There are still many difficulties for developing the projects of using treated effluents. In this study, the efficiency of chlorine deoxide in the process of preparing the effluent of Sahebgharanieh Plant of Tehran for reuse purposes has been determind. Major results are as follows: Total COD reductions resulted from effluent treatment by ClO2 solutions having concentrations equal to 1/4, 1/2 and 1/1 of COD samples at one hour contact time have been about 42%, 49% and 59% respectively. Total suspended solids were also reduced by treatment with ClO2 solutions having the certain concentrations mentioned, and the reductions were about 37% ,47% and 58% respectively. Besides total and fecal coliforms results indicated that ClO2 apllied was quite efficient in effluent disinfection. The conclusion is that reasonable reductions would be expected in the amounts of remained major pollutants and so reuse applications for some non-potable purposes may become possible. The acidification of chlorite has been used for ClO2 generation as it is better suited to small treatment systems.

Potential energy surface was calculated for the ground electronic state of the triatomic ion ClO2− using the coupled-cluster method CCSD(T). Calculations were carried out for 1200 points on the potential energy surface, and the calculated points were fitted to the potential energy expression in terms of the internal coordinates, from which the quadratic, cubic and quartic force fields were determined. Using the second-order rovibrational perturbation theory, harmonic vibrational frequencies, anharmonicity constants and several other spectroscopic parameters were calculated, and accurate fundamental vibrational frequencies were obtained. Also, the energies of 30 lowest vibrational levels were calculated using the anharmonicity constants.

Statement of Problem: Dental Unit Water Systems (DUWS) have been demonstrated to be contaminated with biofilms. This biofilm could be a site for growth and colonization of pathologic microorganisms. Purpose: The aim of this research was to measure the Total Cultivable Flora (TCF) in DUWS of Khorasgan dental school and the effect of stabilized chlorine DIOXIDE on its reduction.Materials and Method: In this research, 60 samples of water from high speed turbines, air-water syringes, cavitrons and wash basins were collected. The samples were cultured in agar nutrition media and incubated for 5 days. After the incubation period, colonial counting was done by HPC method. In the next stage, stabilized chlorine DIOXIDE was added in a container for each unit and the samples were taken from air-water syringes, cavitrons and turbine outlets .As for the first stage, after 5 days of culture and incubation, the samples were observed under microscope for counting the bacterial colonies. Kruskal-Walis and Mann-Whitney tests were used for statistical analysis.Results: A high level of bacterial contamination (more than 200 CFU) was observed in high speed turbines, air-water syringes, cavitrons and wash basins. The highest colonial count was observed from cavitron and the lowest from washbasin outlets but the difference was not statistically significant .After using chlorine DIOXIDE, the amount of bacterial colonies was significantly reduced (p <0.05). Conclusion: The amount of bacterial contamination in DUWS of Khorasgan dental school was higher than the accepted level .These bacteria were mainly opportunistic .The addition of an anti-bacterial agent in the DUWS will significantly reduce the bacterial count to an acceptable level.

The chlorine DIOXIDE delignification efficiency of softwood karft pulp in the laboratory liquor displacement reactor (fixed bed reactor) was investigated and compared with conventional batch reactor. The comparison of two reactors was made based on the effective efficiency and overall efficiency of chlorine DIOXIDE. Effective efficiency corresponds to the oxidizing capacity of chlorine DIOXIDE which consumed by organic materials. Comparison of two reactors based on the effective efficiency showed that the selectivity of delignification significantly enhanced in the displacement reactor in which the primary reaction products are eliminated from reaction zone by displacing flow. On the other hand, the formation of high amounts of chlorate in the reaction zone of displacement reactor reduces the overall efficiency of chlorine DIOXIDE delignification stage. Thus, in spite of significant decrease in useless secondary reactions, this type of reactor would not be cost effective in the industrial scale.

To possibly help in understanding the chemistry of the D process using E. urophylla × E. grandis LH 107 as the pulping material, residual lignin in kraft-oxygen pulp bleached by chlorine DIOXIDE was extracted by the dioxane/water acidolysis method. The content of functional groups in the extracted lignin was determined by 13C and 31P NMR spectroscopy. A relatively significant difference could be seen in the chemical properties of residual lignin between oxygen delignified (O) and chlorine DIOXIDE treated (OD) pulp. The results suggest a decreased function group content in the residual lignin of chlorine DIOXIDE treated kraft-oxygen pulps. It is quite interesting that the depletion of phenolic hydroxyl and methoxyl group present in residual lignin is due to the quinone formation during the oxidation of chlorine DIOXIDE, based on the data obtained in HSQC and 13C NMR spectra of non-cyclic and cyclic MATS, and the content in condensed and unsubstituted phenolics is reduced to the same degree, which is contrary to what we generally perceive

The continuous growth of population, surface water and ground water Contamination, non-uniform distribution of water and Periodic droughts, has forced Water and sanitation experts to look for an alternative source for water. The use of treated wastewater technology with high quality as an Reliable water supply has attracted more attention as recycling of waste water and industrial waste to reuse was attracted more attention in dehydrated countries. In addition to the problem of water crisis, environmental pollution caused by waste waters also has stressed refining and production of waste water with minimum pollution. In this research, the possibility of reduction of COD and I.S.S by ClO2 as a strong oxidant was investigated. Tabriz Petrochemistry waste water was examined as a case study.

In order to decrease the Kappa number and bleaching environmental impacts, the effect of several ionic surfactants on delignification and bleachability of bagasse soda pulping were investigated. Results indicated that the applying 1% of some surfactant decreased significantly the Kappa number at the same level of pulp yield. Moreover, addition of surfactant reduced alkali consumption, pulping reject and improved brightness and freeness of pulp. Compared to reference pulp, the pulp obtained with surfactant application produced higher brightness at the same level of chlorine DIOXIDE charge during the bleaching of pulp with DoED1 and DoEpD1 sequences. Resulted pulps had a better Mechanical properties regarding to conventional reference pulp.

Chlorine is a strong oxidizing agent. Hypochlorous acid (HClO) as a simple form of chlorine is an anti-bacterial agent used in drinking water and public swimming pools (1). Because of the higher density of chlorine than the air, it tends to condensate at the bottom and accumulates at high concentrations and may lead to aggravating toxicity (2). Chlorine can be detected with high sensitive devices at 0. 2 parts per million (ppm) and is detectable by smell at 3 ppm; the IDLH (immediately dangerous to life and health) concentration is very low at 10 ppm. . . .