| With the development of industial and agricultural area and improvement of human life, the social demand for mineral resources is increasing day by day, the process of exploitation and processing for mineral resources will inevitably destroy and change the natural environment. H205, as an effective hydroxamic acid floatation collector, is used widly in the mineral processing industry. However, H205 is a refractory organic pollutant whose molecule contains a stable naphthalene, and its direct emission will lead to serious environmental pollution and destruction. In view of this situation, making research on biodegradability of H205, and selecting strains in natural condition that have special effect on degradation of H205, and exploring its biodgradale laws as well, are of great significance for biological treatment of hydroxamic acid mineral processing wastewater and protection of mine environment.In this paper, firstly, by adding activated sludge, the biodegradability of H205 and its biodegradation kinetic models were studied in single substrate through oscillating culure method. At the same time, the biodegradability of H205 was expiored with other substrates so as to decide the factors which can make effect on the biodegradability. Then, drawing on the experience of strain selection from refractory organics such as petroleum hydrocarbons, aromatic compounds, heterocylic compounds and pesticides, this study selected strains that have special effect on degradation of H205 under natural condition, and explored the biodegradability and kinetic models of H205 by using the special strains. Finally, a preliminary study that using the selected strain of H205 to degrade other hydroxamic acids was carried out.The results showed that,(1) With single substrate, the biodegradable process of H205 with different initial concentrations (10～50mg/L) conformed to first-order kinetics.Respectively,the kinetic equations were lnc=-0.11286t+2.39948,lnc=-0.10343t+3.04386,lnc=-0.11571t+3.41521,lnc=-0.12229t+3.68775,lnc=-0.12371t+3.85229. In respond, the rate constants were 0.11286,1.10343,0.11571,0.12229,0.12371.(2) The presence of co-substrates enhanced the biodegradable performance of H205.Under the same experiental conditions, the biodgradation efficiency of H205 was 55.35% with the presence of other substrates,that is,120mg/L sodium acetate and 200mg/L yeast extract.In contrast,the biodegradation efficiency of H205 with single substrate reached 33.63%,which is 18.72% less comparing to the former.Thus,the period for degrading H205 is shorten and the efficiency is enhanced,which can save time and cost for treatment. So co-substrates embolism is an effective way to improve the biodegradation of H205.(3) 27 strains were isolated from two oil samples and three actived sludge samples, of which Q11 was identified as Gram-negative bacteria, and the klebsiella sp..The degradation efficiency of H205 by using Q11 reached to 44.56%.(4)In this study, the optimum conditions for advanced bacteria Q11 degrading H205 were that,the value of pH ranged from 6 to 7; the temperature was 30℃, oscillating speed was 150r/min; inoculum amount was 10%; and the concentration of H205 was 100mg/L. With additional carbon source such as glucose, sucrose and sodium acetate, strain Q11 was inhibited in degrading H205. Peptont and yeast extract substituting for (NH4)2SO4 in medium with same amount (0.5g/L), that promoted strain Q11 to degrading H205.When using peptone as N-source,the degradation efficiency of H265 reached 50.06%,while using yeast extract,that is 46.05%.Compared with (NH4)SO4 as N-source,the degradation efficiency of H205 with peptone or yeast extract respectively was increased by 8.03%,4.02%.(5) In the process of biodgradation of H205 by strain Q11 with different time,and initial concentration, when the concentration of H205 is 15and 50mg/L,the biodegradation process fitted to the first-order kinetics,and the kinetic equations were lnc=-0.03507t+2.47835,lnc=-0.03822t+3.89265,of which the rate constants were 0.03507 and 0.03822.With the initial concentration of H205 of 100,150.200. 500mg/L,its biodegradation process conformed to zero-order kinetics,which was consistent with the Monod equation in biological treatment for wastewater.The Monod equation is that 1/q=399.21266 1/c+3.08772,of which Ks=129.291, qmax=0.323864.(6) Strain Q11 has a certain degradation on hydroxamic acids such as benzohydroxamic acid,salicylic hydroxamic and H205.12 days later, the degradation efficiency of benzohydroxamic acid was 85.04%,and salicylic hydroxamic 63.04%,while H205 44.56%.The dgradation efficiency of benzohydroxamic acid and salicylic hydroxamic by strains Q11 was significantly higher than that of H205, which was related to the structures of three types of hydroxamic.Both benzohydroxamic acid and salicylic hydroxamic have bezene structures, while H205 has a stable naphthalene.
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