BY LEI SHAO
The project I took part in last summer is part of a larger
water resources and purification project within Purdue’s U.S.-China
Ecopartnership for Environmental Sustainability (USCEES) that began
in 2014. I learned about this opportunity from Professor Timothy Filley, whom
I work for during the academic year. This was my first visit to western China
and the second visit by Professor Chad Jafvert, who leads the slow sand filter water
purification project with collaborators at Qinghai Normal University. Together with
Professor Filley, director of the USCEES, and professors Lin Yang and Jiyuan Lan from
Qinghai Normal University, the project was initiated by assembling six sand filtration
units in rural homes in the Huzhu city region. During our visit in 2015, we went back
to the Huzhu villages to evaluate the status of the slow sand filters installed in the
previous year and discuss future plans for projects.
Slow sand filters are a traditional type of municipal water filtration system that
provide inexpensive water purification for rural communities. The sand filter can be
built locally and easily by placing a porous media layer in the bottom of a pail and
placing sand on top of the porous media. Each unit of the filter consist of two 5-gallon
pails, which can be purchased locally in Xining.
As water flows downward through the sand, slow sand filters rely on natural,
microbial-driven processes to break down dissolved and colloidal organics that cause
water turbidity. The microbial activity requires the water to be retained in the filter
for generally four to eight hours of treatment time. Each filter unit can treat up to 30
liters of water per day.
Huzhu city is located in the north of
Xining. The two villages we visited were
Ji Jia Ling and Lian Da. These rural villages are high in the mountains, with no
tap water nor surface or groundwater.
People in the villages used to collect
rainwater and store it in their underground cisterns. However, the water in
the cisterns often appeared to be turbid
and colored due to contamination.
On July 22, Professor Jafvert and I
revisited the two villages, accompanied
by Qinghai Normal faculty. We found that
the government agency had installed tap
water for all the rural homes in Huzhu
city region in February 2015, which was
seven months after the filters were
installed in July 2014. The government
agency also provided subsidized housing