Biodiesel production is worthy of continued study and optimization of production procedures because of its environmentally beneficial attributes and its renewable nature. In Egypt, millions L. of oil used for frying foods are discarded each year into sewage systems. Thus, it adds to the cost of treating effluent or pollutes waterways. This study is intended to consider aspects related to the feasibility of the production of biodiesel from waste/recycled oils in an attempt to help reduce the cost of biodiesel and reduce waste and pollution coming from waste oils. The variables affecting the yield and characteristics of the biodiesel produced from used frying oil were studied, the achieved results were analyzed and a set of recommendations was proposed. From the obtained results, the best yield percentage was obtained using a methanol/oil molar ratio of 6:1, potassium hydroxide as catalyst (1%) and 65 °C temperature for one hour. The yield percentage obtained from waste vegetable oil was comparable to that obtained from neat vegetable oil which reached 96.15% under optimum conditions. From the results it was clear that the produced biodiesel fuel, whether from neat vegetable oil or waste vegetable oil, was within the recommended standards of biodiesel fuel.

Scientists proved that municipal sewage sludge contains many dangerous pathogens, toxic heavy metals, endocrine disruptors, drains, storm water runoff, hospitals, and industrial plants. Sewage sludge represents an extremely high ecological hazard to the environment. Due to the increasing amount of sludge generated from the wastewater treatments plants a strong demand for environmentally and effective safe reuse has arisen. One potential use of that waste is its incorporation in the production of ceramic tiles. The main aim of present work was to study the possibility of usage of this hazardous waste in floor ceramic tiles industry. A dried sludge waste was added in percentages from 5% up to 35% to a standard floor tile mix, molded, pressed uniaxially at 30 MPa and then fired at temperatures reaching 1150°C for 15 min soaking time. The properties of both green and fired tiles were investigated as function of percent waste added. The vitrification parameters, which are linear firing shrinkage, water absorption, apparent porosity, and mechanical property, were determined and compared with ISO standards. Fired samples of the proposed mixtures were investigated by scanning electron microscope (SEM). It was possible to obtain tiles that abided by ISO standards for maximum addition of 7% sludge fired at 1150°C (for water absorption < 10%), and 10% sludge or 5% sludge for tiles fired at 1150°C and 1100°C, respectively (for water absorption > 10%), which are recommended for both their economic and environmental benefits.

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