numbers to minimize health hazards is a very desirable goal (Abdel-Raouf et al.
2012).
A variety of physical or chemical methods are capable of destroying microorganisms under certain conditions. Physical methods might include, for example,
heating to boiling or incineration or irradiation with X-rays or ultraviolet rays.
Chemical methods might theoretically include the use of strong acids, alcohols, or
a variety of oxidizing chemicals or surface active agents (such as special detergents). However, the treatment of wastewaters for the destruction of pathogens
demands the use of practical measures that can be used economically and efficiently at all times on large quantities of wastewaters which have been treated at
various degrees (Pablos et al. 2013).
The prevalent use of chlorine has come about because chlorine is an excellent
disinfecting chemical and, until recently, has been available at a reasonable cost.
However, the rising cost of chlorine coupled with the fact that chlorine even at low
concentrations is toxic to fish and other biota, as well as the possibility that
potentially harmful chlorinated hydrocarbons may be formed, has made chlorination less favored as the disinfectant of choice in wastewater treatment. As a
result, newer technologies are showing promising results, such as the use of nanocatalysts like titanium dioxide (TiO 2 ) as disinfection agent by the photocatalysis
process (Bodaghi et al. 2013; Fang et al. 2013; Hossain et al. 2014; Lin et al. 2013;
Liu et al. 2013; Wang and Lim 2013).
Another important process related to wastewater treatment is that of metal
removal to obtain the best water quality for reuse in food production (Bonnett et al.
2006; Lalov et al. 2000).
Heavy metal ions and waste dye are two major industrial pollutants, and many
methods have been developed to remove them from wastewater (Ahluwalia and
Goyal 2005; Nguyen et al. 2006; Monteagudo et al. 2006; Asma et al. 2006). In
recent years, various methods including foam flotation, filtration, microbial
reduction, chemical oxidation, reverse osmosis, coagulation and flocculation,
biological treatments, photo degradation, and adsorption have been developed for
treating dye contaminated wastewater. Among these methods, adsorption is known
to be a promising technique due to the ease of operation and comparable low cost
of application. These processes may be ineffective or extremely expensive,
especially when the metals in solution are in the range of 1–100 mg/L (Liu and Lu
2011; Kasmuri et al. 2011).
Heavy metal pollution represents an important environmental problem; environmental contamination by heavy metals is of growing concern because of health
risks on live organisms. At least 20 metals are classified as toxic and half of these
are emitted into the environment in quantities that pose risks to human health.
Accumulation of metals like Cd, Cr, Cu, Hg, and Zn, in humans has several
consequences such as growth and developmental abnormalities, mental retardation, and a wide range of other illnesses (Liu and Lu 2011; Kortenkamp et al.
1996; Wang et al. 2008; Thiele 1995).
The above-mentioned are traditional methods of effluent treatment, nevertheless
these methods have to be supplemented with modern and more effective means of
3 Water Recycling in Biosystems for Food Production
81
2012).
A variety of physical or chemical methods are capable of destroying microorganisms under certain conditions. Physical methods might include, for example,
heating to boiling or incineration or irradiation with X-rays or ultraviolet rays.
Chemical methods might theoretically include the use of strong acids, alcohols, or
a variety of oxidizing chemicals or surface active agents (such as special detergents). However, the treatment of wastewaters for the destruction of pathogens
demands the use of practical measures that can be used economically and efficiently at all times on large quantities of wastewaters which have been treated at
various degrees (Pablos et al. 2013).
The prevalent use of chlorine has come about because chlorine is an excellent
disinfecting chemical and, until recently, has been available at a reasonable cost.
However, the rising cost of chlorine coupled with the fact that chlorine even at low
concentrations is toxic to fish and other biota, as well as the possibility that
potentially harmful chlorinated hydrocarbons may be formed, has made chlorination less favored as the disinfectant of choice in wastewater treatment. As a
result, newer technologies are showing promising results, such as the use of nanocatalysts like titanium dioxide (TiO 2 ) as disinfection agent by the photocatalysis
process (Bodaghi et al. 2013; Fang et al. 2013; Hossain et al. 2014; Lin et al. 2013;
Liu et al. 2013; Wang and Lim 2013).
Another important process related to wastewater treatment is that of metal
removal to obtain the best water quality for reuse in food production (Bonnett et al.
2006; Lalov et al. 2000).
Heavy metal ions and waste dye are two major industrial pollutants, and many
methods have been developed to remove them from wastewater (Ahluwalia and
Goyal 2005; Nguyen et al. 2006; Monteagudo et al. 2006; Asma et al. 2006). In
recent years, various methods including foam flotation, filtration, microbial
reduction, chemical oxidation, reverse osmosis, coagulation and flocculation,
biological treatments, photo degradation, and adsorption have been developed for
treating dye contaminated wastewater. Among these methods, adsorption is known
to be a promising technique due to the ease of operation and comparable low cost
of application. These processes may be ineffective or extremely expensive,
especially when the metals in solution are in the range of 1–100 mg/L (Liu and Lu
2011; Kasmuri et al. 2011).
Heavy metal pollution represents an important environmental problem; environmental contamination by heavy metals is of growing concern because of health
risks on live organisms. At least 20 metals are classified as toxic and half of these
are emitted into the environment in quantities that pose risks to human health.
Accumulation of metals like Cd, Cr, Cu, Hg, and Zn, in humans has several
consequences such as growth and developmental abnormalities, mental retardation, and a wide range of other illnesses (Liu and Lu 2011; Kortenkamp et al.
1996; Wang et al. 2008; Thiele 1995).
The above-mentioned are traditional methods of effluent treatment, nevertheless
these methods have to be supplemented with modern and more effective means of
3 Water Recycling in Biosystems for Food Production
81