Examinations of landfills with FID (flame ionization detector) are supposed to bring their weak points to our attention. For this end, a grid is applied to a scaled plan (usually 20 m x 20 m).
At its junctions in the field, measurements will be conducted by using the ppm scale (10,000 ppm = 1 vol. % methane). The establishment of four classification areas allows for a more detailed characterization of the emissions produced by a landfill.

Besides point measurements, a screening is also required for area inspections, to adequately document the dimensions of a gas window or cracks.
Also we encourage you to conduct measurements directly next to gas caps to detect possible defects (clay cones, connections).

All data and irregularities are recorded and documented during the examination.
As orientation we use buildings, gas collectors, and shafts etc. In certain cases, we make use of GPS-based localization technology. All values are processed in the reporting system.
The FID inspection is required for the checking of the proper functioning of surface gaskets, for making suggestions for the improvement of gas caps and, during first measurements, for the ability to forecast gas quantities.

- prognostic calculation of the amount of landfill gas flowing off - calculation of the amount of quantifiably measurable gas (for relevant emissions) - economic consideration / such as decisions as to the expansion of the gas capping, passive degasification etc.

- conception and dimensioning of the gas caps (number of gas collectors – type and location)
- utilization schemes

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Besides complying with the requirements of public authorities regarding to the determination of an effectively operated gas capping system by the operator, the single strands of the gas collectors should be supervised by a third party monitoring company on a quarterly basis.

The monitoring would include the measuring and documenting of all main components of the landfill gas system, gas flow, gas pressure and temperature as well as all marginal data (damper positions, diameter of measuring tube, meteorological data).

Irregularities during an FDI inspection are also recorded. The results and particularly its listed interventions are to provide the site operator with clear instructions concerning the installed gas treatment system.

Prior to this, a target value of the major gas flow volume is determined, which differs considerably from a HT gas flare or a gas-powered engine. The single interventions are structured as follows:

1. Increase the gas flow volume!
Evaluation criterion: at CH4 values > target value
Measure: opening of the regulating valve, application of below atmospheric pressure

2. Minimize volume or (temporarily) turn it off!
Evaluation criterion: at CH4 values < target value or from approx. 2 vol. % oxygen
Measure: (continued) closing of the regulating valve

3. Remove existing pockets of water to ensure the proper volume flows
and continue according to 1 and 2!
Evaluation criterion: in case of water, high pressure fluctuation
Measure: application of below atmospheric pressure

4. Basic defects, such as weld socket, defect valves, and leakages are to be repaired!
Evaluation criterion: in case of defects

5. Based on the data collected, the draft gas status of the gas collector is considered adequate.

The recurring examinations bring about a close cooperation with the site operator, who eventually takes over the monitoring tests under his own direction.
Defects or frequent irregularities call for a weak point analysis.

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CONVENTIONAL EXHAUST TESTING

1. Regulating Operation

The composition of the landfill gas depends on the duration and intensity of the exhaustion of the site. For reasons of comparability and relevance of measurements, the examinations are conducted not before the exhaustion of the site over a period of several weeks and the stabilization of the methane concentration through a varying of the exhaustion volume (approximate value 45 – 50 vol. % methane) has been reached and maintained.
The measurement and regulation of single gas collectors allows for a categorization of the total volume flow as follows:

- each collector has similar values of methane concentration
- the collectors are not overly exhausted
- leakages can be localized and repaired

After a regulating operation over a period of 4 to 5 weeks, the wished-for stable situation is being reached. Once the regulating process is completed, you can begin with the measuring operation.
The measuring of gas collectors for the sake of the optimization of volume flows is done by way of handhelds mounted o the major components and marginal parameters.
The values are recorded in charts and, if required, interpreted accordingly.

2. Measuring Operation
2.1 Basic Examinations

The basic examination during the measuring operation (1 week, data logging 2 times a day) measures the major components of the gas, the gas volumes, and the gaseous state in order to draw conclusions as to the extraction status of the landfill.
The measured and calculated values are structured in charts and graphically displayed.

