Desperdício orgânico

When biodegradable organic waste is collected or segregated from a mixed waste stream, it provides value as a fuel for energy production or as raw material for compost or fertilizer. Important categories of organic waste include manure, food waste, grass cuttings and crop residues.

Anaerobic (without oxygen) digestion processes are used to make biogas, while compost is made using an aerobic (with oxygen) digestion process.  Any biodegradation process produces a complex mixture of gases which can create an odour nuisance or, in the case of biogas, a corrosion hazard for the combustion engine. Molecular filtration helps to eliminate these problems.

Treating waste – and the air – crucial at biogas plants

Biogas is gaining importance worldwide as recycled organic waste replaces non-sustainable fossil fuel sources of energy production. When organic waste is digested in an anaerobic process, the resulting methane – the fuel for energy production – can be heavily contaminated with unwanted substances that can cause corrosion or abrasion.

Biogas can contain these damaging substances:

• Hydrogen sulphide (H2S)
• Ammonia (NH3)
• Siloxanes
• Aromatic hydrocarbons
• Halogens (chlorine, fluorine)
• Particulate

If high concentrations of H2S are allowed to reach the gas engine where the methane is combusted to generate energy, the engine can suffer internal corrosion due to a combination of the acidic gas and high temperatures. Engine corrosion requires unscheduled downtime for maintenance and repair – increasing maintenance costs and lowering output and profit for the biogas plant. Many anaerobic digesters and biogas engines are located close to the feedstock of organic waste, i.e. on farms. In-line molecular filtration is the accepted method of removing hydrogen sulphide from biogas prior to combustion.

Control composting odours with molecular filtration

Organic waste can be partially biodegraded in an aerobic process to make compost or soil-enhancing products. Little or no hydrogen sulphide is produced but a lot of the volatile organic content of the waste is released. This can create an odour nuisance due to the very high intensity. The gas mixture responsible for the odour is very complex, but a major constituent will be terpenes such as alpha-pinene.

You can use molecular filtration as an odour control method both on the exhaust from the production building and in the ventilation system of machinery used inside the process hall to turn and mix the rotting waste.

With Camfil’s dedicated molecular filtration solutions, you can keep troublesome odours away from neighbouring areas and filter out contaminated gases before they reach the combustion engine.