Abstract:
Mohenjo-Daro Civilization at about 1500 BC in Pakistan is
considered to be the pioneer's in the construction of wastewater
management system in the world. However, quite unfortunately, at present
like most developing nations, wastewater management system is either
improperly managed or non-existent in Pakistan. It has been reported that
in Pakistan only 1% of the effluent discharge from domestic and industrial
sources receive any treatment. However, after the issuance of revised
National Environmental Quality Standards in 2001 by Government of
Pakistan, due consideration has been given to the treatment of wastewater
in the country. In Islamabad, the sanitation services come under the
jurisdiction of Capital Development Authority. The daily wastewater
production of Islamabad city is about 23 MGD and treatment capacity of
Phase I-IV of Sewage Treatment Plant is 17 MGD.
This study was conducted in two phases. In Phase-1 of this study, the solid
retention time (SRT) was varied with the temperature on full scale sewage
treatment plant phase-IV with a treatment capacity of 200,000 PE
(Population Equivalent), located in humid subtropical environment, and its
effects on treatment performance were investigated. For this purpose,
samples were collected and analyzed from September 2011 to January
2012 from wastewater treatment plant. Temperature variation during the
study period was divided into three ranges and SRT was adjusted with
temperature in order to maintain the desired effluent quality. This study
also evaluates and compares the plant's observed effluent quality and the
removal efficiency in terms of TSS, BOD, COD, TN and TP with typical
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values available in the literature. From the result obtained, significant
improvement in effluent quality was observed by variation of SRT with
temperature.
In Phase-2 of this study, AQUASIM 2.0 was used as simulation software.
For this purpose, ASM1 reduce order model was used to evaluate the
steady state performance of the plant. The model developed was first
calibrated using data set for five days SRT and then it was validated with
for six days and seven days SRT. The model developed in this study can
be effectively utilized for the prediction of plant behavior in advance as a
result of variation in operating parameters such as, influent wastewater
characteristics and waste sludge flow rate.
