lab

CE 431L Summer 2024 (Section II) Water Treatment

Lab

1

Lab #4 - Determination of Nutrients

Prepare an individual long report for this lab.

Introduction

The purpose of this lab is to evaluate the removal of phosphate (PO4 3-) from water by

coagulation. The concentration of PO4 3-will be measured by the Hach photometric

method. Furthermore, the PO4 3-concentration in tap water and Raw Red River water will

be also measured.

Experimental procedures:

Coagulation and settling.

1) Collect 1 L tap water in each of the six jars.

2) Add coagulant (alum) at the following dosages (see Table 1), and measure and

record the initial phosphate concentration in the jar.

3) Start the coagulation (rapid mixing, 150 rpm for 1 min) and flocculation (slow

mixing, 40 rpm for 15 min) processes at different alum doses

4) At the end of the slow stirring period, stop the stirrer.

5) After 20 minutes of settling, during which time the jars should not be disturbed,

pipette out sufficient supernatant and test it for phosphate.

Table 1.

Jar number 1 2 3 4 5 6

Volume of alum stock solution added

(mL) 1 2 4 6 8 10

Alum dosage (mg/L) 10 20 40 60 80 100

Experimental details and results:

• Report the data collected.

Table 2. Experimental data collected during coagulation and flocculation processes

Jar # Volume of alum

stock solution

added (mL)

Alum

dosage

(mg/L)

Phosphate

(PO4 3-)

concentration

(mg/L)

Raw water

1

2

3

4 5