# Impact of 50 Hz Electromagnetic Field on the Growth of _Chlorella vulgaris_  
[PERSON]  
1 Research-Development Institute for Environmental Protection Technologies and Equipment, S.C. ICPE Bstritza S.A., Parcului Str., No. 7, 240035 Bstritza, Romania; [EMAIL_ADDRESS] (IL); [PERSON]IL_ADDRESS] (M.V.J. ); [EMAIL_ADDRESS] (A.T.); [EMAIL_ADDRESS] (C.B.) [PERSON]  
1 Research-Development Institute for Environmental Protection Technologies and Equipment, S.C. ICPE Bstritza S.A., Parcului Str., No. 7, 240035 Bstritza, Romania; [EMAIL_ADDRESS] (IL); [PERSON]IL_ADDRESS] (M.V.J. ); [EMAIL_ADDRESS] (A.T.); [EMAIL_ADDRESS] (C.B.) [PERSON]  
2 National Institute for Research and Development in Electrical Engineering ICTE-CA Bucharest, 313 Splaiul Un  
intestinal Lactobacillus). _Spirulina_ sp. and _Dunaliella_ sp., due to their high content in carotenoids, have demonstrated anticancer effects [5; 6; 7]. Different studies have explored the proper conditions for efficient algal biomass growth [8; 9; 10], with wastewater proving to be a suitable environment. On the other hand, through their oil content, oil-rich algae represent a renewable energy source. Thus, the third-generation biofuels are based on algal biomass production [11]. In this context, the demand for algal biomass--a product with increased added value--on the world market shows an upward trend [7; 11]. The photobiochemical processes are relatively slow, which makes the productivity of bioreactors, including microalgae growth photobioreactors, relatively low, which has a substantial influence on production costs [2; 12]. In this context, it is considered that research aimed at stimulating the processes of metabolism and growth of microalgae represents a way to reduce production costs, thus presenting economic importance. Numerous studies have highlighted the fact that electromagnetic fields (EMFs) can influence the mechanism and kinetics of cellular biochemical processes of microorganisms [13; 14; 15; 16; 17; 18]. The exhaustive investigations of [PERSON] et al. [19] and, more recently, [PERSON] et al. [20] show that by exposing biomass to an electromagnetic field, under certain specific conditions (waveform, frequency, applied field intensity), certain biochemical processes can be significantly modified. The excellently documented study of [PERSON] et al. [21] regarding the influences of magnetic fields of natural origin (magnetic storms) and/or anthropogenic causes (electromagnetic pollution of the environment [22; 23; 24] with an extremely-low-frequency EMF in the 0-1 kHz range) demonstrated complex biological effects. The changes produced by ELF-EMF exposure in the mechanism and kinetics of biochemical processes are correlated with dielectric relaxation in biological systems. Thus, they are selectively produced at a proper frequency given by the relaxation frequency of certain chemical species (polarized molecules--with dipole moment) present in the system [21]. Dielectric spectroscopy is a useful tool for studying the behavior of biological systems in a sinusoidal electric field [24; 25; 26; 27]. The rapid method of determining the proper frequency at which changes occur in the behavior of biochemical systems is based on the technique of dielectric spectroscopy [28]. Thus, by studying the dielectric behavior of the active sludge suspension from wastewater treatment plants, proper frequencies of 49.9, 99.9, 130.8, and 150.4 Hz were found [17; 27]. Through specific chemical determinations, it was found that the rate of metabolism of wastewater pollutants increases significantly (doubles) following the exposure of the active sludge suspension to a 5 V/m electric field of 50 Hz [17]. Based on these results, a pilot installation was developed for the stimulation by exposure to ELF-EMF of microbiological activity in the biological treatment of wastewater.