(US EPA 2012), Escherichia coli maximum value is 10 CFU/100 mL (WHO 2006),
and nematode eggs less than or equal to 1 (WHO 2006). The raw effluent is generally
disposed of on agricultural lands within urban and peri-urban areas to grow vegetables even though it contains a range of contaminants such as metal ions (Siebe 1998;
Bouwer 2000; Qadir et al. 2000; Elgallal et al. 2016). Wastewater has several
benefits, but an excessive amount of heavy metals is the inevitable part of wastewater. India’s maximum value of iron and zinc is 7.74 and 3.24, respectively, in
wastewater. Wastewater reuse in irrigation has some regulations and standards that
have been recommended by many countries and international agencies (CPCB,
FAO, WHO, US EPA).
Biological characteristics are an important factor in wastewater. According to
Sarkar et al. (2018), the main concerns of the microorganism group in wastewater are
bacteria, fungi, algae, protozoa, viruses, and pathogenic microorganisms. Some
important bacteria are Pseudomonas sp., which reduces NO 3 to NO 2 , and
Acinetobacter sp., which stores large amounts of phosphates under aerobic conditions and releases it under an anaerobic condition (Jin et al. 2015a, b). Wastewater
also contains several fungal species, which mainly help in decomposing the complex
organic matter to its simple forms. The microbial population of wastewater also
includes different types of algal species, which execute eutrophication phenomenon
and oxidation of ponds; protozoa, which mainly feed on bacteria and help in the
purification of treated wastewater; and viruses (Szymanski and Patterson 2003;
Sarkar et al. 2018) (Table 8.1).
8.4 Effect of Wastewater Irrigation
8.4.1 On Physicochemical Properties of Soil
The response of irrigating soils with wastewater has been extensively studied
(Kayikcioglu 2012; Durán–Álvarez and Jiménez–Cisneros 2014). Wastewater is a
repository of nutrients and improves soil properties. Irrigating soil with wastewater
is an attractive option because it can improve the physical, chemical, biological, and
biochemical properties of soil (Pomares et al. 1984; Kiziloglu et al. 2008). Physical
properties are found to be improved such as electrical conductivity (EC), organic
matter, cation exchange capacity, and water-holding capacity (Aydin et al. 2015),
and it also maintains the stability of the soil aggregates and soil porosity (Durán–
Álvarez and Jiménez–Cisneros 2014). Wastewater-irrigated soils showed slightly
lower pH values compared to non-wastewater-irrigated, probably due to the high
organic matter content of irrigation water (Nayak et al. 2007; Mosse et al. 2011).
Kulandaivelu and Bhat (2012) amended coffee processing wastewater (CPW) at
different loading rates such as 25, 50, 75, and 100 L per 1 m
2 at 0–15 cm soil depth.
The application of higher rate of CPW, leads to significant increase in the bulk
density (BD) and water-holding capacity (WHC), as well reduced the soil
8 Application of Wastewater in Irrigation and Its Regulation with Special. . .
181
and nematode eggs less than or equal to 1 (WHO 2006). The raw effluent is generally
disposed of on agricultural lands within urban and peri-urban areas to grow vegetables even though it contains a range of contaminants such as metal ions (Siebe 1998;
Bouwer 2000; Qadir et al. 2000; Elgallal et al. 2016). Wastewater has several
benefits, but an excessive amount of heavy metals is the inevitable part of wastewater. India’s maximum value of iron and zinc is 7.74 and 3.24, respectively, in
wastewater. Wastewater reuse in irrigation has some regulations and standards that
have been recommended by many countries and international agencies (CPCB,
FAO, WHO, US EPA).
Biological characteristics are an important factor in wastewater. According to
Sarkar et al. (2018), the main concerns of the microorganism group in wastewater are
bacteria, fungi, algae, protozoa, viruses, and pathogenic microorganisms. Some
important bacteria are Pseudomonas sp., which reduces NO 3 to NO 2 , and
Acinetobacter sp., which stores large amounts of phosphates under aerobic conditions and releases it under an anaerobic condition (Jin et al. 2015a, b). Wastewater
also contains several fungal species, which mainly help in decomposing the complex
organic matter to its simple forms. The microbial population of wastewater also
includes different types of algal species, which execute eutrophication phenomenon
and oxidation of ponds; protozoa, which mainly feed on bacteria and help in the
purification of treated wastewater; and viruses (Szymanski and Patterson 2003;
Sarkar et al. 2018) (Table 8.1).
8.4 Effect of Wastewater Irrigation
8.4.1 On Physicochemical Properties of Soil
The response of irrigating soils with wastewater has been extensively studied
(Kayikcioglu 2012; Durán–Álvarez and Jiménez–Cisneros 2014). Wastewater is a
repository of nutrients and improves soil properties. Irrigating soil with wastewater
is an attractive option because it can improve the physical, chemical, biological, and
biochemical properties of soil (Pomares et al. 1984; Kiziloglu et al. 2008). Physical
properties are found to be improved such as electrical conductivity (EC), organic
matter, cation exchange capacity, and water-holding capacity (Aydin et al. 2015),
and it also maintains the stability of the soil aggregates and soil porosity (Durán–
Álvarez and Jiménez–Cisneros 2014). Wastewater-irrigated soils showed slightly
lower pH values compared to non-wastewater-irrigated, probably due to the high
organic matter content of irrigation water (Nayak et al. 2007; Mosse et al. 2011).
Kulandaivelu and Bhat (2012) amended coffee processing wastewater (CPW) at
different loading rates such as 25, 50, 75, and 100 L per 1 m
2 at 0–15 cm soil depth.
The application of higher rate of CPW, leads to significant increase in the bulk
density (BD) and water-holding capacity (WHC), as well reduced the soil
8 Application of Wastewater in Irrigation and Its Regulation with Special. . .
181