How Close Is The Narragansett Bay Commission to
Achieving Zero Discharge of Metals and Cyanide?

Vanessa Li
Bachelor's of Arts in Environmental Studies
May 2002

In this thesis, I examine how close the Narragansett Bay Commission (NBC) is to reaching zero discharge of metals. The Narragansett Bay Commission (NBC) has reduced the amount of metals in influent flow to its Field's Point Wastewater Treatment Plant (FP WWTP) by approximately 95 % from 1981 levels. But in 2000, NBC still received 53,857 pounds of metals. In this study, I examine whether industrial sources continue to be important sources of metals and cyanide and to uncover other possible sources of metals and cyanide.

To conduct my study on industrial contribution of metals and cyanide, I have made a basic assumption that the amount of metals going into the WWTP equals the total metals going out of the plant. The effluent metals can be in the form of sludge or remain in the treated water that goes into Narragansett Bay. For the purpose of my study, I will be focusing on influent mass loadings of seven heavy metals and cyanide. The seven metals are cadmium, chromium, copper, lead, nickel, silver, and zinc. This thesis focuses on FP WWTP. The purpose of this study involves examination of different sources of heavy metals and cyanide. FP WWTP serves a larger industrial and commercial population therefore it is an appropriate candidate facility for my analysis.

To focus on enforcement and pollution prevention on industrial users have resulted in the large decrease of total metals influent into the plant. However, my results show that the significant industrial users currently (year 2000) discharge, in the worst-case scenario, only 60% of all metals influent into FP WWTP. My findings also show that the decrease in total metals was at a constant rate from 1992-2000. This leads me to suspect most the largest drop in metals and cyanide occurred during the 80s, when the treatment program was established.

To identify other possible significant sources of metals and cyanide in wastewater, I interviewed a wide range of professionals and gathered secondary sources of information. Furthermore, there are other sources of metals that require further exploration. These sources include: hazardous waste sites, residential, commercial and transportation. From several studies conducted in the west coast, it is evident that domestic products are most likely the most predominant sources of metals in our wastewater. Hence, NBC needs to further consider investigating non-industrial sources of metals.

It is vital to continue the good efforts of the Industrial Pretreatment and Pollution Prevention Programs. My recommendations for minimizing metals in influent wastewater into FP include placing a tax on the amount of metals the company discharges. It could be useful if the scope and breath the Pollution Prevention Program were extended to other users of the WWTP. NBC can also carryout a household products inventory. Another suggestion also includes placing a tax on products that contain high levels of metals.