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

Basic features are:

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

Overview Case Study Examples Lessons Learnt

Nine Key Components of an EWERS

Biological Mechanisms

Direct or indirect use of Biogas

Biological Mechanisms

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

• Large Sewage Digestor (Denmark)

Gas collectors

1)

Overview Case Study Examples Lessons Learnt

Nine Key Components of an EWERS

Gas collectors

• Northern IrelandAdvanced 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.

The mineralised remains of the dead bacteria from within the digesters.

Digestate can come in three forms; fibrous, liquor or a sludge-based combination of the two.

Overview Case Study Examples Lessons Learnt

Nine Key Components of an EWERS

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;

The material can resembles domestic compost and can be used as compost or to make low grade building products such as fibreboard

Overview Case Study Examples Lessons Learnt

Nine Key Components of an EWERS

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.

This effluent may be released from the dewatering of the digestate or may be separate from the digestate.

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

Overview Case Study Examples Lessons Learnt

Nine Key Components of an EWERS

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.

Overview Case Study Examples Lessons Learnt

Nine Key Components of an EWERS

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.

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Irrigation

Feed

Waste

AD - Biogas

Fertiliser water

Integrated approach

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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