Disposal of domestic sludge and sludge ash on volcanic soils.
Column leaching experiments were conducted to test the ability of Chilean volcanic soils in retaining the mineral constituents and metals in sewage sludge and sludge ash that were incorporated into the soils. Small or negligible amounts of the total content of Pb, Fe, Cr, Mn, Cd, and Zn (0 to <2%), and more significant amounts of mineral constituents such as Na (7-9%), Ca (7-13%), PO4 (4-10%), and SO4 (39-46%) in the sludge and sludge ash were readily soluble. When they were incorporated on the surface layer of the soils and leached with 12 pore volumes of water over a 3 month period of time, less than 0.1% of the total amount of heavy metals and PO4 in the sludge and sludge ash were collected in the drainage water. Cation exchange selectivity, specific anion adsorption and solubility are the processes that cause the reduction of leaching. The volcanic soils were capable of retaining the mineral constituents, P, and metals in applied sewage sludge and sludge ash and gradually released them as nutrients for plant growth.
Escudey
Mauricio
M
Facultad de Química y Biología, Universidad de Santiago de Chile, Av. B. O'Higgins, 3363 Santiago, Chile. mescudey@lauca.usach.cl
Förster
Juan E
JE
Becerra
Juan P
JP
Quinteros
Magdalena
M
Torres
Justo
J
Arancibia
Nicolas
N
Galindo
Gerardo
G
Chang
Andrew C
AC
D002677:Chile; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D018707:Volcanic Eruptions / Q000032:analysis
D012722:Sewage; D012987:Soil