Feasibility study on EO/EG wastewater treatment using pilot scale SBR

The sequencing batch reactors were developed to treat the actual wastewater from ethylene glycol/ethylene oxide producing industry. Four identical reactors with total and effective liquid volumes of 9 and 7 L were operated respectively in parallel. Laboratory experiments were conducted with different organic loadings of 500, 1000, 1500 and 3000 g-COD/m[3]. day and the performance of the reactors was studied under different sludge ages of 10, 20 and 30 days, the kinetic constants at optimal operational conditions were also determined. According to the results, the efficient removal of COD was 79.5 and 83.5% [SRT = 20 days] and 86% [SRT = 30 days] for SBR 1 and 2 respectively [OLR = 0.5 to 1 kg-COD/m[3]. day] with required reaction time of about 17 h. In order to reach the COD removal efficiencies over 86% at higher OLR values, the researchers required longer reaction periods about 34.5 h for SBR 3 and 4. However, the SRT values have no significant effects on the performance of SBR 1 and 2 at the aeration times greater than 22.5 h while in the case of reactors 3 and 4, with an increase on SRT at all aeration times, the COD removal efficiency increased. It is concluded that the system used in the present study could show an acceptable stability and performance in the treatment of the wastewater containing high concentrations of organic matters especially from EO/EG industries

Comparison of some properties of four provisional restorations resin: Trim, Tempron, Acropars TRII and Duralay [Aria Dent]

Use of provisional restorations is one of the important phases in the treatment of patients who need fixed prosthesis. Some physical properties are required for these materials. The purpose of this study was the comparison of some physical properties of 4 kinds of resins: Trim, Tempron, Duralay [Aria Dent] and Acropars TRII. In this experimental study, transverse-strength [TS], setting time [ST], polymerization shrinkage [PS] and temperature rise [TR] during polymerization were tested. In transverse strength test, 5 samples of each resin were made. TS testing was done with an Instron testing machine. ST testing [5 samples in each group] was done with Gilmore needle. In PS test, 11 cylindric samples were prepared from each resin and the shrinkage was examined with digital micrometer [up to 24 hours]. In TR test, after mixing the powder and liquid of resins [8 samples in each group], the temperature rise was recorded with 10 seconds interval [up to 15 minutes]. Data were analyzed with one-way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance. In TS test, all samples of Trim were bent and no fracture was observed, while Tempron and Duralay showed no significant difference. Both Tempron and Duralay revealed high significant difference with Acropars TRII [P <0.01]. In ST test, the difference between groups was significant [P<0.01]. The lowest ST was observed in Acropars TRII [7 min], and the highest in Tempron [9.53 min]. In PS test, significant difference was observed between Trim and Acropars TRII [P<0.01]. PS was completed after 120 min in Tempron and Trim groups. However, PS continued to increase in other groups. In TR test, the difference between groups was significant [P<0.05]. Duralay showed the highest TR and the lowest was seen in Trim. In this study, Trim showed better properties than other studied groups. Acropars TRII had the lowest strength. The highest temperature rise was recorded for Duralay and Tempron, respectively