Thesis - faculty.ait.ac.th - Asian Institute of Technology
Thesis - faculty.ait.ac.th - Asian Institute of Technology
Thesis - faculty.ait.ac.th - Asian Institute of Technology
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
efficient in <strong>th</strong>e removal <strong>of</strong> <strong>th</strong>e biodegradable organics in <strong>th</strong>e le<strong>ac</strong>hate. At 24 h HRT,<br />
<strong>th</strong>e range <strong>of</strong> BOD concentration was from 30 to 55 mg/L which followed <strong>th</strong>e present<br />
effluent standard. Bo<strong>th</strong> YMBR and BMBR effluents, contained low BOD/COD ratio<br />
indicated <strong>th</strong>at <strong>th</strong>ere were high refr<strong>ac</strong>tory organic substances, which may be due to <strong>th</strong>e<br />
contribution <strong>of</strong> <strong>th</strong>e slowly biodegradable organics and non-biodegradable organics,<br />
containing in <strong>th</strong>e raw le<strong>ac</strong>hate. Whereas, <strong>th</strong>e average TKN removal efficiency in all<br />
conditions was greater <strong>th</strong>an 80%.<br />
5. YMBR system gave significantly better reduction in <strong>th</strong>e membrane fouling rate <strong>th</strong>an<br />
BMBR system. The trend <strong>of</strong> membrane clogging in BMBR was higher <strong>th</strong>an in<br />
YMBR wi<strong>th</strong> correspondingly higher transmembrane pressure. However, YMBR<br />
might be operated wi<strong>th</strong> a relatively low pressure for a prolonged filtration cycle.<br />
Therefore, <strong>th</strong>e b<strong>ac</strong>teria membrane frequently requires cleaning. The average filtration<br />
time for <strong>th</strong>e yeast system was 1.3-2.5 times <strong>of</strong> <strong>th</strong>e b<strong>ac</strong>teria system. As a result, yeast<br />
in a MBR re<strong>ac</strong>tor can enhance membrane performance and has <strong>th</strong>e potential to<br />
improve <strong>th</strong>e economics <strong>of</strong> treatment system because <strong>of</strong> <strong>th</strong>e reduction <strong>of</strong> operational<br />
problems and maintenance cost.<br />
6. For <strong>th</strong>e biokinetic study, a comparative evaluation <strong>of</strong> <strong>th</strong>e biokinetic parameters for<br />
bo<strong>th</strong> yeast and b<strong>ac</strong>teria sludge, which were used to treat le<strong>ac</strong>hate, illustrated <strong>th</strong>at <strong>th</strong>e<br />
maximum specific grow<strong>th</strong> rate (µmax) was less <strong>th</strong>an <strong>th</strong>e typical values for domestic<br />
wastewater whereas yield coefficient (Y) was still in <strong>th</strong>e range <strong>of</strong> domestic<br />
wastewater. Additionally, <strong>th</strong>e parametric group (µmax/Y.Ks) for yeast and b<strong>ac</strong>teria<br />
treating le<strong>ac</strong>hate were 1.77 x 10 -3 and 3.06 x 10 -3 L/mg.h, respectively. This<br />
indicated <strong>th</strong>at <strong>th</strong>e biodegradation <strong>of</strong> organics by yeast was less <strong>th</strong>an <strong>th</strong>at <strong>of</strong> b<strong>ac</strong>teria.<br />
It was confirmed <strong>th</strong>at <strong>th</strong>e biodegradation rates for bo<strong>th</strong> yeast and b<strong>ac</strong>teria in treating<br />
le<strong>ac</strong>hate were lower <strong>th</strong>an <strong>th</strong>at <strong>of</strong> domestic wastewater.<br />
7. The influence <strong>of</strong> ammonium nitrogen on a b<strong>ac</strong>teria culture was very sensitive,<br />
compared to a yeast culture. Also <strong>th</strong>e values <strong>of</strong> biokinetic coefficients show <strong>th</strong>at <strong>th</strong>e<br />
specific grow<strong>th</strong> rate in a b<strong>ac</strong>teria system was influenced by ammonium nitrogen. At<br />
ammonium nitrogen concentration <strong>of</strong> 2,000 mg/L, <strong>th</strong>e response <strong>of</strong> OUR inhibition in<br />
a b<strong>ac</strong>teria system was approximately 37%, whereas <strong>th</strong>at in a yeast system was around<br />
6%. Thus, <strong>th</strong>e ammonia concentration slightly affected <strong>th</strong>e yeast system but it<br />
inhibited <strong>th</strong>e microbial grow<strong>th</strong> in <strong>th</strong>e b<strong>ac</strong>terial system. Moreover, ammonia stripping<br />
was used to prevent <strong>th</strong>e inhibition <strong>of</strong> <strong>th</strong>e toxic compounds to <strong>th</strong>e organisms and to<br />
provide <strong>th</strong>e better efficiency <strong>of</strong> <strong>th</strong>e biological system.<br />
8. For <strong>th</strong>e effect <strong>of</strong> lead on OUR inhibition <strong>of</strong> b<strong>ac</strong>teria and yeast cultures, we found <strong>th</strong>at<br />
<strong>th</strong>e soluble lead concentration <strong>of</strong> 2.38 mg/L in b<strong>ac</strong>terial system showed 55%<br />
inhibition wi<strong>th</strong> non-linear correlation while <strong>th</strong>e soluble lead concentration <strong>of</strong> 1.50<br />
mg/L gave 50% inhibition wi<strong>th</strong> linear correlation in yeast system.<br />
9. The total membrane resistance (Rt) in <strong>th</strong>is study was depended mainly on a cake<br />
resistance (Rc). This might be due to <strong>th</strong>e cake layer deposited over <strong>th</strong>e membrane<br />
surf<strong>ac</strong>e. The formation <strong>of</strong> cake layer plays a major role in flux decline during<br />
filtration.<br />
10. The BOD5/COD <strong>of</strong> bo<strong>th</strong> YMBR and BMBR effluents was 0.01. Whereas, <strong>th</strong>e<br />
BOD20/COD ratio <strong>of</strong> <strong>th</strong>e YMBR and BMBR effluents varied wi<strong>th</strong> a ratio <strong>of</strong> 0.04 and<br />
120
Change language