三峡库区香溪河流域磷矿废石磷素浸出特性

为评价三峡库区香溪河流域内所堆存的磷矿废石对地表水体的磷污染风险,以香溪河支流高岚河流域内磷矿废石为研究对象,依据EPA M1316所规定的实验方法,开展了5种不同液固比(0.5~10.0 mL/g-dry)条件下磷矿废石磷素浸出特性的实验研究,探讨了液固比条件对磷矿废石磷素浸出浓度以及浸出率的影响。结果表明,磷矿废石浸出液中总磷浓度随液固比的增加而减小,其变化范围为0.74~0.47 mg/L;在液固比<7 mL/g-dry的条件下,浸出液中的总磷浓度均超出《污水综合排放标准(GB 8978-1996)》中所规定的最高允许排放浓度(0.5 mg/L);磷矿废石中磷素浸出率随液固比的增加而增大,其变化范围为0.37~4.70 mg/kg;磷矿废石将以点源的形式对其附近的地表水体形成长期的磷污染,属于第II类一般工业固体废物,应考虑在其堆置场顶部设置封盖层以降低其环境污染风险。

Phosphorus leaching characteristics of phosphate waste rock deposited within Xiangxi River watershed

To evaluate the potential phosphorus pollution risk of phosphate waste rocks deposited within Xiangxi River watershed of the Three Gorges Reservoir,the phosphate waste rock stacked in Gaolan River,which is one tributaries of Xiangxi River,was selected as the study objective.The leaching behaviors of the phosphate waste rock under five different liquid-to-solid ratios (0.5—10 mL/g-dry) were characterized following the EPA Method 1316 and the effect of liquid-to-solid ratio on phosphorus leaching concentration and leachability were discussed.The results indicated that the eluates total phosphorus concentrations decreased with the increasing liquid-to-solid ratio,varied in the range of 0.74—0.47 mg/L.Under the condition of the liquid-to-solid ratio less than 7 mL/g-dry,all eluates total phosphorus concentrations exceeded the maximum concentration level (i.e.,0.5 mg/L) specified by the Integrated Wastewater Discharge Standard (GB 8978-1996).The phosphorus leachability of phosphate waste rock increased with the increasing liquid-to-solid ratio,varied in the range of 0.37—4.70 mg/kg.The phosphate waste rocks would pollute the nearby surface water body as the point pollution sources and they should be considered as the second type of general industrial solid waste.The surface coverage layers should be set up in the top of the phosphate waste rock piles to reduce their environmental pollution risk.