Specific membrane bioreactor systems for municipal wastewater treatment and reuse
- Publication Type:
- Thesis
- Issue Date:
- 2012
Closed Access
Filename | Description | Size | |||
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01Front.pdf | contents and abstract | 75.59 MB | |||
02Whole.pdf | thesis | 170.78 MB |
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NO FULL TEXT AVAILABLE. This thesis contains 3rd party copyright material. ----- This study is to evaluate and investigate the ability of specific membrane bioreactor
systems in municipal wastewater treatment and reuse. The performance of up-flow
sponge bioreactor, fluidised bed bioreactor (FBBR) with and without aerobic sponge
reactor, and membrane bioreactor was separately investigated in the first stage of this
study. The second part includes the evaluation of submerge membrane bioreactor and
membrane bioreactor hybrid system integrated sponge bioreactor and/or fluidised bed
bioreactor as a pre-treatment for membrane bioreactor.
The effects of polyurethane sponge size and type on the performance of an up-flow
sponge bioreactor were studied. Three different sponge cube sizes ( 1 x 1 x 1 cm, 2 x 2
x 2 cm and 3 x 3 x 3 cm) and four types of sponge (S28-30/45R, S28_30/60R, S28-30/80R
and S28_30/90R) were investigated. The results indicate that there was no significant
difference in the organic and nutrient removal rates between sponge types while the
medium size sponge performed the best in terms of both biomass growth and pollutant
removal. Under anaerobic conditions, the COD, T-N and T-P removal efficiencies
were up to 70%, 45% and 55%, respectively, and significantly improved under aerobic
conditions (e.g. > 90% DOC, 95% COD, 65% T-N and 90% T-P). Another 1ype of
sponge bioreactor was also introduced, namely an attached growth sponge tray
bioreactor (STB).At short hydraulic retention time (HRT) of 40 minutes, the STB
could remove up to 92% of DOC and 40-56% of T-N and T-P at an organic loading
rate (OLR) of 2.4 kg COD/m3sponge.day. This OLR also appeared to be the best for
the STB as compared to the OLRs of 0.6, 1.2 and 3.6 kg COD/m3sponge.day. At 28
mL/min of flow velocity, STB achieved the highest efficiencies with 92% of DOC,
87.4% ofT-P, and 54.8% ofT-N removal.
The anaerobic - aerobic FBBR (AAFBBR) coupled with granular activated carbon
(GAC) could remove almost 95% of DOC. The highest nutrient removal efficiencies
(75.4% P04-P and 70.4 % NH4-N) were achieved at organic loading rate (OLR) of
43.2 kg COD /m3.d. This OLR operating condition also resulted in the highest specific
oxygen uptake rate (SOUR) and the amount of biomass attached on aerobic and
anaerobic GAC. From the critical flux and modified fouling index (MFI) experiments,
it was found that at OLR of 43.2 kg COD /m3.d, the AAFBBR could reduce membrane
fouling which was evident from the higher critical flux (20 L/m2.h) and lower MFI
(3.7 x 104 s/L2) achieved. A novel GAC-sponge FBBR was also investigated. The
results indicate that during 30 days of operation, the FBBR could remove more than
95% of DOC and COD. The highest nutrient removal efficiencies of 74% P04-P and
65 % NH4-N were also achieved at day 7. After 30 days, membrane fouling was
investigated by conducting critical flux experiments. The critical flux value was higher
in the new FBBR (30 and 35 L/m2.h) as compared to the anaerobic GAC-FBBR only
(25 L/m2.h).
MBR performance was tested with a new combined inorganic-organic flocculant
(CIOF) of FeCh and membrane performance enhancer (MPE5o). This system could
remove almost 100% total phosphate while eliminating over 90% NH4-N and DOC
during an 80-day of operation. The respiration tests revealed that the SOUR was stable
around 1.5-2.0 mg 0 2/g MLVSS.h. The sludge volume index (SVI) of less than 100
mL/g during the operation showed the importance of CIOF on the improvement of
settling properties of the sludge. Soluble carbohydrate concentration was also well
correlated with DOC of the supernatant. CIOF was successful in the reduction of
fouling of membrane as the membrane was only chemically cleaned after 53 days of
operation. When STB was combined with MBR as a pre-treatment, the system could
remove 95% of DOC, 83.6% ofNH4-N and 75.5% of P04-P. The SVI ofless than 100
mL/g during the operation indicated the good settling property of the sludge.
The pilot-scale MBR hybrid system was experimented at Sydney 0 lympic Park to
treat a municipal wastewater. The results showed that the system could successfully
remove 92% of organic carbon and 95% of NH4-N. The system can also control the
trans-membrane pressure (TMP) development at a significant low rate of 0.65
kPa/day. This result indicated that using new FBBR with aerobic sponge reactor as a
pre-treatment for MBR is a promising method for reducing membrane fouling.
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