Journal
JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING
Volume 50, Issue 12, Pages 1282-1290Publisher
TAYLOR & FRANCIS INC
DOI: 10.1080/10934529.2015.1055157
Keywords
stripping recovery; manganese precipitation; electrolytic manganese residue; Ammonia-nitrogen; calcium oxide
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Funding
- National Natural Science Foundation of China [51274261]
- Natural Science Research Project of the Education Department of Guizhou Province, China [Qianjiaohe KY[2013]202]
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Leaching tests of electrolytic manganese residue (EMR) indicated that high contents of soluble manganese and ammonia-nitrogen posed a high environmental risk. This work reports the results of simultaneous stripping recovery of ammonia-nitrogen and precipitation of manganese by air under calcium oxide assist. The ammonia-nitrogen stripping rate increased with the dosage of CaO, the air flow rate and the temperature of EMR slurry. Stripped ammonia-nitrogen was absorbed by a solution of sulfuric acid and formed soluble (NH4)(2)SO4 and (NH4)(3)H(SO4)(3). The major parameters that effected soluble manganese precipitation were the dosage of added CaO and the slurry temperature. Considering these two aspects, the efficient operation conditions should be conducted with 8wt.% added CaO, 60 degrees C, 800mL min(-1) air flow rate and 60-min reaction time. Under these conditions 99.99% of the soluble manganese was precipitated as Mn3O4, which was confirmed by XRD and SEM-EDS analyses. In addition, the stripping rate of ammonia-nitrogen was 99.73%. Leaching tests showed the leached toxic substances concentrations of the treated EMR met the integrated wastewater discharge standard of China (GB8978-1996).
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