Commentaries: Annex 5

(Art. 6 para. 1 and 7 para. 1)

Discharge of industrial wastewater into waters or into public sewer systems

1 Definition and principles

¹Industrial wastewater includes:

wastewater from industrial plants;
comparable wastewater, such as that from laboratories and hospitals.

²Any person who discharges industrial wastewater must, during production processes and wastewater treatment take the require state-of-the-art measures to avoid polluting waters. In particular, they must ensure that:

as little wastewater is generated and as few potential water pollutants are discharged as is technically and operationally feasible and economically acceptable;
unpolluted wastewater and cooling water are separated from polluted wastewater;
polluted wastewater is neither diluted nor mixed with other wastewater in order to comply with the requirements; dilution or mixing is permitted if this is appropriate for the treatment of the wastewater and as a result no more potential water pollutants are discharged than would be the case if the wastewaters were treated separately.

³At the site of discharge, when discharging wastewater into waters or public sewers they must comply with:

the general requirements in accordance with No 2; and
the special requirements for specific substances in accordance with No 3 for wastewater from certain industrial sectors.

⁴If the person responsible for the concern can prove that they have taken the required state-of-the-art measures mentioned in paragraph 2, and that compliance with the general requirements specified in No 2 would be disproportionate, the authorities shall specify less stringent values.

⁵If the required state-of-the-art measures mentioned in paragraph 2 make it possible to comply with more stringent requirements than those specified in Nos 2 and 3, the authorities shall apply more stringent values based on the information received from the person responsible for the concern and after having heard this person.

⁶If Nos 2 and 3 contain no requirements for specific potential water pollutants, the authorities shall specify the necessary requirements based on the state of the art in the authorisation. In so doing they shall take account of international or national standards, directives published by the FOEN or standards drawn up by the industrial sector concerned in collaboration the FOEN.

⁷If industrial wastewater also containing communal wastewater (Annex 3.1) or other polluted wastewater (Annex 3.3) is discharged into a body of water, the authorities shall specify the requirements in the authorisation in such a way that no more potential water pollutants are discharged with the wastewater than would be the case if the different wastewaters were treated separately in compliance with the requirements of the corresponding Annexes.

2 General requirements

No.	Parameter	Column 1: requirements for discharge into waters	Column 2: requirements for discharge into public sewers
1	pH	6.5 to 9.0	6.5 to 9.0; divergences are admissible if there is sufficient mixing with other wastewaters in the sewers.
2	Temperature	At most 30 °C. The authorities may allow minor short-term excesses in summertime.	At most 60 °C. The temperature in the sewer system must not exceed 40 °C after mixing.
3	Transparency(Snellen method)	30 cm	–
4	Total suspended solids	20 mg/l	–
5	Arsenic(As)	0.1 mg/l As (total)	0.1 mg/l As (total)
6	Lead(Pb)	0.5 mg/l Pb (total)	0.5 mg/l Pb (total)
7	Cadmium(Cd)	0.1 mg/l Cd (total)	0.1 mg/l Cd (total)
8	Chromium(Cr)	2 mg/l Cr (total); 0.1 mg/l Cr-VI	2 mg/l Cr (total)
9	Cobalt(Co)	0.5 mg/l Co (total)	0.5 mg/l Co (total)
10	Copper(Cu)	0.5 mg/l Cu (total)	1 mg/l Cu (total)
11	Molybdenum(Mo)	–	1 mg/l Mo (total)
12	Nickel(Ni)	2 mg/l Ni (total)	2 mg/l Ni (total)
13	Zinc(Zn)	2 mg/l Zn (total)	2 mg/l Zn (total)
14	Cyanide(CN ^–)	0.1 mg/l CN^–(free and easily releasable cyanide)	0.5 mg/l CN^–(free and easily releasable cyanide)
15	Total hydrocarbons	10 mg/l	20 mg/l
16	Volatile chlorinated hydrocarbons(VOCl) or volatile organic halogens(VOX)	0.1 mg/l Cl or 0.1 mg/l X	0.1 mg/l Cl or 0.1 mg/l X

3 Special requirements for specific substances from certain industrial sectors

In addition to the following requirements, the internationally agreed decisions and recommendations approved by the Federal Council or the Department in under Article 51 apply to the whole of Switzerland.¹

31 Foodstuff processing

No.	Sector/process	Column 1: requirements for discharge into waters	Column 2: requirements for discharge into public sewers
	– Milk processing – Fruit and vegetable processing – Manufacture and bottling of soft drinks – Potato processing – Meat processing – Breweries – Manufacture of alcohol and alcoholic drinks – Manufacture of fodder from plant products – Manufacture of leather glue, gelatine and bone glue – Malt factories – Fish processing	Requirements for communal wastewater in accordance with Annex 3.1 apply. Excepted are the requirements for total phosphorus in cases in where phosphorus must be added in the wastewater treatment plant for the biological treatment step.	In fat and oil processing plants, separators must be fitted if necessary.

