M Malakootian, B Hatami, Sh Dolatshahi, A Rajabzadeh,
Volume 7, Issue 1 (7-2014)
Abstract
Background and Objectives: As a green fuel and environmentally friendly energy, biodiesel has recently attracted much attention and efforts are ongoing to optimizing biodiesel production from microalgae’s. The aim of this study was to determine the appropriate method of dewatering and drying biomass and selecting a suitable organic solvent for extraction lipids from biomass. Materials and Methods: After culturing Nannochloropsis Oculata in Gillard F/2 medium and reaching at the end of the stationary growth phase, algal biomass was separated from aqueous by centrifuge and drying in three methods: fore, air-dried and lyophilized. Lipid extractions of each sample was performed using soxhlet apparatus and three solvents including diethyl ether, n-hexane and n-pentane. At each stage, the quantity and quality of the extracted lipids was determined by gas chromatography. Results: In all three drying methods, palmitic acid and palmitoleic acid were significantly the main fatty acid composition of microalgae. The fatty acid composition of palmitic acid extracted by diethyl ether was significantly more than the other two solvents. Maximum production of triglyceride was observed in air dried and lyophilized (using diethyl ether solvent) microalgae as 75.03 and 76.72 % of fatty acid respectively. Conclusion: The use of lyophilized method for dewatering and drying of biomass and diethyl ether as solvent for the extraction of lipids from biomass yielded more compared with other methods studied in this paper and would be more efficient in research works related to the production of biodiesel from microalgae’s lipid.
Reza Shokoohi, Salah Azizi, Said Amir Ghiasian, Javad Fredmal,
Volume 7, Issue 2 (10-2014)
Abstract
Background and Objectives: Pentachlorophenol (PCP) is an organic compound and phenolic derivatives categorized as priority pollutants that have harmful effects on humans, animals, and plants in low concentrations. Therefore, PCP removal from water and wastewater is very important. The aim of this study was to assess the efficiency of A. niger fungus biomass in PCP absorption. Materials and Methods: This was an experimental study in which different steps of the experiments were performed. A. niger strain was prepared from Persian Type Culture Collection of Iranian Research Organization for Science and Technology (IROST). After activation in potato dextrose agar (PDA) culture plates, fungi were incubated for 7 to 10 days at 25 °C. The prepared A. niger biomass was modified by NaOH and then it was used for PCP absorption assay. The concentration of PCP was measured using high-performance liquid chromatography. Results: The findings of present study showed that contact time is an important and effective factor in the PCP absorption rate. Two hours was selected as the optimum retention time in this experiment and after that the removal percentage did not raise significantly. The results of PCP absorption in different pH demonstrated that the adsorption efficiency decreases by rising pH and initial PCP concentration. The effects of contact time, pH and initial PCP concentration on the absorption process was significant (P-value <0.001). Conclusion: The results show that absorption efficiency increases by rising retention time under constant conditions. In addition, at low pH the modified A. niger biomass could be a good absorber for PCP.
S. A. Mirzaee, M.m Amin, M Sarafraz, M Heidari, M.m Ahmad Moazzam,
Volume 7, Issue 4 (1-2015)
Abstract
Background & Objectives: Disposal of pharmaceutical compounds to environment as an emerging pollutants cause concerns significantly and it is necessary to use new methods of sewage treatment for removal of these compounds. The aim of this study was to investigate the inhibition effects of metronidazole before and after using UV254/H2O2 process on specific methanogenic activity of.anaerobic biomass. Materials & Methods: Fourteen anaerobic digestion tests were carried out at batch scale before and after using UV254/H2O2 process in 500 ml reactors with 30% anaerobic biomass and 70% substrate. The liquid displacement method was used. Duration of each test was in the range of 10-17 days. Results: Cumulative Biomethane production in concentrations of 1, 5, 10, 25, 50, and 100 mg/l metronidazole was 34.04, 95.12, 100.86, 3.28, 27.88, and 6.97 ml respectively. This production was 800.73, 243.54, and 10.66 ml in concentrations of 25, 50, and 80 mg/l respectively using UV254/H2O2 process as pretreatment at 60 min retention time. Biomethane production in concentrations of 80,120, and 150 mg/l was 377.2, 380.48, and 63.14 ml respectively at 90 min retention time. Conclusion: Different concentrations of metronidazole had an inhibition effect on anaerobic digestions and therefore the efficient pretreatment method is needed to reduce this inhibition effect. The UV254/H2O2 process is an effective method for degradation and conversion of metronidazole to more biodegradable compounds for anaerobic bacteria consumption and, in turn, to increase biogasproduction in anaerobic digestions.
Sadegh Hosseinniaee, Mohammad Jafary, Ali Tavili, Salman Zare,
Volume 17, Issue 3 (12-2024)
Abstract
Background and Objective: Ethylenediaminetetraacetic acid (EDTA) is known as a synthetic chelating agent used for the remediation of soils contaminated with potentially toxic elements. Marrubium cuneatum is a medicinal plant with phytoremediation capabilities. This study investigated the effect of EDTA on the morph-physiological characteristics of this species and its rhizosphere soil.
Materials and Methods: Under greenhouse conditions, M. cuneatum was grown for six months in mine-contaminated soil with different levels of EDTA (0, 1, 3, 5 mmol/kg). Subsequently, its biomass, concentration of macro- and micronutrients, and soil biochemical properties—such as organic matter content, soil enzyme activity, and microbial biomass—were measured. Additionally, a regression model was established between EDTA concentration and shoot weight to predict the plant's growth response.
Results: A concentration of 5 mmol/kg EDTA decreased the dry weight of shoots and roots by 11% and 21.9%, respectively, compared to the control. The reduction in root macronutrient content was less pronounced with EDTA application compared to that of the shoots, with the greatest decrease observed for shoot potassium (40.70% compared to the control). The potassium-to-sodium ratio also decreased significantly. Despite improvements in some soil biochemical parameters at low EDTA levels, the 5 mmol/kg dose resulted in a 30% and 10% inhibition of urease and dehydrogenase activity, respectively. The regression relationship between EDTA concentration and shoot weight indicated that the maximum dry weight was obtained at a concentration of 2.4 mmol/kg.
Conclusion: Considering the adverse effects of EDTA at concentrations of 3 mmol/kg on soil and plants, as well as the predictive model of the growth response of M. cuneatum, it is suggested to investigate EDTA levels above 2.4 mmol/kg to determine the precise dose that initiates negative effects in soil and plants.
