Research On Screening And Characterization Of Dominant Bacteria For The Degradation Of Nickel-Containing Electroplating Wastewater

Biological method is better than traditional physics and chemistry method in the aspects of invest, circulation, operation management, metals recovery and waters recycle with etc., When treatment the electroplating wastewater that contain the heavy metals in low concentration (≤100 mg/ L).This topic screen a high efficient strain of degradation nickel from waste water and sludge of the electroplate factory. Through identification, it's the bacillus: gram-positive bacteria, has the subpolar spore, figure is spheroidal, cyst make the thalli to expand, the brim of thalli is tidy and the surface presents the frosted glass form.This text study on the growth rule of the high efficient strain of degradation nickel, from the growth curve, we know the germ experienced a delay period, raise period, stabilization period and descend period. These four period mean four periods of the germ growth: Lag phase, Logarithmic phase, stationary phase and decline phase. Experiment result show: pH have a considerable effect on degradation nickel by germ stub, there's two peaks on degradation process: when pH is 5, the maximal removal rate of nickel is 91.5%;and when pH is 11, the maximal removal rate of nickel is 93.5%;The best temperature of degradation nickel is 35℃;The best shaking rate is 150 r/ min;when the nickel removal rate arrive 91%,adding more bacteria solution cannot rasie the nickel removal rate obviously;When the nickel concentration is 80 mg/ L, the removal rate is 93.6%, culturing 16—24h, adding the germ body which is placed in this growth period to the water sample containing nickel, it is beneficial for nickel accumulation.This paper discuss the mechanism about degradation nickel from the germs of extracellular enrichment or deposition, surface adsorption and complexation on the cell wall, intracellular enrichment etc. We believe that the microorganism adapt the heavy metal's toxicity by mainly two ways: to adapt by the cell membrane composition and the change of the permeability;to adapt by producing the gene of anti- heavy metals toxicity.The microorganism adsorption for heany metal nickel match the model of Langmuir and Freundlich isothermal adsorption, it's dominantly monolayer adsorption.