# Microalgal Biomass Generation via Electroflotation: A Cost-Effective Dewaring Technology
## 6 Modified Electroflotation to Improve Biomass Production  
Recently, several modified procedures have been included in the conventional electroflotation or combined with other dewatering approaches to reduce their limitations and improve biomass production. For instance, [PERSON] et al. (2016) modified an electroflotation process into a two-stage process that inculcated flocculation with chitosan first and a subsequent sequential bubbling flotation via usage of nonsacrificial graphite electrodes. The study showed that the dosage of chitosan, pH, density of microalgal cells, rate of stirring, time of mixing, intensity of current and voltage, and interelectrode distance influenced the efficiency of flocculation. The above-mentioned approach, when employed to harvest biomass of _Chlorella_ species in a 1000 L pilot electroflotation bench, yielded a concentration rate 50 times that of the input concentration (0.715 g/L) and a total recovery efficiency of 90%, with only 23.7 g of chitosan and 0.43 kWh of electricity needed to harvest 1 kg of biomass [89]. Similarly, [PERSON] et al. (2018) evaluated the process of electroflotation, combined with oxidation, for the effective harvesting of biofloculated algal biomass of green microalgae, _Scenedesmus quadricauda_, with the simultaneous treatment of the residual pollutant in coke wastewater, after an algal-bacterial process. In this study, a novel boron-doped diamond and Al electrode was used for the electroflotation process. The authors reported that, for a near complete harvesting of microalgae, a current density of 15 mA/cm\({}^{2}\) or more with electrolysis time of 40 min with polarity exchange was needed. The study also emphasized that the sequential anodic oxidation via the use of novel electrode possesses the ability to simultaneously mineralize thiocyanate and the residual soluble chemical oxygen demand, which were, otherwise, nondegradable by algal-bacterial mixed culture [90]. Likewise, [PERSON] et al. (2014) investigated the removal of microalgae from Ghrib Dam water in Algeria via electroflotation approach using electrodes from stainless steel. The study revealed that the modification of electroflotation with enhanced electrodes will help in the 100% removal of microalgal biomass, which is influenced by parameters such as current density, initial solution pH, and the interelectrode distance [91]. Recently, [PERSON] (2017) utilized corrosive rectangle electrodes made up of Fe or Al plates for the electrochemical flotation-mediated dewatering of microalgae (_Chlorella_ species). The study demonstrated that by utilizing a current density of 1.5 mA/cm\({}^{2}\) for 30 min, Al was more beneficial to the electroflotation process than Fe as 90% of microalgae was harvested with the former. Additionally, 0.74-1.5 g/L concentration of microalgal biomass was harvested in this study with a power consumption of 1.36 kWh/kg [92]. Further, [PERSON] et al. (2018) designed a unique electroflotation system for the effective harvesting of freshwater microalgae as well as to increase the biomass concentration. In this study, the significance of factors such as voltage, pH, time, and electrode distance as well as types of electrode materials, including Al, steel, Fe, and Cu were studied for the efficient recovery of biomass (_Chlorella vulgaris_ UTEX 1803 microalgal culture). The results revealed that, 1-2 cm of electrode distance within 20 min of electroflotation with 15 V of voltage could yield 40% and 80% of biomass via Cu and Al electrode, respectively. Moreover, an increment in the voltage to 50 V and reaction time to 25 min was proven to increase the biomass recovery efficiency up to 95%, while using Al electrode, as compared to Cu electrode (85%) [77]. Furthermore, [PERSON] et al. (2019) also evaluated the electro-coagulation-flocculation approach for the enhanced harvesting of _Scenedesmus_ microalgal species.