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The benefits of ASAC's patented technology in 10 points

1Zero CO2 emissions

2Ability to process difficult biomass

3Absence of composting and bad odors

4Minimal self-consumption

5Flexible, easily scalable, ideal for reconversions and upgrades

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Profit maximization emissions6

Anaerobic digestion volumes halved7

Hydrolysis with complete nitrogen stripping8

Small footprint9

Disposal of digestate to sewer without nitro-denitro treatment10

ASAC GREEN GAS is not a merely upgrading of biogas to biomethane, but it is a complete and innovative process of anaerobic fermentation, in which organic matrices are better digested, produce more and give no residues.

Choose ASAC GREEN GAS for a zero-emission plant: the only plant with complete seizing.

1. Zero CO2 emissions

ASAC’s patented technology seizes CO₂ present in biogas by converting it into calcium bicarbonate, avoiding no gaseous CO₂ emissions

  1. By not emitting CO₂ the ASAC system does not require the recovery of gaseous CO₂ an operation that is generally complex and expensive, as well as difficult to manage. In fact, the recovered CO₂ is generally not suitable for food use without further investment.
  2. Does not require off-gas post combustion
  3. Highest quality, CO₂-free biomethane in compliance with UNI 11537-2019

2. Ability to process difficult biomass

ASAC’s patented hydrolysis section makes it easy to use difficult biomasses, such as poultry manure, FORSU (Organic Fraction of Domestic Wastes), domestic or industrial sludge, even without adding additional organic matrices, and achieving advanced biomethane standards.

3. Absence of composting and bad odors

ASAC’s patented technology involves an innovative first hydrolysis step that allows for the complete volatilization of nitrogenous substances in the form of ammonia, which is converted to ammonium sulfate that can be used in agriculture. As a result, the solid digestate is nitrogen-free.

  1. Solid digestate does not require composting and can be delivered as a soil improver outside the Nitrates Directive;
  2. Due to preparation by hydrolysis, both liquid and solid digestate are nitrogen-free and well digested, and therefore they have no impactful odor;
  3. Nitrogen is recovered as ammonium sulfate,a fertilizer that is easily stored, handled and sold.

4. Minimal self-consumption

Decreasing the volume of anaerobic fermentation, in addition to resulting in less clutter, means less thermal and electrical consumptions to pump and mix. In addition, there is no need for energy-intensive downstream treatments such as composting and nitro-denitro. Throughout the process, the biogas remains at atmospheric pressure, avoiding compression energy costs as needed in membrane or PSA treatment systems.

  1. Overall electrical and thermal self-consumption are minimized and easily covered by the installation of a small biogas-fueled co-generator
  2. Thermal recovery from the hydrolysis phase with preheating of the initial sludge
  3. The biogas is kept at atmospheric pressure at all times.

5. Flexible, easily scalable, ideal for reconversions and upgrades

The ASAC system can be used realize small and large sizes facilities, without difficulties in operation or management, being in fact a simple and easy chemical-physical process. Moreover, by utilizing halved anaerobic digestion volumes, it is possible to double the production capacity in case of reconversion and upgrading from biogas to biomethane. For example, a 1MW electric plant operating actually to produce electricity from biogas, can be reconverted and upgraded to a 500 Sm3h biomethane facility while keeping the same fermentation equipment.

6. Profit maximization

ASAC’s patented technology saves both investment and operating costs:

  1. Civil facilities (digesters, storage, posttreatment) minimized
  2. No cost of storing and spreading liquid digestate that is disposed of in the sewer system
  3. Minimal costs to spread solid digestate as a soil improver
  4. Maximum yield of anaerobic fermentation means maximum utilization of available biomass
  5. Minimal self-consumption means minimal operating costs
  6. Selling ammonium sulfate as fertilizer recoups makes possible the recovery of most of the operating costs
  7. A simple and reliable plant means less plant shut-down, easier maintenance of with standardized items and, most important, no cost for special components (membranes, PSA regeneration, steam boiler O&M, etc.)…

