treatment of high strengthen synthetic wastewater Qidong Yin - PowerPoint PPT Presentation

Effect of ferroferric oxide on batch anaerobic treatment of high strengthen synthetic wastewater Qidong Yin Graduate School at Shenzhen Tsinghua University Sep 16, 2016

Contents • Background • Materials and Methods • Results and Discussions • Conclusions

1 Background

1.1 Anaerobic treatment • Anaerobic treatment is a sustainable technology • A severe environmental issue Water Pollution • Wastewater Resources Water Reuse • Energy Recovery Treatments Recycling • Methane Production Anaerobic Treatment • Sustainable Technology

1.1 Anaerobic treatment • Three-step mechanisms Hydrolysis/ Methanogenesis 1 3 Acidification Complex organic Small organic Acetate/ CH 4 , matters matters Formate/ H 2 CO 2 Hydrogenesis 2 /Acetogenesis • Syntrophic Communities: The complete conversion from organic matters to methane requires a microbial consortium composed of various types of species.

1.2 Interspecies electron transfer ， IET • Interspecies electron transfer (IET) Interspecies H 2 transfer ( Methanothermus, Methanocaldococcus ) Interspecies formate transfer (Methanobacterium,Methanothermococcus) Direct interspecies electron transfer (Methanosaeta, Methanothermobacte, Methanosarcina) CH 4 , CO 2 Electron Transfer Production (H 2 /Formate) Acidogenic Methanogens bacteria Syntroph

1.3 Direct interspecies electron transfer, DIET • DIET is a new mechanism  DIET means acidogenic bacteria ( Geobacter ) can transfer electron to methanogens directly using its conductive pili or outer membrane cytochromes, rather than H 2 /Formate. acidogenic bacteria methanogen (Rotaru et al. 2013. A new model for electron flow during anaerobic digestion: direct interspecies electron transfer to Methanosaeta for the reduction of carbon dioxide to methane.)

1.3 Direct interspecies electron transfer, DIET • Conductive materials  Dosing conductive materials could accelerate the electron transfer among syntrophic communities. CH 4 , CO 2 Pili/Cytochromes Acidogenic Methanogens Conductive bacteria materials

1.3 Direct interspecies electron transfer, DIET • Conductive materials  Conductive materials can facilitate the methanogenesis. Conductive Carbon source Effect Reference materials Carbon Glucose/ Rotaru et al.,2014; materials Ethanol Liu et al.,2012; （ GAC/ carbon Facilitate CH 4 Chen et a.,2014; cloth/ biochar ） production Luo et al.,2015 rate/Shorten lag Magnetite Acetic acid/ phase /Facilitate the Kato et al.,2012; (Fe 3 O 4 )/ Propionic consumption of Carolina et al.,2014; Hematite acid/Butyric VFA Yamada et al.,2015; (Fe 2 O 3 ) acid/ Li et al.,2015; Beef extract Zhu et al.,2015

1.3 Direct interspecies electron transfer, DIET • Conductive materials  Conductive materials facilitated the production rate and shortened the lag phase during CH 4 production. (Luo et al. 2015) (Li et al. 2015)

1.4 Research Purposes The aims of this study were to – Examine the effect of conductive material Fe 3 O 4 on the performance of anaerobic treatment of high strengthen synthetic wastewater. – Compare the effect of Fe 3 O 4 on anaerobic sludge acclimated with different carbon substrates.

2 Materials and Methods

2 Materials and Methods • System operation  2 ASBR: Starch based reactor/ Tryptone based reactor  COD concentration: 3 g COD/L (starch or tryptone)  Starch and tryptone were used to represent carbohydrate and protein substrate, respectively. Operating conditions heater CH 4 、 CO 2 Parameter ASBR Volume 2 L synthetic effluent wastewater HRT 48 h SRT 33 d 35 ℃ Temperature sludge 23 h anaerobic （ 5min filling ） +1 h settling Operation mode gas flow meter （ 5min decanting ） mixer

2 Materials and Methods • Batch effect by the dosage of Fe 3 O 4 Hydrolysis/ Methanogenesis Acidification Complex organic Small organic Acetate, CH 4 , materials matters H 2 CO 2 Hydrogenesis /Acetogenesis • Operating condition Experimental conditions Parameter Value Effect of carbon by Fe 3 O 4 dosage ： 10 g/L Fe 3 O 4  Conductive material Volume 500 mL Effect of Fe 3 O 4 dosage concentrations: 2.5 g/L, 5 g/L, 10 g/L, 15 g/L, 20 g/L. Mixer speed 170 rpm  Groups: Control group/ Fe 3 O 4 group 35 ℃ Temperature  Inoculated Sludge: taken from ASBRs

3 Results and Discussions

3.1 Batch experiments • Short term effect by the dosage of Fe 3 O 4 120 210 (b) (a) Tryptone- Tryptone- 100 180 Acetic acid CH 4 150 80 Acetic acid (mg/L) CH 4 (mL) 120 60 90 40 Control Control Fe 3 O 4 Fe 3 O 4 60 20 30 0 0 10 20 30 40 50 0 0 10 20 30 40 50 Time (h) Time (h)  The R max was increased by Ultimate Lag Maximum Correlation 35.3% and the lag time was Reactor CH 4 yield phase production coefficient λ (h) R 2 shortened by 48% after (mL) rate (mL/h) dosing Fe 3 O 4 . Control 117.3 5.0 5.1 0.999  Acetic acid consumption rate 112.5 2.6 6.9 0.995 Fe 3 O 4 was also improved.

