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
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emoval <strong>of</strong> 38%. A higher removal in <strong>th</strong>e present study could be due to <strong>th</strong>e high<br />
concentration <strong>of</strong> biomass used. The COD removal at 16 and 24 h HRT wi<strong>th</strong> and wi<strong>th</strong>out<br />
ammonia stripping is presented in Figure 4.26.<br />
From Figure 4.26, it is clear <strong>th</strong>at <strong>th</strong>e ammonia stripping improved <strong>th</strong>e performance <strong>of</strong><br />
COD removal <strong>of</strong> <strong>th</strong>e BMBR much more <strong>th</strong>an <strong>th</strong>at <strong>of</strong> <strong>th</strong>e YMBR system as anticipated from<br />
<strong>th</strong>e toxicity studies.<br />
COD Removal<br />
(%)<br />
100<br />
95<br />
90<br />
85<br />
80<br />
75<br />
70<br />
65<br />
60<br />
55<br />
50<br />
Figure 4.26 COD Removal wi<strong>th</strong> and wi<strong>th</strong>out Ammonia Stripping at 16 and 24 h HRT<br />
Figure 4.27 shows <strong>th</strong>e expected improvement by ammonia stripping <strong>th</strong>rough<br />
biokinetic study and <strong>ac</strong>tual improvement for <strong>th</strong>e influent ammonium concentration.<br />
Though, <strong>th</strong>e expected improvement in terms <strong>of</strong> COD removal in <strong>th</strong>e yeast system was low,<br />
<strong>th</strong>e <strong>ac</strong>tual improvement was found to be much higher wi<strong>th</strong> 24 h HRT better <strong>th</strong>an <strong>th</strong>e 16 h<br />
HRT. The probable reason for <strong>th</strong>is could be <strong>th</strong>at <strong>th</strong>e biokinetic studies were done at a low<br />
substrate concentration as compared to <strong>th</strong>e <strong>ac</strong>tual simulated le<strong>ac</strong>hate. For <strong>th</strong>e BMBR<br />
system, <strong>th</strong>e improvements in <strong>th</strong>e COD removal for 24 h HRT was as anticipated <strong>th</strong>ough<br />
lower for 16 h HRT. This is ano<strong>th</strong>er indication to <strong>th</strong>e f<strong>ac</strong>t <strong>th</strong>at <strong>th</strong>e system was more<br />
stabilized at 24 h HRT <strong>th</strong>an at 16 h HRT. The standard deviation in <strong>th</strong>e COD removal at<br />
24 h HRT was 2 mg/L in <strong>th</strong>e BMBR system. Thus, suggesting <strong>th</strong>at in terms <strong>of</strong> COD<br />
removal was better at 24 h HRT.<br />
(2) BOD Removal Efficiency<br />
Wi<strong>th</strong>out Ammonia Stripping<br />
Wi<strong>th</strong> Ammonia Stripping<br />
BMBR-16h BMBR-24h YMBR-16h YMBR-24h<br />
As <strong>th</strong>e study wi<strong>th</strong>out ammonia stripping did not show a significant difference in <strong>th</strong>e<br />
COD removal, BOD was monitored in bo<strong>th</strong> <strong>th</strong>e effluents in addition to <strong>th</strong>e COD while<br />
working on ammonia stripped le<strong>ac</strong>hate. The BOD data for 16 and 24 h HRT is presented in<br />
Figure 4.28 and 4.29. The BOD removal in bo<strong>th</strong> <strong>th</strong>e BMBR and YMBR systems were<br />
above 94%. Ahn, et al. (2002) found <strong>th</strong>at a le<strong>ac</strong>hate wi<strong>th</strong> BOD around 250 to 300 mg/L,<br />
BOD removal was 97%. Though <strong>th</strong>e membrane biore<strong>ac</strong>tor was moderately efficient in <strong>th</strong>e<br />
removal <strong>of</strong> COD, <strong>th</strong>e BOD removal was high. This shows <strong>th</strong>at <strong>th</strong>e membrane biore<strong>ac</strong>tors<br />
are efficient in <strong>th</strong>e removal <strong>of</strong> <strong>th</strong>e degradable organics in <strong>th</strong>e le<strong>ac</strong>hate and <strong>th</strong>e probable<br />
99