Question

***Environmental Engineering***

Well water in Sullivan County, Pennsylvania was sampled and found to contain 6,590µg/L of Fe2+

(a)What is the Secondary Maximum Contaminant Level (SMCL)of iron? What noticeable/aesthetic effects can it have?

(b) Determine what pH is necessary to precipitate iron as Fe (OH)2 from 6,590µg/L down to the SMCL. Please note, the textbook's appendix has an extensive list of solubility products.

Answer 1

a) Secondary drinking water contamination do not pose health risks to humans at levels usually found in water. The drinking water standard for iron is 0.3 milli- grams per liter (mg/l) or 300 microgram/litre, so it exceeds the limit here in our sample then noticeable aesthetics are color, odour and taste.

b)The form of iron in water depends on the water pH and redox potential, as shown in the Pourbaix diagram of Iron below. Usually groundwater has a low oxygen content, thus a low redox potential and low pH (5.5- 6.5).