الفهرس 
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Abstract
This study aims to evaluate change of microbial loads along the processes in Wastewater Treatment Plant (WTP) at Zagazig City as well as study the chemical analysis of untreated and treated wastewater. Results revealed that the removal efficiency of total bacterial counts was approximately 15 -74% during all the periods of study from April 2011 up to January 2012. However, the average total Enterobacteriaceae count in the wastewater samples reduced in all the periods by 85% except in June , one sample of july and December 2011in which the reduction was varied between 29-37%. The results show a high level of coliforms, Escherichia coli, Salmonella and Shigella in the raw wastewater; although their total removal is not achieved (the removal efficiency was 4 to 83%). The maximum total yeasts and Candida counts in the wastewater samples were reduced by 64.29 and 95.24%, respectively in August and October 2011. There was a slight difference in the physicochemical properties found in the treated wastewater during all the periods of the study in WTP. The maximum reduction efficiency of biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), nitrate, sulphate and oil in the treated wastewater samples was 91.6, 89.8, 8.6, 45.4, 99.2 and 90.2 %, respectively. The most predominant species of yeast in wastewater were Candida parasopili (n=5), Candida krusei (n=8) Cryptococcus neoformans (n=3), Geotrichum candidum. (n=9) and Saccharomyces cerevisiae (n=5). However, between the 30 isolated yeast isolates, only the 11 isolates (3: C. parasopili, 3: C. krusei, 3: G. candidum and 2: S. cerevisiae) showed a high growth rate at 20 mg / L phenol and 24 mg / L zinc sulpate The control of C. parasopili and treatment with 0.7 mg/ml phenol concentration had a normal morphology with no cell morphological changes by scanning electron microscope. The results indicated that this strain is a good candidate especially C. parasopilis strain to be used in further studies and different applications in the field of treated wastewater form phenol and heavy metal biosorption.