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035 _a.b10192657
099 9 _aAIT Thesis no. 643
100 1 _aYau, Chap Hoi
245 1 0 _aDesign parameters for oxidation ditches in the tropics
260 _aBangkok :
_bAsian Institute of Technology,
_c1974
300 _a56 p.
490 1 _aThesis ;
_vno. 643
500 _aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science of the Asian Institute of Technology,Bangkok, Thailand.
502 _aThesis (M.Sc.) - Asian Institute of Technology, 1974
520 _aA pilot scale oxidation ditch was built to evaluate whether the design parameters recommended by PASVEER (1969) could be improved under tropical conditions. While nutrient and D.O. were maintained at non-limiting levels, 8 different organic loadings of Pepsi-Cola waste, ranging from F/M = 0.07 to 0.78, were studied at a common detention time of 48 hours. Results showed that the effluent COD, increased with increasing loading. But the COD removal efficiency remained above 96% throughout the whole organic loading range. Ash content of the sludge was about 24% at loadings below F/M = 0.2, but decreased down to 13% at higher organic loadings. Keeping the organic loading with F/M about 0.38, the results. of 3 tests with different detention times showed that the change of hydraulic retention time from 48 hours to 17.5 hours did not change the COD removal rate, nor. the ash content of the sludge. However, at the same organic loading, a low influent COD lowered effluent COD and SVI . In a separate test, laboratory scale aeration units were set up to find out the chemicals which can restore the settling properties of a bulking sludge, once it occurs in an oxidation ditch, by changing its microbial composition. It was found that addition of calcium acetate at a concentration of 0.6 g per litre of bulked sludge, with NaN03 at a concentration of 0.5 g per litre of bulked sludge, suppressed the growth of Sphaerotilus, and selectively promoted to growth of other desirable bacteria so that the bulking problem was completely eliminated in a period of 8 days.
650 0 _aWater
_xPollution
650 0 _aOxidation
700 1 _aPescod, M.B.,
_eChairpeson
700 1 _aYang, Yi Ping,
_eCo-Chairperson
810 2 _aAsian Institute of Technology.
_tThesis ;
_vno. 643
856 _3Full-Text
_uhttp://203.159.5.9/ait-thesis/detail.php?q=B24197
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