One-step disposal of Cr (VI)-bearing wastewater by natural pyrrhotite

• Published in: Chinese science bulletin Vol. 45; no. 17; pp. 1614 - 1616
• Main Authors: Lu, Anhuai, Chen, Jie, Shi, Junxian, Lu, Xiaoying, Tang, Junli, Guo, Min
• Format: Journal Article
• Language: English
• Published: Beijing Springer Nature B.V 01.09.2000; Department of Geology,Peking University,Beijing 100871,China; National Laboratory of Mineral and Rock Materials,China University of Geosciences,Beijing 100083,China%National Laboratory of Mineral and Rock Materials,China University of Geosciences,Beijing 100083,China
• Subjects: Calcium hydroxide; Chromium; Drinking water; Iron sulfides; Mineral resources; Precipitates; Pyrrhotite; Reducing agents; Slaked lime; Sodium sulfite; Sulfite; Technology; Trivalent chromium; Wastewater; Wastewater treatment; one-step disposal; reduction Cr(Ⅵ); natural pyrrhotite; Cr(Ⅵ)-bearing wastewater; rational use of mineral resources; precipitation Cr(Ⅲ)
• ISSN: 1001-6538; 2095-9273; 1861-9541; 2095-9281
• DOI: 10.1007/BF02886224

Cr(VI)-bearing wastewater can be treated by natural pyrrhotite which is used for reductant to reduce Cr(VI) and precipitant to precipitate Cr(III) simultaneously. The disposal products can be divided into three parts in the beakers, namely supernatant in the upper part, the yellowish colloidal precipitates in the middle part and the pyrrhotite in the lower part. The content of total Cr=Cr(VI)+Cr(III) in the supernatant liquid is 0.06 mg/L, which is lower than 1.5 mg/L of the discharge standard of China and near to 0.05 mg/L of the standard of potable water. This one-step disposal composing of both reduction and precipitation which is traditionally divided into two independent steps called reducing technology and precipitating technology respectively. The new method is of obvious economic advantage and favourable to decreasing surplus mud derived from adding Ca(OH)2 to precipitate Cr(III) traditionally so as to avoid recontamination. In fact, sodium sulfite (Na2SO3) used in disposal of Cr(VI) was traditionally produced from natural mineral of pyrrhotite (FeS). One molecule of FeS is 4 times more than that of Na2SO3 from a view point of rational use of mineral resources. Therefore the prospective of application of the one-step disposal of Cr(VI) method is full of promise.