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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

The drain is the ubiquitous black hole where waste goes, and, once it’s gone, most of us tend to think nothing more about it. Out of sight is out of mind. Well, not anymore. The drain-disposal route is a significant waste outlet we must consider in our environmental best practices journey. We encourage printers to be aware of their responsibilities to their drain systems and to the ever increasing restrictions on what can go down them.

Among the various catch phrases prevalent in our industry today, one is “drain safe,” which is a misleading term at best. Water can be thought of as drain safe, but too much of it down a drain can cause problems. Assurances made about the safety of products that will inevitably find their way to the drain are meant to offer printers wrestling with disposal issues a sense of security. But ignorance of true waste-disposal requirements is no safety net when the local water authorities decide to inspect your company.

Every region has focuses on different aspects of what goes down a drain, but these aspects are all variants of four key factors:

• volume of effluent

• percent solids and biological oxygen demand (BOD) and chemical oxygen demand (COD) of the effluent

• effect on bacteria in the effluent system

• effect on the outflow of the sewage system

We’ll discuss each in turn after a short description of how an ideal sewage system functions.

 

A stable sewer

The basic idea is that any waste sent down the drain should get converted into harmless byproducts by the bacteria in a sewage system. This degradation takes time, so a balance must be found. A very large sewage system will cope with nearly anything you can throw at it—but such systems represent a large investment, and regulators will still control what you can send down the drain. A small sewage system might cope well with average loads of effluent, but they can be overwhelmed by big surges of waste. So the ideal waste stream is a steady, modest load that gives the bacteria ample time to do their job.


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