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1. Figure 5 shows phosphorous in water taken at different stages from the Spokan

ID: 157722 • Letter: 1

Question

1. Figure 5 shows phosphorous in water taken at different stages from the Spokane wastewater treatment plant. That last two bars (on the right) show the water that leaves the plant and is discharged into the river. The bar heights indicate the fraction of total P that was bioavailable.

What percent of total P was bioavailable in effluent from the Spokane water treatment plant, without the alum treatment to increase P removal (i.e. second from the right)? Report the approximate mean, and the range shown by the error bars. (2 points)

Read the article abstract to familiarize yourself with the study, and then look at Figures 4 and 5, also copied below 100 1.00 80 BAP/TRP 0.80 0.60 60 0.40 40 0.20 0.00 INF INF INT INT EFFL EFFL 20 (2nd WWTP (2nd WWTP (2nd WWTP (2nd WWTP (2nd WWTP (2nd WWTP wo/A w w/A wo/A w w/AI wo/A w w/AI addtion) addtion) addtion) addtion addti addtion) Fig. 5 - BAP/TRP for six different sample types. INF- Influent, INT-Intermediate Effluent, EFFL-Final Effluent. Error bars represent standard deviations. W represents (with" while WO represents “without". 1000 100 10 Wastewater TP (ug L Fig·4- Relationship between the %BAP of TP and TP concentrations in the effluents. Error bars represent standard deviations.

Explanation / Answer

Seeing from the available values

0.20/0.50*100= 40 percent

range for without alum ranges upto 100 percent and for with alum ranges to 40

if we take average it will be 0.20+0.50/2= 0.35

With error bars it will be 0.140/2=0.70