32 Secondary iron and steel industry

No.	Sector/process	Parameter/requirements for discharge into waters and public sewers
1	Continuous casting	Process water: – at least 95 per cent recirculation Total suspended solids: – 10 g/t processed steel ( daily average) Oil: – 5 g/t processed steel (daily average)
2	Cold rolling	Total suspended solids: – 10 g/t processed steel (daily average) Oil: – 5 g/t processed steel (daily average)
3	Hot rolling	Process water: – at least 95 per cent recirculation Total suspended solids: – 50 g/t processed steel (daily average) Oil: – 10 g/t processed steel (daily average)
4	Pickling plants	Cadmium (Cd): – 0.2 mg/l Cd (daily average) or Chromium (Cr): – 0.1 mg/l Cr-VI (daily average) – 1 mg/l Cr (total) (daily average) Nickel (Ni): – 1 mg/l Ni (daily average) Zinc (Zn): – 2 mg/l Zn (daily average) Acid regeneration: – Acid regeneration for reduction of nitrate discharge from pickling plants using more than 20 tonnes of nitric acid per year, or other equivalent measures

For plants that were commissioned before 1 January 1993, the authorities shall specify the requirements on a case-by-case basis.

33 Surface treatment / electroplating

No.	Sector/ process	Parameter / requirements for discharge into waters and public sewers
1	Use of 1,2-dichloroethane to degrease metals	1,2-dichloroethane: – 0.1 mg/l (monthly average) – 0.2 mg/l (daily average)
2	Use of trichloroethene to degrease metals	Trichloroethene: – 0.1 mg/l (monthly average) – 0.2 mg/l (daily average)
3	Use of tetrachloroethene to degrease metals	Tetrachloroethene: – 0.1 mg/l (monthly average) – 0.2 mg/l (daily average)
4	Surface treatment	Volatile organic halogens (VOX): – 0.1 mg/l VOX (daily average) Cyanide (CN ^–): – 0.2 mg/l CN^–(unbound) (daily average) Mercury (Hg): – 0.05 mg/l Hg (daily average) or – 0.03 kg Hg per tonne of mercury used (daily average) Cadmium (Cd): – 0.2 mg/l Cd (daily average) or – 0.3 kg Cd per tonne of cadmium used (daily average) Chromium (Cr): – 0.1 mg/l Cr-VI (daily average) – 0.5 mg/l Cr (total) (daily average)^a Lead (Pb): – 0.5 mg/l Pb (daily average)^a Copper (Cu): – 0.5 mg/l Cu (daily average)^a Nickel (Ni): – 0.5 mg/l Ni (daily average)^a Zinc (Zn): – 0.5 mg/l Zn (daily average); in justified cases the authorities may admit up to 2 mg/l Zn (daily average) Silver (Ag): – 0.1 mg/l Ag (daily average) Tin (Sn): – 2 mg/l Sn (daily average).
^a For surface treatment plants discharging small quantities of metals (defined as: sum of total chromium, lead, copper, nickel and zinc less than 200 g/day), the authorities may admit up to 2 mg/l (monthly average).

34 Chemical industry

No.	Sector/process	Parameter/requirements on discharge into waters and public sewers
1	Manufacture of chlorine by chlorine-alkali electrolysis	Mercury (Hg): Use of mercury-free processes.
2	Production of cadmium pigments	Cadmium (Cd): – 0.2 mg/l Cd (monthly average) – 0.4 mg/l Cd (daily average)

35 Manufacture of paper, cardboard and pulp

No.	Sector/process	Parameter/requirements on discharge into waters	Parameter/requirements on discharge into public sewers
1	Production of paper or cardboard	Total suspended solids: – 1 kg per tonne production of paper or cardboard (daily average) or 50 mg/l (daily average) Chemical oxygen demand (COD)/dissolved organic carbon (DOC): – according to type of paper: 2,5–5 kg COD per tonne production of paper or cardboard (daily average) or 1,5–2,5 kg DOC per tonne production of paper or cardboard (daily average) Biochemical oxygen demand (BOD 5 ): – according to type of paper: 0.5–1 kg per tonne production of paper or cardboard (daily average); in justified cases the authorities may instead of the above-mentioned requirement admit a value of 25 mg/l BOD5(daily average).	The authorities set the requirements from case to case

