Wastewater Biogas Production
Wastewater biogas production is the process by which anaerobic digestion works on the organic matter found within various forms of wastewater to generate biogas. This is a natural chemical process occurring when bacteria and other microorganisms process organic matter in the absence of oxygen.
Biogas is combustible, so it can be highly useful as a renewable source of fuel. However, there are important safety measures and other factors to consider when producing it and putting it to good use.
What’s Involved in Biogas Production
Although each industrial or wastewater treatment plant will have its own go-to approach to biogas production, the basic process remains the same across the board.
When wastewater undergoes treatment, its organic components are converted to sludge. Naturally, this sludge must be disposed of, treated further, or both. Biogas production is part of this process and includes steps like the following:
- Organic waste is mixed with substances like manure to introduce anaerobic bacteria and added to a receiving tank.
- The mixture is heated to optimal temperatures – typically between 100 and 125 degrees Fahrenheit – and pumped into a digestor receptacle (or a series of several) along with organic biomass.
- The activated sludge then undergoes a controlled vacuum fermentation process.
From there, the resulting matter is recycled as water, biogas, or a combination of the two and put to various uses.
Wastewater Biogas Production
1. What is the Composition of Biogas?
Biogas typically consists of carbon dioxide (CO2) and methane. Trace amounts of ammonia (NH3), hydrogen sulfide (H2S), and other gasses are often present. As its main combustible component is methane, biogas is considered a highly valuable renewable energy source.
2. What Does the Process of Anaerobic Digestion Involve with Wastewater Treatment Plants and Facilities?
Wastewater treatment solutions involve combining organic waste with substances such as manure, resulting in the creation of anaerobic bacteria. Temperatures are then monitored and heated to ideal ranges, followed by being pumped directly into specialized tanks. As the bacteria introduced breaks down organic material, biogas is then produced, resulting in the overall reduction of sludge.
3. What Role Does Anaerobic Bacteria Play in Wastewater Biogas Production?
During biogas production, anaerobic bacteria play a vital role, assisting with the breaking down of introduced organic material (such as manure) in the absence of oxygen. As bacteria is introduced, it works to convert complex organic compounds and molecules into simplified molecules. Once this process is complete, biogas is produced as a byproduct.
4. Why is H2S, or Hydrogen Sulfide, Removal Important in Biogas Production?
Removing H2S from biogas prevents corrosion, ensures environmental compliance, and prevents potential toxic and safety hazards. Proper removal of H2S from wastewater treatment centers can prevent equipment damage, corrosion, and potential health effects involving the respiratory and neurological systems.
5. What are the Advantages of Producing Biogas From Wastewater?
Producing biogas in wastewater facilities and treatment plants can significantly reduce pathogens, odors, and reliance on traditional fossil fuels. Additionally, producing biogas from wastewater is also optimal for those interested in reducing emissions for environmental purposes.
6. What are the Risks of Biogas Production in Wastewater Treatment Centers?
Excessive exposure to biogas that is untreated in wastewater treatment centers can lead to expedited corrosion and damage to equipment in use. H2S toxicity can also lead to potential risks of exposure to pathogens and respiratory effects. Increased maintenance, reduced safety measures, and potential equipment failure are all risks of unregulated biogas production in wastewater treatment centers today.
7. How Does H2S Removal for Wastewater Treatment Centers Work?
The use of various biological and chemical methods is used to remove H2S from biogas produced by wastewater. Physical adsorption and chemical absorption with the use of biological treatments or activated carbon are the most common solutions that are optimal for wastewater treatment centers.
8. What Safety Measures are Taken in Biogas Production?
Monitoring gas concentration levels, ensuring proper ventilation, and routine maintenance of equipment (to prevent leaks) are all vital safety measures to ensure safe biogas production. PPE, or personal protective equipment, alongside gas detectors, is also used to ensure protection from all angles.
9. How is the Quality of Biogas Measured and Monitored?
At MV Technologies, we measure calorific value, impurity levels, and methane content to determine the overall quality of biogas produced by wastewater. We also use various gas analyzers to monitor parameters to ensure the quality of biogas produced is as pure as possible, with little to no impurities or risks of pathogens.
10. Which Industries are Linked to Wastewater Biogas Production?
Wastewater biogas production is often associated with industries that include municipal wastewater treatment plants, agricultural operations, meat processing facilities, and food and beverage processing centers.
Biogas Production and Use at
Industrial or Municipal Wastewater Treatment Facilities
Biogas, produced in anaerobic digesters or covered lagoons at meat/poultry, food or beverage processing facilities is often used as fuel for boilers or other process equipment, to power generator sets, or is converted to CNG on-site or at third-party compressor stations through utility pipeline transmission.
When used as a fuel source, the presence of H2S in the biogas will have a damaging effect on reciprocating or turbine engine life, increase maintenance costs, and shorten time between rebuilds. Generator set manufacturers have begun setting limits on H2S concentrations as part of their conditions imposed on the user to maintain warranty coverage.
In order to meet sulfur dioxide emission limits on engine exhausts, H2S may need to be removed prior to combustion. In cases of extremely low general emission limits, where a catalytic converter is necessary, the H2S must be removed prior to combustion or the life of the expensive catalyst will be reduced substantially.
If the biogas is converted to CNG, those specifications include very low limits on H2S. When the gas is transported via a utility pipeline to a CNG compression station, even lower pipeline specifications will have priority.
In other words, monitoring and controlling the H2S levels in combustible biogas is crucial for many reasons, safety-related and otherwise. That’s where reliable, safe removal options from companies like MV Technologies come in.
In other words, monitoring and controlling the H2S levels in combustible biogas is crucial for many reasons, safety-related and otherwise. That’s where reliable, safe removal options from companies like MV Technologies come in.
Typical User Conditions
Flow rates are typically mid to high range, 800scfm to 2000scfm. Many wastewater treatment facilities can see H2S concentrations generally around 800 to 1500ppmv. Siloxanes are often present. MVTechnologies H2SPlus and BioH2SPlus Hybrid systems deliver superior value in this application.
Safe Removal of H2S from Combustible Biogas
There are a number of ways to reduce or eliminate the amounts of H2S in usable biogas.
Liquid scavengers like triazine, ether, amine, aldehydes, and similar options can be used to absorb H2S. It’s also possible to adsorb H2S into solid formats like iron oxide or activated carbon. Whether absorption or adsorption is better depends on the situation and circumstances.
In some cases, it’s also possible to address the presence of H2S via biological conversion, membrane separation, and additional options.
Naturally, it’s also important to observe strict safety protocols when removing or otherwise dealing with H2S. For example, all personnel should wear personal protective equipment (PPE), including face shields, safety goggles, and protective chemical-resistant apparel. Respirators and other forms of breathing protection are also essential.
Additional safety measures to take include (but aren’t necessarily limited to):
- H2S gas level monitoring before and during the removal
- Awareness and protocol training or review for all personnel
- Emergency drills to help prepare teams for the unexpected
- Airstream treatment with activated carbon or a similar option
MV Technologies specializes in a variety of different solutions with a special emphasis on dry scrubber H2S management systems – systems that are highly effective at addressing H2S associated with landfill gas, wastewater biogas production, and more.
Solutions are further customized with companies' unique needs and objectives and their projects in mind.
