New plant,A plant first permitted at the site of the installation following the publication of these BAT conclusions or a complete replacement of a plant following the publication of these BAT conclusions.,
Existing plant,A plant that is not a new plant.,
Biochemical oxygen demand (BOD 5 ),Amount of oxygen needed for the biochemical oxidation of the organic matter to carbon dioxide in 5 days. BOD is an indicator for the mass concentration of biodegradable organic compounds.,
Chemical oxygen demand (COD),Amount of oxygen needed for the total oxidation of the organic matter to carbon dioxide. COD is an indicator for the mass concentration of organic compounds.,
Total organic carbon (TOC),Total organic carbon, expressed as C, includes all organic compounds.,
Total suspended solids (TSS),Mass concentration of all suspended solids, measured via filtration through glass fibre filters and gravimetry.,
Total nitrogen (TN),Total nitrogen, expressed as N, includes free ammonia and ammonium (NH 4 -N), nitrites (NO 2 -N), nitrates (NO 3 -N) and organic nitrogen compounds.,
Total inorganic nitrogen (N inorg ),Total inorganic nitrogen, expressed as N, includes free ammonia and ammonium (NH 4 -N), nitrites (NO 2 -N) and nitrates (NO 3 -N).,
Total phosphorus (TP),Total phosphorus, expressed as P, includes all inorganic and organic phosphorus compounds, dissolved or bound to particles.,
Adsorbable organically bound halogens (AOX),Adsorbable organically bound halogens, expressed as Cl, include adsorbable organically bound chlorine, bromine and iodine.,
Chromium (Cr),Chromium, expressed as Cr, includes all inorganic and organic chromium compounds, dissolved or bound to particles.,
Copper (Cu),Copper, expressed as Cu, includes all inorganic and organic copper compounds, dissolved or bound to particles.,
Nickel (Ni),Nickel, expressed as Ni, includes all inorganic and organic nickel compounds, dissolved or bound to particles.,
Zinc (Zn),Zinc, expressed as Zn, includes all inorganic and organic zinc compounds, dissolved or bound to particles.,
VOC,Volatile organic compounds as defined in Article 3(45) of Directive 2010/75/EU.,
Diffuse VOC emissions,Non-channelled VOC emissions which can result from ‘area’ sources (e.g. tanks) or ‘point’ sources (e.g. pipe flanges).,
Fugitive VOC emissions,Diffuse VOC emissions from ‘point’ sources.,
Flaring,High-temperature oxidation to burn combustible compounds of waste gases from industrial operations with an open flame. Flaring is primarily used for burning off flammable gas for safety reasons or during non-routine operational conditions.,
    Monitoring frequencies may be adapted if the data series clearly demonstrate a sufficient stability.    ,
    The sampling point is located where the emission leaves the installation.    ,
    TOC monitoring and COD monitoring are alternatives. TOC monitoring is the preferred option because it does not rely on the use of very toxic compounds.    ,
    TN and N inorg monitoring are alternatives.    ,
    An appropriate combination of these methods can be used.    ,

Total organic carbon (TOC) ,EN 1484,Daily,
Chemical oxygen demand (COD) ,No EN standard available,
Total suspended solids (TSS),EN 872,
Total nitrogen (TN) ,EN 12260,
Total inorganic nitrogen (N inorg ) ,Various EN standards available,
Total phosphorus (TP),Various EN standards available,
Adsorbable organically bound halogens (AOX),EN ISO 9562,Monthly,
Metals,Cr,Various EN standards available,
Cu,
Ni,
Pb,
Zn,
Other metals, if relevant,
Toxicity ,Fish eggs ( Danio rerio ),EN ISO 15088,To be decided based on a risk assessment, after an initial characterisation,
Daphnia ( Daphnia magna Straus ),EN ISO 6341,
Luminescent bacteria ( Vibrio fischeri ),EN ISO 11348-1, EN ISO 11348-2 or EN ISO 11348-3,
Duckweed ( Lemna minor ),EN ISO 20079,
Algae,EN ISO 8692, EN ISO 10253 or EN ISO 10710,
    These techniques are further described and defined in other BAT conclusions for the chemical industry.    ,
    See BAT 11.    ,
    See BAT 12.    ,

(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 descriptions of the techniques are given in Section 6.1.    ,


(a),Equalisation,All pollutants,Generally applicable.,
(b),Neutralisation,Acids, alkalis,
(c),Physical separation, e.g. screens, sieves, grit separators, grease separators or primary settlement tanks,Suspended solids, oil/grease,

