Completely treating heavy metal laboratory waste liquid by an improved ferrite process

This work proposes a scheme for completely treating heavy metal laboratory waste liquid. Ten common heavy metals and various anions were adopted to synthesize the simulated laboratory waste liquid. Experimental results demonstrated that although conventional ferrite process (FP) could not be used to treat the simulated waste liquid completely, the enhanced FP, i.e., the extended reaction ferrite process (ERFP), could be used to satisfy regulatory limits. FeSO4 can be added in the extended stage of ERFP intermittently rather than continuously. Elutriation was conducted to reduce the cost of ERFP and ensure that the sludge met toxicity characteristic leaching procedure (TCLP) standards. The pH of the elutriation liquid should be greater than 2.88. This work also establishes that FP or ERFP can be applied directly to treat dichromate and permanganate without a prior reduction step.