The properties of water and soil change due to release of toxic chemicals during
various operations carried out by industries. The effluents often contain high level of
biological oxygen demand (BOD) and chemical oxygen demand (COD), low level
of dissolved oxygen (DO), and high concentration of toxic metals such as cadmium,
chromium, and lead, polyaromatic hydrocarbons (PAHs), petrochemicals, phenolic
compounds, and dioxin. Sludges generated from various industrial sectors have also
been utilized in various agricultural uses due to the fact that significant amount of
nitrogen, phosphorus, and other organic matters are available in industrial as well as
domestic sludge (Warman and Termeer 2005).
7.5 Biological and Natural Treatment of Effluents
and Sludge
Wastewater from municipal sewage and industry effluent mainly consists of both
organic and inorganic waste. It may also contain various forms of pathogenic
organisms, heavy metals, carcinogens, and toxins. So proper treatment of this
wastewater before discharging it into the land or to the water source is the need of
the hour. The amount of contaminated wastewater can be treated before being
discharged into the natural ecosystems (Escapa et al. 2015). In dry climates, a
practical alternative to wastewater treatment process is recycling that can help to
solve limited water resource problem (Almuktar et al. 2015). Over the past few
decades, several methods like physical, chemical, and biological methods have been
reported such as flotation, precipitation, oxidation, solvent extraction, evaporation,
carbon adsorption, ion exchange, membrane filtration, electrochemistry, biodegradation, and phytoremediation (Berefield et al. 1982; Liu and Liptak 2000; Harvey
et al. 2002; Chen 2004; Forgacs et al. 2004; Anjaneyulu et al. 2005; Crini and Badot
2010; Cox et al. 2007; Hai et al. 2007; Barakat 2011; Rathoure and Dhatwalia 2016;
Morin-Crini and Crini 2017). But among the given methods, management of
wastewater through biological treatment has become a trend in the recent year. It
is basically depending upon the biological organisms to break down organic wastes
into simpler forms using normal cellular processes. In contrast to physiochemical
processes, biological treatment/processes of wastewater can remove organic contaminants like biodegradable organic material with the help of microbiological and
plant metabolic activities. Biological treatment is also known as secondary treatment
of wastewater in which microbial communities are mainly used, under varying
growth conditions, to biochemically decompose organic compounds in the waste
that have passed from primary treatment units. Biological treatment methods include
aerobic treatment and anaerobic treatment sometimes through phytoremediation also
is common. Depending on the availability and utilization of oxygen, the biological
processes are classified as aerobic and anaerobic and as per the uses of plant and the
organisms as bioremediation and phytoremediation.
7 Natural Biological Treatment of Effluent and Sludges to Combat the Burden of. . .
111
various operations carried out by industries. The effluents often contain high level of
biological oxygen demand (BOD) and chemical oxygen demand (COD), low level
of dissolved oxygen (DO), and high concentration of toxic metals such as cadmium,
chromium, and lead, polyaromatic hydrocarbons (PAHs), petrochemicals, phenolic
compounds, and dioxin. Sludges generated from various industrial sectors have also
been utilized in various agricultural uses due to the fact that significant amount of
nitrogen, phosphorus, and other organic matters are available in industrial as well as
domestic sludge (Warman and Termeer 2005).
7.5 Biological and Natural Treatment of Effluents
and Sludge
Wastewater from municipal sewage and industry effluent mainly consists of both
organic and inorganic waste. It may also contain various forms of pathogenic
organisms, heavy metals, carcinogens, and toxins. So proper treatment of this
wastewater before discharging it into the land or to the water source is the need of
the hour. The amount of contaminated wastewater can be treated before being
discharged into the natural ecosystems (Escapa et al. 2015). In dry climates, a
practical alternative to wastewater treatment process is recycling that can help to
solve limited water resource problem (Almuktar et al. 2015). Over the past few
decades, several methods like physical, chemical, and biological methods have been
reported such as flotation, precipitation, oxidation, solvent extraction, evaporation,
carbon adsorption, ion exchange, membrane filtration, electrochemistry, biodegradation, and phytoremediation (Berefield et al. 1982; Liu and Liptak 2000; Harvey
et al. 2002; Chen 2004; Forgacs et al. 2004; Anjaneyulu et al. 2005; Crini and Badot
2010; Cox et al. 2007; Hai et al. 2007; Barakat 2011; Rathoure and Dhatwalia 2016;
Morin-Crini and Crini 2017). But among the given methods, management of
wastewater through biological treatment has become a trend in the recent year. It
is basically depending upon the biological organisms to break down organic wastes
into simpler forms using normal cellular processes. In contrast to physiochemical
processes, biological treatment/processes of wastewater can remove organic contaminants like biodegradable organic material with the help of microbiological and
plant metabolic activities. Biological treatment is also known as secondary treatment
of wastewater in which microbial communities are mainly used, under varying
growth conditions, to biochemically decompose organic compounds in the waste
that have passed from primary treatment units. Biological treatment methods include
aerobic treatment and anaerobic treatment sometimes through phytoremediation also
is common. Depending on the availability and utilization of oxygen, the biological
processes are classified as aerobic and anaerobic and as per the uses of plant and the
organisms as bioremediation and phytoremediation.
7 Natural Biological Treatment of Effluent and Sludges to Combat the Burden of. . .
111