3.1 Batch experiments • Short term effect by the dosage of Fe 3 O 4 80 250 (c) (d) Starch- Starch- 70 200 CH 4 60 Acetic acid Acetic acid (mg/L) 50 150 CH 4 (mL) 40 100 30 Control Control Fe 3 O 4 20 Fe 3 O 4 50 10 0 0 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Time (h) Time (h)  The addition of Fe 3 O 4 had Ultimate Lag Maximum Correlation little effect on the CH 4 Reactor CH 4 yield phase production coefficient λ (h) (mL) rate (mL/h) R 2 production rate or the lag phase. Control 73.5 5.4 2.8 0.999  The produced acetic acid Fe 3 O 4 80 6.4 3.3 0.999 concentration was increased.

3.1 Batch experiments • Short term effect by the dosage of different Fe 3 O 4 concentrations 75 180 Tryptone- Tryptone- (b) (a) 160 60 CH 4 140 Acetic acid 120 Acetic acid (mg/L) Control 45 F2.5 100 CH 4 (mL) F5 80 F10 Control 30 F15 F2.5 60 F20 F5.0 F10 40 15 F15 F20 20 0 0 0 4 8 12 16 20 24 28 32 0 4 8 12 16 20 24 28 32 Time (h) Time (h) Ultimate Maximum Correlation  Generally, the R max was Lag phase Reactor CH 4 yield production coefficient λ (h) R 2 (mL) rate (mL/h) increased and the lag phase Control 77.35 9.19 4.31 0.9931 became shorter with the F2.5 72.67 7.51 4.98 0.9931 Fe 3 O 4 concentration. F5 66.56 6.96 5.19 0.9967  Acetic acid consumption rate F10 68/96 6.56 5.51 0.9981 was faster. F15 65.38 5.51 5.54 0.9980 F20 58.06 4.31 4.85 0.9963

3.1 Batch experiments • Short term effect by the dosage of different Fe 3 O 4 concentrations 55 160 Starch- (d) Starch- 50 (c) 140 45 Control CH 4 Acetic acid 120 F2.5 40 F5 Acetic acid (mg/L) 35 100 F10 CH 4 (mL) 30 F15 80 F20 25 Control F2.5 60 20 F5 15 F10 40 F15 10 F20 20 5 0 0 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Time (h) Time (h) Ultimate Lag Maximum Correlation  Different Fe 3 O 4 concentrations Reactor CH 4 yield phase production coefficient λ (h) R 2 (mL) rate (mL/h) all led to longer lag phase. Control 45.37 4.28 3.04 0.9931  Only the R max of F2.5 and F5 F2.5 47.82 4.93 3.40 0.9931 increased. F5 52.57 4.92 3.48 0.9967  No significant improvement F10 44.71 6.37 2.98 0.9981 was found. F15 56.71 4.8 2.46 0.9980 F20 54.39 5.0 1.79 0.9963

3.1 Batch experiments • Short term effect of Fe 3 O 4 (10g/L) on hydrolysis and acidification phase of tryptone 700 600 500 VFAs (mg/L) 400 BES was added to inhibit the 300 activity of methanogens Control 200 Fe 3 O 4 (BES: 2-bromoethanesulfonic acid sodium 100 salt) 0 0 5 10 15 20 25 Time (h)  The control group and the Fe 3 O 4 group had similar trend of VFAs production, indicating that short term dosage of Fe 3 O 4 might not facilitate the hydrolysis and acidification of tryptone.  Similar results were obtained by the metabolic end product of hydrolysis and acidification, acetic acid.

3.1 Batch experiments • Short term effect of Fe 3 O 4 on methanation 80 Ultimate Lag Maximum Correlation 70 Reactor CH 4 yield phase production coefficient 60 Control λ (h) (mL) rate (mL/h) R 2 50 Fe 3 O 4 CH 4 (mL) 40 30 72.6 17.91 6.42 0.9915 Control 20 10 Fe 3 O 4 67.87 19.64 1.72 0.9828 0 0 10 20 30 40 50 60 Time (h)  Only acetate was added as carbon substrate, instead of tryptone.  Without hydrolysis and acidification, adding Fe 3 O 4 seemed to hinder the activities of methanogen.  The R max was decreased by 73.1% and the lag time was delayed by 9.7%.

3.2 Microbial community  Short-term effect – Microbial community 100 100 (a) (b) 80 80 Other Acidobacteria Methanosarcina Relative abundance (%) Raltive abundance (%) Synergistetes Methanosaeta Spirochaetes 60 60 Methanospirillum Chloroflexi Methanolinea Euryarchaeota Methanoculleus Proteobacteria 40 Methanothermobacter 40 Firmicutes Methanosphaera Bacteroidetes Methanobrevibacter Methanobacterium 20 20 0 0 Tryptone Starch Tryptone Starch  Methanosarcina (66.28%) was the dominant methanogen in the sludge acclimated with tryptone and Methanosarcina was proved to accept electrons via DIET.  Methanobacterium (92.80%) was predominant in the sludge acclimated with starch. And its ability of DIET is still controversial.

4 Conclusions