[Study on the leaching toxicity and disposal method of arsenic-bearing sludge].
OBJECTIVE
To study the leaching toxicity of the ferric salt and aluminum salt containing arsenic-bearing sludge coming from the high arsenic drinking water treated by coagulation/microfiltration process and its disposal method.


METHODS
The Chinese standard method and TCLP method issued by USEPA were used to test the leaching toxicity of arsenic-bearing sludge and its Portland cement solidification tests were conducted. Minor ferric salt containing arsenic-bearing sludge was added into road-application concrete for its utilization.


RESULTS
The arsenic concentrations in TCLP leaching solutions of ferric salt and aluminum sludge were 118 microg/L and 420 microg/L, respectively, which were higher than 9.5 microg/L and 11.8 microg/L of the Chinese standard method. However, all of them were less than identification standard for hazardous wastes of China. When arsenic-bearing sludge was solidified with cement, its leaching toxicity reduced about 90%. The unconfined compression strengths of solidification products were 3.25MPa and 0.76MPa which could meet the requirement for the landfill and sludge reclamation. The compression strengths of road-application concrete were upgraded about 12% when minor parts of ferric salt arsenic-bearing sludge was added.


CONCLUSIONS
Ferric salt and aluminum salt arsenic-bearing sludge do not belong to the hazardous waste with leaching toxicity. Cement solidification is an efficient method for the disposal of arsenic-bearing sludge. The mix of arsenic-bearing sludge with road-application concrete could provide a method for the efficient utilization of arsenic-bearing sludge. At the same time, the possible environmental problems should be avoided.
Li
Xiaobo
X
School of Environmental Science & Engineering, Tianjin University, Tianjin 300072, China.
Wu
Shuibo
S
Hu
Baoan
B
Gu
Ping
P
D017607:Aluminum Compounds / Q000737:chemistry; D001151:Arsenic / Q000032:analysis / Q000633:toxicity*; D005290:Ferric Compounds / Q000737:chemistry; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D014881:Water Supply / Q000032:analysis*
D017607:Aluminum Compounds; D005290:Ferric Compounds; D012722:Sewage; D014874:Water Pollutants, Chemical; D001151:Arsenic