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Chemical Oxygen Demand Analysis of Wastewater Using Trivalent Manganese Oxidant with Chloride Removal by Sodium Bismuthate Pretreatment
Author(s) -
Miller Donald G.,
Brayton Scott V.,
Boyles Wayne T.
Publication year - 2001
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143001x138705
Subject(s) - chemical oxygen demand , chemistry , hexavalent chromium , potassium dichromate , wastewater , chlorine , chloride , chromium , mercury (programming language) , biochemical oxygen demand , manganese , titration , sodium , environmental chemistry , inorganic chemistry , nuclear chemistry , environmental engineering , environmental science , organic chemistry , computer science , programming language
Current chemical oxygen demand (COD) analyses generate wastes containing hexavalent and trivalent chromium, mercury, and silver. Waste disposal is difficult, expensive, and poses environmental hazards. A new COD test is proposed that eliminates these metals and shortens analysis time, where trivalent manganese oxidant replaces hexavalent chromium (dichromate). A silver catalyst is not required. Optional pretreatment removes chloride via oxidation to chlorine using sodium bismuthate, eliminating the need for mercury. Sample aqueous and solid components are separated for chloride removal, then recombined for total COD measurement. Soluble and nonsoluble COD can be determined separately. Digestion at 150 °C is complete in 1 hour. Results are determined by titration or by spectrophotometric reading. Test wastes contain none of the metals regulated for disposal under the Resource Conservation and Recovery Act. Results are shown for selected organic compounds and various wastewaters. Statistical comparisons are made with dichromate COD and biochemical oxygen demand (BOD 5 ) test values.