7. Anaerobic digestion volumes halved

Through ASAC’s patented hydrolysis system, fermentation hold-up time is significantly decreased:

  1. Small size with much smaller anaerobic digestion volumes compared to traditional technologies

8. Hydrolysis with complete nitrogen stripping

Through the special hydrolysis system developed and patented by ASAC, organic matrices are much easier digested, facilitating the anaerobic fermentation process, and allowing upstream of the system nitrogen stripping, completely avoiding the risk of ammonia formation in the digesters

  1. Maximum efficiency (by utilising hydrolysis, the maximum possible biogas production is achieved, with negligible unfermented residue)
  2. Steady biology (a hydrolyzed sludge enters the digester completely free of ammonia, toxic to methanogenic bacteria, creating in such a way perfect conditions for anaerobic digestion, which occurs in a very steady manner)

9. Small footprint

10. Disposal of digestate to sewer without nitro-denitro treatment

ASAC GREEN GAS is not a merely upgrading of biogas to biomethane, but it is a complete and innovative process of anaerobic fermentation, in which organic matrices are better digested, produce more and give no residues.

Choose ASAC GREEN GAS for a zero-emission plant: the only plant with complete seizing.

Biomethane plant with CO2 sequestration

1
After hydrolysis, the sludge is sent to a mesophilic anaerobic digestion stage. Compared to a traditional system, the sludge is much easier to be digested because, on the one hand, ASAC hydrolysis has solubilized the COD making it readily available to methanigenic bacteria, and on the other hand, it has also eliminated all the ammonia, a toxic and inhibiting substance for anaerobic bacteria. Finally, the process of anaerobic digestion under these conditions takes place in less time and with a greater efficiency, having as output a digestate with very low COD, BOD and nitrogen values and suitable for direct discharge into the sewer system, after separation of the dry matter by thickening and/or centrifugation or filter pressing. The time required for the entire anaerobic digestion process for the highest possible biogas recovery, can be reduced increase significantly, in case of difficult biomasses such as poultry manure and FORSU. In addition, the methanogenic residue is minimized and in fact more gas is produced than with traditional technologies.
2
Any type of organic matrix even difficult-to-process biomasses such as: poultry manure, FORSU, sewage sludge, industrial sludge, waste with high ammonia conten.
3
Recirculation system for minimising water requirements.
4
By using this technology, anaerobic digestion volumes are extremely small compared to those required by other technologies, which means, in addition less clutter, lower thermal and electrical consumptions for pumping and mixing. In addition, no downstream energy-intensive treatments such as composting and nitro-denitrogen are required. Throughout the process, the biogas remains at atmospheric pressure, avoiding compression energy costs as needed in membrane or PSA systems. Self-consumption is easily covered by a small cogenerator possibly flanked by a small biogas boiler.
5
At this stage, organic matrices are dosed and prepared by fine grinding, preheating with heat recovered from the process, and mixing them to obtain a pumpable sludge to be sent to the next stages.
6
ASAC’s patented technology allows for severe nitrogen stripping and complete degradation of organics during anaerobic fermentation. As a result, the liquid digestate output is suitable to be disposed in the sewer system (D. Lgs 152/06) by simple separation of solids and further eventual passage to a small oxygenation tank. It does not require nitro-denitrogen treatment section. It does not require spreading of digestate (digestate can be discharged to sewer).
7
ASAC’s patented technology makes it possible to obtain high-purity biomethane suitable for feeding into the grid in compliance with current regulations.
8
In this section, the sludge is treated through an innovative hydrolysis process developed and patented by ASAC where the organics solubilize and are made into a more digestible form. In addition, the nitrogen compounds are converted to gaseous ammonia which is then recovered as ammonium sulfate through a sulfuric acid scrubber. What performed at this stage is not a simple hydrolysis as is usually done in normal pretreatment plants, but it is an hydrolysis especially optimized to strip ammonia and to solubilize organic components, in a very high efficient way. At this stage an initial upgrading step takes place where a portion of the CO2 in the biogas is absorbed and converted to calcium bicarbonate. At this stage the process also allows for the complete purification of H2S and other undesired components in the biogas. The ASAC process last step is the final upgrading and purification of the biogas into biomethane, which occurs through a second step of CO2 convertion into calcium bicarbonate.
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Biomethane plant with CO2 sequestration

