6.3.1 Chemical Compounds in Wastewater
6.3.1.1 Inorganic and Organic Chemicals
In wastewater, different types of inorganic constituents occur such as heavy metals,
different salts, oxyhalides (bromate, chlorate, and perchlorate), and types of
nanomaterials whose concentration depends upon their source and degree of treatments received. National (Bureau of Indian Standard) and International agencies
(FAO/WHO) set guidelines for industrial discharge of wastewater to reduce health
risk. These guidelines set limit for the standards for metals and metalloids in the
sewage discharge. Heavy metals and oxyhalides are bioaccumulative in nature and
highly persistent in nature. Due to long-term wastewater irrigation in agriculture
field, the contaminants get rapidly accumulated in soil and cause an adverse effect on
living organisms through food chain contamination. Macronutrients such as nitrogen
and phosphorous also present in excess amount in wastewater stream. These excess
occurrences of macronutrients cause eutrophication in water body due to more algal
growth.
Sources of organic components in wastewater include household wastes (liquid
waste, humic substances, fecal materials through toilets), types of industrial waste,
fats, greases, and oils, etc. Wastewater irrigation of soil is low-cost resource of
macronutrients and organic matter content. These strategies can be successfully
applied in restoration of degraded croplands, eroded soil in hilly areas, or arid and
semi-arid areas (Chatzistathis and Koutsos 2017). Organic materials act as a source
of carbon for microbial growth and also sometimes lead to clogging which promote
growth of microorganism in wastewater. In wastewater treatment process, secondary
treatment is done for organic matter removal through microbial population. Organic
materials present in the wastewater are beneficial for agricultural purpose as it
contain not only organic carbon but also macronutrients, which help in enhancing
the fertility of irrigated soil.
6.3.1.2 Emerging Contaminants
The emerging contaminants (EC) are newly identified compounds, organic in nature,
and released into the environment by anthropogenic activities (Yankui et al. 2019).
The pharmaceutical companies of personal care products, pesticides synthesizer,
household chemicals, transformation products, etc., are mostly responsible for their
generation. ECs include different natural or synthetic hormones, pharmaceutical
products, endocrine disrupting compounds, artificial sweetener, etc. These contaminants are new in the origin, have alternate route to human exposure. A sequence of
biological treatment coupled with advanced tertiary treatment such as activated
carbon adsorption or chemical oxidation is used to remove such trace chemicals
from wastewater.
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6.3.1.1 Inorganic and Organic Chemicals
In wastewater, different types of inorganic constituents occur such as heavy metals,
different salts, oxyhalides (bromate, chlorate, and perchlorate), and types of
nanomaterials whose concentration depends upon their source and degree of treatments received. National (Bureau of Indian Standard) and International agencies
(FAO/WHO) set guidelines for industrial discharge of wastewater to reduce health
risk. These guidelines set limit for the standards for metals and metalloids in the
sewage discharge. Heavy metals and oxyhalides are bioaccumulative in nature and
highly persistent in nature. Due to long-term wastewater irrigation in agriculture
field, the contaminants get rapidly accumulated in soil and cause an adverse effect on
living organisms through food chain contamination. Macronutrients such as nitrogen
and phosphorous also present in excess amount in wastewater stream. These excess
occurrences of macronutrients cause eutrophication in water body due to more algal
growth.
Sources of organic components in wastewater include household wastes (liquid
waste, humic substances, fecal materials through toilets), types of industrial waste,
fats, greases, and oils, etc. Wastewater irrigation of soil is low-cost resource of
macronutrients and organic matter content. These strategies can be successfully
applied in restoration of degraded croplands, eroded soil in hilly areas, or arid and
semi-arid areas (Chatzistathis and Koutsos 2017). Organic materials act as a source
of carbon for microbial growth and also sometimes lead to clogging which promote
growth of microorganism in wastewater. In wastewater treatment process, secondary
treatment is done for organic matter removal through microbial population. Organic
materials present in the wastewater are beneficial for agricultural purpose as it
contain not only organic carbon but also macronutrients, which help in enhancing
the fertility of irrigated soil.
6.3.1.2 Emerging Contaminants
The emerging contaminants (EC) are newly identified compounds, organic in nature,
and released into the environment by anthropogenic activities (Yankui et al. 2019).
The pharmaceutical companies of personal care products, pesticides synthesizer,
household chemicals, transformation products, etc., are mostly responsible for their
generation. ECs include different natural or synthetic hormones, pharmaceutical
products, endocrine disrupting compounds, artificial sweetener, etc. These contaminants are new in the origin, have alternate route to human exposure. A sequence of
biological treatment coupled with advanced tertiary treatment such as activated
carbon adsorption or chemical oxidation is used to remove such trace chemicals
from wastewater.
6 Wastewater Reuse in Peri-Urban Agriculture Ecosystem: Current Scenario,. . .
127