Iranian Journal of Chemical Engineering (IJChE)

Abstract The membrane bioreactor (MBR) is a  treatment bioreactor of urban and industrial wastewaters. The advantages of the MBR technology encompass high-quality effluents, less space requirements, and high-speed startups. This study aims to investigate the fouling phenomenon in the flour industry sewage treatment. The pilot has been designed and constructed in line with the research concerning the industrial wastewater treatment. After the adaptation of microorganisms, physical and chemical tests such as chemical oxygen demands (COD), turbidity and total suspended solids (TSS), extracellular polymeric substances (EPS), and soluble microbial products (SMP) were conducted during the process. The concentration of mixed liquor suspended solids (MLSS) in the membrane bioreactor ranged between 5000 and 8500 mg/L. Hydraulic retention times (HRTs) were fixed at 4, 8, and 16 h. Three types of resistance were considered via measuring the leakage current and transmembrane pressure (TMP). Accordingly, the total resistance rates for HRTs of 4, 8, and 16h were 22.5×10¹⁰, 21.3×10¹⁰, and 20.4×10¹⁰ m^-1 respectively. Considering the average organic loading rate (OLR) in three HRTs of 4, 8, and 16 h (8.84, 5.13, and 2.84 kg the COD/m³×day respectively), the daily feed was provided to the bioreactor, and the removal efficiency of COD was assessed. An average removal of 95 % was achieved in the whole process. In this method, the input turbidity of the effluent has been increased to 187 NTU and, then, reduced to less than 3 NTU. It was also observed that EPS, SMP, and the extracted carbohydrates played more vital roles in the membrane biofouling than the extracted proteins.

Abstract In recent decades, large amounts of hydrocarbon derivations have contaminated the environment due to industrial developments and neglecting the environmental issues. In this study, the ability of biological removal of hydrocarbon pollution from contaminated soil around Sarkhun gas refinery was investigated. This study was done for seven samples with three different nutrient ratios and by moisture controlling and continuous aeration. During experiments, concentration of Total Petroleum Hydrocarbon (TPH) was measured. Results showed that with a nutrient ratio of 100:5:1 for C:N:P during an 18-day remediation period, the mean contaminant removal was about 50%. By using these results a practical plan was suggested for running in real scale situations. Developing a model was done by considering the Monod model as microbial growth model. Results showed good accordance to empirical data.

Abstract Heterogeneous photocatalytic degradation of Polynuclear Aromatic Hydrocarbons (PAHs) contaminated soil in the Pars Economic and Energy Zone was carried out under laboratory conditions to evaluate the potential use of this technology for in situ remediation. Analysis of soil samples show that contaminated soil is primarily related to the concentration of phenanthrene. Hence phenanthrene is used for photocatalytic degradation under laboratory conditions. Soil samples were spiked with two phenanthrene concentrations (50 and 100 mg kg-1), loaded with catalyst TiO2 and exposed to uv light with 125 W power. Different catalyst loads (1, 2, 3 and 4 % w/w) were tested in phenanthrene contaminated soil (50 mg kg-1) for up to 16h exposure. Both the catalyst and phenanthrene concentration show no influence on the kinetics of the phenanthrene degradation. The results indicated that the optimum removal condition was at 2% w/w catalyst and 100% w/w water with 85% degradation efficiency. The degradation efficiency of other PAHs was also assessed with the optimum condition. This paper shows that photocatalytic is a particularly important methodology, in which a major process is being made in the oxidative methods for the degradation of organics such as PAHs in contaminated soil