Arsenic removal from high-arsenic water by enhanced coagulation with ferric ions and coarse calcite.
Arsenic removal from high-arsenic water in a mine drainage system has been studied through an enhanced coagulation process with ferric ions and coarse calcite (38-74 microm) in this work. The experimental results have shown that arsenic-borne coagulates produced by coagulation with ferric ions alone were very fine, so micro-filtration (membrane as filter medium) was needed to remove the coagulates from water. In the presence of coarse calcite, small arsenic-borne coagulates coated on coarse calcite surfaces, leading the settling rate of the coagulates to considerably increase. The enhanced coagulation followed by conventional filtration (filter paper as filter medium) achieved a very high arsenic removal (over 99%) from high-arsenic water (5mg/l arsenic concentration), producing a cleaned water with the residual arsenic concentration of 13 microg/l. It has been found that the mechanism by which coarse calcite enhanced the coagulation of high-arsenic water might be due to attractive electrical double layer interaction between small arsenic-borne coagulates and calcite particles, which leads to non-existence of a potential energy barrier between the heterogeneous particles.
Song
S
S
Instituto de Metalurgia, Universidad Autónoma de San Luis Potosí, Avenida Sierra Leona 550, San Luis Potosí, C. P. 78210, Mexico. shaoxian@uaslp.mx
Lopez-Valdivieso
A
A
Hernandez-Campos
D J
DJ
Peng
C
C
Monroy-Fernandez
M G
MG
Razo-Soto
I
I
D001151:Arsenic / Q000737:chemistry / Q000302:isolation & purification*; D002119:Calcium Carbonate / Q000737:chemistry; D005374:Filtration; D007501:Iron / Q000737:chemistry; D008906:Mining; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D014873:Water Pollutants; D007501:Iron; D002119:Calcium Carbonate; D001151:Arsenic