A mathematical model for the steady and unsteady state kinetics of bio-oxidation in the activated sludge process | |
| Author | Venkitachalam, Trichur Hariharan |
| Call Number | AIT Diss. no. D33 |
| Subject(s) | Sewage--Purification--Mathematical models Sewage--Purification--Activated sludge process |
| Note | A Dissertation submitted in partial fulfilment of the requirements for the degree of Doctor of Engineering of the Asian Institute of Technology, Bangkok, Thailand |
| Publisher | Asian Institute of Technology |
| Abstract | The activated sludge process is one of the more commonly adopted treatment method for bio-degradable wastes. Several mathematical models have been proposed to describe the kinetics of bio-oxidation in the pro-cess but have been found to only partially describe observed phenomena. In the present study a model is proposed for both steady and unsteady state kinetics of bio-oxidation in activated sludge reactors. The model is essentially an empirical extension of the earlier models based on available information in the literature. In addition to depicting sub-strate removal and sludge production, the model provides for a quantitative prediction of sludge viability and at the same time allows for the possibility of total oxidation. It also incorporates features to account for observed deviations in the dynamic responses of substrate uptake rate and organism growth rate from those predicted by earlier models. For steady state operation of a completely mixed reactor, the materials ba-lance equations incorporating the proposed kinetic model reduce to the viability model of GRADY and ROPER (1974). Experimental reactor performance data obtained from laboratory scale completely mixed reactors with and without solids recycle under both steady and transient operating conditions are presented to verify the validity of the proposed model. The model presented here requires the determination of ten kinetic or stoichiometric parameter values from experimental data. The steady state equations for a completely mixed reactor, however, involve only six of these which may be reliably estimated by a graphical or sequential linear regression procedure. The remaining four needed for describing dynamic reactor performance should be simultaneously estimated from transient response data. The suitability of employing one of the available computer-based techniques for this purpose remains to be investigated. The investigations show that the completely mixed activated sludge process possesses a significant capacity for absorbing shock increases in organic loading rate without appreciable deterioration of effluent quality. This buffer capacity is higher when the viable organism concentration is higher. |
| Year | 1977 |
| Type | Dissertation |
| School | AIT Publication (Year <=1978) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Dissertation (D) (Year <=1978) |
| Chairperson(s) | Nguyen Cong Thanh |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1977 |