Parametric Study on Solidification/Stabilization of Chromium Containing COD Waste using Rice Husk Ash as Binder

Author : Catogal, Laurence Parma
Major Adviser : Migo-Sumagang, Maria Victoria P.
Committee Members : Migo, Veronica P.; Arocena, Rhebner E. 
Year : 2018
Month : June
Type : Thesis
Degree: BS
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A parametric study on the Solidification/Stabilization (S/S) with rice husk ash (RHA) as binder of chromium containing COD waste sludge derived from laboratory COD waste through alkali precipitation was conducted. The effectiveness of S/S was evaluated through Toxicity Characteristic Leaching Procedure (TCLP). X-Ray Fluorescence results of the COD sludge show that it has a chromium content of 1204.90 ppm. The effects of varying proportions of RHA, sludge, and Portland cement were investigated through a simplex centroid mixture experiment with TCLP values in ppm Cr as response that was designed using Design-Expert 10®. Increasing the RHA loading resulted to decrease in Cr leachate concentration while increasing sludge loading resulted to increase in Cr leachate concentration. S/S samples with cement only as binder yielded the highest TCLP results (6.34 and 5.58 ppm); while samples solidified with RHA-blended cement at 25 wt% RHA, 25 wt% sludge, and 50 wt% OPC composition yielded the lowest TCLP result (2.13 ppm). The sample with the lowest TCLP also passed the DENR standards for Cr that is 5 ppm. The average retention capacity of the solidified materials was found to be 99.65% further verifying the effectiveness of the S/S treatment. Lastly, a cost-analysis for the S/S treatment of COD waste using the component proportions with the best results shows that the approximate cost for COD waste S/S with RHA-blended cement is Php 14.31 per liter COD waste. The approximate cost of treatment S/S for COD waste is much lower compared to the treatment cost offered by industrial treaters which is “~Php 75.00 per liter COD waste.

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