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13. Bespoke waste assessment

Environment Agency

September 21
08:25 2022

Waste you accept must be suitable for biological treatment. This section applies to bespoke waste types which are more novel, for example chemical process waste and sets out inhibition values.

Inhibition values for aerobic and anaerobic processes

Table A: general inhibitors for anaerobic processes

Determinant Threshold
pH hydrolysis and fermentation acido and aceto genesis Optimal pH 5 to 7
Methanogenesis Optimal pH 7 to 8, Operational 6.5 to 8.5
Temperature below optimum (mesophillic optimum temperature 37C, thermophillic optimum temperature 55C) The rate of activity will drop by approximately 50% for every 10 degrees below the respective optimum temperature (Caine, 1990).
Temperature above optimum (mesophillic optimum temperature 37C) Where the temperature is raised gradually above the mesophillic optimum, the cultures will adapt and thermophiles will become established. During this period performance will be reduced. Where temperature is raised suddenly by 10C performance may reduce significantly.
Temperature above optimum (thermophilic optimum temperature 55C) Performance of thermophiles will drop if temperature is raised above the optimum values but will survive extreme increase up to 100C
Ammonium inhibition Ammonium build up may inhibit the anaerobic process.

Table B: general inhibitors for aerobic processes

Determinant Threshold
Moisture content Optimal range of 50 to 70%
pH Optimal range of 6 to 8
C/N Optimal range of 25:1 to 40:1

Table C: specific guideline inhibitors for aerobic treatment

The following table contains indicative inhibitive concentrations for a range of substances for aerobic treatment processes.

Blanks mean that no data is available in literature.

The first column of data for aerobic treatment is based on the inhibition of respirometric activity, the second is based on the inhibition of nitrification.

You must show that where you receive waste that falls within these inhibition ranges you can manage and maintain a stable process.

The waste must be capable of being treated and recovered by the aerobic process.

This table does not list every substance which may be inhibitory to aerobic or anaerobic organisms. You must also consider the potential inhibitory effect of other substances used or generated at your facility.

Parameter Aerobic treatment threshold mg/L
Activated sludge Nitrification
Anthracene ug/l 500
Arsenic (As) 0.1 1.5
Cadmium (Cd) 1 to 10 5.2
Chloride mg/kg 180
Chromium (Cr) III 10 to 50
Chromium (Cr) total 1 to 100 0.25 to 1.9
Chromium (Cr) VI 1 1 to 10 (as chromate)
Copper (Cu) 1 0.05 to 0.48
Cyanide 0.1 to 5 0.34 to 0.5
Iodine (I) 10
Lead (Pb) 1 to 5 or 10 to 100 0.5
Mercury (Hg) 0.1 to 1; 2.5 as Hg(II)
Naphthalene 500 (EPA); 29 to 670 IC50 (mg/L) for Nitrosomonas and aerobic heterotrphs respectively
Nickel (Ni) 1.0 to 2.5; 5 0.25 to 0.5; 5
Phenantherene ug/l 500
Sulphide 25 to 30
Total ammonia nitrogen 480
Zinc (Zn) 0.3 to 5; 5 to 10 0.08 to 0.5

Table D: specific inhibitors for anaerobic treatment

The following table contains guideline indicative inhibitive concentrations for a range of substances for anaerobic treatment processes. Blanks mean that no data is available in literature. You must show that where you receive waste that falls within these inhibition ranges you can manage and maintain a stable process. The waste must be capable of being treated and recovered by the anaerobic process. This table does not list every substance which may be inhibitory to aerobic or anaerobic organisms. You must also consider the potential inhibitory effect of other substances used or generated at your facility.

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Parameter Anaerobic treatment threshold g/l
Acrylates 62 to 150 mg/l
Alcohols 22 to 43000 mg/l
Alkylbenzenes 160 to 580 mg/l
Aluminium (Al) 1 (2% inhibition of methane production after 59 days)
Amines 13000 1-methylpyrrolidine mg/l
Arsenic (As) 0.0016
Cadmium (Cd) 0.15 to 0.33
Calcium (Ca) 2.5 to 4
Chlorinated aliphatics 0.5 to 600 mg/l
Chromium (Cr) total 0.2
Copper (Cu) 0.009
Fluoride (F) 0.018
Halobenzenes 20 to 750 mg/l
Halogenated alcohols 0.3 to 630 mg/l
Halogenated carboxylic acids < 0.001 to 0.01 mg/l
Halogenated phenols 2-300 for mono,-di and trichloros; 0.04 and 0.13 for penta and tetra mg/l
Ketones 6000 to 50000 mg/l
Lead (Pb) 3.2 to 8
Magnesium (Mg) 12
Nickel (Ni) 0.1 to 1.6
Nitriles 90 to 28000 Acrylonitrile and Acetonitrile respectively mg/l
Nitrobenzenes 13 nitrobenzene
Nitrophenols 4 to 12 mg/l
Phenol and alkylphenols phenol 1850; o,m,and p-cresol 850, 925, 975 mg/l
Potassium (K) 2.8 to 14
Silver (Ag) 0.1
Sodium (Na) 5.6 to 53
Sulphate
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