commitment of the management, including senior management; an environmental policy that includes the continuous improvement of the installation by the management; planning and establishing the necessary procedures, objectives and targets, in conjunction with financial planning and investment; implementation of procedures paying particular attention to: structure and responsibility; recruitment, training, awareness and competence; communication; employee involvement; documentation; effective process control; maintenance programmes; emergency preparedness and response; safeguarding compliance with environmental legislation; checking performance and taking corrective action, paying particular attention to: monitoring and measurement (see also the Reference Report on Monitoring of emissions to Air and Water from IED installations — ROM); corrective and preventive action; maintenance of records; independent (where practicable) internal or external auditing in order to determine whether or not the EMS conforms to planned arrangements and has been properly implemented and maintained; review of the EMS and its continuing suitability, adequacy and effectiveness by senior management; following the development of cleaner technologies; consideration for the environmental impacts from the eventual decommissioning of the plant at the design stage of a new plant, and throughout its operating life; application of sectoral benchmarking on a regular basis; waste management plan (see BAT 13).

The scope (e.g. level of detail) and nature of the EMS (e.g. standardised or non-standardised) will generally be related to the nature, scale and complexity of the installation, and the range of environmental impacts it may have.

For relevant emissions to water as identified by the inventory of waste water streams (see BAT 2), BAT is to monitor key process parameters (including continuous monitoring of waste water flow, pH and temperature) at key locations (e.g. influent to pretreatment and influent to final treatment).

BAT is to monitor emissions to water in accordance with EN standards with at least the minimum frequency given below. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality.

sniffing methods (e.g. with portable instruments according to EN 15446) associated with correlation curves for key equipment; optical gas imaging methods; calculation of emissions based on emissions factors, periodically validated (e.g. once every two years) by measurements.

See Section 6.2.

Emissions can be monitored by dynamic olfactometry according to EN 13725. Emission monitoring may be complemented by measurement/estimation of odour exposure or estimation of odour impact.

The applicability is restricted to cases where odour nuisance can be expected or has been substantiated.

These techniques are further described and defined in other BAT conclusions for the chemical industry.
See BAT 11.
See BAT 12.
	Technique	Description
(a)	Process-integrated techniques	Techniques to prevent or reduce the generation of water pollutants.
(b)	Recovery of pollutants at source	Techniques to recover pollutants prior to their discharge to the waste water collection system.
(c)	Waste water pretreatment	Techniques to abate pollutants before the final waste water treatment. Pretreatment can be carried out at the source or in combined streams.
(d)	Final waste water treatment	Final waste water treatment by, for example, preliminary and primary treatment, biological treatment, nitrogen removal, phosphorus removal and/or final solids removal techniques before discharge to a receiving water body.

The BAT-associated emission levels (BAT-AELs), for emissions to water given in Table 1, Table 2 and Table 3 apply to direct emissions to a receiving water body from:

the activities specified in Section 4 of Annex I to Directive 2010/75/EU; independently operated waste water treatment plants specified in Section 6.11 of Annex I to Directive 2010/75/EU provided that the main pollutant load originates from activities specified in Section 4 of Annex I to Directive 2010/75/EU; the combined treatment of waste water from different origins provided that the main pollutant load originates from activities specified in Section 4 of Annex I to Directive 2010/75/EU.

