Photo-Activated Sludge System (PAS): A novel algal-bacterial biotreatment for nutrient rich wastewater

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1 Photo-Activated Sludge System (PAS): A novel algal-bacterial biotreatment for nutrient rich wastewater PhD candidate: Angélica María Rada, MSc. Delft, April 215

2 OUTLINE Background and problem statement Objectives Experimental Setup Results & discussion Conclusions Future works

3 Background & problem statement Organic matter NH 3 Bacterial Oxidation (OHO) Nitrification (AOO, NOO) CO 2 NO 3 - Microalgal photosynthesis (PHO) Light Biomass Advantages: High effluent quality Low energy consumption Small areal footprint Technically easy to operate P O 2 Energy intensive activated sludge process 1. Exchange of carbon dioxide and oxygen. 3. Negative effect of the algae in the microbial growth. 4. Alterations of ph in the culture medium. 5. Exudates from the algae used as source of carbon to the bacteria. Low energy demanding algaebased natural processes Photo Activated Sludge System

4 Objectives Main Objective The main objective of the present research is to maximize the efficiency of the Photo- Activated Sludge System for the treatment of wastewater rich in nutrients, while achieving a valuable recovery of biomass. 1. Key kinetics parameters. Determination of the kinetics of the microalgae-bacteria 2. Optimal conditions of the key parameters (ph, SRT, HRT). consortia and the differences with the known kinetics of 3. Nutrient removal mechanisms. solely cultures of algae and bacteria. 4.Mathematical Model

Experimental Setup Starting Phase Inoculation Medium: BG 11 1.

Chlorella sp (1 ml) N-NH 4+ /L = 35 mg/l 3.

Chlorococcus sp (1 ml) Control of ph with buffer (ph 7.5) 5.

REACTOR 1 Inoculums 1. Scenedesmus quadricauda 2.

Anabaena variabilis Wastewater Treatment Plant) 4.

Anabaena variabilis (1 ml) 4. Chlorococcus sp (1 ml) 5.

Panel 3 Microbial communities Mixture of algae strains +

5 Experimental Setup Starting Phase Inoculation Medium: BG Scenedesmus quadricauda (1 ml) Volume = 4 L 2. Chlorella sp (1 ml) N-NH 4+ /L = 35 mg/l 3. Anabaena variabilis (1 ml) PO 3-4 = 1 mg/l 4. Chlorococcus sp (1 ml) Control of ph with buffer (ph 7.5) 5. Spirulina sp (1 ml) Temperature 25 Irradiance =1 µmol/m2/s REACTOR 1 Inoculums 1. Scenedesmus quadricauda 2. Chlorella sp ml of Activated Sludge (Harnaschpolder 3. Anabaena variabilis Wastewater Treatment Plant) 4. Chlorococcus sp 5. Spirulina sp 6. Activated Sludge bacteria REACTOR 2 1. Scenedesmus quadricauda (1 ml) 2. Chlorella sp (1 ml) 3. Anabaena variabilis (1 ml) 4. Chlorococcus sp (1 ml) 5. Spirulina sp (1 ml) Flat Reactor Flat Panel 1 Flat Panel 2 Flat Panel 3 Microbial communities Mixture of algae strains + enriched culture of nitrifiers Mixture of algae strains + Nitrification inhibitor Chlorella vulgaris + Nitrification inhibitor REACTOR 3.25x.2x.1 m for a total 1. working Chlorella volume sp ( of ml) 5 L Flat Panel 4 Activated Sludge bacteria

6 Experimental Setup Operation Periods P NH4-N Operation NH4-N loading rate HRT concentration scheme (mg NH 4 -N /l/d) Operation time 12.5 ((NH 4 ) 2 SO 4 ) Batch days ((NH 4 ) 2 SO 4 ) SBR days ((NH 4 ) 2 SO 4 ) SBR days ((NH 4 ) 2 SO 4 ) SBR days (NH 4 Cl) SBR days (NH 4 Cl) SBR days Operation Scheme Start effluent discharge (2L) Duration: 15 min Hour: 12. pm Influent 1 (1L) Duration: 15 min Hour pm Influent 2 (1L) Duration: 15 min Hour 12. am Start settling Stirrers turn off Duration: 3 min Hour: 11.3 pm

7 Results & Discussion - N compounds 1. Nitrogen compounds concentration 1.1 Nitrogen concentrations along the periods for R1: Microalgae-bacteria consortia N-compounds concentration (mg/l) Day Reactor 1 - Microalgae-bacteria consortia P1 P2 P3 P4 P5a P5b EFF - NH4 EFF-NO2 EFF-NO3 INF Increase of Alkalinity (171d)

8 Results & Discussion - N compounds 1. Nitrogen compounds concentration 1.2 Nitrogen concentrations along the periods for R2: Microalgae consortia N-compounds concentration (mg/l) Day Reactor 2 - Microalgae consortia P1 P2 P3 P4 P5a P5b EFF - NH4 EFF-NO2 EFF-NO3 INF Increase of Alkalinity (171d) ATTU addition (184d)

