The Beneficial Use of a BioWaste Product in the Biological Nutrient Removal Technology

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The Beneficial Use of a Bio-Waste Product in the
Biological Nutrient Removal Technology

• Harma Greben
• Division for Water, Environment and Forestry
  Technology
• CSIR

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Lay out of presentation

• Use of Bio waste Product (BWP)
• Fermentation of BWP
• Utilisation of BWP in NO3 removal
• Utilisation of BWP in SO4 removal
• Costs
• Conclusions

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Bio waste product (Cellulose, polysaccharide)

• When treated
• Reduces the pollution potential
• When utilized
• Synthesis of useful products

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Re-use of organic waste

• Literature
• Domestic Sewage (Wilsenach et al., 2003)
• (Anaerobic digestion re-use nutrients)
• Municipal Solid Waste (Yu et al.,2000)
• (Agriculture, garden, green household waste)

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Degradation pattern of cellulose material
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Volatile organic acids and alcohols

• In the Biological Nutrient Removal
• The intermediates are the substrate for the
  Biological NO3 removal
• while
• The Volatile Fatty Acids (VFA) form the substrate
  for the Biological SO4 removal

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Biological NO3 removal(de-nitrification)

• In the presence of an electron acceptor (NO3)
• In the presence of an electron donor,
• (carbon and energy source, e.g Methanol)
• 6NO3- 5CH3OH ? 5CO2 3N2 7H2O 6OH-

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Alternative Carbon and Energy source

• Delwiche et al., (1981) and Robertson et al.,
  (1995, 2000) showed the use of waste cellulose
  solids (sawdust and leaf compost) as the carbon
  and energy source for biological de-nitrification
  5CH2O 4NO3- ? 2N2 5CO2 3H2O 4OH-
• Semmelink (1975) South Africa showed the use of
  molasses as the CE source

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Biological treatment of nitrate rich (ground)
water

• Either in-situ (permeable wall)
• By pumping groundwater to the surface
• After treatment
• ground water suitable for drinking water
• (cattle, game, rural population)

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Laboratory scale experiment

• Artificial nitrate rich feed water
• (100/200 mg/L Nitrate NO3-N)
• Reactor(Vol. 2L)
• Biomass from anaerobic digester, Daspoort,
  Pretoria
• Carbon and energy source Saw dust obtained from
  CSIR wood workshop

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Carbon and Energy Source
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Experimental Setup
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Experimental periods
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Nitrate removal (Period 1)
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Nitrate removal (period 2)
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Nitrate removal (Period 3)
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COD concentration NO3 removal
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Saw dust economics

• 25g saw dust added between days 6484
• (20 days)
• Total of 8 g NO3 was removed
• (0.4 g NO3/day)
• Cost of sawdust R10 per 50 kg
• Nitrate removal cost 0.625 Rand /kg NO3

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Comparison with methanol

• Theoretically
• 1g methanol reduces 1.937g NO3
• Price of methanol
• R4.43 per kg methanol
• Nitrate removal cost
• R2.3/kg NO3

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Biological SO4 removal

• These conditions have to be adhered to
• SO4 concentration in feed water
• SRB
• Anaerobic conditions
• Cost effective carbon and energy source
• pH 7.5-8.5
• 20-30 degrees C

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CSIR Demo Plant Witbank
Treating AMD, Rich in SO4 and acidity, using
EtOH/sugar as the CE source
Aim to use fermented Bio-waste products as
CE source
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Fermentation Study

• 3 fermentation reactors (F1 F3) Vol 2.5L each
• All contained 30g BWP/L tap water
• F1 no additional biomass
• F2 contained anaerobic sludge (Dasprt Digester)
• F3 contained SRB from Demo Plant
• pH between 6-7
• Temperature 35oC

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Biological SO4 removal study

• 4 SO4 removal reactors (2L each)
• (B1 B4)
• All contained 1500 mg/l SO4
• All contained 250ml SRB and 2ml nutrients/l
• (macro and micro)
• All contained a different carbon and energy
  source obtained from F1-F3 (Table 1)
• Operated at room temperature

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Table 1
Table 1 The carbon sources used in the
different batch reactors
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SO4 reduction and sulphide production
SO4 reduction
S2- production
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VFA Utilization
B1 Glucose
B2
B3 Anaerobic sludge
B4 SRB
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Cost effectiveness

• In order to remove 1500 mg/L SO4 from 1 m3 of AMD
  1 kg of sugar _at_ R 5.56 is needed
• Alternatively to remove the same amount of SO4 a
  BWP _at_ R 2.20 can be used.

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Conclusions

• Fermentation of BWP produces
• Intermediates, e.g. Alcohols
• substrate for NO3 removal
• 100 NO3 removal
• VFA substrate for SO4 removal
• Higher removal rate than with sugar
• Use of BWP is cost effective

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Acknowledgement

• The authors want to thank the CSIR and BioPad for
  funding this project.
• THANK YOU