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The chemical redesign of the SMI wastewater pretreatment system to optimize the effluent quality / by Deborah L. Franke.

by Franke, Deborah L.

Factory and trade waste

Water -- Purification

Metals -- Finishing -- Waste disposal

viii, 81 leaves : ill., charts ; 28 cm.

Advisor: Dr. Deborah Jackman

Committee members: Dr. Francis Mahuta, Jeffrey MacDonald

Abstract -- Preface -- Introduction -- Literature review -- Determination of the treatment chemistry -- Results of testing -- Environmental impact -- Cost analysis -- Conclusions and recommendations -- Appendices: Appendix A: Test matrices, results, and calculations -- B: Effluent nickel and zinc test procedures and results -- C: Cost analysis data -- D: Chemical data sheets and MSDSs.

In order to achieve improved pretreatment of the wastewater effluent for Steeltech Manufacturing, this study of pretreatment chemicals was initiated. The purpose was to determine the most efficient chemicals for removing zinc and nickel from Steeltech's wastewater for an E-Coat systems's nine stage pretreatment (wash and phosphating system), especially, the wastewaters produced by Stages One and Two. In conjuction with determining effective chemicals, the cost of treating with those chemicals should reduce the cost per gallon of treating Steeltech's wastewaters. The final choice of chemicals should produce an effluent containing zinc and nickel concentrations below Steeltech's permit limits at a decreased cost compared to past treatment costs.

First, the determination of the appropriate chemicals and their effectiveness in the treatment process was made through jar (bench) testing. The testing methodology included the adjustment of pH, the use of inorganic metal salts such as ferric chloride and various aluminum based salts, and organic polymers used as coagulants and flocculants. The pH adjustments and chemicals were tested in multiple combinations to ascertain the most effective treatment during bench testing on Stage One wastewater.

The results from these tests were used to determine the chemical combinations and dosage plus the pH adjustments required for the pilot tests for Stage One. Then the chemicals that treated effectively in the pilot tests from Stage One were used in the treatment of other stages in subsequent jar and pilot testing.

By February 1998, Stages One and Two were successsfully treated. At an initial pH of two, the chemicals calcium chloride, ferric chloride, MaFloc 2012, and Booth Control 8009 were used in the treatment of the wastewater. In the neutralizing tank, the formation of a pink floc occurred as the pH was raised to ten. The addition of MaFloc 951 created fast settling flock and clear, yellow tinted effluent. The nickel and zinc concentration in the effluent were less than Steeltech's discharge permit limits of 2.38mg/l and 1.48 mg/l (monthly averagtes), respectively.

During March 1998, Stages Three, Four, Five, and Eight were successfully treated using only ferric chloride and calcium chloride, and then, flocculation with MaFloc 951. Again, Steeltech's effluent was below its permit limits for zinc and nickel. Also, Stage Seven's pretreament required ferric chloride, calcium chloride, and MaFloc2012 to treat the watewater to meet the permit limits.

Before this study, Steeltech hauled Stages One and Two off-site and was inconsistent in the treament of its wastewater. As a result of the project, Steeltech treats all of its wastewater streams to the requirements of its discharge permit.. An estimated savings of $450,000.00 per year in avoided chemical costs, hauling fees, and permit violation penalties was obtained as a result of this project.

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