Production of Biodiesel from Safflower Plant Cultivated Using MBR Treated Wastewater

Nowadays some management changes are necessary to have long-term productivity in agriculture and sustainable energy production. Application of advanced treatment technologies for wastewater is so important to generate cost-effective and potentially climate-independent water resources with appropriate quality for agricultural irrigation. In this study, safflower plants were cultivated using different irrigation strategies in a field next to a wastewater treatment plant of an industrial zone. Safflower plant (Carthamus tinctorius L.), a member of the Compositeae/Asteraceae family, is a plant tolerant to drought, coldness and salinity compared to other oilseed plants. It has different varieties which could be grown both in summer and winter seasons. This plant has a good potential for the production of edible oil and biodiesel. The irrigation strategies applied were as follows: T1: irrigation with wastewater treated with membrane bioreactor (MBR) process weekly; T2: irrigation with well water weekly; T3: irrigation with MBR treated wastewater during only three phenological periods of the plant; T4: no irrigation was applied. During the cultivation process, qualities of water samples employed for irrigation were analyzed using various instrumental methods. Immediate field measurements were made for pH and electrical conductivity (EC) values. Also suspended solids (SS), total nitrogen (TN) and total phosphate values were measured using DR3900 Benchtop VIS spectrophotometer. Concentrations of some monovalent and divalent cations (Ca2+, Na+, K+ Mg2+) and some heavy metal ions (Zn2+, Cd2+, Pb2+, Ni2+) were measured using Shimadzu AA-7000 model atomic absorption spectrophotometer. Anion concentrations (Cl-, SO42-, NO3-) were measured using LC20AD model ion chromatography equipment. Boron concentration was determined with Azomethine-H method by Jasco V-530 model UV-VIS spectrophotometer. After harvesting, the seeds were separated from the cones of the safflower plant. The seeds were first air dried and then dried in an oven at 60°C for 24 h. The soxhlet extraction system was employed to extract oil from the seeds by using n-hexane as solvent. The oil and n-hexane were separated from each other using a rotary evaporator. For biodiesel production, NaOH was used as catalyst and methanol as alcohol during transesterification process. The mixture of fatty acids methyl esters obtained from the transesterification reaction was purified by successive washing steps with water to remove the remains of methanol, catalyst and glycerol. Finally the traces of water was eliminated by a drying step. After drying, the purified product was characterized as biodiesel according to international standards. As a result of the gas chromatography evaluation for these saffloer oil methyl esters (SOME), the ester contents and ester yields of T1, T2, T3 and T4 were 94.6, 94.5, 94.1 and 94.1 (%, g SOME/g biodiesel) and 71.3, 81.4, 62.1 and 76.4 (%, g biodiesel/g oil), respectively.

Keywords:

Biodiesel , irrigation , safflower , wastewater treatment and reuse , MBR process