WASTE WATER

Use of water and discharge of wastewater can be critical issue for many industrial companies.

However for furniture industry it might be still of high relevance in some cases:

• if companies having also process for timber processing - the wood is watered during the processing what makes big amounts of the water used and waste water potentially with problematic substances discharged or surface water run-off from timber storage areas; such effluents might pollute surface or groundwater;
• if company has wood impregnation and coating processes the emissions of priority substances to environment can occur;
• if company perform spray painting using water curtains to collect oversprayed solvent based paint/varnish/adhesives; organic solvents can be harmful to the environment and may be toxic to a large range of species such as aquatic invertebrates;
• if company using water based paints/varnish;
• if company discharges cooling water from the processes;
• the presence of solids, such as wood dust and wood chips, can also cause pollution of watercourses as they settle out and coat the bed of the watercourse, smothering the aquatic life below.

Also for printing houses it takes important place. Discharges to water bodies mainly contaminated by photographic and residual chemicals, silver, copper, chromium, organic solvents and other toxic organic compounds.
While the printing industry is very diverse, the water issue may be of different relevance to different companies, e.g. it could be discharges from developing, fixing and rinsing processes, which contain hazardous substances; strong acid/alkaline etch and counter-etch solutions etc.

Use of water and discharge of wastewater is one of the most critical issues for most of metal processing industry. Metal finishers differ widely in the types of items that are finished and in the types of plating or finishing that they do. Each variation in the finishing process results in a different waste stream and, in fact, no two metal finishers will generate exactly the same types of wastewater.
Wastewater issue is of high relevance in many cases, e.g.:

• while performing metal surface treatment or coating (electroplating) - plating baths with metals, acid solutions, rinse waters - they may contain metals, acids, alkalines, other dangerous components, which may be emitted to the environment, e.g.
• hydrochloric, nitric, phosphoric, and sulphuric acids are highly corrosive and by side of high risk to human health may cause very large threat to the environment through a sudden large release as happens during a spill;
• alkaline solutions such as sodium hydroxide, potassium hydroxide, and other bases due to very high pH can kill many organisms;
• if company perform spray painting using water curtains to collect oversprayed solvent based paint/varnish/adhesives; organic solvents can be harmful to the environment and may be toxic to a large range of species such as aquatic invertebrates;
• if company discharges cooling water from the processes, they may contain different hazardous substances.

The chapter mainly focuses on discharges of wastewater and occurrence of hazardous substances in it. However, the best available practices, information sources and practical tools also cover consumption of the water. 

• Leaflet for industry using chemicals “Take action and avoid use of hazardous substances: advices for identification of hazardous substances in industrial chemicals”
  
• Good housekeeping guides with checklists for efficient use of water
  Good Housekeeping. Eco-efficient environmental actions:
  http://www.sba-int.ch/pdffiles/GHKGuideEnglish.pdf
• Guidance for the use of environmentally sound substances. For producers and professional users of chemical products relevant to the aquatic environment
  http://www.umweltbundesamt.de/umweltvertraegliche-stoffe-e/guidehome.htm (english)
• Best available techniques in the printing industry (Surface treatment using organic solvents):
  http://www.umweltdaten.de/publikationen/fpdf-l/2457.pdf 
• Biochemicals for the printing industry: http://www.carbohydrateeconomy.org/library/admin/uploadedfiles/Biochemicals_for_the_Printing_Industry.pdf

Furniture industry

• Reduce the pollution of water:
• replace at least most hazardous substances (CMR, PBT) with more environmentally sound substances;
• separate flows of hazardous and non-hazardous wastewater;
• keep the storage place of chemicals in order;
• avoid spillages and leakages;
• spray preservatives or coating materials on the wood using a high velocity spray system, high volume, low pressure (HVLP) spray guns to reduce overspray, increase transfer efficiency and less drippage;
• use concrete pads for wood treatment area and intermediate storage areas to ensure collection of drippage;
• switch to water-based preservatives and paints, which are less toxic and damaging than typical solvent-based preservatives or paints;
• pre-treat waste water before discharging it to surface water or municipal sewage system, i.e. use c oagulation/flocculation/precipitation, sedimentation/filtration/floatation, biofilters, activated sludge/aeration lagoons etc.
• Monitor water consumption and quality optimise it, e.g.by dry equipment cleaning and vacuum systems, where feasible
• Avoid spillages and leakage:
• place equipment on trays, it will help to prevent chemicals or oil spillages onto the ground, into drains and into surface waters and groundwater;
 
• have a cut off valve on the exit of your surface water system to a watercourse or sewer. This can then be closed if a spillage occur;
• regularly inspect the equipment and whole system for leakages from flanges, pumps, seals, valve glands etc. ;
• use inexpensive automatic flow controlers in containers to avoid water overflow;
• properly store the sludge from the “water curtains” systems for overspray;
• Reuse and /or recycle suitable water sources:
• collect and use rain water;
• recirculate cooling water;
• reuse water in a closed circuits.

