In this study, removal of para-nitrophenol (PNP) from synthetic wastewater by Alcaligens faecalis was investigated for the first time in an EXTERNAL AIRLIFT BIOREACTOR. The effect of factors such as pH (6, 7 and 8) and nitrogen source (yeast extract, peptone and urea) as well as initial PNP concentration (50, 75, 100 and 125 mg/lit) on PNP removal and bacterial growth was first examined in shake flask experiments. Then, performance of AIRLIFT BIOREACTOR was studied at various aeration rates (1, 2 and 4 l/min) and initial PNP concentrations (50, 75 and 100 mg/lit). In shake flask experiments, yeast extract and pH value of 8 led to the highest bacterial growth and PNP removal. In all BIOREACTOR experiments, PNP removal was higher and biodegradation time was lower compared to shake flask experiments. The maximum of 40 and 60% PNP removal were obtained in shake flask and BIOREACTOR experiments at 50 mg/l initial PNP concentration respectively. Among examined aeration rates, 2 L/min resulted in the highest PNP removal percentage at all initial PNP concentration.

Water contamination by Methylene Blue (MB) is a significant environmental challenge that requires cost-effective purification strategies. The green algae Coelastrella was used as an adsorbent inside the AIRLIFT BIOREACTOR as an effective and inexpensive material. Experiments were conducted over a range of conditions, including initial MB concentration (3-30 mg/L), contact time (0-60 min), air flow rate (200-300 mL/min), algae dosage (0.1-2 g/L), and temperature (20-40 ˚C). Diverse characterization techniques were employed to comprehensively understand the process and its outcomes. These techniques include Energy Dispersive Spectroscopy (EDS), Fourier Transform-InfraRed (FT-IR) spectroscopy, UV-Visible (UV-Vis) spectrophotometry, and Scanning Electron Microscopy (SEM). Adsorption isotherms were analyzed in this study, with a focus on the Langmuir, Freundlich, and Temkin models. The Langmuir model had the highest (R² = 0.9998), indicating monolayer adsorption with a maximum adsorption capacity of 30 mg/g. Additionally, kinetic studies found the pseudo-second-order model to be the most accurate (R² = 0.9990). Under optimal conditions, the process achieved a high removal efficiency of 98.9%. Finally, mass transfer adsorption models were examined using three models. When these models were compared, the Liquid film diffusion model had the highest value (R² = 0.9736). These results suggest that algae biomass is an effective, green adsorbent for MB removal, presenting a viable alternative to conventional treatments..

Uranium is leached from the uranium ore of the second anomaly of Saghand by the Acidithiobacillus ferrooxidans bacteria in an internal AIRLIFT bio-reactor. This study has been made to find the effect of aeration rate as well as its optimal value. The experiments have been carried out at 4 aeration rates to find the best recovery results in the least possible time duration. The results showed that the most percentage of the uranium recovery is in the superficial gas velocity of 0.010 m/s. The recovery at this aeration rate has an efficiency of more than 95% in 11 days. Also, the best range for aeration study in the AIRLIFT bio-reactor is calculated with a minimum value of 0.0065 m/s which is the critical value of the uranium particle suspension as well as the maximum value of 0.015 m/s. The stress on the bacteria increases the recovery time process in velocities of more than 0.015 m/s.

Blakeslea trispora, a filamentous fungus, was cultured both in a 15lit stirred tank and 75lit AIRLIFT BIOREACTOR. Different rates of aeration and agitation were investigated in related BIOREACTORs in order to find the more appropriate culture conditions for better production of ß-carotene. The results showed that the ß-carotene production by Blakeslea trispora is highly dependent on the degree of aeration of culture medium. ß-carotene yield was enhanced up to 120mg/L when the aeration and agitation rate was increased in stirred BIOREACTOR, up to 2vvm and 400rpm, respectively. However, under similar aeration condition, the production of the desired product was about 0.7 times more in AIRLIFT than the stirred BIOREACTOR.

In this work, mathematical modeling of microbial (Trichosporon sp.) biomass production in a stirred tank BIOREACTOR din an EXTERNAL AIRLIFT BIOREACTOR has been investigated. A model based on a tanks-in-series model without back-flow has been used to simulate the production of single cell protein in the EXTERNAL AIRLIFT BIOREACTOR under an unsteady condition and without oxygen limitation, utilizing cheese whey as a substrate.