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

BAT-AELs for direct emissions of TOC, COD and TSS to a receiving water body

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.
Either the BAT-AEL for TOC or the BAT-AEL for COD applies. TOC is the preferred option because its monitoring does not rely on the use of very toxic compounds.
The lower end of the range is typically achieved when few tributary waste water streams contain organic compounds and/or the waste water mostly contains easily biodegradable organic compounds.
The upper end of the range may be up to 100 mg/l for TOC or up to 300 mg/l for COD, both as yearly averages, if both of the following conditions are fulfilled: — Condition A Abatement efficiency ≥ 90 % as a yearly average (including both pretreatment and final treatment). — Condition B If a biological treatment is used, at least one of the following criteria is met: A low-loaded biological treatment step is used (i.e. ≤ 0,25 kg COD/kg of organic dry matter of sludge). This implies that the BOD5 level in the effluent is ≤ 20 mg/l. Nitrification is used.
The upper end of the range may not apply if all of the following conditions are fulfilled: — Condition A Abatement efficiency ≥ 95 % as a yearly average (including both pretreatment and final treatment). — Condition B same as Condition B in footnote (4). — Condition C The influent to the final waste water treatment shows the following characteristics: TOC > 2 g/l (or COD > 6 g/l) as a yearly average and a high proportion of refractory organic compounds.
The upper end of the range may not apply when the main pollutant load originates from the production of methylcellulose.
The lower end of the range is typically achieved when using filtration (e.g. sand filtration, microfiltration, ultrafiltration, membrane bioreactor), while the upper end of the range is typically achieved when using sedimentation only.
This BAT-AEL may not apply when the main pollutant load originates from the production of soda ash via the Solvay process or from the production of titanium dioxide.
Parameter	BAT-AEL(yearly average)	Conditions
Total organic carbon (TOC)	10-33 mg/l	The BAT-AEL applies if the emission exceeds 3,3 t/yr.
Chemical oxygen demand (COD)	30-100 mg/l	The BAT-AEL applies if the emission exceeds 10 t/yr.
Total suspended solids (TSS)	5,0-35 mg/l	The BAT-AEL applies if the emission exceeds 3,5 t/yr.

BAT-AELs for direct emissions of nutrients to a receiving water body

Either the BAT-AEL for total nitrogen or the BAT-AEL for total inorganic nitrogen applies.
The BAT-AELs for TN and Ninorg do not apply to installations without biological waste water treatment. The lower end of the range is typically achieved when the influent to the biological waste water treatment plant contains low levels of nitrogen and/or when nitrification/denitrification can be operated under optimum conditions.
The upper end of the range may be higher and up to 40 mg/l for TN or 35 mg/l for Ninorg, both as yearly averages, if the abatement efficiency is ≥ 70 % as a yearly average (including both pretreatment and final treatment).
The lower end of the range is typically achieved when phosphorus is added for the proper operation of the biological waste water treatment plant or when phosphorus mainly originates from heating or cooling systems. The upper end of the range is typically achieved when phosphorus-containing compounds are produced by the installation.
Parameter	BAT-AEL(yearly average)	Conditions
Total nitrogen (TN)	5,0-25 mg/l	The BAT-AEL applies if the emission exceeds 2,5 t/yr.
Total inorganic nitrogen (Ninorg)	5,0-20 mg/l	The BAT-AEL applies if the emission exceeds 2,0 t/yr.
Total phosphorus (TP)	0,50-3,0 mg/l	The BAT-AEL applies if the emission exceeds 300 kg/yr.

BAT-AELs for direct emission of AOX and metals to a receiving water body

The lower end of the range is typically achieved when few halogenated organic compounds are used or produced by the installation.
This BAT-AEL may not apply when the main pollutant load originates from the production of iodinated X-ray contrast agents due to the high refractory loads. This BAT-AEL may also not apply when the main pollutant load originates from the production of propylene oxide or epichlorohydrin via the chlorohydrin process due to the high loads.
The lower end of the range is typically achieved when few of the corresponding metal (compounds) are used or produced by the installation.
This BAT-AEL may not apply to inorganic effluents when the main pollutant load originates from the production of inorganic heavy metal compounds.
This BAT-AEL may not apply when the main pollutant load originates from the processing of large volumes of solid inorganic raw materials that are contaminated with metals (e.g. soda ash from the Solvay process, titanium dioxide).
This BAT-AEL may not apply when the main pollutant load originates from the production of chromium-organic compounds.
This BAT-AEL may not apply when the main pollutant load originates from the production of copper-organic compounds or the production of vinyl chloride monomer/ethylene dichloride via the oxychlorination process.
This BAT-AEL may not apply when the main pollutant load originates from the production of viscose fibres.
Parameter	BAT-AEL(yearly average)	Conditions
Adsorbable organically bound halogens (AOX)	0,20-1,0 mg/l	The BAT-AEL applies if the emission exceeds 100 kg/yr.
Chromium (expressed as Cr)	5,0-25 μg/l	The BAT-AEL applies if the emission exceeds 2,5 kg/yr.
Copper (expressed as Cu)	5,0-50 μg/l	The BAT-AEL applies if the emission exceeds 5,0 kg/yr.
Nickel (expressed as Ni)	5,0-50 μg/l	The BAT-AEL applies if the emission exceeds 5,0 kg/yr.
Zinc (expressed as Zn)	20-300 μg/l	The BAT-AEL applies if the emission exceeds 30 kg/yr.

