Modeling of ozone as a disinfectant of indicators bacteria in the drinking water

Ozone is considered one of the most effective disinfectants that can inactivate resistant pathogenic microorganisms in which conventional disinfectant such as chlorine and chlorine dioxide fail due to its strong biocidal oxidizing properly. The study aimed at modeling of ozone as a disinfectant of indicators bacteria in the drinking water. This work involved a series of batch experiments with raw water, taken from the intake of El-Nozha Water Purification Plant, Alexandria governorate. The ozone doses applied in this study were 1.2, 2.2, 3.4, and 4.3 mg/l. The disinfected effluent was collected at 5, 10, 20 and 30 min. The indicator microorganisms HPC bacteria, total coliforms, faecal coliforms and Streptococcus faecalis were examined before and after the ozonation. The optimum ozone dosage applied in raw water to achieve 90% reduction of the indicator microorganisms was 2.5 mg/l. The optimum contact time to achieve 90% reduction of the indicator microorganisms in raw water was 8 min. By applying of ozone as post disinfection on filtered water the reduction percent of the indicator microorganisms were 100%. This study estimated that the ozones cost was 1.76 piasters/m[3]. Ozone as a primary disinfection must be applied on raw water to reduce the formation of THMs due to pre-chlorination of raw water at present, in addition to effective killing power of ozone onto microorganisms that will improve water quality

Environmental education and its effect on the knowledge and attitudes of preparatory school students

Considering the serious environmental threats facing Egypt, environmental education [EE] that provides the knowledge, skills, and motivation to take individual or collective action is needed to create a sustainable quality of life. This study was carried out aiming at measuring the level of environmental knowledge among preparatory school students in Alexandria, determining their attitudes towards some environmental concepts, and assessing the effect of EE on these knowledge and attitudes. The study sample was selected by stratified random method, and the assessment was conducted using a questionnaire. Results of the study revealed that 77% of the students had poor level of environmental knowledge and that 23% had fair level. In addition, 80% of the students were found to have negative attitude toward the environment and the remainder 20% were indifferent. Such knowledge and attitudes were positively correlated to their socio-economic levels. Following six EE sessions, an improvement in their knowledge and attitudes was observed where 69% of the students had a satisfactory level of knowledge and 88% had positive attitude toward the environment. Attitude was found to be positively correlated to their level of knowledge prior to and following the EE sessions. These results support the need for development and implementation of environmental education programs as part of the regular school curriculum