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Environmental Best Practices, Part 3

(October 2008) posted on Mon Oct 06, 2008

Structuring your company around safe environmental practices is becoming a necessity


By Neil Bolding, Steven Abbott

It’s worth reminding yourself and your staff that the outflow leaving a sewage- treatment facility isn’t just something you can forget about. That outflow might be going into a local river that, in turn, is the source of your drinking water. Thinking of it like that helps concentrate the mind on the real problems. There are basically three effects to be concerned with that can create a potentially dangerous out-flow situation:

Overload There’s nothing the sewage system can do about too much effluent coming in, and when the system is overwhelmed, raw sewage can get into the local river or other outflow site. For this reason, authorities do their best to take account of not only on your average load, but also the extreme loads you can produce.

Chemicals bacteria can’t consume Some chemicals show a high degree of environmental persistence (i.e., they are very stable and don’t decompose easily or are insoluble in water) and they may accumulate and harm the bacteria. Organo-halogen and organophosphorous compounds are typical examples of such chemicals, with the latter frequently found in industrial detergents. Pesticides or biocides, such as Aldrin, DDT, and Lindane, create similar problems.

Nitrogen content Lots of nitrites and nitrates in the outflow can cause problems, and the solvents you put down the drain can affect the concentration of these substances. A complex nitrification test (ISO 9509) can be used to divide solvents into two types—those that affect the balance and those that don’t. Presently, few countries are alert to the nitrification issue. But screen-cleaning products that have no negative effect on the nitrification process are available and will become more common as more countries adopt stricter standards concerning this issue.

 

Other problems lurking in the water

Within the screen industry, the use of nonylphenol surfactants in cleaning products was once widespread. Unfortunately, these materials mimic natural hormones, causing sterility in fish and other aquatic life that ingests them. So many cleaning-chemical manufacturers have removed these materials from their products. Note, however, that some less reputable suppliers of cleaning chemicals still include nonylphenol surfactants in their products, and the burden falls on the printer to avoid such formulations.

 

Reducing BOD/COD


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