الفهرس 
Dissolved air flotationOnly 14 pages are availabe for public view
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Abstract
Egypt’s annual quota of Nile water is 55.5 billion in3 used to fulfill the different wates demands. Looking to the future of the stsessing wates demands. whether for drinking purposes, industsial development or agsicultusal expansion, it is quite obvious that a vely caseful use of the available water resources is a must. Meanwhile a strategy fos the proper- management and development of non-conventional wates resources should be usgently considered by the responsible authosities. The use of h.eated wastewater constitutes one of the most appsopriate and self-cont-rollable resources so far. As a substitute for fresh water in irrigation or aquaculh11-e: wastewater- has an important role to play in watelresources management. By releasing fi-esh water sources for potable wates supply and other priority uses, wastewater I-euse contsibutes to wates conservation and has certain economic advantages. Therefore, the i~nportance of wastewater reclamation in the field of water resources managemelit is noiv commonly acknowledged in Egypt. The pri1na1-y objective, however, must be to ensure that wastewater is seused sationally while at the same time health and the envisonment are protected. Four main measuses can be taken to protect Iiealtli in wastewater seuse. na~nelv wastelvates treatment, c~r~estrpicti on, contsol of wastewates application, and exposure contr-01 and psomotion of hygiene. Of those. wastewates treatment has been the most widely adopted in controlled reuse schemes. The main objective of this study was thesefore as follows: 1- To develop the design pal-ametess required. 2- To evaluate the efficiency of the system fos removing biodegradable organic compounds. 3- To evaluate the efficiency of the system in removing pathogenic bacteria. 4- To evaluate the use of treated effluents for i~rigation purposes and aquaculture. For- this study, two continuous h-eahnent schemes have been investigated. The first step in the two schemes was physico-chemical treahnent. The second step was biological h-eatnlent. For the biological Qeahnent, two different technologies have been chosen, namely HRAP and biological sand fil tes To determine the variation in the characteristics of the wastewater under investigation, physico-chemical analysis, as well as bacteriological examination of the rnunicipal wastewater were canied out. Available data indicated that the total solids content ranged from 0.048 to 0.2 1 1 percent, 57.6% of which is organic in nahire. Suspended solids were relatively high, ranging fiom 260 to 544 mg/L and constituting 37.4% of the total solids content. The BODj values of the wastewater were around 5 13 ~ng 02/L. Conesponding average COD value was 825 rng 02/L. Around 67% of the COD and 64% of the BODj were in a particulate fonn. Mean total phosphorous concentration was 8.9 mg P/L. The concentration of oil and grease was selatively high. It ranged from 66 to 206 mglL with an average value of 104 1ng1L. The geometr-ic mean of total colifo~~nf,a ecal colifol-111, faecal stseptococci, total staphylococci and salmonellae in raw wastewater were 2.06 x 10’ ’, 1.91~0” ’. 0.81 I o”, 7.61~0’ and 4.08 x I o’, respectively. In general, the wastewater can be classified as above-medium stsengtli for physico-clie~nical chal-actesistics, bi~t as stsong in telms of bacteriological parameters. To develop the design pasametess for the continuous systems, batch laborato~y experiments were carricd out. The results indicated that the optimum time for plain sedimentation is 120 min. COD and suspended solids rernovals ranged from 49.7 to 53.2% and from 50.6 to 5S.4%, respectively. To improve the quality of the prima~y effluent and reduce the load applied to the biological treatment step, the addition of coagulants have been investigated. The coagulants used were fen-ic chloride. lime, fen-ic chlor-ide aided with lime. alum, alum aided with polyelectl-olyte ” Nalco-600” and fen-ous sulphate. The experiments were can-ied out for settled and 11011-settled municipal wastewater. Optimum operating conditions, namely pH-value and coagulant dose were determined. Assessment of the available data indicated that the efficiency of the different coagulants investigated, at their optimum operating conditions are in the following descending order: ferric chloride aided with lime > lime :. alum aided with polyelectrolyte (Nalco-600) > fen-ic chloride ;. alum > fen-ous sulphate. The use of 250 mg FeC13/L aided with 200 mg/L lime to adjust the pH to the optimum value led to a considerable i~nprovement in the quality of the effluent. Turbidity. COD and SS semoval values wese 98.6%, 91.l%, and 97.3%, respectively. It has also been noticed that there is no significant difference between the t7-eatment of settled and non-settled municipal wastewater.