Sharif Digital Repository

In this research the performance of the Moving Bed Biofilm Rector (MBBR) in different amounts of dissolved oxygen (DO) was investigated. Reactor with a useful volume of 15 liters was used in this study. In order to obtain optimum oxygen concentration, stayed at 6, 10 and 15 hours, and at different levels of dissolved oxygen in the range 0.5 -6 mg/lit, the amount of organic material was removed respectively. Also, in two different aeration intensity of 3.5 and 5.5 liters per minute at different values of e% (percentage of filling of media) the mass transfer coefficient values were obtained. When the aeration intensity increases from 3.5 to 5.5 liters per minute, and the percentage of 40%... 

In this research, we have studied optimization of culture medium and process factors for high alkaline protease production from Bacillus subtilis ATCC 6633 for detergent usage. Five parameter soy bean meal, initial pH, agitation rate, MgSO4, CaCl2 were selected for more studies. At first, one-factor-at-a-time method was applied to investigate effect of each factor separately. Then, optimum condition for maximum protease production was achieved using Minitab software Box-benhnken procedure. According to results, high protease production was seen in soy bean meal, 35 (g/L); MgSO4, 1 (g/L); CaCl2 , 1.5 (g/L); initial pH, 7; agitation rate, 150; inoculum ratio, 12% (v/v). The activity of the... 

Soil and water pollution is one of the most common types of pollution in terrestrial and aquatic ecosystems. The development of mines and the oil and petrochemical industry on one hand and the non-compliance with environmental requirements on the other hand have caused large amounts of hydrocarbon pollutants and heavy metals to enter the environment in recent decades. Petroleum materials and heavy metals leak into the surrounding environment during drilling and extraction in oil sites and mines or during land and sea transportation, despite the measures taken to control their pollution. The conducted studies show that human industrial activities are the only cause of environmental pollution... 

Oil pollutants are among the important sources of pollution in countries with oil and gas industries such as Iran. Soil pollution by these pollutants is one of the environmental issues and hazards. All kinds of organic and inorganic pollutants in the soil may penetrate the underground water or enter the atmosphere in the form of gas, which respectively enters the food chain through absorption by plants or enter the body of living organisms through breathing. They include humans, which are a threat to the health and life of living beings. For example, many of these pollutions cause diseases such as cancer, suppression of the body's immune system, or even obesity; therefore, it is necessary to... 

In this research, the optimization of culture medium and process conditions for the production of alkaline protease enzyme from Bacillus subtilis ATCC6633 strain for use in the detergent industry has been discussed. Among all the conditions affecting the growth and production of enzymes, the stirrer cycle in the fermenter, which causes different shear rates and is one of the most important factors in the amount of mixing and aeration, was chosen for further study. At first, the results obtained from the incubator shaker were carefully examined, and then different checks were made to adjust the fermenter stirrer speed through diagrams in three flow states: 1-laminar, 2-transitional, and...