Overpopulation, industrialization, rapid urbanization, unplanned land use pattern,
overexploitation of groundwater, chemical spills, storage tank leakage, unmanaged
transportation, overuse, and surface runoff of agriculture fertilizers, etc., are the main
cause of wastewater generation (Xia et al. 2017). Only one-tenth part of total
generated sewage is treated and only one-third part of total urban household are
connected to closed sewerage system (Sugam and Ghosh 2013). Most of the
industries are not capable to treat wastewater due to their higher cost of operation
and conventional chemicals. According to CPCB (2013), the total amount of sewage
generation from 35 metropolitan cities (population one million and above) is 15,644
MLD and the treatment capacity is for 8040 MLD, i.e., only 51%.
Reuse of wastewater increased in the developed countries than developing
countries due to the availability of more resources or facilities, e.g., in Europe and
United States wastewater reuse increased 10–29% per year, and in Australia it
increased up to 41% per year (Aziz and Farissi 2014).
For treatment of wastewater, types of sustainable infrastructure continuously
increase by using several approaches such as physico-chemical approaches (sedimentation, chemical precipitation, adsorption, ion exchange, coagulation, catalytic
removal, and nanotechnology) and biological or green approaches (different types of
bioreactors, trickling filters and rotating biological contactor). By emphasizing these
several techniques, we are expected to understand that how the wastewater is easily
collected through drainage system, well treated, discharged, and reutilized. But
unfortunately, in present time progress toward these several sustainable approaches
is not well evenly distributed among all the nations (Rarasati et al. 2017).
There are several factors which affect the wastewater irrigation in agriculture
field, e.g., chances of availability of freshwater or groundwater through tube well or
canals for irrigation at affordable rates, consistency and reliability of wastewater
generation through drainage system, level of nutrients in wastewater, acidity, alkalinity or salinity level of wastewater, contamination level of industrial effluents in
wastewater, etc. Instead of freshwater irrigation, agriculture field irrigated by wastewater due to freshwater scarcity lead to food chain contamination, i.e., heavy metals
transfer from soil to food plants (Fig. 6.1). Mobility of heavy metal depends upon its
bioavailability in soil (present in different chemical forms) as well as its translocation
and distribution varies by the species and population of plants (Liu et al. 2007;
Sharma et al. 2020a).
Knowledge of the long-term impact of wastewater irrigation on metal or metalloid dynamics in soil-plant system should be improved for maximizing the benefits
of wastewater irrigation as a viable source. Muchuweti et al. (2006) suggested drip
irrigation method as a suitable and eco-friendly approach for mitigating the negative
effect of wastewater irrigation on soil properties whereas flood irrigation in agriculture field badly affected the soil qualities. In present time, it becomes necessary to
think about the existing urban wastewater disposal infrastructure, wastewater agriculture practices, quality of water consumed and its health implications, and the level
of institutional awareness on wastewater-related issues (Rutkowski et al. 2007). By
re-engineering the whole treatment plant structure, energy can be saved in wastewater treatment plants for increasing its reliability and efficiency. Combined heat
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P. K. Singh and R. K. Sharma
overexploitation of groundwater, chemical spills, storage tank leakage, unmanaged
transportation, overuse, and surface runoff of agriculture fertilizers, etc., are the main
cause of wastewater generation (Xia et al. 2017). Only one-tenth part of total
generated sewage is treated and only one-third part of total urban household are
connected to closed sewerage system (Sugam and Ghosh 2013). Most of the
industries are not capable to treat wastewater due to their higher cost of operation
and conventional chemicals. According to CPCB (2013), the total amount of sewage
generation from 35 metropolitan cities (population one million and above) is 15,644
MLD and the treatment capacity is for 8040 MLD, i.e., only 51%.
Reuse of wastewater increased in the developed countries than developing
countries due to the availability of more resources or facilities, e.g., in Europe and
United States wastewater reuse increased 10–29% per year, and in Australia it
increased up to 41% per year (Aziz and Farissi 2014).
For treatment of wastewater, types of sustainable infrastructure continuously
increase by using several approaches such as physico-chemical approaches (sedimentation, chemical precipitation, adsorption, ion exchange, coagulation, catalytic
removal, and nanotechnology) and biological or green approaches (different types of
bioreactors, trickling filters and rotating biological contactor). By emphasizing these
several techniques, we are expected to understand that how the wastewater is easily
collected through drainage system, well treated, discharged, and reutilized. But
unfortunately, in present time progress toward these several sustainable approaches
is not well evenly distributed among all the nations (Rarasati et al. 2017).
There are several factors which affect the wastewater irrigation in agriculture
field, e.g., chances of availability of freshwater or groundwater through tube well or
canals for irrigation at affordable rates, consistency and reliability of wastewater
generation through drainage system, level of nutrients in wastewater, acidity, alkalinity or salinity level of wastewater, contamination level of industrial effluents in
wastewater, etc. Instead of freshwater irrigation, agriculture field irrigated by wastewater due to freshwater scarcity lead to food chain contamination, i.e., heavy metals
transfer from soil to food plants (Fig. 6.1). Mobility of heavy metal depends upon its
bioavailability in soil (present in different chemical forms) as well as its translocation
and distribution varies by the species and population of plants (Liu et al. 2007;
Sharma et al. 2020a).
Knowledge of the long-term impact of wastewater irrigation on metal or metalloid dynamics in soil-plant system should be improved for maximizing the benefits
of wastewater irrigation as a viable source. Muchuweti et al. (2006) suggested drip
irrigation method as a suitable and eco-friendly approach for mitigating the negative
effect of wastewater irrigation on soil properties whereas flood irrigation in agriculture field badly affected the soil qualities. In present time, it becomes necessary to
think about the existing urban wastewater disposal infrastructure, wastewater agriculture practices, quality of water consumed and its health implications, and the level
of institutional awareness on wastewater-related issues (Rutkowski et al. 2007). By
re-engineering the whole treatment plant structure, energy can be saved in wastewater treatment plants for increasing its reliability and efficiency. Combined heat
122
P. K. Singh and R. K. Sharma