11 Sludge Hygienisation—A Novel Technology for Urban Areas …
273
schematically the possible interaction mechanism between the SARS-CoV-2 particulates and its surrounding, that includes both the host, as well as, the environment.
It encompasses the manifestation in the host, sustenance in the environment and
subsequent transmission into the receptor.
Overall, from the samples analysed at different geographical locations, it has
emerged that the SARS-CoV-2 particles emerging from the infected individuals via
the respiratory droplets and through the faeces cause a definite level of contamination in the environment [61], and it is likely that both the mediums serve as the
potential pathways towards large-scale transmission of the disease, which may eventually lead to community spread. Consequently, the hygienisation becomes an issue
of prime importance. Therefore, apart from thorough sanitization of the spaces of
mass gathering, and maintenance of the hand hygiene at the individual level; it is
also of importance to employ a suitable technology towards hygienising the municipal sewage sludge of the densely populated urban centres, as the sludges serve as
the breeding ground for a lot of pathogens that can be transmitted to the community during the time of handling or through accidental indirect contact with the
contaminated wastewater flowing through the urban canals. International experts
have opined and advised that the countries should adopt the waste treatment pathways that are environmentally sound, following the guidelines provided by UNEP
(United Nations Environment Programme) regarding Sustainability Assessment of
Technologies (SAT) pertinent to Best Available Technology and Best Environmental
Practices (BAT/BEP) [62].
11.3 Overview of Sludge Hygienisation Techniques—Focus
on the Irradiation Treatment Technology
Since early years of 1980s, some of the European countries have been directing
substantial research effort towards innovating effective sludge hygienisation technology. In Switzerland, a 2-stage biological procedure emerged in 1983, which
encompassed partial aerobic thermophilic fermentation in the first stage followed
by anaerobic sludge digestion in the second stage. Researchers associated with this
development had claimed to have achieved effective hygienisation of sludge, along
with improved sludge thickening and reduced digestion time. The innovators also
claimed that the abovementioned process facilitated lesser energy consumption and
enhanced process stability [63]. Serious research work went on for about a decade
with a view to optimizing the procedure and a few pilot plants had been installed
at the wastewater treatment plants (WWTP) in and around the city of Altenrhein.
During those times, it was pointed out that processes like sludge drying and sludge
composting might not be capable of entirely preventing the regrowth of pathogenic
microorganisms. Keller pointed out that liquid sludge irradiation could be an effective
pathway towards disinfecting the sewage sludge [63].
273
schematically the possible interaction mechanism between the SARS-CoV-2 particulates and its surrounding, that includes both the host, as well as, the environment.
It encompasses the manifestation in the host, sustenance in the environment and
subsequent transmission into the receptor.
Overall, from the samples analysed at different geographical locations, it has
emerged that the SARS-CoV-2 particles emerging from the infected individuals via
the respiratory droplets and through the faeces cause a definite level of contamination in the environment [61], and it is likely that both the mediums serve as the
potential pathways towards large-scale transmission of the disease, which may eventually lead to community spread. Consequently, the hygienisation becomes an issue
of prime importance. Therefore, apart from thorough sanitization of the spaces of
mass gathering, and maintenance of the hand hygiene at the individual level; it is
also of importance to employ a suitable technology towards hygienising the municipal sewage sludge of the densely populated urban centres, as the sludges serve as
the breeding ground for a lot of pathogens that can be transmitted to the community during the time of handling or through accidental indirect contact with the
contaminated wastewater flowing through the urban canals. International experts
have opined and advised that the countries should adopt the waste treatment pathways that are environmentally sound, following the guidelines provided by UNEP
(United Nations Environment Programme) regarding Sustainability Assessment of
Technologies (SAT) pertinent to Best Available Technology and Best Environmental
Practices (BAT/BEP) [62].
11.3 Overview of Sludge Hygienisation Techniques—Focus
on the Irradiation Treatment Technology
Since early years of 1980s, some of the European countries have been directing
substantial research effort towards innovating effective sludge hygienisation technology. In Switzerland, a 2-stage biological procedure emerged in 1983, which
encompassed partial aerobic thermophilic fermentation in the first stage followed
by anaerobic sludge digestion in the second stage. Researchers associated with this
development had claimed to have achieved effective hygienisation of sludge, along
with improved sludge thickening and reduced digestion time. The innovators also
claimed that the abovementioned process facilitated lesser energy consumption and
enhanced process stability [63]. Serious research work went on for about a decade
with a view to optimizing the procedure and a few pilot plants had been installed
at the wastewater treatment plants (WWTP) in and around the city of Altenrhein.
During those times, it was pointed out that processes like sludge drying and sludge
composting might not be capable of entirely preventing the regrowth of pathogenic
microorganisms. Keller pointed out that liquid sludge irradiation could be an effective
pathway towards disinfecting the sewage sludge [63].