2.2 Trace Gases

The sum parameters provide an overview of the harmful substances of the landfill gases, which develop when being flared or used for gas-powered engines. They allow estimates regarding to the state of emissions and provide glues as to the corrosive properties of materials used (such as gas-powered engines). The samplings and analyses are described and processed in the report:

2.3 Measuring Emissions at the Landfill’s Surface

The FID measurement method allows for the recording of gas escapes along their concentration (ppm CH) and the determination of areas of risk. The effectiveness of degassing systems can be measured by periodically conducted measurements of remaining emissions. During the gas exhaustion test, a zero measurement (one-time measurement prior to the regulating operation) and a flow measurement (one-time measurement conducted during the stable operation of the system) are conducted.
The measurement results are mapped and analyzed:

3. Display of Results
3.1 Final Report

The descriptions, calculation results, tables, graphics, and interpretations as shown in Position 1 and 2 are summarized in a final report. The report contains also a statement as to the secured opportunities for the disposal, winning, and utilization of gas and their consequences for further developments and projects.


OTHER APPROACHES


Experience and the consideration of applying cost-effective methods lead to the following version:

Preparation
- collecting of soil air samples under particular consideration of emissions (FID inspection) to determine the location of the measurement levels
- expansion of (or utilization of existing levels) single levels in 2 to 3 meters below top ground surface
- zero measurement – measurement of all components in a non-exhaustion state
Parameter: CH4, CO2, O2, p, t, meteorological data

Exhaust Testing
- low level of exhaustion – exhaustion of the single gas level amount: if required, (approx. 20 m³/h) at a continual measuring of the parameters as shown above. For reasons of simplicity, the short-term treatment of gases is conducted by help of activated carbon, as a continual burning cannot usually be guaranteed due to the fact that it falls below the required concentration.
- probably a further increase
- over-exhaustion – increase of the through-put quantity (trial) up to the tipping point; after that lowering to about 50 to 70% of the stable or static value; after this - turn-off

Duration: depending on requirement

- resting phase – with continual measuring of the parameters as referred to above in order to identify the time required for a gas regression ( perhaps by using a data logger over night).
- documentation

This shortened conduction (about 2 - 48 h/ level) holds also some other advantages:

- The high costs of incorrect drillings for the expansion of (trial-) collectors can be circumvented.
- In cases of negative evidences (no relevant reproduction of landfill gas), the costs for trial collectors and plant equipment can be saved.
- Easy reduction of the number of measurement levels or re-use as monitoring levels.
- The localization allows for the measuring of different areas of the landfill site without the additional costs of expensive tubes.
- The power supply for the compressor can be secured by using a power generator in the field.
- Clear and thorough decision to the active and passive degassing of landfills.

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A mobile TV camera system is used for the inspection of gas caps.

The drive-in mouth can be anything from 50 mm upwards. An all-wheel-drive vehicle with an independent power supply allows the personnel to reach the inspection site (such as a vertical collector) in the field.

All data (date, distance in meter) are monitored and recorded by a video camera system. It documents visually mechanical defects and indicates where a clear need for action is.

The criteria for the evaluation of the gas collector or a collecting tube (horizontally up to approx. 50 m) are categorized as follows:

- checking of the connector of the gas collector head of the gas pipe line
- calcium sinter processes in the collector area
- clogging of filters
- remnants of the production processes
- turns and cracks
- water level / water cloggings

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These types of analyses take advantage of nearly all available measurement methods.

Weak point analyses of existing gas utilization systems on landfill sites include, besides the regulatory requirements, a considerable cost-benefit potential.

The operator is presented a detailed documentation for every single gas cap location, the drainage of landfill gases, and the operation of gas utilization systems, including a “data sheet gas collector.”

The approach is adapted to the given location.
At first, the landfill is usually FID-inspected. This method checks in particular the on-site constructions, such as collector heads and clay cones.

Subsequently, a pressure test is supposed to prove the proper functioning of the cap location, compare the target – performance relation, and conduct a camera inspection.

It also guarantees a precise assignment of the collectors to their field/gas collecting sites.
In cases of erroneous/ fault functions or discontinued operations of the gas utilization system, the elaboration of concepts is intended to remedy these lacks in the future and target an optimized collection of gases.

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The trace substances, which have been mixed with the landfill gas via the compressor, may be harmful to the machinery used for the generation of energy.

It is, particularly, the elements of sulfur, silicon, chlorine, and fluorine that are of note here.
As these freights vary considerably on landfills with active degassing systems, the dimensioning of a potential gas treatment has to be carefully outlined.

This effort comprises an analytical assessment and the selection of the appropriate plant and cleaning technology, such as activated carbon.

For the treatment of sulfur we use, besides the well-known granulated carbon, a specially activated carbon that is impregnated with potassium iodide.

The avoidance of material stress (reduction of corrosion, deposits) helps modify in a positive way the emission values and delay revisions and maintenance of machinery.

