Judging Adaptability of Anaerobic Biomass to Changed Feed Substrates through Methanogenic Activity Tests and its Verification

Transcription

1 Judging Adaptability of Anaerobic Biomass to Changed Feed Substrates through Methanogenic Activity Tests and its Verification Mohammad Jawed and Mohd. Zulquer Nain Department of Civil Engineering Indian Institute of Technology Guwahati Guwahati 78139, India

2 Introduction Anaerobic Processes investigated for Sudden/gradual change in operational/ environmental conditions short duration impacts (without any change in feed type) Hydraulic shock Organic shock Other shock types Focused on temporal performance of processes

3 Feeds causing secondary operational problems Sludge bulking Foaming Difficulty in biomass settling Identified sludge settleability as a serious problem

4 Reactor maintained on a typical substrate suddenly fed with altogether different substrate type? Relevant for developing countries?

5 Objective Assessing anaerobic biomass adaptability to sudden change in feed substrate through methanogenic activity tests

6 Experimental Suspended growth batch reactors: R1, R and R3. Aspirator Bottle. Anaerobic Biomass. Gas Outlet. 11.% (w/v) KOH Trap. Gas Flow Meter. Thermometer. Rubber Tubes/Connectors Reactor Charging: 1.5 L of anaerobic seed L of tap water Feeding: Once in a day (5 ml of supernatant replaced with feed)

7 Selected feed substrate types: Substrate Characteristics per 1 g: Sucrose sugar=65-85 g, Reducing sugar=5-15 g, Protein Jaggery (Soluble) Cerelac (Suspended) Neutralized acetic acid (Acetate) =.4 g, Fat=.1 g, Calcium=8 mg, Phosphorous=3-4 mg, Total minerals=.6-1 g, Moisture content=3-8 g, Carotene (Vitamin A)= 8 μg, Nicotinic acid=1 μg, Thiamine (Vitamin B)= μg, Colour =Golden yellow to brown, Energy=383 kcal. COD=957± mg/g Jaggery per 1 g: Carbohydrate=67.9 g, Protein=15 g, Fat=9 g, Calcium= 48 mg, Potassium=5 mg, Sodium=15 mg, Phosphorous=37 mg, Moisture content=.5 g, Folic acid=5 μg, Thiamine (Vitamin B)=.8 mg, Ash=3. g, Colour=White, Energy=413 kcal. COD=155±49 mg/g Cerelac 1 ml AR grade acetic acid + 5 ml distilled water + AR grade NaOH pellets to obtain a ph of 7 and final volume made up to 5 ml with distilled water to give a stock acetate solution. COD=161± mg/ml of stock solution

8 Methanogenic activity test set-up. Serum Bottle. Anaerobic Biomass. Reaction Mixture. CO Scrubber (11.% w/v KOH + thymol blue indicator). Rubber Tubing. Pinch-Cock. Hypodermic Needle. Conical Funnel. Displaced Liquid. Liquid Displacement System Serum

9 Operating Conditions: Three different phases maintained OLR = 1.4 kg COD/m 3 d Room temperature (18-6 o C) Phase I Aim: To obtain similar steady responses Feed: Model Feed (Jaggery( Jaggery) ) to R1, R & R3 Period: 65 days

10 Phase II Aim: To impose changed feed substrate types Feed: Model feed (Jaggery( Jaggery) ) to R1 Cerelac to R & Neutralized acetic acid to R3 Period: 64 days Phase III Aim: To discontinue changed feeds & to restore Phase - I model feed Feed: Model feed (Jaggery( Jaggery) ) to R1, R & R3 Period: 54 days

11 Performance Monitoring: COD (feed & effluent) alternate day VFA & BA every -3 3 days Room temp. & biogas or CH 4 production daily Methanogenic activity tests in Phase II

12 Results and Discussion Steady Response in Phase I: Parameters Reactor Phase I 5 65 d Temp = 5± o C Biogas R1.9±.7 (13) Produced R 1.91±.11 (14) (L/d) R3.15±.14 (13) R1.59±. () Methane R.73±.1 () Produced (L/d) R3.67±.1 () Phase I: Similar steady response for biogas/methane