Printing industry

• Reduce the pollution of water:
• collect spent fixing solution, reuse ir or manage as hazardous waste;
• do not use halogenated solvents;
• recover electrolytically silver from fixer prior to discharge of spent fixer to sewage system;
• minimise silver in waste water: use silver-free films (vesicular, diazo and electrostatic films, photopolymer films contain carbon black as a substitute for silver); recover silver from fixing baths and have a commercial recycler pick it up; purchase a silver recovery unit and perform the recycling of fixer on premises; add ammonium thiosulfate to silver contaminated baths to extend the allowable build-up of silver.
• use an acid stop bath prior to the fixing bath; this reduces the effect of an alkaline developer on the fixing bath pH; add acetic acid to the fixing bath, keeping the pH low to maximize soluble complexes;
• use floating lids on bleach and developer containers to keep them fresh;
• substitute non-hazardous raw materials for hazardous materials whenever possible;
• employ counter current rather than parallel rinse techniques (counter current rinsing means water from previous rinsings is used in the initial film washing stage; fresh water enter the process at the final rinse stage, at which point much of the contamination is already rinsed off the film);
• replace metal etching processes, with the associated hazardous chemical solutions and heavy metals, wherever possible (alternative plates include: presensitized lithographic, plastic or photopolymer, flexographic, electrostatic
• use water based inks whenever possible to cut down on the use of solvent based inks that cause employee and environmental hazards;
• clean ink fountains only when changing colours or when the ink might dry out between runs; fountains can be left with ink overnight if sprayed with special non-drying aerosol materials;
• dedicate one press for inks with hazardous pigments or solvents;
• use a fountain solution that contains low concentrations of isopropyl alcohol (IPA) or one containing no IPA;
• use soap or detergent solutions for cleaning wherever possible; use solvents only for cleaning inks and oils;
• use acetic acid based solvents, which are less toxic than other solvents;
• use vegetable based inks and cleaning preparations;
• organise jobs by colour, it reduces fountain cleaning;
• use alternative methods for developing the printing forms without photochemical process, e.g  so- called computer-to-plate (CTP) method is more and more applied.   
•  Monitor water consumption and quality optimise it, e.g. by dry equipment cleaning and vacuum systems, where feasible.
• Estimate the quantity of developing bath and fixing bath used per year and maintain these at acceptable levels.
• Minimise the rinse water flow in the developing machines by, foe example, use of “stand-by”.
• Avoid spillages and leakage:
• place equipment on trays, it will help to prevent chemicals or oil spillages onto the ground, into drains and into surface waters and groundwater;
• have a cut off valve on the exit of your surface water system to a watercourse or sewer. This can then be closed if a spillage occur;
• regularly inspect the equipment and whole system for leakages from flanges, pumps, seals, valve glands etc.;
• use inexpensive automatic flow controllers in containers to avoid water overflow;
• collect and properly store environment hazardous waste such as dyes, inks and solvents so that risk of spillage into the waste water system is minimised
• use dry methods for cleanup wherever possible.
• Reuse and /or recycle suitable water sources:
• collect and use rain water;
• aim for the closed washing system;
• use equipment wash down waters as makeup solutions for subsequent batches;
• use counter current flow fixing and rinsing processes;
• segregate wastes to increase recyclability.

