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008 180699s1993 th uzm rtt 00| a1eng d
035 _a.b10598091
099 9 _aAIT Diss. no. EV-93-2
100 1 _aKrishna, Manandhar Uttam
245 1 0 _aSewage circulating reactor :
_ban approach to recirculating wastewater in sewers
260 _aBangkok :
_bAsian Institute of Technology,
_c1993
300 _a180 leaves :
_bill.
490 1 _aDissertation ;
_vno. EV-93-2
502 _aThesis (Ph.D.) - Asian Institute of Technology, 1993
500 _aA doctoral dissertation submitted in partial fulfillment of the requirements for the degree of Doctoral of Engineering.
520 _aIt has been established that biological reactions occur in sewer systems, and decompose organic matter and other constituents in wastewater. Thus, it appears worthwhile to utilize the self-purifying capacity of sewer systems. This study deals with recirculation of wastewater so that a portion of the conveyance conduit works as a circulating biological reactor (referred to as Sewage Circulating Reactor). Experiments were performed with a pilot scale unit made of a 87 m long galvanized iron channel (8 cm wide) in which wastewater was recirculated back to the starting point. Surface reaeration was the only source of oxygen. The unit was first fed with synthetic wastewater at Chemical Oxygen Demand (COD) and Total Nitrogen (TN) loading rates of 16.81 - 62.02 gCOD/m2/d and 1.8 - 7.84 gTN/m2/d respectively. An optimal TN removal of 0.77 gTN/m2/d was obtained at a TN loading rate of 3.78 gTN/m2 /d. The corresponding COD loading and removal rates were 27.45 and 22.0 gCOD/m2/d respectively. The biofilm areal density was higher and more fluctuating in the beginning of the channel while it was lower and more uniform towards the end. Later campus wastewater was fed to the unit at loading rates of 15.73 - 19.06 gCOD/m2/d and 4.66 - 5.44 gTN/m2/d. In spite of zero dissolved oxygen (DO) in the influent, the system showed COD removal rates close to 9.5 gCOD/m2/d (40 - 60%), and TN removal rates about 1.6 gTN/m2/d (23 - 26%). The biofilm in the experiments with campus wastewater was thicker than in the experiments with synthetic wastewater. The ratio of total volatile solids (TVS) to total solids (TS) in experiments with campus wastewater was approximately half of that for experiments with synthetic wastewater. A distinct decrease in the DO level in the system was observed with increasing organic and TN loading rates in experiments with synthetic and campus wastewater. This resulted in a decrease in nitrification rates at higher loadings. Thus, the overall system performance at high loadings was limited by hampered nitrification due to lack of oxygen.
650 0 _aSewage
_xPurification
_xBiological treatment
650 0 _aSewage
_xPurification
_xActivated sludge process
700 1 _aSchroder, Hans,
_eChairperson
700 0 _aChongrak Polprasert,
_eExamination Committee
700 0 _aTawatchai Tingsanchali,
_eExamination committee
700 1 _aJorgensen, Sven Erik,
_eExamination committee
710 2 _aAustrian Government,
_eScholarship donor
810 2 _aAsian Institute of Technology.
_tDissertation ;
_vno. EV-93-2
856 _3Full-Text
_uhttp://203.159.5.9/ait-thesis/detail.php?q=B15978
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