When the Clean Water Act was implemented in the U.S. in the 1970s it meant tough restrictions in water management for the construction industry and for industrial sites. In the Pacific Northwest the new water quality standards meant that contractors started having problems meeting water quality benchmarks.

This meant that many construction projects were shut down during the rainy winter season from November to March, as they failed to meet the new stormwater discharge standards. It is difficult to fully comprehend the resulting economic impacts.

In response to the new regulations the construction industry sent out a call for help to environmental and water treatment experts around the U.S. John Macpherson has been working with water treatment technologies since the 1970s and was one of the experts who took on the challenge to develop more effective methods to manage construction stormwater. During the 1990s he worked with several different technologies before discovering a new treatment solution – chitosan!

Chitosan is a waste product from the food industry (processed crab shell) and has been used in health care and military applications as a blood coagulant. These same properties of chitosan which also makes it a very good flocculant in water treatment. John developed a method using chitosan for the treatment of stormwater for construction projects, which made it possible to meet the strict regulations to discharge stormwater from construction sites. Today it is possible to keep construction projects active throughout the winter, extending the season from 7 to 12 months.

This treatment method has been extensively evaluated and documented, showing effective treatment results and an excellent environmental safety record. Water treatment with chitosan has been used in thousands of treatment projects throughout the U.S. and is approved by most U.S. states.

Applications include:

• The construction industry
• Industrial sites
• The forest industry
• The Department of Transportation
• Public Utility Districts

Swedish Hydro Solutions has developed the technology further, resulting in lowers cost, easier maintenance and improved reliability. The technology is patented and has previously been unavailable. It is designed to meet all authority environmental standards and to handle high flow rates that are common for the construction industry.