Division Applicability

United Kingdom

For existing plants, the technique may not be applicable due to lack of space and/or due to the layout of the waste water collection system.

BAT 12. In order to reduce emissions to water, BAT is to use an appropriate combination of the techniques given below.

	Technique ^f1	Typical pollutants targeted	Applicability
The descriptions of the techniques are given in Section 14.1.
Preliminary, primary and general treatment
(a)	Equalisation	All pollutants	Generally applicable.
(b)	Neutralisation	Acids, alkalis
(c)	Physical separation, e.g. screens, sieves, grit separators, oil/fat separators, or primary settlement tanks	Gross solids, suspended solids, oil/grease
Aerobic and/or anaerobic treatment (secondary treatment)
(d)	Aerobic and/or anaerobic treatment (secondary treatment), e.g. activated sludge process, aerobic lagoon, upflow anaerobic sludge blanket (UASB) process, anaerobic contact process, membrane bioreactor	Biodegradable organic compounds	Generally applicable.
Nitrogen removal
(e)	Nitrification and/or denitrification	Total nitrogen, ammonium/ammonia	Nitrification may not be applicable in the case of high chloride concentrations (e.g. above 10 g/l). Nitrification may not be applicable when the temperature of the waste water is low (e.g. below 12 °C).
(f)	Partial nitritation — Anaerobic ammonium oxidation	Total nitrogen, ammonium/ammonia	May not be applicable when the temperature of the waste water is low.
Phosphorus recovery and/or removal
(g)	Phosphorus recovery as struvite	Total phosphorus	Only applicable to waste water streams with a high total phosphorus content (e.g. above 50 mg/l) and a significant flow.
(h)	Precipitation		Generally applicable.
(i)	Enhanced biological phosphorus removal		Generally applicable.
Final solids removal
(j)	Coagulation and flocculation	Suspended solids	Generally applicable.
(k)	Sedimentation
(l)	Filtration (e.g. sand filtration, microfiltration, ultrafiltration)
(m)	Flotation

The BAT-associated emission levels (BAT-AELs) for emissions to water given in Table 1 apply to direct emissions to a receiving water body.

The BAT-AELs apply at the point where the emission leaves the installation.

Table 1

BAT-associated emission levels (BAT-AELs) for direct emissions to a receiving water body

Parameter	BAT-AEL ^f2 ^f3 (daily average)
The BAT-AELs do not apply to emissions from grain milling, green fodder processing, and the production of dry pet food and compound feed.
The BAT-AELs may not apply to the production of citric acid or yeast.
No BAT-AEL applies for biochemical oxygen demand (BOD). As an indication, the yearly average BOD₅ level in the effluent from a biological waste water treatment plant will generally be ≤ 20 mg/l.
The BAT-AEL for COD may be replaced by a BAT-AEL for TOC. The correlation between COD and TOC is determined on a case-by-case basis. The BAT-AEL for TOC is the preferred option because TOC monitoring does not rely on the use of very toxic compounds.
The upper end of the range is: 125 mg/l for dairies; 120 mg/l for fruit and vegetable installations; 200 mg/l for oilseed processing and vegetable oil refining installations; 185 mg/l for starch production installations; 155 mg/l for sugar manufacturing installations; as daily averages only if the abatement efficiency is ≥ 95 % as a yearly average or as an average over the production period.
The lower end of the range is typically achieved when using filtration (e.g. sand filtration, microfiltration, membrane bioreactor), while the upper end of the range is typically achieved when using sedimentation only.
The upper end of the range is 30 mg/l as a daily average only if the abatement efficiency is ≥ 80 % as a yearly average or as an average over the production period.
The BAT-AEL may not apply when the temperature of the waste water is low (e.g. below 12 °C) for prolonged periods.
The upper end of the range is: 4 mg/l for dairies and starch installations producing modified and/or hydrolysed starch; 5 mg/l for fruit and vegetable installations; 10 mg/l for oilseed processing and vegetable oil refining installations carrying out soap-stock splitting; as daily averages only if the abatement efficiency is ≥ 95 % as a yearly average or as an average over the production period.
Chemical oxygen demand (COD) ^f4 ^f5	25-100 mg/l ^f6
Total suspended solids (TSS)	4-50 mg/l ^f7
Total nitrogen (TN)	2-20 mg/l ^f8 ^f9
Total phosphorus (TP)	0,2-2 mg/l ^f10

The associated monitoring is given in BAT 4.

Annotations

Footnotes

f1

The descriptions of the techniques are given in Section 14.1.

f2

The BAT-AELs do not apply to emissions from grain milling, green fodder processing, and the production of dry pet food and compound feed.

f3

The BAT-AELs may not apply to the production of citric acid or yeast.

f4

No BAT-AEL applies for biochemical oxygen demand (BOD). As an indication, the yearly average BOD₅ level in the effluent from a biological waste water treatment plant will generally be ≤ 20 mg/l.

f5

The BAT-AEL for COD may be replaced by a BAT-AEL for TOC. The correlation between COD and TOC is determined on a case-by-case basis. The BAT-AEL for TOC is the preferred option because TOC monitoring does not rely on the use of very toxic compounds.

f6

The upper end of the range is:

125 mg/l for dairies;
120 mg/l for fruit and vegetable installations;
200 mg/l for oilseed processing and vegetable oil refining installations;
185 mg/l for starch production installations;
155 mg/l for sugar manufacturing installations;

as daily averages only if the abatement efficiency is ≥ 95 % as a yearly average or as an average over the production period.

f7

The lower end of the range is typically achieved when using filtration (e.g. sand filtration, microfiltration, membrane bioreactor), while the upper end of the range is typically achieved when using sedimentation only.

f8

The upper end of the range is 30 mg/l as a daily average only if the abatement efficiency is ≥ 80 % as a yearly average or as an average over the production period.

f9

The BAT-AEL may not apply when the temperature of the waste water is low (e.g. below 12 °C) for prolonged periods.

f10

The upper end of the range is:

4 mg/l for dairies and starch installations producing modified and/or hydrolysed starch;
5 mg/l for fruit and vegetable installations;
10 mg/l for oilseed processing and vegetable oil refining installations carrying out soap-stock splitting;

as daily averages only if the abatement efficiency is ≥ 95 % as a yearly average or as an average over the production period.