Call for Evidence : ​Non Waste Anaerobic Digestion over 100 tonnes per day: Permit technical requirements ​

Closes 9 Jan 2026

BAT 20

In order to reduce emissions to water, BAT is to treat waste water using an appropriate combination of the techniques given below.

For each parameter below, confirm the measurements in place for your particular activity, the equipment used and where these measurements are undertaken. 

References

( 1 ) The averaging periods are defined in the General Considerations.   
( 2 ) Either the BAT-AEL for COD or the BAT-AEL for TOC applies. TOC monitoring is the preferred option because it does not rely on the use of very toxic compounds.
( 5 ) The BAT-AEL may not apply when the temperature of the waste water is low (e.g. below 12 °C). 
( 6 ) The BAT-AEL may not apply in the case of high chloride concentrations (e.g. above 10 g/l in the waste input). 

 

Substance/ Parameter: Total organic carbon (TOC) (2)
BAT-AEL (1)(2): 10-60 mg/l
Waste treatment process to which the BAT- AEL applies:  All waste treatments except treatment of water-based liquid waste 

Compliance Status:

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Substance/ Parameter: Chemical oxygen demand (COD) (2)

 

BAT-AEL (1)(2): 30-180 mg/l
Waste treatment process to which the BAT- AEL applies All waste treatments except treatment of water-based liquid waste

 

Compliance Status:

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Substance/ Parameter: Total suspended solids (TSS)
 
BAT-AEL (1)(2): 5-60 mg/l
Waste treatment process to which the BAT- AEL applies: All waste treatments 

 

Compliance Status:

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Substance/ Parameter: Total nitrogen (Total N)
 
BAT-AEL (1)(2): 1-25 mg/l (5)(6)
Waste treatment process to which the BAT- AEL applies: Biological treatment of waste
 

Compliance Status:

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Substance/ Parameter: Total phosphorus (Total P)
 
BAT-AEL (1)(2): 0.3-2 mg/l
Waste treatment process to which the BAT- AEL applies: Biological treatment of waste
 

Compliance Status:

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