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39 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What types of sludge contain more organic matter and how much? |
Primary sludge and activated sludge (70 and 75% organic matter) |
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Sludge composition |
99% water 1 % solids (70-80% organics) |
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Dry solids Sludge production in netherlands per year |
350,000 tons |
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Amount of solids after thickening |
5 to 8 % dry solids in sludge |
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Water types of bounds |
Free water Capillary bound Cell bound |
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The .... The organic solids fraction, the ... The water fraction. Then, higher destruction of organic matter is pursued to have ... Volume of Sludge |
High High Less |
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How much Volume is reduced during thickening by every 1 % of dry solids increase |
50 % |
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Types of thickeners |
Gravitational or mechanical compression |
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Gravitational thickener size |
Dm = 5 - 25 meters Depth = 3 - 5 meters |
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Solids loading rate (thickener) |
Vds = Q x S / A Vds kg SS/ m2.day |
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Max solids loading rate for primary sludge, activated sludge and its combination |
100 - 150 20 - 30 30 - 50 |
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Solids retention time |
Sludge Volume thickener / daily sludge flow from thickener 1 day |
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Advantages of sludge digestion |
Biogas Hygiene No odours Stabilizes sludge Reduces organic fraction and volume Improves dewatering, adsorbs les water than fresh sludge |
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How much energy does 1 kg of COD represents |
0.35 m3 of CH4 or 3.8 Kwh Considering non degradable COD it is 0.12 m3 of CH4 |
CH4 and kwh |
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Influent of 100 kg of COD how is it split after aerobial digestion |
Effluent 2 - 10 kg COD Sludge 30 - 60 kg COD |
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How much energy of the biogas can be transformed into electricity? |
35 - 40 % |
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First types of digesters |
Septic tank Imhoff tank Clarigester Separate digestion tank |
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Retention time for mesophilic and thermophilic conditions |
30 - 35 days for mesophilic 15 days for thermophilic |
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Sludge digester size |
Height:diameter 1:1 Volume 1000 - 10,000m3 Feeding semicontinuously |
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Energy required for heating a mesophilic digestor in summer and winter |
120 mJ / m3 winter 85 mJ/m3 summer |
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How much biogas is produced per kilogram of destroyed organic matter? |
1000 litters of biogas |
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Caloric value of biogas |
24 mJ per m3 or 6.67 kwh |
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How much organic matter is reduced after digestion? |
50 % |
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Can stalized sludge be used in agricultural purposes? |
No because of heavy metals |
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After dewatering de expect sludge with .... % dry solids |
20 - 30 % |
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Types of dewatering |
Chemical and thermal |
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Chemical dewatering, what is it? |
Addition of lime or ferric chloride. 300 g/ kg SS. Poly electrolites 3 - 8 g/ kg SS |
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Dewatering by thermal means, what is it? |
200 °C and high pressure |
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Equipments for dewatering |
Centrifugation: demands more energy and polyelectrolytes press Filter belt press Chamber filter press: demands more personal but up to 35% ds |
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Influent of 100 kg of COD how is it split after anaerobial digestion |
5 kg sludge 10 - 20 kg effluent Rest to biogas |
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How much m3 CH4 is produced per kg of COD removed |
0.08 to 0.12 m3 |
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Advantages of UASB reactor |
Retains suspended solids in general Retains anaerobial activated sludge Stabilizes sludge Mineralizes organics CH4 CO2 |
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Parts of a UASB reactor |
Primary clarifier Biorreactor Secondary clarifier Sludge digester |
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COD, BOD, SS removal in UASB reactor |
From 70 to 85% |
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COD influent, SS influent, HRT and temperature for a UASB |
<1000 mg/l COD <500 mg/l SS >20°C HRT 8 hours |
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Upward velocities in a UASB |
0.7 m/h |
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UASB height |
5 to 6 meters |
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What are the baffles for in a UASB |
Prevents biogas from reaching the secondary clarifier zone |
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Max volume of a UASB |
2000 m3 |
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