镧改性膨润土对底泥内源磷控制效果

以商业化的锁磷材料—镧改性膨润土(Phoslock®)为对象,研究了Phoslock®对磷的吸附动力学和等温线,同时研究了材料对上覆水体以及底泥内源磷释放的控制效果.结果表明,Phoslock®对磷的吸附可以用Langmuir模型拟合,相关性达到0.96,模型计算磷的最大吸附量为10.4mgP/g,且磷吸附符合拟一级和拟二级动力学模型.室内模拟培养结果表明,当锁磷剂投加剂量为1553g/m2时,70d(好氧17d和厌氧53d)内,对上覆水中的磷酸盐去除率达到90%以上,沉积物内源磷释放削减83.1%,但会引起上覆水体中总氮、氨氮以及硝氮的增加,磷形态分析结果表明,表层(0~2cm)底泥中有超过50%的Mobile-P和Al-P转化为稳定态的Ca-P和Res-P,且控磷效果随着投加量的增加而增加.研究表明,Phoslock®对底泥内源磷具有较好的控制效果,但长期效果需加强研究.

The effect of lanthanum modified bentonite on the control of sediment internal phosphorus loading

The commercial phosphorus inactivation material-Phoslock® was used to investigate its efficiency for sorption isotherm and kinetics. In addition, the control effects on P concentration in overlying water and sediment internal P release was also investigated. The results indicated that P sorption on Phoslock can be fitted well by Langumiur model with a coefficient of 0.996 and the maximum P sorption capacity was estimated to be 10.6mgP/g. P sorption on phoslock can be fitted well by second-order kinetic model. The results of laboratory incubation indicated that the soluble reactive phosphate in overlying water and sediment internal P release can be reduced by more 90% and 80% respectively with a dosage of 1553g/m³ during seventy day of incubation (17days of aerobic and 53days of anaerobic incubation).Unfortuately, the addition of phoslock can induce an elevation of total nitrogen, ammonium nitrogen and nitrate in overlying water. P fractionation analysis indicated that the addition of phoslock can transform more than 50% of mobile P and Al-P into stable Ca-P and Res-P. The control effects can be increased with the increase of dosage of Phoslock. Overall, the results indicated that Phoslcok can effectively control sediment internal phosphorus loading, but the long-term effects still should be studied further.