Document Type
Thesis
Date of Award
1-31-1988
Degree Name
Master of Science in Environmental Engineering - (M.S.)
Department
Civil and Environmental Engineering
First Advisor
Basil Baltzis
Second Advisor
Hsin Neng Hsieh
Third Advisor
Gordon Lewandowski
Abstract
The treatment of wastes via biodegradation is a widely utilized technique in most industries today. The kinetics of biodegradation, in most cases, follow either the Monod (non-inhibitory) or Andrews (also known as Haldane, inhibitory) model as indicated by published experimental data. The present study investigates aspects of the optimal design of a unit treating wastes when the biodegradation kinetics are those mentioned above. The criterion of optimality is the minimum volume achieving a desired conversion under given load conditions.
Two alternatives from the point of view of the number of vessels (one and two), and three alternatives from the operational view point (no recycle, partial recycle of the total effluent of the system, and partial recycle of solids after settling of the system's effluent) are considered. All alternatives studied have a single external input and a single output. The optimal volume as well as the optimal relative size in the case of two vessels is determined. The performance (in terms of treatment level/conversion) achieved by the alternate designs when they have equal volume is investigated. Effects of parameters such as the flowrate of the wastewater stream, the concentration of waste, and the recycle (total or solids only) are studied in detail.
In most cases, it is advantageous to use two vessels in series rather than the conventional single vessel. In the case of Monod kinetics, the recycle of solids is found to be the operational mode that is optimal. Under inhibitory kinetics, the optimal mode of a two-vessel configuration is found to be either solids recycle or no recycle, depending on the concentration of the pollutant in the untreated waste stream and the required conversion.
The transient response of a two-vessel system is studied under conditions of abrupt increases or decreases in the operating parameters (flowrate of wastewater, concentration of waste, recycle ratio). In certain cases, the effluent concentration can be off specification during such transients, which indicates the need for either control devices or an equalization stage. The need for control proves to be indispensable for a wide range of operating parameter values in the case of inhibitory kinetics.
Recommended Citation
Saghafi, Farnaz, "Optimal design aspects of a unit treating hazardous wastes via biodegradation : a theoretical approach" (1988). Theses. 3260.
https://digitalcommons.njit.edu/theses/3260
