Iranian Journal of Chemical Engineering (IJChE)

Abstract This research work is concerned with the bioconversion of a heavy hydrocarbon cut from a petroleum refinery using native anaerobic consortia. The heavy cut is taken from one of the end-cuts of the vacuum distillation column of Tehran refinery which is normally fed into Isomax unit (a catalytic cracking process) called Isofeed. The consortia for this study were prepared from the petroleum-contaminated sludge and soils from Abadan, Shiraz, Isfahan and Tehran petroleum refineries of Iran. Nine microbial samples were collected (A, B, C, and I) and examined. Microorganisms were cultivated in an anaerobic medium to which Isofeed from Tehran refinery was added under anaerobic conditions. After twice sub-culturing the samples, the oil was separated from the liquid and examined to identify its bioconversion extent. For this
purpose, a column chromatograph method was used to separate saturates, aromatics and resins content of the oil. The results demonstrate that consortia A and C were able to increase the saturated and aromatics fractions of the oil and reduce the resins content of the oil. The saturated fractions of the bio-treated oil were also analyzed by a GC-MS analytical instrument. The GC-MS results revealed that the amount of normal chain hydrocarbons are reduced and the branched and cyclic hydrocarbons are increased.

Abstract Membrane technology is one of the few non-pollutant choices when selecting a treatment process. A membrane with suitable pore size can remove almost all pollutants without using any chemicals. In this research, chromium, zinc and lead were removed from synthetic wastewater by a membrane bioreactor. The results showed that by using a membrane bioreactor, the COD removal efficiency was increased in all conditions in comparison with that of an activated sludge process system. According to the test results, in the case of having heavy metals; Chromium with a concentration below 50 mg/l , the removal efficiency was shown to be about 95% and at these concentrations, chromium has no toxic effect on micro-organisms. However, the Activated Sludge Process showed poor removal efficiency in the case of having zinc. But when ASP was used in conjunction with the membrane, the removal efficiency was increased to 76%. Membrane showed an improvement of efficiency from 44% to 65% in the case of having 50 mg/ l of lead.
 
 

Abstract An efficient microbial technique for decolorizing distillery wastewater was achieved using irradiated spores of Aspergillus fumigatus. The fungus was isolated from soil samples taken from the local distillery processing unit. By using the irradiated spores, wastewater decolorization increased by 14.3% as compared to that of the control treatment (68.8% vs. 54.5%). In the presence of sodium nitrate and maltose, as optimum sources of nitrogen and carbon, in the microbe's growth medium, the decolorization rose to 70%.

Abstract n this paper, a mathematical model has been derived to predict the granulation time of anaerobic sludge in UASB reactors. In the proposed model, some physical, chemical and biological parameters affecting the granulation phenomena have been considered. To validate the model, 12 pilot-scale experiments in 4 UASB reactors are carried out and the results are discussed here. The reactors are started up at different environmental conditions and the granulation time in each experiment is determined. The results show that the model is able to explain different mechanisms involved in the granulation process.

Abstract This paper presents the results of an investigation into the treatment of Tehran Refinery effluents in UASB reactors. Four pilot-scale UASB reactors were built with similar dimensions, each with a volume of 45.78 1, and operated in parallel at 37 °C. The sludge seed was prepared from the waste activated sludge of the wastewater treatment unit of the refinery. The organic loading rates were gradually increased from 0.05-0.1 kg COD/m3.d to about 2, 1.5, 0.5 and 1.5 kg COD/m3.d for reactors 1 to 4, respectively, at an influent COD of about 220 mg/l. This is in accordance with hydraulic retention times of 2.5, 4.5 and 8.5 hours for reactors 1 to 3 and 4.5 hours for reactor 4. Methanol was initially added to the reactors in order to increase the microbial activity of the sludge, except for the last one, in order to compare the effect of methanol on start-up. The addition of methanol was stopped after 37 days and the reactors were operated for another 30 days. At this stage, the influent COD was varied between 50-300 mg/l. The results show that the COD removal efficiencies of the reactors are around 30-50%. However, when the influent COD increases above 200 mg/l, the COD removal efficiencies increase up to 70%. It is found that methanol has no significant effect in shortening the start-up period in this case. Scanning Electron Microscopy (SEM) examination and image analysis of the granules of sludge were also performed in order to investigate the structure of granules and the size distribution. Analysis of the biogas shows more than 90% methane content. The results obtained in this research are promising for the anaerobic treatment of refinery wastewaters in UASB reactors.