Volume 18 [2016]

This study investigated the treatability and changes in molecular weight distributions (MWD) of membrane concentrate. Nanofiltration (NF) concentrate from textile wastewater was subjected sole anaerobic treatment (R1) and pre-ozonation (R2) plus anaerobic treatment. BOD₅, COD and TOC, color, sulphate and specific ultraviolet absorbtion at 254 nm (SUVA₂₅₄) were analysed. Pre-ozonation improved the biodegradability of the membrane concentrate. The low molecular weight (LMW) organics was an important reason for the overall biodegradability enhancement of the membrane concentrate. Color was caused mainly by matters with higher than MWD of 10 kDa and 80% of HMW organics were removed during anaerobic treatment. Nearly half of sulfate was lower than 0.5 kDa which indicates that sulfate hardly treated by NF membranes. SUVA₂₅₄ values after anaerobic treatment were generally higher than 2 l mg^-1m^-1 which indicates that membrane concentrate was in hydrophobic characteristics. 

MB decolarization with pure TiO₂ and Ag doped TiO₂ based photocatalytic system were investigated under UV-A and UV-Visible conditions. Different ratios of Ag were used as metal dopant. 1% Ag-TiO₂ increased the decolorization efficiencies of MB and MO dyes, also the k_app constant enhanced under UV-A and UV-Visible conditions. A central composite analysis showed the effect of initial dye concentration, pH, Ag-TiO₂ concentration and the reaction time of photocatalytic process under UV-A irridation in both dyes. The photocatalytic degradation pathways of both dyes by Ag doped TiO₂ catalyst were obtained in this study. According to these results, the application of Ag-TiO₂ catalyst are proved to be more effective than pure TiO₂ catalyst for both MB and MO removal. The toxicity test of Daphnia Magna shows that non toxic wastewater discharge to the receiving environment could be possible with photocatalytic degration by Ag-TiO₂ catalyst.

Most of water sources throughout the world contain natural organic matter (NOM), which is the best description as a complex mixture of organic compounds. The effect of iron ion on removal efficiency of dissolved organic carbon (DOC) using UV/TiO₂ photo catalytic oxidation (TiO₂) was examined. In this quasi-experimental study, the different variables such as pH value, contact time, various concentrations of TiO₂, FeCl₂ on the removal efficiency of DOC by the UV/TiO₂ on raw water of Zayandehroud in Isfahan were studied. The results were analyzed by using Pearson correlation coefficient test and SPSS software. Removal efficiency DOC improved as the amount of catalyst was increased. Maximum removal efficiency was achieved during acidic conditions (pH=3) within 60 minutes of contact time. The removal efficiency of DOC by the UV/TiO₂ decreased with increase of contact time. The presence of iron ions increased the rate of DOC removal by the UV/TiO₂. Removal efficiency of dissolved organic carbon increased when ionic strength and initial concentration of Ferric Chloride was increased. Also, by adding particles of Ferric Chloride, Removal of dissolved organic carbon increased to 98% in comparison with absence of iron ion (78%).

The effect of Zeolux use as soil amendment on the yield and some of the agronomic traits of a home garden plant, Sage (Salvia officinalis), irrigated by either fresh or RO reject waters was studied. Clay and different combinations of clay-Jordanian zeolux were compared for that purpose. Each combination was divided into two subgroups at randomized experiment and irrigated with either fresh or RO reject waters. The combination of 75% clay and 25% zeolux irrigated with fresh water produced the best results in terms of plant height, number of branches, fresh weight, dry weight and root dry weight of sage plant. The results indicate that the use of RO reject water causes significant reduction in all the studied parameters above. The use of zeolux did not reduce the harmful effects of the saline water used for irrigation on the yield of sage.