الفهرس 
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Abstract
This thesis aims to study the effect of the addition of cement kiln dust to sewage sludge for safe disposal and environmental protection. Also aims to study the production of blended cement using burnt sewage sludge. It consists of four chapters: chapter (І) Introduction, chapter (ІІ) Literature review, chapter (ІІІ) Materials and methods of investigation and chapter (ІV) Results and discussion. Chapter (І) presents detailed introduction about the sources, characteristics and quantities of sewage sludge and cement kiln dust also talk about their negative impacts on the environment.
Chapter (ІІ) is divided to two parts; part І show wastewater characteristics and their treatment methods also present in details the types, physico-chemical and biological characteristics of the sewage sludge also show the different applications which sewage sludge where been used in. Part ІІ of this chapter gives a historical background about some natural materials and industrial bi-products which can be used as supplementary cementitious materials substituting OPC in composites as meta kaolin, Fly Ash and silica dust also talk about the pozzolanic reaction nature where pozzolana particles are dispersed in the cement paste and generate a large number of nucleation sites from precipitation of the hydration products. Therefore, the paste tends to be more homogeneous and dense.
Chapter (ІІІ) has two parts; Part І include the materials and methods which were used to study the utilization of cement kiln dust in wet primary and secondary sewage sludge treatment severally. The ideal optimum conditions (dose – flocculation time – speed – settling time) were determined using jar test through pH measurement, turbidity and sludge volume. After optimizing all conditions; physico-chemical measurements as solids, biological oxygen demand, chemical oxygen demand, ammonia, sulfide, total organic carbon, oil and grease, pH, phosphate, total metals and microbiological examination (total coliform and fecal coliform) where carried out for raw sludge and the treated supernatants. Sludge volume index, metals and microbiological examination were carried out for the raw and the treated settled sludge. This part also shows the chemical, reagents and their preparation methods according to the standard methods and the measurement methods for all parameters. Finally, it presents the sites where samples were collected from.
Part ІІ talks about the preparation of blended cement paste using burnt sewage sludge (BSS) and ordinary Portland cement (OPC) where there are four blends were prepared. The four OPC - BSS blends were prepared from the next OPC (Mix 0) and three OPC - BSS mixtures made by the partial substitution of OPC by 5, 10 and 15% of BSS by weight (Mixes M5, M10 and M15 respectively) and their water / cement ratios (W/C) of standard water of consistency were measured. Physico-chemical characteristics for the four blends were studied in time interval 1, 3, 7, 28 days to evaluate the efficiency of BSS to be used in blended cement production.
The obtained results in the part І of chapter (ІV) can be summarized as following:
- For primary sludge
It was found that 8 grams of CKD is the optimum dose added for one liter of primary sludge. Physic-chemical and biological measurements were carried out for raw sewage and the treated supernatant. Removal efficiencies for suspended solids, chemical oxygen demand, biological oxygen demand, oil and grease, ammonia, sulfide, total metals, total coliform and fecal coliform were 92, 88.4, 82.4, 91.7, 87.6, 84.3, 92.7, 100 and 100% respectively. Sludge weight of the treated settled sludge increases with 124% comparing with raw one and removal efficiencies for total and fecal coliforms was 99.9%.
- For return activated sludge (RAS)
The optimum dose was 7 grams of CKD for each liter of RAS. Removal efficiencies for suspended solids, chemical oxygen demand, biological oxygen demand, oil and grease, ammonia, total metals, total coliform and fecal coliform were 94.3, 99.5, 99.2, 61.4, 61.6, 72, 99.9, 99.9 % respectively.
The results shows the high efficiency of CKD as a coagulant and flocculent because it contains high ratio of free lime also have aluminum and iron oxides. CKD composition contains cations such as potassium and magnesium which increase the phosphorus removal. The silicate as well as calcium compounds contained in CKD behaved as an adsorbent material. Under the effect of high pH value, it was also beneficial in heavy metals immobilization and minimization of metal solubility in the treated sludge matrix. Consequently, metal ions were precipitated as hydroxides. Moreover, all pathogenic and viral species were destructed including total and fecal coliforms.
The results obtained from part ІVB, regarding the development of OPC and OPC - BSS blended cement pastes, show that the W/C ratio increase with the increase of BSS content in the pastes which indicates an increasing demand of water with increasing BSS content and therefore, the initial porosity of the OPC - BSS blended cement pastes increase with increasing BSS content. The compressive strength increases with the increase of curing time for all the hardened neat OPC (M 0) and OPC - BSS blended cement pastes (Mixes M5, M10 and M15). This is due to the formation of hydration products which act as binding centers between the remaining unhydrated parts of cement grains.
The partial substitution of OPC by BSS resulted in a slight reduction in the chemically combined water content (Wn) values of OPC - BSS pastes at all hydration ages. This slight decrease in Wn-values increase with increasing substitution of OPC by BSS which indicate that BSS has a reasonable pozzolanic activity with an appreciable contribution in the Wn-values of hydration products as well as the development of compressive strength of the hardened OPC - BSS pastes at all hydration ages.