الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 334 |  |  |
| | | from | 334 | | |
Abstract
INTRODUCTION
1-1 Problem Definition
Biological treatment is the most common process of secondary
treatment for both domestic and industrial wastewater. The activated
sbdge process is one alternative frequently used for the removal of organic
material in wastewater and it is considered the most popular method of
biolot,~cal treatment. The activated sludge is designed to increase the rate
at which self purification of a wastewater occurs by bringing it 111 contact
with a high concentration of microorganisms in the presence of dissolved
oxygen. Given ideal conditions for the growth of the microorganisms,
there rs a maximum rate at which the impurities in a wastewater can be
biochemically oxidized which is related to the physical and biochemical
propertres of bacterial cells, it can be exceeded simply because dissolved
oxygen is readily available. It is possible to increase the rate of treatment
per unit volume of the aeration tank by increasing the concentration of
microorganisms in the mixed liquor, provided that the necessary quantity
of dissolved oxygen is made available. However, the concentration of
microorganisms can only be increased if they can be adequately
concentrated by settlement and recycled. These organisms are reached to
the aeration tank in the form of floes which are dispersed throughout the
liquor to be 111 contact with waste organic material.
In an actrvated sludge plant, heterogenic microorganisms grow as a
continuous culture on organic and morganic substances. The plant
pro\ldes wastewater treatment by a combination of biochemical and
ph,sical processes, including (i) biooxidation of wastewater organics by
mrcrobial synthesis, (ii) flocculation of suspended and colloidal solids in
the wastewater with the microbial mass, and (iii) gravity separatron of the
mrxcd liquor suspended solid (MLSS) from the treated wastewater. The
tirst two processes occur primanly in the aeration tank, whrle the third
occurs in the secondary settling tank. The present research deals primarily
\\lth the processes involved rn the aeration tank.