No abstract

In the present study, the removal performance of phenol and Chemical Oxygen Demand (COD) from a petroleum refinery wastewater (PRW) in a Rotating Biological Contactor (RBC) was investigated. The impact of temperature of wastewater (T) (35-45ºC), rotational speed (ω) (2-14 rpm) and disc submergence (Ω) (30-50%) on phenol and COD removal was examined. The response surface methodology (RSM) was applied to minimize the number of runs and investigate the optimum operating conditions. Seventeen runs were carried out and the optimum conditions for phenol and COD removals were statistically obtained at temperature of 35°C, rotational speed of 11 rpm and disc submergence of 46%. These predicted data were in good agreement with the observed ones, as well. The result indicated that, the removal efficiency of phenol, cyanide, ammonia nitrogen, hydrogen sulfide, COD, biological oxygen demand (BOD 5), total dissolved solid (TDS), total suspended solid (TSS), total organic carbon (TOC) and turbidity respectively were under the 99%, 82%, 40%, 93%, 89%, 87%, 76%, 85%, 55% and 58%, in the optimum conditions that mentioned above. The major group of microbes (for the phenol microbial treatment) isolated from effluent of American Petroleum Institute (API) separator identified as Bacillus and Pseudomonas species. Furthermore, indigenous bacteria no need to acclimate. It also produced low sludge compared with the activated sludge in the RBC. Therefore, this type of bacteria was successfully applied in this research.

One of the serious problems in polybutadiene rubber (PBR) production units is the color change in products, which is due to aging and the inability of antioxidants to protect the product, especially at high temperatures. In this study, the effects of amine-type antioxidant [octylated diphenylamine (OD)] and non-amine-type antioxidant (Irganox 1520) on the color yellowness, gel content and thermal stability of PBR, at concentrations of 500, 1000, 1500, 2500 and 4000 ppm, at temperature of 110 °C, and different aging times (1-10 h) were investigated. The results showed that the polymer with Irganox 1520 antioxidant has a higher thermal stability, less gel formation and lower color than polymer containing OD antioxidant; therefore, the Irganox 1520 antioxidant was more suitable.

No abstract