Method of eliminating hexavalent chromium in sewage by using active sludge microorganism

Abstract

The invention discloses a removing method of hexavalent chromium in the effluent in the anaerobic / aerobic batched reactor through active sludge microbe in the environment protective technical domain, which comprises the following steps: placing active sludge in the SBR; adding effluent with Cr (VI) into the reactor; stirring 1-6h under anaerobic condition; aerating for 1-6h under aerobic condition; sedimenting 1-2h; making the density of hexavalent chromium and total chromium in the outlet supernatant reach the first grade national discharge standard; reducing the harm of environment and human due to chromium; enriching trivalent chromium in the sludge with low toxicity; operating the chromium removing system continuously without inhibiting the growth of microbe.

Description

technical field [0001] The invention belongs to the technical field of environmental protection, and in particular relates to a method for removing hexavalent chromium (Cr(VI)) in sewage in an anaerobic / aerobic sequencing batch reactor (SBR) by using activated sludge microorganisms. Background technique [0002] In recent years, with the development of electroplating, chemical industry, tanning and dyeing industries, the wastewater containing chromium compounds is increasing day by day. Chromium pollution in water is mainly Cr(VI) and Cr(III), and their migration and transformation in water have certain regularity. Cr(III) is mainly adsorbed on the surface of solid substances and exists in sediments. Cr(VI) It is more soluble in water, and is stable, and its toxicity is stronger than Cr(III), and it can be converted into Cr(III) by reduction. In chromium-containing industrial wastewater, the most toxic is water-soluble Cr(VI), because Cr(VI) salt can quickly enter the circu...

AI Technical Summary

Problems solved by technology

[0003] At present, the main methods of treating Cr(VI)-containing wastewater are physical and chemical methods, such as ion exchange resin method, activated carbon adsorption method, chemical precipitation method and electrochemical treatment method, etc., but these methods have common problems in use: when the heavy metal concentration When the concentration is 1-100 mg / L, the operating cost and the cost of raw materials required for treatment are relatively high, and the treatment effect is easily affected by alkaline earth metals, especially Cr(VI) is prone to appear in the supernatant after chemical treatment. Concentration exceeding the standard rebound, and a large amount of sludge produced by sedimentation may cause secondary pollution

In the past research process of the inventor, it was found that only aerobic treatment was carried out to the chromium-containing wastewater, and when the influent Cr(VI) was 2 mg / L, the removal rate of Cr(VI) was less than 10%, and the concentration of Cr(VI) in the effluent was less than 10%. Seriously exceeding the standard, it can be seen that the aerobic activated sludge microbial removal of chromium alone is difficult to meet the national discharge standard

Recent studies have shown that activated sludge under anaerobic conditions alone has a certain effect on the removal of Cr(VI) in the short term, but the results of long-term operation are not good (Bioresource Technology, 96(2005): 1713-1721)

In addition, although Cr(VI) can be better removed in the continuous-flow anaerobic / aerobic (A / O) activated sludge system (BioresourceTechnology, 96(2005): 1713-1721), the process is relatively Single Sequencing Batch Reactor (SBR) process is complex and requires more equipment, so the effective removal of Cr(VI) using a single SBR process is an obvious difference between the present invention and reported in the literature