3) I learned this recently from the U.S. Geological Survey (https://www.usgs.gov/special-topic/water-science-school/science/water-qa-how-much-water-do-i-use-home-each-day?qt-science_center_objects=0#qt-science_center_objects):
"Estimates vary, but, on average, each person uses about 80-100 gallons of water per day, for indoor home uses. Are you surprised that the largest use of household water is to flush the toilet, and after that, to take showers and baths? That is why, in these days of water conservation, we are starting to see toilets and showers that use less water than before."
That's a lot of toilet flushes!
Homework set 10
Due 11/15/21
CHEN 3660
Here we want to determine the approximate surface area of RO membrane that you need for a community of 100 people who use on average 50 gallons of water per day.
In this situation, the bulk salt water concentration on the feed side is 1.5 wt% and the pressure of the feed is 800 psia. The permeate has a concentraiton of 0.05 wt% NaCl and is at a pressure of 15 psia. The permeance of $H_2O$ is $1.0 \times 10^5$ g/(cm$^2$ s atm) and NaCl is $16 \times 10^5$ cm/s. The mass transport coefficient ($k_s$) of NaCl is 0.005 cm/s. Example 14-11 from Seader and Henley found on Canvas is good to understand to answer the following questions.
(a) Find the membrane area needed (m$^2$) to supply the community of 100 people.
(b) What is the concentraiton polarization coefficient?
(c) If there is a membrane with an enhanced permeance of $H_2O$ of $3.0 \times 10^5$ g/(cm$^2$ s atm), how what is the membrane area needed?
(d) What is the concentraiton polarization coefficient?
(e) If the bulk salt concentration is that of sea water 3.5 wt%, what is the membrane area needed (use the original permeance)?
(f) What is the concentraiton polarization coefficient?