(d),Activated sludge process,Biodegradable organic compounds,Generally applicable.,
(e),Membrane bioreactor,

(f),Nitrification/denitrification,Total nitrogen, ammonia,  Nitrification may not be applicable in case of high chloride concentrations (i.e. around 10 g/l) and provided that the reduction of the chloride concentration prior to nitrification would not be justified by the environmental benefits.    Not applicable when the final treatment does not include a biological treatment.  ,

(g),Chemical precipitation,Phosphorus,Generally applicable.,

(h),Coagulation and flocculation,Suspended solids,Generally applicable.,
(i),Sedimentation,
(j),Filtration (e.g. sand filtration, microfiltration, ultrafiltration),
(k),Flotation,
    No BAT-AEL applies for Biochemical oxygen demand (BOD). As an indication, the yearly average BOD 5 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 BOD 5 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.    ,

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.,
    Either the BAT-AEL for total nitrogen or the BAT-AEL for total inorganic nitrogen applies.    ,
    The BAT-AELs for TN and N inorg 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 N inorg , 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.    ,

Total nitrogen (TN) ,5,0-25 mg/l  ,The BAT-AEL applies if the emission exceeds 2,5 t/yr.,
Total inorganic nitrogen (N inorg ) ,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.,
    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.    ,

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.,

(a),Conditioning,Chemical conditioning (i.e. adding coagulants and/or flocculants) or thermal conditioning (i.e. heating) to improve the conditions during sludge thickening/dewatering.,Not applicable to inorganic sludges. The necessity for conditioning depends on the sludge properties and on the thickening/dewatering equipment used.,
(b),Thickening/dewatering,Thickening can be carried out by sedimentation, centrifugation, flotation, gravity belts, or rotary drums. Dewatering can be carried out by belt filter presses or plate filter presses.,Generally applicable.,
(c),Stabilisation,Sludge stabilisation includes chemical treatment, thermal treatment, aerobic digestion, or anaerobic digestion.,Not applicable to inorganic sludges. Not applicable for short-term handling before final treatment.,
(d),Drying,Sludge is dried by direct or indirect contact with a heat source.,Not applicable to cases where waste heat is not available or cannot be used.,

(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.,

(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. NO X , 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.,


(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,

(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,

(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,

(a),Minimise residence times,Minimise the residence time of waste water and sludge in collection and storage systems, in particular under anaerobic conditions.,Applicability may be restricted in the case of existing collection and storage systems.,
(b),Chemical treatment,Use chemicals to destroy or to reduce the formation of odorous compounds (e.g. oxidation or precipitation of hydrogen sulphide).,Generally applicable.,
(c),Optimise aerobic treatment,  This can include:      controlling the oxygen content;      frequent maintenance of the aeration system;      use of pure oxygen;      removal of scum in tanks.    ,Generally applicable.,
(d),Enclosure,Cover or enclose facilities for collecting and treating waste water and sludge to collect the odorous waste gas for further treatment.,Generally applicable.,
(e),End-of-pipe treatment,  This can include:      biological treatment;      thermal oxidation.    ,Biological treatment is only applicable to compounds that are easily soluble in water and readily bioeliminable.,

(a),Appropriate location of equipment and buildings,Increasing the distance between the emitter and the receiver and using buildings as noise screens.,For existing plants, the relocation of equipment may be restricted by a lack of space or excessive costs.,
(b),Operational measures,  This includes:      improved inspection and maintenance of equipment;      closing of doors and windows of enclosed areas, if possible;      equipment operation by experienced staff;      avoidance of noisy activities at night, if possible;      provisions for noise control during maintenance activities.    ,Generally applicable.,
(c),Low-noise equipment,This includes low-noise compressors, pumps and flares.,Applicable only when the equipment is new or replaced.,
(d),Noise-control equipment,  This includes:      noise-reducers;      equipment insulation;      enclosure of noisy equipment;      soundproofing of buildings.    ,Applicability may be restricted due to space requirements (for existing plants), health, and safety issues.,
(e),Noise abatement,Inserting obstacles between emitters and receivers (e.g. protection walls, embankments and buildings).,Applicable only to existing plants; since the design of new plants should make this technique unnecessary. For existing plants, the insertion of obstacles may be restricted by a lack of space.,

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 (NH 4  + ) to the intermediate nitrite (NO 2  – ), which is then further oxidised to nitrate (NO 3  – ). 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 (H 2 SO 4 ), hydrochloric acid (HCl) or carbon dioxide (CO 2 ) 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.,

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.     ,