| landfill leachate is a complex and high polluted organic wastewater, and considered to be a potential pollution sources for the surrounding environment, and long-term environmental impacts will last for several decades. Chinese government attaches great importance to the problem of pollution of leachate, to implement the newly revised GB16889-2008 "Landfill Pollution Control Standards" in July 2008, targets its CODCr, BOD5, ammonia, nitrogen, heavy metals and other physical and chemical indicators proposed a more stringent control standards. Ion exchange resins have been endowed with high mechanical strength, chemical stability, high switching capacity, are widely used in wastewater treatment, and have been gradually applied to landfill leachate treatment in recent years.Nowadays, ecological toxicological methodology, as an effective complement to physical and chemical testing, has become a priority worldwide to detect and assess the risk of wastewater contaminants.It fully reflects the combined effects of a variety of toxic and hazardous substances in wastewater on the surrounding environment. Based on the complexity quality of leachate, combined the environmental engineering technology with the ecological toxicological technology can not only conduct quantitative analysis of its main components of pollutants, but also take a comprehensive evaluation of its impact on the ecological environment around, has the very vital significance.In the present study, the collected landfill leachate was treated with ion exchange resins, genotoxicity of leachate was investigated with the Hordeum vulgare cytogenetic bioassay, using the total salt and CODcr as the estimate of leachatye chemical concentration. Then leachate was treated in two ways:(i) diluted the crude leachate with distilled water to 98%,90%, 69%,52%,45%, respectively, to obtain a similar concentration of TS with the IEX resin-treated groups corresponding, (ii) laid aside the IEX resin-treated leachate samples naturally for one year, ensure its natural degradation, to prevent interference of foreign substances. Contrast with the ion exchange treated leachate, to investigate the combined effects of root tip cell division and genotoxic damage, to provide a theoretical basis for future safe disposal of leachate.The results showed that:1. Ion exchange resin can be well used for landfill leachate treatment, the optimum resin dosage was 200g/L, when the removal rate of the concentration of CODcr and TS was 90% and 56%, respectively.2.Ion exchange treated leachate can affect the early growth of barley, delay its germination; restrain the root length, shoot growth, and the inhibition related with both resin dosage and exposure time; influence the fresh weight, dry weight of barley seedlings.3. Leachate conducted both positive and negative effects on the mitotic index of barley root tips. Low concentrations of leachate can promote root tip cells in mitosis, to the contrary, high concentrations inhibit mitosis. The examination result s of MCN showed that after Ion exchange resin-treated, the ecological risks of leachate to the surrounding environment remained.4. The results of the MI of three treatment ways of leachate showed that barley root tip MI increases with the decrease of TS concentration. With the same TS concentration, the CODcr with an Intermediate concentrations could benefit the MI.5. The results of the MCN showed that, with the increase of ion exchange resin dosage, the MCN decreased gradually. When TS concentration constant, MCN decreased with the decreasing concentration of CODcr. |
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