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This thesis aims to evaluate the performance of dairy industrial wastewater treatment by undertaking a process auditing of one of the major factories in Egypt, namely Nestlé (Ice Cream) Factory in the 6th of October City. Type of treatment is extended aeration activated sludge process. Experimental work was done at Nestlé factory laboratory, the selected performance parameter is COD. Data are collected from Nestlé Factory for three design and operation phases:
Degremont Original Design (2000 – 2008)
The design consists of a static fat separator, a CAF unit, a balancing tank, three aeration tanks, and finally a clarifier.
Degremont design was satisfactory but Nestlé factory did not construct the second stage of design, which made the plant hydraulically and organically overloaded, particularly the CAF unit.
Overall COD removal ratio was poor ranging from 23 to 76% with an average of 52% in year 2007.
The WWTP failed to comply with legal limits.
Aqua Design Modification 1 (2009 – 2010)
Aqua added new automated rotary screen with high capacity and DAF unit with flocculation unit, which improved the performance of the WWTP.
• The DAF achieved a significant average COD removal ratio of 32% in year 2010. However, the overall COD removal ratio was still low at 39%. The WWTP failed to comply with legal limits.
Aqua Design Modification 2 (2010 – to Date)
An aeration tank was added in series to the old ones and modifications are made for the balancing tank to be an aeration tank so that the aeration tanks become five connected in series, a new balancing tank was added before the CAF and DAF units, and finally a new clarifier was added to the old one.
This modification achieved overall COD removal ratio 87% in year 2011
The WWTP complied with legal limits.
Dairy wastewater treatment plant is best designed with the following flow line, this system can achieve COD removal ratio of about 90%.