​The quality of biogas depends mainly on the amount of methane present. A good quality biogas has high calorific value has over about 55% v/v methane.
However, the quality can be reduced if there are high quantities of ammonia and sulphur(,as sulphides) that originate from excessive amounts of proteineous feedstock.
Adjusting feedstock mix is necessary if not there are means of removing sulphur from the biogas.

There are several means of improving biogas quality, but the appropriate and most economic method depends upon the biochemical and physical environment. They are as follows:

1. Digester Optimization:
   1. Adjust the hydraulic retention time to optimize the balance between retention and loading rates.
   2. Ensure proper mixing to prevent the formation of dead zones and promote even microbial activity
2. Feedstock Quality and Mix:
   • Ensure a consistent and balanced mix of carbon and nitrogen sources for microbial health.
   • Optimize the feedstock mix to enhance microbial activity and gas quality.​
3. Use of Enzymes and Micro-elements​
   1. Depending on the current 'health status' of the digester enzymes can improve performance by 10 to 20% in some cases
   2. Micro-element balance maybe good for digesters using livestock waste.
4. Use of Higher Digester Temperatures ​
   1. Can make a significant improvement of methane content, especially effective if the plant has spare heat.
   2. Appropriate heating system is required and more attention to process control is necessary

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