13 Response in Phase II (under shock conditions): Time (d) Biogas (L/d) 4 Biogas Methane Reactor R1 1 Methane (L/d) Biogas (L/d) 4 Biogas Methane Reactor R 1 Methane (L/d) Biogas (L/d) 4 Biogas Methane S i 5 S i 3 Reactor R Methane (L/d) Time (d) Variation in biogas and methane production

14 Steady Response in Phase II: Parameters Reactor Phase II d Temp = 19±1 o C Biogas R1 1.96±.31 (9) Produced R 1.7±.3 (8) (L/d) R3 -- R1.6±.11 (11) Methane R.58±.15 (11) Produced (L/d) R3 -- Reduced biogas production in reactor R Complete cessation of biogas production in reactor R3

15 Methanogenic Activity Tests in Phase II: Reactor R1 Cum. Methane (ml) Reactor R1 Feed: Jaggery VSS(F):.76 g 1st Feeding nd Feeding 3rd Feeding 4 6 Time (h) Cum. Methane (ml) Reactor R1 Feed: Cerelac VSS(F):.764 g 1st Feeding nd Feeding 3rd Feeding 4 6 Time (h) Cum. Methane (ml) Reactor R1 Feed: Acetate VSS(F):.555 g 1st Feeding nd Feeding 3rd Feeding 4 6 Time (h) MA Jaggery =.16 g CH 4 -COD/g VSS d MA Cerelac =.16 g CH 4 -COD/g VSS d MA Acetate =.33 g CH 4 -COD/g VSS d Good adaptability of biomass from model feed to cerelac feed Non-adaptability of biomass from model feed to acetate feed

16 Biomass Adaptability to Model Feed: Phase II (Reactor R) Cum. Methane (ml) Reactor R Feed: Cerelac VSS(F): 1.94 g 1st Feeding nd Feeding 3rd Feeding 4 6 Cum. Methane (ml) Reactor R Feed: Jaggery VSS(F):.897 g 1st Feeding nd Feeding 3rd Feeding 4 6 Time (h) Time (h) MA Cerelac =.88 g CH 4 -COD/g VSS d MA Jaggery =.1 g CH 4 -COD/g VSS d Indicates good adaptability of biomass from cerelac to model feed

17 Biomass Adaptability to Model Feed: Phase II (Reactor R3) Cum. Methane (ml) Reactor R3 Feed: Acetate VSS(F):.46 g 1st Feeding nd Feeding 3rd Feeding Cum. Methane (ml) Reactor R3 Feed: Jaggery VSS(F):.843 g 1st Feeding nd Feeding 3rd Feeding 4 6 Time (h) 4 6 Time (h) MA Acetate =.7 g CH 4 -COD/g VSS d MA Jaggery =.136 g CH 4 -COD/g VSS d Indicates good adaptability of biomass from acetate to model feed

18 Response in Phase III (model feed again): Time (d) Biogas (L/d) 4 Biogas Methane Reactor Reactor R1 R1 1 Methane (L/d) Biogas (L/d) 4 Biogas Methane Reactor R 1 Methane (L/d) Biogas (L/d) 4 Biogas Methane Reactor R Methane (L/d) Time (d) Variation in biogas and methane production

19 Steady Response in Phase III: Parameters Reactor Phase III 3 6 d Temp = 5±1 o C Biogas R1.16±.33 (18) Produced R.11±.1 (19) (L/d) R3 1.9±.14 (19) R1.6±.1 (1) Methane R.79±.4 (1) Produced (L/d) R3.54±.3 (1) Comparable performances as of Phase I Complete recovery of reactor R3 in Phase III

20 Summary Impact of change in feed types (Phase II) Steady biogas production for R goes down Complete cessation in biogas production for R3 Biomass adaptability to cerelac but not to acetate MA values for reactor R1 indicated: Adaptability to cerelac feed but not to acetate feed MA values for reactor R and R3 indicated: Adaptability to model feed Impact of restoration of model feed (Phase III) Reactors recover steady responses of Phase I

21 Adaptability of anaerobic biomass to newer feed substrate types may be assessed through methanogneic activity tests

22 Thank You