280
R. Majumdar
MLD of wastewater), the total amount of accumulated sludge turns out to be about
42.5 TPD. When the capacity of the STP compound is enhanced to 440 MLD, the
amount of accumulated sludge will be approximately 61 TPD (assuming the current
plant utilization factor of 0.828).
In the dry sludge hygienisation facility at Ahmedabad, in order to deliver 10 kGy
radiation dose to 6 tons dry sludge per day, 150 kCi Co-60 pencil is found to be
adequate. Therefore, for hygienising 61 TPD sludge, peak source strength of 1.5
MCi (i.e. approximately 10 pencils with a strength of 150 kCi each) will be required,
so that the exposure time can be effectively reduced. The thickness and the size of the
stainless-steel buckets need to be planned accordingly. The capital cost for setting
up the facility will be about 30–40% higher as compared to that in Ahmedabad,
considering the costs of a metropolitan city. Therefore, the capital cost for putting
up a dry sludge hygienisation at Bengaluru facility will be about INR 43 Cr. The
operating cost will be approximately INR 2–2.5 Cr per year, depending on the profile
of the contractor. A schematic diagram for the proposed STP facility aided by the
sludge hygienisation unit is depicted in Fig. 11.4.
In order to have a further futuristic estimate, if we take the average of the sludge
accumulation rates found at the two different STPs in Bengaluru, viz. 1 TPD per
6 MLD of wastewater at KC Valley STP compound and 1 TPD per 15 MLD of
wastewater at Kadubeesanahalli STP; the average sewage sludge accumulation rate
turns out to be 1 TPD for every 10 MLD of wastewater. Considering the estimated
peak sewage generation of 1500 MLD in Bengaluru in 2024 as suggested by JICA,
using the rough estimate for average sludge accumulation and STP utilization factor
of 1, the total amount of accumulated sludge will be approximately ~150 TPD.
In order to hygienise 150 TPD of dried sludge, 25 number of Co-60 source pencils,
each with activity of 150 kCi, will be required and the total cost for procuring the
Fig. 11.4 A schematic layout of the proposed STP complex comprising of secondary treatment of
wastewater and sludge hygienisation facility
R. Majumdar
MLD of wastewater), the total amount of accumulated sludge turns out to be about
42.5 TPD. When the capacity of the STP compound is enhanced to 440 MLD, the
amount of accumulated sludge will be approximately 61 TPD (assuming the current
plant utilization factor of 0.828).
In the dry sludge hygienisation facility at Ahmedabad, in order to deliver 10 kGy
radiation dose to 6 tons dry sludge per day, 150 kCi Co-60 pencil is found to be
adequate. Therefore, for hygienising 61 TPD sludge, peak source strength of 1.5
MCi (i.e. approximately 10 pencils with a strength of 150 kCi each) will be required,
so that the exposure time can be effectively reduced. The thickness and the size of the
stainless-steel buckets need to be planned accordingly. The capital cost for setting
up the facility will be about 30–40% higher as compared to that in Ahmedabad,
considering the costs of a metropolitan city. Therefore, the capital cost for putting
up a dry sludge hygienisation at Bengaluru facility will be about INR 43 Cr. The
operating cost will be approximately INR 2–2.5 Cr per year, depending on the profile
of the contractor. A schematic diagram for the proposed STP facility aided by the
sludge hygienisation unit is depicted in Fig. 11.4.
In order to have a further futuristic estimate, if we take the average of the sludge
accumulation rates found at the two different STPs in Bengaluru, viz. 1 TPD per
6 MLD of wastewater at KC Valley STP compound and 1 TPD per 15 MLD of
wastewater at Kadubeesanahalli STP; the average sewage sludge accumulation rate
turns out to be 1 TPD for every 10 MLD of wastewater. Considering the estimated
peak sewage generation of 1500 MLD in Bengaluru in 2024 as suggested by JICA,
using the rough estimate for average sludge accumulation and STP utilization factor
of 1, the total amount of accumulated sludge will be approximately ~150 TPD.
In order to hygienise 150 TPD of dried sludge, 25 number of Co-60 source pencils,
each with activity of 150 kCi, will be required and the total cost for procuring the
Fig. 11.4 A schematic layout of the proposed STP complex comprising of secondary treatment of
wastewater and sludge hygienisation facility