Transcript Document

Module 3: Environmental Objectives, Programme
of Measures, Economic Analysis, Exemptions
An Important Measure applied for Agricultural
and Animal Waste Management
Michael Jackman- Chemistry Expert
Afyon, 2015
Construction of Anaerobic Digestors
The systems are relatively easy to establish but the
actual mechanisms are complex.
In 1907, in Germany, a patent was issued for the Imhoff
tank, an early form of anaerobic digester for treating
waste-water
Biological Mechanisms
The process has to take place in the absence of air.
It is a biological process using a range of bacteria
There are four important types of bacteria for each which need to
work together sequentially
.
1) Bacterial hydrolysis of the input materials in order to break
down insoluble organic polymers such as carbohydrates and
make them available for other bacteria.
2) Acidogenic bacteria then convert thesugars and amino
acids into carbon dioxide, hydrogen, ammonia, and organic
acids.
Biological Mechanisms
3) Acetogenic bacteria then convert these resulting organic acids
into acetic acid, along with additional ammonia, hydrogen, and
carbon dioxide.
4) Methanogen bacteria, finally convert these products to methane
and carbon dioxide
Biological Mechanisms
Biological Mechanisms
Different species of bacteria are have different optimum temperature
ranges and digestion times
Psyrophilic bacteria- temperatures >10°C - digestion times- > 100 days
Mesophilic bacteria temperatures >30°C - digestion times- > 50 days
Thermophilic bacteria temperatures >55°C -- digestion times- > 10 days
So temperature control is important
EUROPEAN DEVELOPMENTS
Historically, experience of small on-farm AD is mixed;
Many plants built in the 1970s/early 1980s closed due to various
operational problems.
This situation is improving. Developments since the late 1980s to
simplify design, improve operation and decrease costs are
showing great promise.
The EU are keen to promote this.
EUROPEAN DEVELOPMENTS
Farm digester
Electrical Generator
Overview
Case Study Examples
Lessons Learnt
Basic features
are:Key Components of an EWERS
Nine
1) Predominantly mesophilic systems
2) Residence times typically 10-30 days
3) On-farm applications usually environmentally driven
3) Opportunities to produce heat and electricity
4) Opportunities for fibre production
Biological Mechanisms
Direct or indirect use of Biogas
Biological Mechanisms
•Large Sewage Digestor (Denmark)
Waste Water
If there is a possibility of the water being shed into
surface water bodies or into ground water further
treatment of the wastewater will be required.
This treatment will typically be an oxidation stage
where air is passed through the water e.g. trickle
filters and then to ideally to controlled wetlands
Gas collectors
1)
Overview
Case Study Examples
Gas collectors
Lessons Learnt
Nine Key Components of an EWERS
•Northern Ireland
Advanced system in Germany
(Flare)
Advanced system in Germany
(Flare)
Disinfection Process of AD
Another benefit of AD is that it kills pathogenic bacteria and parasitic Ova,
e,g.:
Salmonela
Psyrophilic fermentation- temperatures >10°C -100% Fatality 44 days
Mesophilic fermentation- temperatures >30°C - 100% Fatality 7 days
Thermophilic fermentation- temperatures >55°C 100% Fatality 2 days
Schistosoma Ova
Psyrophilic fermentation- temperatures >10°C -100% Fatality 30 days
Mesophilic fermentation- temperatures >30°C - 100% Fatality 10 days
Thermophilic fermentation- temperatures >55°C 100% Fatality 1 day
EU Commitment
The European Commission White Paper on Renewable
Sources of Energy has set a target to increase the
contribution of renewable energy supply from 6% to
12% between 1995 and 2010.
Biomass has been targeted to increase from 44.8
million tonnes of oil equivalent (Mtoe) to 135Mtoe
over the same time period.
European Farm Biogas Production
1)
Overview
Case Study Examples
Lessons Learnt
Nine Key Components of an EWERS
European Farm Biogas Production
Overview
Case Study Examples
Lessons Learnt
Nine Key Components of an EWERS
Importance of Livestock
Bi-Products as an Energy Resource
It is estimated that the total energy content of landfill gas and
digestible agricultural wastes in the EU exceeds 80 Mtoe.
The contribution that could be made by biogas exploitation from
livestock production, agro-industrial effluents, sewage
treatment and landfill by 2010 is estimated to 15 Mtoe).
Livestock manure contributes with more than 90% of the total
digestible waste/biomass resources in Europe
Livestock Bi-Products as an Energy
Resource
If the gas production per day will approximately correspond to the
following average values:
·
1 kg cattle dung 40 litre biogas
· 1 kg buffalo dung 30 litre biogas
· 1 kg pig dung 60 litre biogas
1 kg chicken droppings 70 litre biogas
Or
1,5 litres biogas per day will be produced by per 1 kg live livestock
weight
Digestate Components:
Solid remnants of the original input material to the digesters
that the microbes cannot use.
Overview
The mineralised remains
of the dead bacteria from within the
Case Study Examples
digesters.
Lessons Learnt
Nine Key Components of an EWERS
Digestate can come in three forms; fibrous, liquor or a
sludge-based combination of the two.
Digester residue
The acidogenic digestate is a stable organic material comprised
largely of lignin and cellulose, but also of a variety of mineral
components in a matrix of dead bacterial cells;
Overview
Case Study Examples
The material can resembles
domestic compost and can be used
Lessons Learnt
as compost
or to make low grade building products such as
Nine Key Components of an EWERS
fibreboard
Waste Water
The final output from is a liquid.
This effluent is from the moisture content of the original waste but
also includes water produced from he microbial reactions in the
digestion systems.
Overview
Case Study Examples
This effluent may be
released from the dewatering of the
Lessons Learnt
digestate Nine
or may
be separate from the digestate.
Key Components of an EWERS
This wastewater will have elevated levels of biochemical oxygen
demand (BOD) and chemical oxygen demand (COD). Which
means it has high nutrient content for irrigation only.
The liquid bi-product is rich in nutrients and can be used as a
fertiliser
Waste Water
If there is a possibility of the water being shed into surface water
bodies or into ground water further treatment of the wastewater
will be required.
Overview
Case Study Examples
This treatment will typically
be an oxidation stage where air is
Lessons Learnt
passed through
the water e.g. trickle filters and then to ideally
Nine Key Components of an EWERS
to controlled wetlands.
Integrated System
This system is complementary, as the control of the livestock and
the treatment of the associated manure is used to produce
biogas and also to improve the quality of effluent wastewater
for irrigation/ fertiliser but has additional positive effects:
(i) the reduction of non-point pollution,
(ii) the increase control of the supply of fertiliser for
irrigation.
(iii) the production of an alternative sustainable energy
source.
.
Integrated
approach
Irrigation
Feed
Fertiliser water
Waste
AD - Biogas
Finally..
Therefore, by the correct application and optimisation of such
systems, they can produce win-win situations, which are
especially important in the current global climate change
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