COST EFFECTIVE CONDITIONING & DEWATERING OF RESIDUALS – FROM LAB TO FULL-SCALE
Abstract:The residuals generated from biological treatment of perchlorate contaminated groundwater at the Kerr-McGee facility at Henderson, NV were conditioned with lime and ferric chloride prior to dewatering via standard plate and frame press. The high cost of chemical conditioning and the subsequent cost of residuals disposal represent a burden on the plant's operation budget. Options to enhance dewatering were investigated, including enzyme pre-treatment prior to inorganic conditioning, enzyme treatment prior to polymer conditioning, and polymer conditioning alone. Initial laboratory tests were conducted using a capillary suction time (CST) and a bench scale pressure filter device. Full-scale tests were conducted to verify laboratory results.
Laboratory results showed that enzyme pre-treatment is capable of enhancing residuals dewaterability with either iron/lime or polymer conditioning. Polymer conditioning alone seems to properly condition the sludge prior to dewatering, and at a much lower dose than usually practiced. Economic evaluation of the different conditioning schemes was conducted to determine the best option for full-scale trials. Results showed that the increased in cake dewatering with enzyme pretreatment does not offset the cost of enzyme addition. Accordingly, polymer alone was tested in full-scale. Results from full-scale tests confirmed laboratory findings. The plant converted to polymer conditioning with satisfactory results. Accordingly, laboratory testing followed by economic evaluation provided a useful tool for full-scale implementation.
Document Type: Research Article
Publication date: January 1, 2006
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