الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Wastewater commonly includes organic solids, micro-organisms, and
toxic compounds. Biological treatment is one of important stages to treat
sewage and contains two chief tanks, aeration tank and final settling tank.
Aeration process using in return activated sludge system is very costly and it is required to operate WWTPs with low dissolved oxygen (DO) concentration in aeration process without risking poor effluent quality. To achieve this study, a
model plant was made for adding chemicals with responsible calibration for this model must be performed from November 2017 to June 2018. This study
will discuss the impact of DO concentration on sludge properties by using a pilot plant model WWTP and find the optimum doses of Hydrogen peroxide H2O2 concentration with using little dissolved oxygen concentration to reach good sedimentation. In this study, the value of dissolved oxygen was changed every 3 weeks from (0.5: 4.5) mg / L. During activated sludge process for wastewater treatment plants (WWTPs), micro-organisms play a vital role as an
indicator of wastewater treatment efficiency. Identification of micro-organisms
population may be achieved by counting based on image analysis. There are
some types of these micro-organisms found in wastewater, such as filamentous bacteria, which cause sedimentation problems in final settling tanks. This thesis discusses kinds of microbiological issues that may happen in activated sludge operation and how to control these problems at a pilot plant scale model
WWT. Hydrogen peroxide is one of vital chemical additions in WWTPs to
achieve good sedimentation.
Experiments were carried out to determine the optimal ratio and dosage
of H2O2 /Fe+2 was 5 as 30/6 mg/l. BOD, COD, TSS and VSS removal
efficiency by using H2O2 /Fe+2 were 91%, 89% 90% & 89%, respectively with
DO = 1.5 mg/l at an increased rates were 21.3%, 25.4%, 20% & 12.7%,
respectively. Furthermore, the aim of this work is also to prove that the
addition of optimum H2O2 /Fe+2 = 5 with (DO=1.5 mg/l) was equivalent
(DO=3.5 mg/l) without H2O2 /Fe+2 for wastewater treatment. Results of this
study proves that the addition of optimum H2O2 will save 2 mg/l of DO
concentration and providing a high cost of using electricity and mechanical equipment compared to the non-use of H2O2.