, 25:75, 5:5, 75:25, 1: 2. 1% wash water milling vs. non-milling / filtered vs. unfiltered / inoculated vs. non-inoculated 1

12 Growth Rate and Biomass Productivity 1.21 d mg/l d 1.4 Maximum Growth Rate 12 Biomass Productivity day Umax.77 d -1 mg dry biomass/l day Pmax 2 mg/l d.2 2. :1 25:75 5:5 75:25 1: BBM :1 25:75 5:5 75:25 1: BBM Wash water: Evaporator water BBM = Bold s Basal media control 11

13 2. Maximum Growth Rate 186 mg/l d 3 Biomass Productivity 244 mg/l d Umax 25 Pmax day mg dry biomass/l day FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc a: milling season 1% wash water b and c: post-milling 1% wash water F = filtered, UF = unfiltered I = inoculated, NI = non-inoculated 12

14 Theoretical Biomass Yields Ratio Experimental Mixed Water P max *Theoretical Yield Temp ( C) Temp ( C) (mg/l d) (ton/ha yr) 1: 25 ± ± :25 25 ± ± :5 25 ± ± BBM 25 ± 2 25 ± *Based on 3 day operating season and 5 cm cultivation pond depth 1 acre: 81 tons/yr 4 acres: 324 tons/yr 8 acres: 648 tons/yr Reclaimed water 13

15 Nutrient Uptake Effects 5 Total Nitrogen Filtered 5 Total Nitrogen Unfiltered mg-n/l Initial TN* Final TN* mg-n/l Initial TN Final TN 7-89% TN (filtered) removal 1 1 Control: 3% :1 25:75 5:5 75:25 1: BBM :1 25:75 5:5 75:25 1: BBM 1 Total Phosphorus Filtered 1 Total Phosphorus Unfiltered % TP (filtered) removal mg-p/l 6 4 Initial TP* Final TP* mg-p/l 6 4 Initial TP Final TP Control: 13% 2 2 :1 25:75 5:5 75:25 1: :1 25:75 5:5 75:25 1: 14

16 6 Total Nitrogen Filtered 6 Total Nitrogen Unfiltered mg-n/l Initial TN* Final TN* mg-n/l Initial TN Final TN 63-84% TN (filtered) removal FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc 35 Total Phosphorus Filtered 35 Total Phosphorus Unfiltered 83-94% TP (filtered) removal mg-p/l Initial TP* Final TP* mg-p/l Initial TP Final TP FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc 15

17 Organic Carbon Consumption/Transformation 1 COD Filtered 14 COD Unfiltered 8 Initial COD* Final COD* 12 Initial COD Final COD 1 mg-cod/l 6 4 mg-cod/l FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc FIa FIb FIc FNIa FNIb FNIc UFIa UFIb UFIc UFNIaUFNIbUFNIc COD (filtered) Milling season: 67-76% removal Post-milling: 18-48% removal 16

18 Water Quality Model 17

19 Water Quality Model Series of stabilization ponds modeling COD, N, and P removal/transformation over time Time consideration: beginning of milling season to 7 months after milling ends (~3 days) STELLA modeling software 18

20 Model Description Component Volume Total Nitrogen Total Phosphorus Governing Equation Q Q Q Q Q dn V dt Q N Q N K N V K. / N cl Q P Q P σ P V Chemical Oxygen Demand (COD) dl V dt Q L Q L K X L V 1 Y K / L Y A V Heterotrophic biomass Q X Q X / K X V Autotrophic biomass (algae) da V dt K A V K / A K L L N K N K A V Temperature K K θ 19

21 Model Calibration 1 Total Nitrogen 5 Total Phosphorus mg-n/l Observed Model Output mg-p/l Observed Model Output Time (d) Time (d) 12 COD 1 8 Observed Model Output mg-cod/l Time (d) 2

22 Acknowledgments USDA-NIFA Award No.: Sustainable Bioproducts Initiative Advisors: M.T. Gutierrez-Wing and Ronald Malone 21