04920cas|a2200469 i 4500 20260818095246.0 181197s1987 th u m rtt 0| a eng d .b10230506 AIT Diss. no. EV-87-1 Chalermraj Wantawin Effects of heterotrophic activity on nitrification Bangkok : Asian Institute of Technology, 1987 202 p. Dissertation ; no. EV-87-1 Thesis (Ph.D.) - Asian Institute of Technology, 1987 The investigation on the mutual relationships between heterotrophic and nitrifying activity in the same stage of continuous process was done in order to determine the relationships aside from the certain effects of sludge age and dissolved oxygen which usually were referred to be the reasons for no nitrification in reactors receiving high organic loading. More emphasis was placed on to clarify whether the heterotrophic growth exerts the adverse effects on nitrification. Chemostats were employed with various values of investigated hydraulic retention time which is equal to sludge age in once through reactor. Ammonia was fed without organic carbon in one series of experiment as the control and ammonia was fed with different concentration of organic carbon in other series to introduce the different degree of the growth of terotrophsin the system. Experimental data collected at steady state in this study reveals that utilization of ammonia for heterotrophic cell synthesis exhibited the preferential process over nitrification and the extent of achievable high ammonia removal by nitrifying organism was dependent on the growth of heterotrophs . Inhibition on the growth of ammonia oxidizers by the presence of heterotrophs was found, more ammonia leakage being observed under higher COD concentration in the influent. The larger value of saturation constant for ammonia oxidation in Monod equation, K 1 was obtained from the data of system fed with higher s' influent COD concentration, which means the low affinity of ammonia with ammonia oxidizers under the high activity of heterotrophs. More inhibition on nitrification has been observed when heterotrophs grew excessively during the transient state than that under steady state condition. Accumulation of ammonia was found in this period and was adequately explained by the simulation of the model in which the increase of Ks 1 value with the temporary increase of the heterotrophs was taken s, into account. Reduced dissolved oxygen level controlled at 0.5 mg/l did not affect ammonia oxidation but nitrite oxidation in the control and nitrite was accumulated up to 60 mg/l at hydraulic retention time of 6.5 days . The degree of inhibitory effect of ammonia oxidation in the presence of heterotrophs increased under this reduced dissolved oxygen concentration. Providing longer mean cell residence time and maintaining higher dissolved oxygen are necessary for nitrifying system to achieve the reliable stability of nitrification in the combined treatment process, and the required mean cell residence time to maintain certain level of effluent ammonia depends on organic carbon concentration in the substrate . A dissertation submitted in the partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Environment, Resources and Development Nitrification Hanaki, K., Chairperson Vigneswaran, Saravanamuthu, Co-Chairperson Suphat Vongvisessomjai, Examination Committee Chongrak Polprasert, Examination Committee Henze, M., Examination Committee Japan, Scholarship Donor Asian Institute of Technology. Dissertation ; no. EV-87-1 Full-Text http://203.159.5.9/ait-thesis/detail.php?q=B18949 .b10230506 mnait y 240329 2 951012 m a y 0 mnait mnait mnarc mnarc 22 40 20 Barcode : 30050120726335 CREATED : 2012-08-16 RECORD # : i12686736 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050160036512 CREATED : 2016-01-02 RECORD # : i12875971 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050121099948 CREATED : 2023-09-10 RECORD # : i13467591 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 Barcode : 30050121052228 CREATED : 2023-08-11 RECORD # : i13471120 LPATRON : 0 LCHKIN : - # RENEWALS : 0 # OVERDUE : 0 IUSE3 : 0 TOT CHKOUT : 0 TOT RENEW : 0 35165 35165 0 0 0 0 MAIN MAIN mnait 2026-08-18 0 AIT Diss. no. EV-87-1 30050120726335 2026-08-18 09:52:46 3 2026-08-18 22 0 0 0 0 MAIN MAIN mnarc 2026-08-18 0 AIT Diss. no. EV-87-1 30050160036512 2026-08-18 09:52:46 1 2026-08-18 40 0 0 0 0 MAIN MAIN mnait 2026-08-18 0 AIT Diss. no. EV-87-1 30050121099948 2026-08-18 09:52:46 1 2026-08-18 20 0 0 0 0 MAIN MAIN mnarc 2026-08-18 0 AIT Diss. no. EV-87-1 30050121052228 2026-08-18 09:52:46 2 2026-08-18 40