DSA ASAC Anaerobic Digester High-performance anaerobic digester

After hydrolysis, the sludge is sent to a mesophilic anaerobic digestion stage. Compared to a traditional system, the sludge is much easier to be digested because, on the one hand, ASAC hydrolysis has solubilized the COD making it readily available to methanigenic bacteria, and on the other hand, it has also eliminated all the ammonia, a toxic and inhibiting substance for anaerobic bacteria. Finally, the process of anaerobic digestion under these conditions takes place in less time and with a greater efficiency, having as output a digestate with very low COD, BOD and nitrogen values and suitable for direct discharge into the sewer system, after separation of the dry matter by thickening and/or centrifugation or filter pressing. The time required for the entire anaerobic digestion process for the highest possible biogas recovery, can be reduced increase significantly, in case of difficult biomasses such as poultry manure and FORSU. In addition, the methanogenic residue is minimized and in fact more gas is produced than with traditional technologies.

Biomass

Any type of organic matrix even difficult-to-process biomasses such as: poultry manure, FORSU, sewage sludge, industrial sludge, waste with high ammonia conten.

Curva

Recirculation system for minimising water requirements.

Skid cogenerator/Biogas boiler self-consumption

By using this technology, anaerobic digestion volumes are extremely small compared to those required by other technologies, which means, in addition less clutter, lower thermal and electrical consumptions for pumping and mixing. In addition, no downstream energy-intensive treatments such as composting and nitro-denitrogen are required. Throughout the process, the biogas remains at atmospheric pressure, avoiding compression energy costs as needed in membrane or PSA systems. Self-consumption is easily covered by a small cogenerator possibly flanked by a small biogas boiler.

Organic matrices pretreatment basin

At this stage, organic matrices are dosed and prepared by fine grinding, preheating with heat recovered from the process, and mixing them to obtain a pumpable sludge to be sent to the next stages.

Digestate discharge to sewer

ASAC’s patented technology allows for severe nitrogen stripping and complete degradation of organics during anaerobic fermentation. As a result, the liquid digestate output is suitable to be disposed in the sewer system (D. Lgs 152/06) by simple separation of solids and further eventual passage to a small oxygenation tank. It does not require nitro-denitrogen treatment section. It does not require spreading of digestate (digestate can be discharged to sewer).

Biomethane

ASAC’s patented technology makes it possible to obtain high-purity biomethane suitable for feeding into the grid in compliance with current regulations.

Skid ISU ASAC Hydrolysis Ammonia stripping Biomethane Upgrading

In this section, the sludge is treated through an innovative hydrolysis process developed and patented by ASAC where the organics solubilize and are made into a more digestible form. In addition, the nitrogen compounds are converted to gaseous ammonia which is then recovered as ammonium sulfate through a sulfuric acid scrubber. What performed at this stage is not a simple hydrolysis as is usually done in normal pretreatment plants, but it is an hydrolysis especially optimized to strip ammonia and to solubilize organic components, in a very high efficient way. At this stage an initial upgrading step takes place where a portion of the CO2 in the biogas is absorbed and converted to calcium bicarbonate. At this stage the process also allows for the complete purification of H2S and other undesired components in the biogas. The ASAC process last step is the final upgrading and purification of the biogas into biomethane, which occurs through a second step of CO2 convertion into calcium bicarbonate.

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