The associated monitoring is in BAT 4.

In order to prevent or, where this is not practicable, to reduce the quantity of waste being sent for disposal, BAT is to set up and implement a waste management plan as part of the environmental management system (see BAT 1) that, in order of priority, ensures that waste is prevented, prepared for reuse, recycled or otherwise recovered.

In order to reduce the volume of waste water sludge requiring further treatment or disposal, and to reduce its potential environmental impact, BAT is to use one or a combination of the techniques given below.

	Technique	Description	Applicability
(a)	Correct plant design	This includes the provision of a gas recovery system with sufficient capacity and the use of high-integrity relief valves.	Generally applicable to new plants. Gas recovery systems may be retrofitted in existing plants.
(b)	Plant management	This includes balancing the fuel gas system and using advanced process control.	Generally applicable.

	Technique	Description	Applicability
(a)	Correct design of flaring devices	Optimisation of height, pressure, assistance by steam, air or gas, type of flare tips (either enclosed or shielded), etc., aimed to enable smokeless and reliable operation and to ensure the efficient combustion of excess gases.	Applicable to new flares. In existing plants, applicability may be restricted due to e.g. maintenance time availability during the turnaround of the plant.
(b)	Monitoring and recording as part of flare management	Continuous monitoring of the gas sent to flaring, measurements of gas flow and estimations of other parameters (e.g. composition, heat content, ratio of assistance, velocity, purge gas flow rate, pollutant emissions (e.g. NOX, CO, hydrocarbons, noise)). The recording of flaring events usually includes the estimated/measured flare gas composition, the estimated/measured flare gas quantity and the duration of operation. The recording allows for the quantification of emissions and the potential prevention of future flaring events.	Generally applicable.

	Technique	Applicability
Techniques related to plant design
(a)	Limit the number of potential emission sources	Applicability may be restricted in the case of existing plants due to operability requirements.
(b)	Maximise process-inherent containment features
(c)	Select high-integrity equipment (see the description in Section 6.2)
(d)	Facilitate maintenance activities by ensuring access to potentially leaky equipment
Techniques related to plant/equipment construction, assembly and commissioning
(e)	Ensure well-defined and comprehensive procedures for plant/equipment construction and assembly. This includes using the designed gasket stress for flanged joint assembly (see the description in Section 6.2)	Generally applicable.
(f)	Ensure robust plant/equipment commissioning and handover procedures in line with the design requirements
Techniques related to plant operation
(g)	Ensure good maintenance and timely replacement of equipment	Generally applicable.
(h)	Use a risk-based leak detection and repair (LDAR) programme (see the description in Section 6.2)
(i)	As far as it is reasonable, prevent diffuse VOC emissions, collect them at source, and treat them

The associated monitoring is in BAT 5.

The associated monitoring is in BAT 6.

