Keywords
Wastewater treatment Á Resource recovery Á Microalgae Á Phosphate accumulating organisms (PAOs) Á Phosphorous recovery Á Anoxygenic phototrophic
bacteria (APB) Á Purple phototrophic bacteria (PPB) Á Polyhydroxyalkanoates Á
Purple phototrophic bacteria ponds
1 Introduction
In the last decades, the world has been facing several environmental problems
created by pollution, increasing urbanization and resources over-exploitation. Pollutants have spread throughout nature as mixtures of organic and inorganic compounds originated from industrial activity (e.g., petrochemical, dye, manufacturing,
paper industry), agriculture and commuting (e.g., traffic emissions) [1]. Water and
soils are under constant pressure from accumulation of recalcitrant compounds, and
CO 2 concentrations in the atmosphere have reached alarming values, with more
than a 30% rise in comparison to pre-industrial levels [2]. The existence of such
high levels of hazard and polluting components in the environment is affecting
human and animals’ health, as well as damaging ecosystems and contributing to
global warming and climate change [3, 4].
Since it is increasingly urgent to control pollution, prevent water streams contamination, and recover soil fertility, it is fundamental to develop efficient, clean,
and environmentally sound technologies and adopt the use of sustainable alternatives to conventional everyday products. Although these practices may seem to
conflict with economic development, research and industries are focusing on
developing new, low-cost, and eco-friendly technologies that can couple environmental protection with economic growth. With both physical/chemical and biological approaches at hand, biological strategies have been the subject of great
development, making use of living organisms (microorganisms and plants), that can
be environmentally friendly and can efficiently promote the complete conversion of
toxic molecules into safe end products [5]. Also, biological systems can be applied
to processes for which efficient chemical solutions are yet to be developed. Such
wide application of biological systems to different environmental scenarios is
founded on the richness of metabolic pathways that are present in living organisms
which makes them natural catalysts that can play an important role in solving most
environmental issues [5–7]. Enzymes are the main effectors of the metabolic
pathways being able to detoxify polluting substances and transform them into safer
and innocuous products [1]. These biomolecules can perform very specific chemical
transformations, making them attractive not only for environmental applications but
also for industrial processes. Either intracellularly (inside of their originating cells)
or extracellularly (in the presence or absence of their originating cells), free or
immobilized, enzymes have been used as green alternatives to complex chemicals
414
J. C. Fradinho et al.
Wastewater treatment Á Resource recovery Á Microalgae Á Phosphate accumulating organisms (PAOs) Á Phosphorous recovery Á Anoxygenic phototrophic
bacteria (APB) Á Purple phototrophic bacteria (PPB) Á Polyhydroxyalkanoates Á
Purple phototrophic bacteria ponds
1 Introduction
In the last decades, the world has been facing several environmental problems
created by pollution, increasing urbanization and resources over-exploitation. Pollutants have spread throughout nature as mixtures of organic and inorganic compounds originated from industrial activity (e.g., petrochemical, dye, manufacturing,
paper industry), agriculture and commuting (e.g., traffic emissions) [1]. Water and
soils are under constant pressure from accumulation of recalcitrant compounds, and
CO 2 concentrations in the atmosphere have reached alarming values, with more
than a 30% rise in comparison to pre-industrial levels [2]. The existence of such
high levels of hazard and polluting components in the environment is affecting
human and animals’ health, as well as damaging ecosystems and contributing to
global warming and climate change [3, 4].
Since it is increasingly urgent to control pollution, prevent water streams contamination, and recover soil fertility, it is fundamental to develop efficient, clean,
and environmentally sound technologies and adopt the use of sustainable alternatives to conventional everyday products. Although these practices may seem to
conflict with economic development, research and industries are focusing on
developing new, low-cost, and eco-friendly technologies that can couple environmental protection with economic growth. With both physical/chemical and biological approaches at hand, biological strategies have been the subject of great
development, making use of living organisms (microorganisms and plants), that can
be environmentally friendly and can efficiently promote the complete conversion of
toxic molecules into safe end products [5]. Also, biological systems can be applied
to processes for which efficient chemical solutions are yet to be developed. Such
wide application of biological systems to different environmental scenarios is
founded on the richness of metabolic pathways that are present in living organisms
which makes them natural catalysts that can play an important role in solving most
environmental issues [5–7]. Enzymes are the main effectors of the metabolic
pathways being able to detoxify polluting substances and transform them into safer
and innocuous products [1]. These biomolecules can perform very specific chemical
transformations, making them attractive not only for environmental applications but
also for industrial processes. Either intracellularly (inside of their originating cells)
or extracellularly (in the presence or absence of their originating cells), free or
immobilized, enzymes have been used as green alternatives to complex chemicals
414
J. C. Fradinho et al.