ABSTRACT
The aim of this study was to compare xenograft scaffold and prous Hydroxyapatite/Tricalcium phosphate for the repair of bony defect. 5 New Zealand rabbits with the average weight of 2 kg were used. The rabbits were anesthetized with ketamine 60 mg/kg and xylazin 6 mg/kg After creating a critical-sized segmental defect [2x3 cm] in tibia bones, an implant of HA/TCP with osteoblasts in the hole of left tibia and an implant of xenograft with osteoblasts in the hole of right tibia was inserted. At the end of the second month, the animals were sacrificed. To follow up the new bone formation, x-ray images were taken at 8[th] week post-operation. To confirm the tissue repairment, the histology of repaired defects was evaluated with H and E staining after decalcification. The present study demonstrates that the critical-size segmental defect of tibia can be repaired with both synthetic HA/TCP and xenograft implants. xenograft implants showed better osteointegration compared to HA/TCP phosphate
ABSTRACT
Introduction: Methyl tert-butyl ether [MTBE] has been incorporated in reformulated gasoline at concentrations up to 15% [vol] to replace lead tetraethyl in order to comply with the octane index and to reduce the polluting emissions in exhaust gases. This compound is water soluble [48,000 mg/L] and one of the most common pollutants of ground water and surface water. Because of its undesirable effects on drinking water and ecologically harmful effects, MTBE removal has become a public health and environmental concern
Objective: Evaluatin of biodegradability of MTBE by isolated microorganisms from activated sludge
Materials and Methods: In this study a microbial consortium that efficiently degraded methyl tert-butyl ether was obtained by Isolated microorganisms of Activated Sludges in the Aqueous Solutions. Microorganisms were isolated from a variety of sources, generally from petroleum or chemical and urban wastewater treatment plants. All experiments were conducted at a constant temperature of 25°C. Vials of 50 ml and 125 ml volume sealed with Teflon-lined Mini-Nert caps were used for microcosm experiments. In all experiments 1% sodium azide were used as controls. Cultures were incubated at 25°C in the dark on an orbital shaker [rotation speed of 150 rpm]. The mineral medium was used for batch cultures. Samples of bacterial cultures that metabolize MTBE have been analysed for both MTBE and its metabolite TBA by direct GC analysis using FID. Cultures able to metabolize MTBE have been found in activated sludge and soils. Microbial consortium were plated on agar with MTBE vapor as the carbon source. After three weeks growth to saturation, independent clones were diluted into fresh mineral medium. This microorganisms, was a gram-positive bacterium. An aerobic microbial consortium able to biodegrade methyl tert-butyl ether [MTBE] was enriched in laboratory for four months
Results: MTBE has been shown to biodegrade under aerobic conditions and cometabolic conditions. Clearly, aerobic biodegradation of MTBE is demonstrable. In our laboratory, a microbial consortium was isolated from activated sludges based on its ability to grow on MTBE and was identified as cocobacillus. The capacity of this microbial consortium to degrade and grow on MTBE as a sole carbon and energy source is described in this paper. No biomass aggregates were observed during all the batch cultures, but the attached biomass was observed [the concentration of the initial attached biomass was about 0.11 g/ L of dry weight]. 500 mg of yeast extract per liter and 20 mg of Peat humic support growth of microbial consortium, it clearly had a stimulatory effect on consumption upper than 20%. Consortium was capable of degrading concentration as great as 1000 mg/l MTBE, whereas concentrations of 1000 mg/l MTBE and higher was not degraded
Conclusion: MTBE in low concenteration is biodegradable and biodegradability of MTBE enhanced by stimulator substances
ABSTRACT
Introduction: 2, 4, 6 trichlorophenol [TCP] is one of the most toxic Chlorophenols and is very difficult to biodegradation. Advanced oxidation processes [AOPs] are the most effective processes for the degradation of persistent compounds, since the mineralization of recalcitrant compound by AOPs often requires long reaction time and strong dose of oxidant, the combination of this process with biological one considered as one efficient and economic method
Objective: Integration of Fenton oxidation with activated sludge as an efficient and economic method for removal of 2, 4, 6 trichlorophenol and on kinetics of activated sludge in this integrated system was studied
Materials and Methods: This study performed in pilot scale of Fenton oxidation / Activated sludge Integration for treatment of 2-4-6 TCP wastewater and all analytical methods were according to 19Th edition of standard methods
Results: The study results showed that intermediates in effluent from Fenton reactor [H2O2] /[Fe2+] =3 , [H2O2] / [TCP] =3 Oxidation Time = 1hr and pH= 3 [TCP] 0 = 120 mg/ equal COD=150 mg/L], was degraded by activated sludge process and COD reduction was %75. Increasing aeration time from 6 hr to 18 hr has no significant effect on removal efficiency [alpha =0.01]. ML VSS increasing from 200 mg/L to 800 mg/L after 21 days indicated that TCP concentration in Fenton reactor effluent didn't have inhibitory effect on microbial growth. Increasing of TCP concentration from 120mg/L to 240mg/L has no significant effect on removal efficiency, however removal efficiency decreases to %71. Activated sludge kinetics were studied and y= 0.66 mg/mg Kd =0.088 day-1 Ks = 109 mg/ L, K = 2.04 day-1 determined
Conclusion: As results this integrated system was an efficient method for removal of 2,4, 6TCP and result from increasing aeration time and TCP concentration, as sole substrate source for Activated sludge combined with Fenton oxidation was not adopted with Monod equation