11 Sludge Hygienisation—A Novel Technology for Urban Areas …
265
order to ensure that the sewage sludge from the dense urban centres in India is free
from contagious and hazardous pathogens.
Urban wastewater (UWW) typically comprises of domestic, agricultural, commercial and industrial components, as well as, the faecal sludge [3]. In addition to
the abovementioned components, another pivotal, as well as, critical component
of UWW is the wastewater released from the healthcare establishments in the urban
centres [11]. The criticality of the individual components in determining the overall
quality of the municipal wastewater stream depends on the constituents and the
success of the strategies aimed at controlling the discharge of pollutants in the
wastewater streams is largely dependent on the identification and quantification of
the sources [12].
Typically, the domestic wastewater (DWW) comprises of simple elements, mainly
carbon (C), nitrogen (N) and phosphorus (P), as well as, biodegradable macromolecules coming from fat, oil, starch and grease (e.g. amino acids, proteins and
polysaccharides) [13], accompanied by other organic materials (e.g. creatinine, urea,
etc.), detergents, pesticides, toxic metals (e.g. Hg, Pb, Cd, Cr, Cu, Ni) and microorganisms such as pathogenic bacteria, virus and worm eggs [14]. The principal source
of metals in the DWW stream is the faecal matter and every kilogram of faecal matter
typically adds about 250 mg of Zn, 70 mg of Cu, 10 mg of Pb, 5 mg of Ni and 2 mg
of Cd to the DWW in the form dissolved solids [12]. In the areas where the running
water possesses higher extent of hardness, more than 50% of Cu load in DWW
comes from the plumbing work that is done especially for the hot water installations,
and in the areas with extensive Pb pipework, typically 25% of the total Pb load is
attributed to the pipes used for water conveyance [12]. The other identified sources of
metals in the DWW include body-care products, pharmaceuticals, cleaning products
and liquid wastes. DWW potentially contains four main groups of pathogens, viz.
bacteria, viruses, protozoa and helminths, and they are known to enter the wastewater
stream through the human excreta (faecal sludge). Although the faeces of an average
human being contain a very large number of bacteria (>10
10 /g), in case of a healthy
person most of these bacteria are not pathogenic (e.g. E. Coli). Pathogenic or potentially pathogenic bacteria occurs in large numbers in the intestinal track only when
an infection occurs and those are passed on to the faeces, thereby increasing the risk
of spreading the infection to the adjacent communities. Bacteria population responsible for diarrhoea, cholera, typhoid, paratyphoid and other Salmonella type diseases
occur frequently in the human faeces, and hence, there is a substantial chance of their
presence in the DWW as well [15]. Numerous viruses are known to infect humans
and the typical viral load in the faeces of an infected person is more than 10
9 /g. In the
human excreta, five group of viruses, viz. human adenoviruses (e.g. HAdV-C (relative abundance 78%) and HAdV-B (relative abundance 20%)) [16], enteroviruses
(e.g. polioviruses), diarrhoea-causing viruses (e.g. rotavirus), hepatitis-A virus and
reoviruses have been predominantly observed. Hence, their presence is also possible
in the DWW streams. Additionally, three species of pathogenic protozoa that cause
diarrhoea and dysentery, viz. Balantidium coli, Entamoeba histolytica and Giardia
lamblia; and also the eggs or larval forms belonging to two groups of helminths
(parasitic worms), viz. roundworm and flatworm are found in the human faeces,
265
order to ensure that the sewage sludge from the dense urban centres in India is free
from contagious and hazardous pathogens.
Urban wastewater (UWW) typically comprises of domestic, agricultural, commercial and industrial components, as well as, the faecal sludge [3]. In addition to
the abovementioned components, another pivotal, as well as, critical component
of UWW is the wastewater released from the healthcare establishments in the urban
centres [11]. The criticality of the individual components in determining the overall
quality of the municipal wastewater stream depends on the constituents and the
success of the strategies aimed at controlling the discharge of pollutants in the
wastewater streams is largely dependent on the identification and quantification of
the sources [12].
Typically, the domestic wastewater (DWW) comprises of simple elements, mainly
carbon (C), nitrogen (N) and phosphorus (P), as well as, biodegradable macromolecules coming from fat, oil, starch and grease (e.g. amino acids, proteins and
polysaccharides) [13], accompanied by other organic materials (e.g. creatinine, urea,
etc.), detergents, pesticides, toxic metals (e.g. Hg, Pb, Cd, Cr, Cu, Ni) and microorganisms such as pathogenic bacteria, virus and worm eggs [14]. The principal source
of metals in the DWW stream is the faecal matter and every kilogram of faecal matter
typically adds about 250 mg of Zn, 70 mg of Cu, 10 mg of Pb, 5 mg of Ni and 2 mg
of Cd to the DWW in the form dissolved solids [12]. In the areas where the running
water possesses higher extent of hardness, more than 50% of Cu load in DWW
comes from the plumbing work that is done especially for the hot water installations,
and in the areas with extensive Pb pipework, typically 25% of the total Pb load is
attributed to the pipes used for water conveyance [12]. The other identified sources of
metals in the DWW include body-care products, pharmaceuticals, cleaning products
and liquid wastes. DWW potentially contains four main groups of pathogens, viz.
bacteria, viruses, protozoa and helminths, and they are known to enter the wastewater
stream through the human excreta (faecal sludge). Although the faeces of an average
human being contain a very large number of bacteria (>10
10 /g), in case of a healthy
person most of these bacteria are not pathogenic (e.g. E. Coli). Pathogenic or potentially pathogenic bacteria occurs in large numbers in the intestinal track only when
an infection occurs and those are passed on to the faeces, thereby increasing the risk
of spreading the infection to the adjacent communities. Bacteria population responsible for diarrhoea, cholera, typhoid, paratyphoid and other Salmonella type diseases
occur frequently in the human faeces, and hence, there is a substantial chance of their
presence in the DWW as well [15]. Numerous viruses are known to infect humans
and the typical viral load in the faeces of an infected person is more than 10
9 /g. In the
human excreta, five group of viruses, viz. human adenoviruses (e.g. HAdV-C (relative abundance 78%) and HAdV-B (relative abundance 20%)) [16], enteroviruses
(e.g. polioviruses), diarrhoea-causing viruses (e.g. rotavirus), hepatitis-A virus and
reoviruses have been predominantly observed. Hence, their presence is also possible
in the DWW streams. Additionally, three species of pathogenic protozoa that cause
diarrhoea and dysentery, viz. Balantidium coli, Entamoeba histolytica and Giardia
lamblia; and also the eggs or larval forms belonging to two groups of helminths
(parasitic worms), viz. roundworm and flatworm are found in the human faeces,