Metal industry

• Reduce the pollution of water:
• spray coating materials on the wood using a high velocity spray system, high volume, low pressure (HVLP) spray guns  to reduce overspray, increase transfer efficiency and less drip page;
• use concrete pads for metal treatment area and intermediate storage areas to ensure collection of drip page;
• if technically possible, substitution of hazardous substances (e.g. cyanide, cadmium, mercury, EDTA and similar sequestering agents, nonylphenol‑ethoxylates, chlorinated organics) by substances which are readily biodegradable, non‑bioaccumulating and non‑mutagenic and have a low toxicity;
• substitution of EDTA in degreasing baths, stripping baths and chemical nickel plating baths. Possible substitutes include e.g. citric acid, tartaric acid and gluconic acid;
• substitution of processes generating noxious substances wherever possible (e.g. cyanide oxidation with hypochlorite);
• treatment of process baths using suitable processes in order to have the longest possible service life. Such processes include, e.g. membrane filtration, ion exchange, electrolysis, thermal processes and evaporation;
• retention of bath ingredients by suitable means, such as transporting the goods in such a way that drag‑out is minimised; splash guards or optimised bath composition;
• multiple use of counter‑current rinse waters (at least three rinsing steps should be applied). Suitable techniques to keep more than 90% of the drag‑out in a small volume for recovery/recycling are, e.g.: i) static rinse in combination with metal recovery; ii) 2‑stage cascade rinsing plus closed cycle rinsing with ion exchange; iii) combined dip/spray/mist rinsing techniques. If possible these rinsing concentrates should be returned into the process baths, if necessary after specific treatment/concentration. By applying these rinsing techniques process baths can often be operated as closed water/low waste systems;
• separation of suitable non‑ferrous metal waste water streams to carry out internal recycling (e.g. by electrolysis) or external recovery (e.g. by non‑ferrous metal industry);
• recovery of EDTA from chemical copper plating baths (e.g. by precipitation as H4EDTA) and their rinse baths (e.g. by precipitation after a concentration step, e.g. by anion exchange);
• replacement of chlorinated solvents by water-based systems or non-halogenated organic solvents,
• use alternative methods for metal surface treatment from oils, greases, rosin fluxes, e.g. cleaning with dry ice.  
•  Monitor water consumption and quality optimise it, e.g. by dry equipment cleaning and vacuum systems, where feasible.
• Avoid spillages and leakage:
• place equipment on trays, it will help to prevent chemicals or oil spillages onto the ground, into drains and into surface waters and groundwater;
• have a cut off valve on the exit of your surface water system to a watercourse or sewer. This can then be closed if a spillage occur;
• regularly inspect the equipment and whole system for leakages from flanges, pumps, seals, valve glands etc.;
• use inexpensive automatic flow controllers in containers to avoid water overflow;
• properly store the sludge from the “water curtains” systems for overspray or electroplating baths;
• Reuse and /or recycle suitable water sources:
• collect and use rain water;
• recirculate cooling water;
• reuse water in a closed circuits.

Besides these advices, also draft EU BAT references document (BREFs) for ferrous metals processing, non-ferrous metals processing, surface treatment of metals can also provide guidance to reduce emissions to water. Although these documents are binding only for large companies (which fall under IPPC directive), also for smaller companies they can give some ideas for the improvement of own performance: see in English http://eippcb.jrc.es/pages/FActivities.htm

• Other lists of undesirable substances
• N-CLASS Database on Environmental Hazard Classification:
  http://apps.kemi.se/nclass/default.asp
• Substances hazardous to environment and criteria set – PRIO database:
  http://www.kemi.se/templates/PRIOEngframes____970.aspx
• OSPAR:
  http://www.ospar.org/eng/doc/04-12e_2005%20amended%20LCPA.doc
• HELCOM:
  http://www.helcom.fi/Recommendations/en_GB/rec19_5/
• Useful databases:
• RISKLINE Database - Information on environment and health related properties of substances:
  http://apps.kemi.se/riskline/index.htm
• TOXNET – Toxicology Data Network
  http://toxnet.nlm.nih.gov/
• HSDB (Hazardous Substances Data Bank) à extensive information on toxicity, environmental fate, human exposure, chemical safety, waste disposal, emergency handling
• IRIS (Integrated Risk Information System) à carcinogenic and non-carcinogenic health risk assessment
• Haz-Map à health effects of exposure to chemicals at work, jobs and hazardous tasks with occupational diseases and their symptoms
• ECOTOX Database – Information on single chemical toxicity information for aquatic and terrestrial life:
  http://www.epa.gov/ecotox/
• Database on harmonised classifications and labelling for substances or groups of substances included into Annex I of Directive 67/548/EEC – Classlab database:
  http://ecb.jrc.it/classification-labelling/

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