University of Hawaii

CEE 330

Abstract
This experiment focuses on determining the diluted concentration of orthophosphate in five
different samples of tap water, manoa stream, treated effluent, primary effluent and raw wastewater
from the Honouliuli Wastewater Treatment Plant. To accomplish this, a phosphate standard is set
by combining different amounts of orthophosphate with water equalling 100 mL each and each
resulting in different concentrations ranging from 0.2mg/L to 1.5mg/L. Then we analyze the
concentrations using a commercial reagent called Hach Phosver3. Once the sample reacts after two
minutes, it is then transferred to a cuvette and placed into the spectrophotometer with a wavelength
of 890nm, where the absorbance can be determined. In the data, it is determined that the diluted
concentrations of orthophosphate were 0.249 for tap water, 0.196 for manoa stream, 2.246 for
treated effluent, 1.242 for secondary effluent, and 1.468 for raw wastewater.