Reduction of Heavy Metals Leaching from Sludge of Activated Sludge of Domestic Wastewater Treatment System

pimchanok boonchoo

Abstract


This research deal with the reduction of heavy metals leaching from sludge to utilize for cultivation by adsorbents such as bamboo charcoal, egg shell, lime, etc. The heavy metals concentration was determined by acid digestion of US. EPA method 3051 for sludge and US. EPA method 3015a for leachate. With the Synthetic Precipitation Leaching Procedure (SPLP), if revealed that at pH 2.0 all heavy metals were leached from sludge at the high level. The reduction of heavy metals leaching at pH 6.0 were conducted. It was found that bamboo charcoal and egg shell were able to reduce the leaching of Zn as 98.26% and 98.04% respectively. While lime gave the highest reducing efficiency of Cd leaching as 95.29%. In addition, the continuous leaching test by 3 simulated model unit were performed by leaching with the extract pH 6.0 rain. The 1st simulated model unit was used as the control unit, the 2nd was sludge mixed with the mixture of egg shell and lime (1,200:120:36 by wt.) and the 3rd was sludge the mixed with mixture of egg shell and bamboo charcoal (1,200:120:600 by wt.) It was found that the 2nd simulated model unit was able to decrease the leaching of heavy metal better than the 3rd the simulated model unit. in the run-off as indicated by decreasing percentage leaching of Cu, Cd, Fe, and Pb. As well as, in the permeate the decreasing percentage leaching of Cd, Zn, Fe and Cr. Therefore, the adding egg shell and bamboo charcoal was able to reduce the heavy metals leaching by acid rain from the AS sludge.


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