Optimization of bioclogging in vermifilters: A statistical approach.

In the present research, an experiment was conducted with the objective of optimization of the role of earthworms in alleviating the bioclogging of a horizontal subsurface flow vermifilter (HSSFVF), caused due to the application of organics rich brewery wastewater. In this experiment, for the optimization of bioclogging of the vermifilters, the Box-Behnken Design (BBD) and response surface methodology (RSM) were involved. Hydraulic loading rate (HLR), influent COD and earthworm density (EWD) are the variables against which the bioclogging of the HSSFVF has been optimized. EWD of 9475 earthworms/m ³ , HLR of 1.84 m ³ /m ² -d and influent COD of 3701 mg/L have been observed as the optimized values for the minimum bioclogging in the vermifiltration of brewery wastewater. At this optimum boundary conditions, the reduction in hydraulic conductivity was obtained as 1.49%, against the predicted value of 1.67% based upon the BBD model. The verification of the model against real brewery wastewater yielded insignificant error and thus very strongly portrays the suitability of the derived BBD model. The study indicates that the bioclogging from the vermifilters can be minimized, if the variables are optimized using the response surface methodology.
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