No.	Sector/process	Parameter/requirements on discharge into waters
2	Production of sulphite pulp	(BOD5): – 5 kg per tonne production of air dry pulp (monthly average) Chemical oxygen demand (COD): – 35 kg per tonne production of air dry pulp (monthly average) – 70 kg per tonne production of air dry pulp (monthly average) for plants which were commissioned before 1.1.1997 If the correlation between the COD and the total organic carbons (TOC) is given and proved, monitoring may be carried out on the TOC instead of on the COD. Total suspended solids: – 4.5 kg per tonne production of air dry pulp (monthly average) 8.0 kg per tonne production of air dry pulp (monthly average) from 1.1.2000 for plants which were commissioned before 1.1.1997 and did not increase their production capacity after 1.1.1997 by more than 50 per cent. Adsorbable organic halogens (AOX), for plants which do not produce exclusively chlorine-free bleached pulp: – 0.5 kg per tonne production of bleached air dry pulp (monthly average) Molecular chlorine ratio: – less than 0.05 to 0.1, according to type of pulp

36 Public utilities and waste disposal plants

No.	Sector / process	Column 1: requirements on discharge into waters	Column 2: requirements on discharge into public sewers
1	Filter water from water treatment	Total suspended solids: – 30 mg/l (daily average) (guide value)	No special requirements
2	Waste incineration plants	Antimony (Sb): – 0.1 mg/l Sb^a Arsenic (As): – 0.1 mg/l As^a Lead (Pb): – 0.1 mg/l Pb^a Cadmium (Cd): – 0.05 mg/l Cd^a Chromium (total Cr): – 0.1 mg/l Cr^a Copper (Cu): – 0.1 mg/l( Cu)^a Nickel (Ni): – 0.1 mg/l Ni^a Zinc (Zn): – 0.1 mg/l Zn^a Mercury (Hg): – 0.001 mg/l Hg^a Dissolved organic carbon (DOC): – 10 mg/l DOC	Sulphate : If there is a risk of corrosion in the public sewers, the authorities shall specify a value for admissible sulphate concentrations in each individual case.
3	Processing wastes containing mercury	Mercury (Hg): – 0.05 mg/l Hg in monthly average – 0.1 mg/l Hg in daily average	Mercury (Hg): – 0.05 mg/l Hg in monthly average – 0.1 mg/l Hg in daily average
4	Desilverisation of fixative baths	Silver (Ag): The authorities set the requirements from case to case.	Silver (Ag): – 5 mg/l Ag
5	Desilverisation of bleach- hardeners	Silver (Ag) and bleaching agents: The authorities shall apply the requirements in each individual case.	Silver (Ag) and bleaching agents: – 5 mg/l Ag Poorly biodegradable bleaching agents (especially Fe-EDTA -complex and EDTA-surplus): – the authorities set the requirements from case to case.
^a Guide value for requirements on discharge to be specified by the authorities on a case by case basis depending on the actual conditions.

37 Other sectors

No.	Sector/ process	Column: requirements on discharge into waters	Column 2: requirements on discharge into public sewers
1	Photographic processes	Silver (Ag): the authorities set the requirements from case to case.	Silver (Ag): 50 mg/l Ag in cases where annual consumption of fixative bath does not exceed 1000 l/a 5 mg/l Ag in cases where consumption of fixative bath is in excess of 1000 l/a
2	Manufacture of primary batteries containing mercury	Mercury (Hg): – 0.05 mg/l Hg (monthly average) – 0.1 mg/l Hg (daily average) – 0.03 g/kg Hg per kg of mercury used (monthly average) – 0.06 g/kg Hg per kg of mercury used (daily average)
3	Manufacture of other primary batteries and secondary batteries	Cadmium (Cd): – 0.2 mg/l Cd (monthly average) – 0.4 mg/l Cd (daily average)
4	Processes requiring use of pathogenic micro-organisms	–	Pathogenic micro ‑organisms: inactivation
5	Dental surgeries and clinics	Amalgam : The authorities specify the requirements on a case to case basis.	Amalgam : Treatment units in which amalgam is processed, shall be equipped with an amalgam separator with a removal efficiency of at least 95%.

Available from the Federal Office for the Environment, 3003 Bern. ↩