Applied Research On Eichhornia Crassipes In Lead-zinc Mine Floatation Wastewater Treatment

In the Lead-zinc flotation process, a lot of flotation reagents are required in different operations to improve the metal flotation separation efficiency, including collector, foaming agent, organic and inorganic activator, inhibitors, dispersant etc. These agents in the ore dressing wastewater and tailings are the residues, resulting in high COD wastewater beneficiation, and will lead to serious environmental pollution if directly discharged. Biotechnology is a new type of ecological wastewater treatment technology, which has a low investment, strong impact, simple operation, easy maintenance, and good water quality. The biological technology application in wastewater treatment for solving lead-zinc mine environment pollution, water waste, the bioremediation problem in tailings base is playing a positive role.Purification effect of three kinds of artificial wastewater is researched by steady processing, including the enrichment laws of heavy metals in the stems and leaves and roots of Eichhornia crassipes, the degradation laws of aniline aerofloat, butyl xanthate, diethyldithiocarbamate and turpentine, the COD removal laws and growth status of Eichhornia crassipes in wastewater treatment process, etc. According to the results analysis, the conclusions are as follows:(1) Eichhornia crassipes have good enrichment effect for lead, zinc, copper. Its enrichment ability for lead, zinc increases with the concentration increases, and the enrichment quantity of lead is large than zinc. The enrichment ability for copper is increasing with the decrease e of copper concentration. Limited by the strategy of avoiding harm, most lead remained in the roots. As the essential elements, the transfer quantity of zinc from roots to stems and leaves is much larger than lead. The enrichment coefficient of stems and leaves is very different from roots, which show that the heavy metals are most enriched in the roots, only a few be transferred to stems and leaves. According to the result, lead and zinc in wastewater have best removal rate in the first two days of wastewater processing, and the removal rate of lead is large than zinc.(2) Beneficiation reagents have played a certain inhibition in the enrichment of lead and zinc, and the inhibition increases with the concentration of the reagents increasing. The inhibition of butyl xanthate and aniline aerofloat is obviously stronger than zinc, which of turpentine is relatively similar between lead and zinc. The inhibition for lead of three reagents size order is:aniline aerofloat> diethyldithiocarbamate> turpentine, that for zinc: turpentine> diethyldithiocarbamate> aniline aero float.(3) While enriching heavy metals, Eichhornia crassipes also can effectively degrade beneficiation reagents, and in a certain range, the degradation rate was increased with the initial concentration of reagents increasing. The degradation rate order of reagents which exist alone is:diethyldithiocarbamate≈aniline aerofloat> turpentine. The degradation rates of the three are all from fast to slow, and become the lowest in the last two days. The order of degradation of the reagents when coexisting is:butyl xanthate> diethyldithiocarbamate> aniline aerofloat. The degradation rate of aniline aerofloat and diethyldithiocarbamate becomes the largest between the fourth and sixth days, and remains slow in the rest of time. The degradation rate of butyl xanthate becomes largest between the second and sixth days. The degradation rate of the three grows little larger with the increase of concentration, but the degradation rate has not significant correlation with the concentration.(4) The order of contribution for COD of beneficiation reagents is:turpentine> aniline aerofloat> diethyldithiocarbamate, while the COD removal rate is:aniline aerofloat> diethyldithiocarbamate> turpentine. The results showed that the COD removal rate depends not only on the concentration of the reagents, but also on the composition. In the wastewater of reagents that existed alone, COD removal rate was preferable. In the wastewater of reagents that coexisted, COD removal rate was poor, for the reason that COD consisted of various reagents could be difficultly removed and meanwhile, affluent microbe were lack in the wastewater in the short term for the collaborative purification with Eichhornia crassipes. This might lead to COD removal rate be lower than which in the actual wastewater.(5) The beneficiation reagents could inhibit the growth of Eichhornia crassipes, and the inhibition would be strengthened with the concentration increasing. Diethyldithiocarbamate inhibited the growth of Eichhornia crassipes on the largest, turpentine followed by, and aniline aerofloat minimum. In the three experiments, Eichhornia crassipes have shown different growth characteristics. In the wastewater of inhibitor reagents, the Eichhornia crassipes could grow normally, even that the growth status was better in low concentrations wastewater than in natural water. In the single factor experiment, Eichhornia crassipes could still keep continuous growth in spite of certain inhibition. In the composite wastewater, the Eichhornia crassipes could only grow normally at low concentration, the concentration in the medium and high had shown growth arrest or even die.