Opportunities of biogas production
from dairy wastewater
Kristóf Szabó
2014
Introduction
 Biogas:
-made at anaerobic circumstances
-renewable energy source
-biogas contains CO2 and CH4
-formation:
hydrolisis=>acetogenesis=>methanogenesis
-gas production depends on:
pH, temperature, carbon:nitrogen ratio
Dairy wastewater
 Has high organic matter content
 It is hard to fermentate without adding other
organic matter
 Its lactose and fat concent is relatively low
 Compared to the lactose and fat content, its protein
content is higher
Aim of the experiment
 Compare of microbe cultures
 Determine the ideal concentration of the
inoculum
 Examine the gas production from model
wastewaters, containing glucose and lactose, at
anaerob circumstances
 Examine the changing of gas production from
model dairy wastewaters with pre-setted basic
pH at anaerobic circumstances
Equipments and materials
 Equipments:
- Armfield anaerobic digester
- Oxitop laboratory fermentation system
 Used materials:
- model wastewater containing glucose ( 8 g/l glucose
and other trace elements)
- model dairy wastewater (3 g/l and 6g/l milk powder)
-concentratum of 3 g/l milk powder solution
(concentrated with 10 kDa ultrafiltration to its half
cubic content)
- decomposited wastewater sludge
- Microcat-UASB microorganism culture
Armfield
digester
from frontwise
Oxitop
machine
Armfield
digester
from
side-view
Results
1. Examination of inoculum-wastewater sludge
Cumulative quantitiy of gas (10-day)
21000
Equipment: Armfield
Model wastewater:
glucose-containing
19500
18000
15000
Gas produced in the 1st
reactor
13500
12000
Cumulative gas
quantity from
decomposed
watewater sludge
pH-day
10500
9000
Gas produced in the 2nd
reactor
8
7500
7
6000
6
4500
5
3000
pH
Gas production (ml)
16500
1500
4
3
0
0
1
2
2
3
4
5
6
7
8
9
10
11
12
t (day)
1
0
1
2
3
3
4
6
7
8
9
10
t (day)
The changing of
pH through the
experiment
Examination of inoculum- Microcat-UASB
Equipment: Armfield
Model wastewater:
glucose-containing
Cumulative gas
quantity with
The
changing
Microcat
UASBof pH
through the
experiment
2. Examination of the inoculum’s homogenity and concentration
Equipment: Oxitop
Model wastewater:
glucose-containing
Gas
production at
different
concentration
and
homogenity
of the
inoculum
Biogas
production
at different
concentrati
Biogas
on
production
at
different
concentration
, calculated to
unit inoculum
mass (mg/ml)
3. Effect of the concentration of the inoculum
Equipment: Oxitop
Model wastewater:
glucose-containing
Effect of the
concentration of the
inoculum to the methane
production
4. Examination of the effect of pH to the gas
production from dairy model wastewaters
Equipment: Oxitop
Model wastewater:
lactose-containing
Gainable biogas quantity
from pH-controlled and noncontrolled solutions
Gainable methane quantity
from pH-controlled and noncontrolled solutions
5. Examination of the pH effect to the gas
production from ultrafiltrated dairy model
wastewaters
Gainable methane quantity
from pH-controlled (pH=9)
and non-controlled solutions
Gainable biogas quantity
from pH-controlled (pH=9)
and non-controlled solutions
Summary
• Homogeneous sampling from inoculum gives higher gas
production
• Optimal inoculum concentration was 15 mg/100 ml; higher
concentration is not giving proportionately higher gas
production
• Milk powder’s concentration does not affect to the gas
production significantly if milk powder solutions has the same
pH at the beginning
• Higher pH gives higher gas production
• Concentrate of the ultrafiltered milk powder’s solution (with
higher protein content) as good gas production can be
achieved as the solution that has the same concentration
before ultrafiltration
Thank you for your attention!