The influent flow (dwf) is 30,000 m3/day and the influent BOD concentration is 300 mg BOD/l. The suspended solid concentration in the influent is 150 mg/l of which 40% is removed in the primary clarifier, which agrees with about 20% BOD removal. The sludge yield (Y) is 0.6 kgX/kgBODremoved.
Calculate the biomass production (kg biomass per day) assuming all BOD entering the biological process is removed.
Calculate the primary sludge production (kg per day), but for simplicity neglect the remainder of the suspended solids.
The sludge is directly dewatered to a final dry solid concentration of 18%. How much trucks (we are talking about truck transport, thus movements of trucks, not the physical truck itself), that can transport a load of 30 ton, will be needed per year for sludge transport to the incineration plant?
How can the produced sludge be reduced maximally, to minimize transport costs?
Kamran, did you get the answer?
Anyone can help, please?
To calculate the biomass production:
Step 1: Calculate the BOD removal in the primary clarifier.
BOD removal in primary clarifier = 300 mg BOD/l * 20% = 60 mg BOD/l
Step 2: Calculate the total BOD removed.
Total BOD removed = 60 mg BOD/l * 30,000 m3/day = 1,800,000 mg BOD/day
Step 3: Calculate the biomass production.
Biomass production = Total BOD removed / sludge yield
Biomass production = 1,800,000 mg BOD/day / (0.6 kgX/kgBODremoved)
Biomass production = 3,000,000 kg biomass/day
Therefore, the biomass production is 3,000,000 kg biomass per day.
To calculate the primary sludge production:
Step 1: Calculate the primary sludge produced.
Primary sludge produced = Total suspended solids removed in primary clarifier
= 150 mg/l * 40% * 30,000 m3/day
= 1,200,000 mg/day
However, for simplicity, we will neglect the remainder of the suspended solids. Therefore, the primary sludge production is 1,200,000 mg/day.
To calculate the number of trucks needed for sludge transport:
Step 1: Calculate the total sludge produced per year.
Total sludge produced per year = primary sludge production * 365 days
= 1,200,000 mg/day * 365 days
= 438,000,000 mg/year
Step 2: Convert the total sludge produced to kilograms.
Total sludge produced per year (kg/year) = 438,000,000 mg/year / 1,000,000 mg/kg
= 438,000 kg/year
Step 3: Calculate the number of truckloads needed.
Number of truckloads needed = Total sludge produced per year (kg/year) / 30,000 kg/truckload
= 438,000 kg/year / 30,000 kg/truckload
= 14.6 truckloads/year
Since we can't have partial truckloads, we would need a total of 15 truckloads per year for sludge transport.
To minimize transport costs and reduce sludge production:
1. Increase the efficiency of the primary clarifier to remove more suspended solids, thus reducing the amount of sludge produced.
2. Implement advanced wastewater treatment technologies that can further reduce BOD and suspended solids, thus reducing the sludge production.
3. Implement sludge thickening techniques to increase the dry solids content, reducing the volume of sludge that needs to be transported.
4. Explore options for sludge reuse or beneficial use, such as land application, composting, or energy recovery, to minimize the amount of sludge that needs to be transported to the incineration plant.
To calculate the biomass production, we need to determine the amount of BOD removed per day. Since 20% of the influent BOD is removed in the primary clarifier, the remaining 80% enters the biological process.
Influent BOD load = dwf * BOD concentration
= 30,000 m3/day * 300 mg BOD/l
= 9,000,000 mg BOD/day
BOD entering the biological process = 9,000,000 mg BOD/day * 80%
= 7,200,000 mg BOD/day
Since the sludge yield (Y) is 0.6 kgX/kgBODremoved, we can calculate the biomass production:
Biomass production = BOD entering the biological process / 1000 * Y
= 7,200,000 mg BOD/day / 1000 * 0.6 kgX/kgBODremoved
= 4,320 kg biomass/day
So the biomass production is 4,320 kg per day.
For calculating the primary sludge production, we can use the suspended solids concentration in the influent and the percentage removed in the primary clarifier. However, since we are neglecting the remainder of the suspended solids for simplicity, we will consider only the portion that is removed.
Primary sludge production = dwf * suspended solid concentration * percentage removed
= 30,000 m3/day * 150 mg/l * 40%
= 180,000 mg/day
To calculate the total primary sludge production, we need to convert the units:
Total primary sludge production = 180,000 mg/day / 1000
= 180 kg/day
So the primary sludge production is 180 kg per day.
To determine the number of trucks needed for sludge transport to the incineration plant, we need to know the annual sludge production. Assuming 365 days in a year:
Annual sludge production = primary sludge production * 365
= 180 kg/day * 365
= 65,700 kg/year
To convert the sludge production to tons, we divide by 1000:
Annual sludge production in tons = 65,700 kg/year / 1000
= 65.7 tons/year
To calculate the number of trucks needed, we divide the annual sludge production by the load per truck:
Number of trucks needed = Annual sludge production in tons / Load per truck
= 65.7 tons/year / 30 tons/truck
≈ 2.19 trucks
Therefore, approximately 3 trucks would be needed per year for sludge transport to the incineration plant.
To minimize transport costs and reduce the produced sludge, some strategies could include:
1. Implementing advanced treatment technologies, such as membrane bioreactors or activated sludge processes, which often result in higher solids removal efficiencies.
2. Optimizing the sludge thickening and dewatering processes to increase the solids concentration in the sludge before transport.
3. Implementing sludge minimization practices, such as optimizing the biological process to reduce excess biomass production or implementing anaerobic digestion to further reduce the sludge volume and increase biogas production.
4. Exploring opportunities for sludge reuse or beneficial use within the treatment plant or neighboring industries. This can reduce the need for long-distance transport altogether.
5. Implementing sludge drying or incineration technologies directly at the treatment plant site, eliminating the need for off-site transport.
By adopting these measures, the production and transport costs of sludge can be minimized.