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Utilization of Biogas

During the anaerobe microbiological decomposing of organic materials, there develops a combustible gas mixture containing approx. 65 % methane and 35 % carbon dioxide, also known as landfill gas, gas from purification plants, or biogas. Carbon dioxide and particularly methane contribute considerably to the greenhouse effect and global warming. Especially its large share of methane with is 23 times as much effective as carbon dioxide, has led to the prohibition of its unpurified emission into the atmosphere, but at the same time, its energy content makes it tremendously important for the generation of energy. When combusted in gas-powered engines with directly docked generators for the production of electric power (combined heat and power units – CHP), it provides valuable energy.

Composition of Landfill Gases

Major Components
Depending on the specific gas production, degree of compaction, sealing, and age of the (household waste) landfill site, concentrations of methane and carbon dioxide vary greatly. In order to prevent these gases from being emitted into the atmosphere, landfills are operated with a slight negative pressure, so that gases fro outside, such as nitrogen, oxygen, and argon enter the landfill body and dilute the biogases there. An exact knowledge of the composition of these gases is therefore imperative for the gas production and the operation of gas-powered engines.

Trace Components
In addition to these primary components, there are traces of many gases (< 0.1 vol. %) in the landfill gas that may have harmful and damaging effects on the operation of gas-powered engines. The origin of these gases can be accounted for by deposits of chemicals (such as solvents), and their high vapor pressures allow them to be removed along wit the biogas. It may also be substances developed by chemical or biological reactions that are continuously reproduced.

By far the most important sulfur compound in landfill sites is hydrogen sulfide. This compound develops in the course of the microbiological decomposition of plaster, plants and animal waste. Organic sulfur compounds (such as thiols) are concentrated only in small amounts. Sulfur compounds are combusted by the gas-powered engine into sulfuric acid, an acid very aggressive against alloying metals used in the engine and with the effect of worsening the lubrication characteristics of engine oils.

Compounds containing chlorine and fluorine (CKW/FCKW) enter the landfill primarily via solvents. The combustion products are strong acids (hydrochloric and hydrofluoric acid) with damaging effects to metals and oils.

Silicon-organic compounds (siloxane compositions and decomposition products) combust into silicon dioxide, a solid material depositing of moving parts of the machinery and leading to leaks and abrasions.

The presence of these trace components leads in cases of higher concentrations to massive faults that may cause considerable economic damage to the gas-powered engines, lowered service lives of oil changes, and narrower maintenance intervals, so that the manufacturers of engines demand in their guidelines strict limit values for combustion gases.

An analysis of the landfill gas intended for further utilization during the planning and operation stage is therefore indispensable.

We work closely with renowned laboratories and offer you our assistance also in the event of the requirement of additional measures (purification of landfill gases).

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We conduct the emission measuring as outlined in the TA Luft (the German Clean Air Act) and other administrative regulations in cooperation with laboratory that is in compliance with the paragraphs 26 and 28 of the Bundes-Immissionsschutzgesetz (the German Federal Emission Protection Act).

DETES assumes all coordination tasks, the examination of the operating permit and the negotiations (such as range of parameters) with the monitoring authority.

Calculations and conclusions with regard to pollutants allow for the adaption (minimization) to the measurement program/ measurement interval concerning the development of emissions.

The examination of emissions required for all gas plants located on landfills as well as biogas, natural gas, mine gas, and sewage gas plants cover the entire spectrum, including dioxins and furans.

These checks provide the basis for the adjustment of the machinery or gas purification plants, apart from the required LAI reports.

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DETES provides for existing landfill sites to assume the entire operation, particularly the gas capping and data logging processes as well as the monitoring of the plant technology.

At the request of the customer, DETES also assumes the maintenance of the site.

This would include the metrological requirements determined by public authorities and an economically effective operating of he gas capping.

Specially designed and adapted programs guarantee the averting of danger in the event of a safety degassing.

We compile and provide comprehensive annual and monthly reports. During the contract period, we offer complete coordination efforts and consultancy services.

This allows the operators, especially those of older landfills, to have more leeway in terms of time and financial savings that can be reused for other works.

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Based on all examinations, we assume the task of the project management and coordinate the planning of the gas caps, the type and dimensioning of the plant technology, cost estimates, performance audits and the distribution and monitoring of all services and products, including bureaucratic procedures.

We also provide these services for forthcoming changes of your landfill facilities and machinery.

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