Algal-Sludge Granules as a Novel Technique for Wastewater Treatment

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1 Algal-Sludge Granules as a Novel Technique for Wastewater Treatment Ahmed S. Abouhend 1,2 1 Civil & Env. Eng. Dep., Umass Amherst, USA 2 Marine Pollution Lab., NIOF, Egypt The Northeast Residuals And Biosolids Symposium, Oct. 19, 2015

2 Background! Conventional Wastewater Treatment Process Cost (Energy): " 3-4 % of US Electricity 2

3 Secondary Treatment! Activated Sludge System Cost (Energy): " 25-60% of costs 3

4 Wastewater as a Significant Energy Source " Chemical energy in wastewater! Based on COD; 1 m 3 = 6-8 MJ " Energy used for treatment! 1 m 3 = 0.6 kw h = 2.16 MJ Wastewater holds about 2-5 times the energy used to treat it.! The Question: How to Recover This Energy? 4

5 Alternative Technologies! Algal-based Wastewater Treatment Technologies " Most wastewater treatment lagoons in the U.S. do not harvest algae biomass. 5

6 The Novel Technology: Algae-Sludge Granules Algae Bacteria 6

7 How the opportunity was identified? Granules Seed Granule 10 mm Wastewater Seed Granules Treated water Biomass Reactor Granules Settling Granules 2-4 mm 7

8 Application: Sequenced Batch Reactors # 2 SBRs (1.5 L each) by 4-6 hrs cycles/day. R1 # The WW is the primary effluent of AWWTP. # 150 days of operation. # 2 Light sequences were studied; R1: 3.5 hr l- 2.5 h d R2: 2.5 hr d- 3.5 h l # HRT: R2 1 day day Days of Operation 8

9 Potential Impact of Treatment Process Influent WW Cycling and Mixing After 15 min Settling 9

10 Effluent Quality! COD Removal 250 TCOD Conentration (mg/l) Inf R1 R Days of Operation 10

11 Effluent Quality! Total Nitrogen (TN) 50 TN Conentration (mg/l) Inf R1 R Days of Operation 11

12 Effluent Quality! Ammonia (NH3) NH3 Conentration (mg/l) Io G1 G Days of Operation 12

13 Effluent Quality! Phosphate (PO4) 10 PO4 Conentration (mg/l) C5H7O2NP0.1 Io G1 G Days of Operation 13

14 Self Aeration : Natural Oxygenation O2 Production Rate DO (mg/l) O2 Production y = x R² = Specific Oxygen Production Rate: 8.0 (mg/gvss)/hr Time (Min) 14

15 Biomass Separation and Energy Production! Algal-sludge granules settled with an average settling velocity of Biofeed 12 m/h. Stock Energy Generation 0 min 1/2 min 1 min 5 min 15 min Anaerobic Digestion Fermentation << 99% Biomass Separation Efficiency Transesterification 15

16 The Yield (Biomass-Energy Conversion)! The biomass yields were up to 400% higher than typical activated sludge: 1 g COD Consumed 1.41 g COD (Biomass) 0.34 g COD (Biomass) Algal Granules Activated Sludge 16

17 Conclusion Algae-Sludge Granules Technology! Demonstrated wastewater treatment without external aeration.! Allows for recovery of energy laden in WW in the form of harvestable biomass and leads to substantial cost reduction in WW treatment.! Achieves environmental benefits reducing the green house gases emitted into the atmosphere! The successful application could provide an alternative to the activated sludge process. 17

18 Current and Future Research! Operating a pilot ASG unit at AWWTP: * Now; 30 L reactor as SBR * Our goal: L System! Investigation on several others $ Pathogens $ Heavy metals! Anaerobic digestion of ASG biogranules. 18

19 Acknowledgement # Park Lab Group $ Chul Park, Ph.D. $ Jeongmi Seo # NIOF, Egypt $ Khalid El-Moselhy, Ph.D. $ Christopher Watt $ Adam McNair Funding 19

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