| Environmental endocrine disruptors, which have negative effect on development of organisms, have caused severe problems around the world, especially in aquatic ecosystems. There are many kinds of pollutants included. In this research, organic endocrine disruptors were selected for tests, including NP (NonylPhenol) and BPF (4,4’-Dihydroxydiphenylmethane) representing for a kind of pollutants that can be biodegraded according to early reports, and TCBPA (Tetrachlorobisphenol-A) and BPS (4,4’-Sulfonyldiphenol) representing for a kind of pollutants frequently detected in tap water. Photolysis and bio-degradation and bio-transformation of NP and BPF by micoorganisms in water column and submerged macrophytes were investigated, in order to illustrate the environmental destination of these pollutants and explore the potential in the bio-remediation of contaminated water. Adsorption experiments of TCBPA and BPS by activated carobon were also undertaken to declare the patterns, influencing factors and machanisms involved, and the effective of household water filters (based on the adsorption of activated carbon) was compared and essessed, whose results will be much beneficial to the removal of such pollutants for health protection in houses.Photolysis of NP and BPF was greater in autoclaved natural water including Nanhu Lake, Donghu Lake and Ziyanghu Lake comparing to that in ultrapure water, implying substances enhanced the process in natural water. Photolysis of NP was easier than that of BPF. Indigenous microorganisms can greatly enhanced the removal of NP in water, which was 72.7%,41.1% and 25.6% greater for Nanhu Lake, Donghu Lake and Ziyanghu Lake, repectively. And they can also greatly increased the removal of BPF in water, which was 10.3%,2.1% and 9.7% of increase, respectively. Such results indicated that microorganisms which can removing these pollutants were popular in natural water. After exchanging the microorganisms in water column between Nanhu Lake and Donghu Lake, the removal of NP in Nanhu Lake water was still 40.1% of increase due to the microorganisms from Donghu Lake water, while the removal of NP in Donghu Lake water was still 57.2% of increase due to the microorganisms from Nanhu Lake water, indicating the effect of microorganisms. After exchanging the microorganisms in water column, microorganisms from Donghu Lake increased the removal of BPF in Nanhu Lake water by 44.2%, which was significantly greater than the indigenous microorganisms in Donghu Lake (about 2.1%), which suggesting that environmental factors can greatly affect the pollutant removal. Effect of microorganisms on BPF removal demanded more oxygen than that on NP removal, because oxygen limiting greatly decreased the BPF removal while showed no significance on NP removal. Mixed pollutions showed great effect on BPF removal but no significant effect on NP removal. It may be caused by the negative effect of NP on microorganisms removing BPF.Submerged macrophytes which are pickted from wuhan botanical garden can effectively remove NP and BPF in water, especially Ceratophyllum demersum which showed over 95% of removal for both NP and BPF in 8 days. Plants, instead of epiphytic bacteria, may contribute the most to degradation and transformation of NP, because no significant difference showed after inhibition of epiphytic bacteria by antibiotics during the 8 days of experiments. Submerged plants showed great ability in biodegradation and biotransformation of NP, like Ceratophyllum demersum and Myriophyllum spicatum, especially C. demersum which can degradate 90%±0.85% of NP in one day. Meanwhile, slight bioaccumulation of NP was found in plants, which will be great in decreasing the environmental risks of such pollution through food chains. Peroxidase may take the role in the degradation process for both NP and BPF.Powdered activated carbon can effectively removing BPS and TCBPA from water by adsorption. The patterns both fitted well with pseudo-second-order model (R2BPS=0.9998, R2TCBPA=0.9987), which was fast at the first stage and reached the equilibration at 50 min and 120 min, respectively. Langmuir isotherm model was more suitable to explain the adsorption of BPS by activated carbon, while Freudlich isotherm model was more suitable for TCBPA adsorption. The calculated maximum adsorption capacity is 83.3 mg/g and 92.91 mg/g for BPS and TCBPA, respectively. Both adsorption process were exothermic (△HBPS=-14.61 kJ/mol,△HTCBPA=-18.06 kJ/mol). Hence the adsorption effectivity both decreased at higher temperature. Increase in pH, or addition with humic acid can greatly decrease the adsorption of BPS and TCBPA by activated carbon. Hydroxy and amino groups were the main functional groups based on Fourier transform infrared spectroscopy analysis. Some household water filters (based on the adsorption of activated carbon) can’t effectively remove the BPS based on the results.It may be caused by the flow control. Household water filters using adsorption technology by activated carbon combined with other like ultrafiltration will be more effective in BPS removal. Therefore, it was recommended to choose water filters with combined technologies and stable flow control for the health protection.From all the results above, microorganisms in water and submerged macrophytes can greatly affect the environmental destination of organic endocrine disruptors in natural water, and submerged macrophtes have great potential in phyto-remediation of contaminatd water by such pollutants. At the meantime, those pollutants can be effectively removed from tap water by adsorption with activated carbon, which will decrease the exposure of people to such pollutants, in other words, ensure the public health. |
PDF Full Text Request