Technique	Description
Activated sludge process	The biological oxidation of dissolved organic substances with oxygen using the metabolism of microorganisms. In the presence of dissolved oxygen (injected as air or pure oxygen) the organic components are mineralised into carbon dioxide and water or are transformed into other metabolites and biomass (i.e. the activated sludge). The microorganisms are maintained in suspension in the waste water and the whole mixture is mechanically aerated. The activated sludge mixture is sent to a separation facility from which the sludge is recycled to the aeration tank.
Nitrification/denitrification	A two-step process that is typically incorporated into biological waste water treatment plants. The first step is the aerobic nitrification where microorganisms oxidise ammonium (NH4 +) to the intermediate nitrite (NO2 –), which is then further oxidised to nitrate (NO3 –). In the subsequent anoxic denitrification step, microorganisms chemically reduce nitrate to nitrogen gas.
Chemical precipitation	The conversion of dissolved pollutants into an insoluble compound by adding chemical precipitants. The solid precipitates formed are subsequently separated by sedimentation, air flotation or filtration. If necessary, this may be followed by microfiltration or ultrafiltration. Multivalent metal ions (e.g. calcium, aluminium, iron) are used for phosphorus precipitation.
Coagulation and flocculation	Coagulation and flocculation are used to separate suspended solids from waste water and are often carried out in successive steps. Coagulation is carried out by adding coagulants with charges opposite to those of the suspended solids. Flocculation is carried out by adding polymers, so that collisions of microfloc particles cause them to bond to produce larger flocs.
Equalisation	Balancing of flows and pollutant loads at the inlet of the final waste water treatment by using central tanks. Equalisation may be decentralised or carried out using other management techniques.
Filtration	The separation of solids from waste water by passing them through a porous medium e.g. sand filtration, microfiltration and ultrafiltration.
Flotation	The separation of solid or liquid particles from waste water by attaching them to fine gas bubbles, usually air. The buoyant particles accumulate at the water surface and are collected with skimmers.
Membrane bioreactor	A combination of activated sludge treatment and membrane filtration. Two variants are used: a) an external recirculation loop between the activated sludge tank and the membrane module; and b) immersion of the membrane module into the aerated activated sludge tank, where the effluent is filtered through a hollow fibre membrane, the biomass remaining in the tank (this variant is less energy-consuming and results in more compact plants).
Neutralisation	The adjustment of the pH of waste water to a neutral level (approximately 7) by the addition of chemicals. Sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)2) is generally used to increase the pH; whereas, sulphuric acid (H2SO4), hydrochloric acid (HCl) or carbon dioxide (CO2) is generally used to decrease the pH. The precipitation of some substances may occur during neutralisation.
Sedimentation	The separation of suspended particles and suspended material by gravitational settling.

Technique	Description
High-integrity equipment	High-integrity equipment includes: valves with double packing seals; magnetically driven pumps/compressors/agitators; pumps/compressors/agitators fitted with mechanical seals instead of packing; high-integrity gaskets (such as spiral wound, ring joints) for critical applications; corrosion-resistant equipment.
Leak detection and repair (LDAR) programme	A structured approach to reduce fugitive VOC emissions by detection and subsequent repair or replacement of leaking components. Currently, sniffing (described by EN 15446) and optical gas imaging methods are available for the identification of leaks. Sniffing method The first step is the detection using hand-held VOC analysers measuring the concentration adjacent to the equipment (e.g. by using flame ionisation or photo-ionisation). The second step consists of bagging the component to carry out a direct measurement at the source of emission. This second step is sometimes replaced by mathematical correlation curves derived from statistical results obtained from a large number of previous measurements made on similar components. Optical gas imaging methods Optical imaging uses small lightweight hand-held cameras which enable the visualisation of gas leaks in real time, so that they appear as ‘smoke’ on a video recorder together with the normal image of the component concerned, to easily and rapidly locate significant VOC leaks. Active systems produce an image with a back-scattered infrared laser light reflected on the component and its surroundings. Passive systems are based on the natural infrared radiation of the equipment and its surroundings
Thermal oxidation	The oxidation of combustible gases and odorants in a waste gas stream by heating the mixture of contaminants with air or oxygen to above its auto-ignition point in a combustion chamber and maintaining it at a high temperature long enough to complete its combustion to carbon dioxide and water. Thermal oxidation is also referred to as ‘incineration’, ‘thermal incineration’ or ‘oxidative combustion’.
Using the designed gasket stress for flanged joint assembly	This includes: obtaining a certified high quality gasket, e.g. according to EN 13555; calculating the highest possible bolt load, e.g. according to EN 1591-1; obtaining a qualified flange-assembling equipment; supervision of the bolt tightening by a qualified fitter.
VOC diffuse emissions monitoring	Sniffing and optical gas imaging methods are described under leak detection and repair programme. Full screening and quantification of emissions from the installation can be undertaken with an appropriate combination of complementary methods, e.g. Solar occultation flux (SOF) or Differential absorption LIDAR (DIAL) campaigns. These results can be used for trend evaluation in time, cross-checking and updating/validation of the on-going LDAR programme. Solar occultation flux (SOF) The technique is based on the recording and spectrometric Fourier Transform analysis of a broadband infra-red or ultraviolet/visible sunlight spectra along a given geographical itinerary, crossing the wind direction and cutting through VOC plumes. Differential absorption LIDAR (DIAL) This is a laser-based technique using differential absorption LIDAR (light detection and ranging), which is the optical analogue of radio wave-based RADAR. The technique relies on the back-scattering of laser beam pulses by atmospheric aerosols, and the analysis of spectral properties of the returned light collected with a telescope.