9 Results & Discussion - N compounds 1. Nitrogen compounds concentration 1.3 Nitrogen concentrations along the periods for R: Cholerra Vulgaris N-compounds concentration (mg/l) Day Reactor 3 - Chlorella Vulgaris P1 P2 P3 P4 P5a P5b EFF - NH4 EFF-NO2 EFF-NO3 INF Increase of Alkalinity (171d) ATTU addition (184d)

10 Results & Discussion - N compounds 1. 2 Ammonium removal rate for microalgae and nitrifiers Ammonium removal rate (mgnh 4 -N/L/d) Ammonium removal rate (mgnh 4 -N/L/d) Day Reactor Ammonium 1 - Ammonium removal rate removal - Reactor rate2 3 P1 P2 P3 P4 P5a P5b Ammonium Removal - Ammonium Removal - Periods algae bacteria mgfsa-n/l/d mgfsa-n/l/d R1 R2 R3 R1 Increase of Alkalinity R2 (171d) R a b Microalgae-Bacteria allows us to have higher ammonium conversion rates!!! Ammonium removal rate - algae Ammonium removal rate - nitrifiers 16 ATTU addition (184d) ATTU Increase of addition Alkalinity (171d) (184d)

11 Results & Discussion - N compounds 1. 2 Suspended solids 5.5 Reactor Reactor 1 - Microalgae-bacteria 32 - Chlorella Vulgaris consortia P1 P1 P2 P2 P3 P3 P4 P4 P4 P5a P5a P5b Solids concentrations (g/l) Day TSS - R1 R2 R VSS - R1 R2 R

12 Results & Discussion - N compounds 1. 2 Suspended solids Solids concentrations (g/l) Reactor Reactor 1 - Microalgae-bacteria 32 - Chlorella Vulgaris consortia P1 P1 P2 P2 P3 P3 P4 P4 P4 P5a P5a P5b Period R2 R3 g/m 2 /d g/m 2 /d a b Day TSS - R1 R2 R VSS - R1 R2 R

13 Results & Discussion - N compounds 3. Nitrogen removal rates and biomass growth rate of algae and Nitrifiers 3.1 Nitrogen removal rates and biomass growth rate of Nitrifiers Period Ammonium loading rate Measured Based on substrate HRT Rxbacteria Rs bacteria µ µmax mgfsa/l/d 1/d mgvss/l/d mgfsa-n/l/d 1/d 1/d a b µmax Max specific growth rate of nitrifiers Ammonium loading rate (mgfsa-n/l/d) 2. y = x R² = Log (1/Rsb) Log (µm/y)

14 Results & Discussion - N compounds 3. Nitrogen removal rates and biomass growth rate of algae and Nitrifiers 3.2 Nitrogen removal rates and biomass growth rate of algae Reactor 1 - ALGAE Ammonium Measured Based on substrate HRT VSS Rxalgae Periods loading rate Rs algae µ µmax mgfsa/l/d 1/d gvss/l mgvss/l/d mgfsa/l/d 1/d 1/d a b Reactor 2 - ALGAE Ammonium Measured Based on substrate HRT VSS Rxalgae Periods loading rate Rs algae µ µmax mgfsa/l/d 1/d gvss/l mgvss/l/d mgfsa-n/l/d 1/d 1/d a b Reactor 3 - ALGAE Ammonium Measured Based on substrate HRT VSS Rxalgae Periods loading rate Rs algae µ µmax mgfsa/l/d 1/d gvss/l mgvss/l/d mgfsa-n/l/d 1/d 1/d a b

15 Results & Discussion - N compounds 3. Nitrogen removal rates and biomass growth rate of algae and Nitrifiers 3.2 Nitrogen removal rates and biomass growth rate of algae µmax Specific growth rate - algae Ammonium loading rate (mgfsa-n/l/d) Ammonium conversion rate (mg mgfsa-n/l/d) R1 R2 R3 Algae ammonium converstion rate (mgfsa-n/l/d) Net ammonium conversion rate per biomass concentration Biomass concentration (mgvss/l) Algae ammonium conversion rate per biomass concentration Biomass concentration (mgvss/l) Rs - R1 Rsalgae - R1 Rsalgae - R2 Rsalgae - R3

16 Conclusions Coupling bacteria with algae process increase the efficiency of ammonium removal without external aeration Ammonium removal rates of 7 mg/l/d by algae and bacteria at HRT of days Higher ammonium removal at higher solid concentrations (3 g/l) Reduction in the specific growth rate of alga and nitrifiers when in a microalge-bacteria system The algae biomass has presented tolerance at high concentration of NO 2 -N

17 Challenges!!! 1. More accurate and precise determination of the kinetic parameters 2. More accurate determination of algae biomass and bacterial biomass 3. Modelling of the Microalgae bacteria system

18 1 THANKS FOR YOUR ATTENTION!

CE421/521 Environmental Biotechnology. Nitrogen and Phosphorus Cycles Lecture Tim Ellis

CE421/521 Environmental Biotechnology Nitrogen and Phosphorus Cycles Lecture 9-269 26-06 Tim Ellis Nitrification Kinetics µ = µ K maxs NH 4 S + S NH4 K O S O2 + S O2 where µ max = maximum specific growth