H. Zare; F. Meiguni; G. D. Najafpour
Abstract
Alkaline proteases are the most important groups of commercial enzymes, which have been broadly used in industrial processes. In this study, Bacillus sp. PTCC 1538 was selected as a biological agent to produce alkaline protease. Enzyme production under submerge fermentation using industrial waste effluent ...
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Alkaline proteases are the most important groups of commercial enzymes, which have been broadly used in industrial processes. In this study, Bacillus sp. PTCC 1538 was selected as a biological agent to produce alkaline protease. Enzyme production under submerge fermentation using industrial waste effluent was investigated. Since the costs of the raw material plays an important role in the cost of enzyme production, corn steep liquor (CSL) was selected as a low-cost substrate to reduce the cost of enzyme production. Various carbon sources were used as the auxiliary substrates to enhance enzyme production. Results showed that maximum enzyme activity was obtained when wheat bran was used as an auxiliary substrate. Optimal media composition and growth conditions for alkaline protease production were defined. The optimum conditions were found to be pH 8, incubation temperature of 37 °C, CSL inoculum size of 5 v/v %, yeast extract and wheat bran concentrations of 2 and 6 g/l, respectively. CaCl2 was used as an activator to enhance proteolytic activity of the enzyme. Under optimum condition, enzyme activity of 100.7 U/ml was obtained at CaCl2 concentration of 1.5 g/l.
A. Ebrahimi; G. D. Najafpour; M. Anazadeh; M. Ghavami
Abstract
Industrial waste management is the main concern of sustainable environment, and the proper control and operation of wastewater treatment plants for efficient removal of pollutants are certainly important. In this study, the L16 orthogonal array of the Taguchi method was applied to determine the optimum ...
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Industrial waste management is the main concern of sustainable environment, and the proper control and operation of wastewater treatment plants for efficient removal of pollutants are certainly important. In this study, the L16 orthogonal array of the Taguchi method was applied to determine the optimum condition of some controlling parameters such as organic loading rate, hydraulic retention time, number of stages, rotational speed and recycling for treating whey effluent in a rotating biological contactor (RBC). In order to determine the impacts of levels and factors, the optimum condition of the experiment was predicted and determined. QUALITEK-4 has reported 76.25% COD removal based on a desired experimental condition (COD: 50000 mg L−1, HRT: 24 h, No. of stages: 3). To improve the performance of the RBC, second optimum condition (COD: 50000 mg L−1, HRT: 24 h, recycling: positive, rotational speed: 10 rpm, No. of stages: 3) was also investigated. According to the above-stated conditions, the highest COD removal was found to be 98%. Furthermore, two sets of test experiments were also conducted in lab scale under optimum conditions, and the prediction of other combinations of factors/levels was evaluated. Overall, the experimental results demonstrated that Taguchi method was able to predict COD removal with an average relative error of 6.5%.
M. Mohammadpour; G. D. Najafpour; M. Rahimnejad; M. Kiakojouri
Abstract
In this paper, HZSM5 zeolite was synthesized through reflux method on support material CaO (25, 35 and 45 wt%) in two specific methods: microwave and impregnation at high temperature. The zeolite catalyst was modified with impregnation of NaOH (2, 4, 8, 12 wt%) at room temperature. The modified zeolite ...
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In this paper, HZSM5 zeolite was synthesized through reflux method on support material CaO (25, 35 and 45 wt%) in two specific methods: microwave and impregnation at high temperature. The zeolite catalyst was modified with impregnation of NaOH (2, 4, 8, 12 wt%) at room temperature. The modified zeolite was used in transesterification of rapeseed oil with methanol in abatch catalytic process.In transesterification of rapeseed oil, the catalyticactivities of HZSM5, NaZSM5, KZSM5 were considered. The prepared catalysts were characterized by several techniques such as X-ray diffraction (XRD), Brunauer Emmett Teller (BET) surface area and also the surface image was scanned by scanning electron microscopy (SEM). The parameters affecting on biodiesel yield at optimum reaction conditions were investigated. The maximum yield was achieved with 8wt% of NaOH loaded on HZSM5 at reaction temperature of 65˚C, reaction time of 12 hours and catalyst/oil mass ratio of 9. Also the yield of CaO loaded with impregnation at high temperature was more desired than CaO loaded with microwave. Meanwhile the catalytic activity of HZSM5, NaZSM5 and KZSM5 was nearly zero; and the catalytic activity of modified zeolite was HZSM5>NaZSM5>KZSM5 subsequently.
N. Azimi; G. D. Najafpour; M. Sadeghpoor
Abstract
In this study the performance of integrated fixed film activated sludge system (IFAS) in Amol industrial wastewater treatment plant (Amol, Iran) in treatment of food industrial wastewater was investigated. In addition, kinetic coefficients were evaluated for the system. The capacity of this system ...
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In this study the performance of integrated fixed film activated sludge system (IFAS) in Amol industrial wastewater treatment plant (Amol, Iran) in treatment of food industrial wastewater was investigated. In addition, kinetic coefficients were evaluated for the system. The capacity of this system was 1700 cubic meters per day; that includes different process comprising physical and biological treatment, disinfection, sludge thickening, digestion and dewatering. COD removal efficiency and kinetic coefficients including yield coefficient (Y), half saturation coefficient (Ks), maximum substrate utilization rate constant (k) and endogenous decay coefficient (kd) were evaluated. The obtained results demonstrated that except Ks other coefficient were in the normal range that was frequently reported for conventional activated sludge in the literature. The COD removal efficiency was about 98 to 99 percent. The results indicated that there is a direct relationship between the variation of kd and Ks with effluent substrate concentration; while, the relationship between rate constant (k) and effluent COD is reversed. Finally, the effect of increasing sludge retention time (SRT) on COD removal was also studied. It was concluded that COD removal increased with an increase active solid retention time to a certain point, behind that point there was no significant changes observed.
A. Ebrahimi; G. D. Najafpour
Abstract
Microorganisms play an important role in biological treatment processes. Biodegradable organic matter in wastewater would be removed completely by proper microbial consortia. The mixed culture is either generally present in the wastewater, or is introduced to the target wastewater by mixing it with domestic ...
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Microorganisms play an important role in biological treatment processes. Biodegradable organic matter in wastewater would be removed completely by proper microbial consortia. The mixed culture is either generally present in the wastewater, or is introduced to the target wastewater by mixing it with domestic wastewater or sewage sludge. However, pure cultures bioprocess may be used in certain cases for the removal of specific contaminants. In favorable environmental condition, microorganisms are capable of presenting high efficiency in destruction of pollutants. If environmental conditions such as nutrition, pH, temperature, dissolved oxygen, hydraulic and sludge retention time are suitable and consistent with the nature of process, microorganisms grow and remove organic pollutants through biochemical activities. The aim of this article was to investigate the performance and mechanism of various systems of suspended and attached growth; while the detail of process in different fabricated systems was evaluated. The advantages and disadvantages of NRBC, UASFF, UAPB and normal activated sludge process were discussed. Growth kinetics and COD removal of effluents were also investigated. The result indicated the combination of fluidized and fixed film has created active biogranules which were quite faster and more efficient in treatment of industrial wastewater.
Mehdi Golestaneh; Ghasem Najafpour; Ghazaleh Amini; Morteza Beygi
Volume 4, Issue 3 , July 2013
Roya Pishgar; Ghasem Najafpour; Bahram Navayi Neya; Nafise Mousavi; Zeinab Bakhshi
Volume 2, Issue 4 , October 2011
Wan Ramli Wan Daud; Ghasem Najafpour; Mostafa Rahimnejad
Volume 2, Issue 3 , July 2011