Thus, pH, contact time, and temperature determine the sorption capacity of heavy
metal ions. Researchers have optimized these variables and achieved maximum
biosorption potential of various algal strains, which are shown in Table 3.4. Temperature ranges (20–96
C) with contact time (30–240 min) with optimal pH ranges
were experimentally investigated by various researchers in the last 15 years, using
different algae.
4 Algal Biomass-Based Remediation Approaches for Heavy
Metals: Traditional vs. Advanced
Conventional practices for metal ion removal were dominated by chemical methods
such as chemical-mediated precipitation, redox reactions, ion-exchange resins,
organic polymers (starch, poly ions, and xanthate), coagulation, osmosis,
chemical-induced extraction, adsorption via activated carbon, electroprecipitation,
and electrodialysis (Lezcano et al. 2010). But these methods are found to be costly
and less effective for HM removal (Plaza et al. 2013). Contrary to these methods,
application of inorganic adsorbents such as clay, mud, ash, alum, and other organic
adsorbents (waste biomass, agricultural residues, plant leaf, etc.) was found to be less
expensive, but most of them resulted in incomplete remediation (Zhang et al. 2016;
Lee et al. 2016). These conventional methods demand large amount of energy and
chemicals (Majumder et al. 2015). So, there have been developed, formulated,
modern, economical, and sustainable adsorbents for the removal of HMs and toxic
substances from wastewaters. Most of the researchers have been escalating their
efforts in developing suitable adsorbents for the complete removal of HMs.
Generally, algal-based HM remediation is considered as a part of bioremediation
and involves biosorption either by passive sorption of pollutant independent of
metabolic process or active sorption of pollutant depending on metabolic pathway.
In case of active sorption process, energy generated by respiration is consumed in
metal sorption; hence this process depends on the efficacy of physiological process
of the living algal biomass. In addition to this, environmental variables such as pH,
temperature, contact time, etc., nature of ionic species, biomass concentration,
contact time, and nature of the adsorbent also affect the biosorption capacity.
4.1 Microalgae Potential in HM Remediation
Microalgae belong to the group of photosynthetic organisms and are found in freshas well as marine water environment. These organisms have tremendous photosynthetic efficiency, and about 32% of the global photosynthesis is carried out by
microalgae (Priyadarshani et al. 2011). Microalgae perform the specific mechanism
to uptake the essential heavy metals required to their cell growth. The benefits of
3 Phycoremediation: Algae as Eco-friendly Tools for the Removal of Heavy. . .
63
metal ions. Researchers have optimized these variables and achieved maximum
biosorption potential of various algal strains, which are shown in Table 3.4. Temperature ranges (20–96
C) with contact time (30–240 min) with optimal pH ranges
were experimentally investigated by various researchers in the last 15 years, using
different algae.
4 Algal Biomass-Based Remediation Approaches for Heavy
Metals: Traditional vs. Advanced
Conventional practices for metal ion removal were dominated by chemical methods
such as chemical-mediated precipitation, redox reactions, ion-exchange resins,
organic polymers (starch, poly ions, and xanthate), coagulation, osmosis,
chemical-induced extraction, adsorption via activated carbon, electroprecipitation,
and electrodialysis (Lezcano et al. 2010). But these methods are found to be costly
and less effective for HM removal (Plaza et al. 2013). Contrary to these methods,
application of inorganic adsorbents such as clay, mud, ash, alum, and other organic
adsorbents (waste biomass, agricultural residues, plant leaf, etc.) was found to be less
expensive, but most of them resulted in incomplete remediation (Zhang et al. 2016;
Lee et al. 2016). These conventional methods demand large amount of energy and
chemicals (Majumder et al. 2015). So, there have been developed, formulated,
modern, economical, and sustainable adsorbents for the removal of HMs and toxic
substances from wastewaters. Most of the researchers have been escalating their
efforts in developing suitable adsorbents for the complete removal of HMs.
Generally, algal-based HM remediation is considered as a part of bioremediation
and involves biosorption either by passive sorption of pollutant independent of
metabolic process or active sorption of pollutant depending on metabolic pathway.
In case of active sorption process, energy generated by respiration is consumed in
metal sorption; hence this process depends on the efficacy of physiological process
of the living algal biomass. In addition to this, environmental variables such as pH,
temperature, contact time, etc., nature of ionic species, biomass concentration,
contact time, and nature of the adsorbent also affect the biosorption capacity.
4.1 Microalgae Potential in HM Remediation
Microalgae belong to the group of photosynthetic organisms and are found in freshas well as marine water environment. These organisms have tremendous photosynthetic efficiency, and about 32% of the global photosynthesis is carried out by
microalgae (Priyadarshani et al. 2011). Microalgae perform the specific mechanism
to uptake the essential heavy metals required to their cell growth. The benefits of
3 Phycoremediation: Algae as Eco-friendly Tools for the Removal of Heavy. . .
63