粉煤灰与污水沉淀物复合土壤添加剂中磷的有效化实验研究

AN EXPERIMENTAL STUDY ON THE VALIDITY OF PHOSPHORUS IN COMPLEX SOIL ADDITIVE PREPARED BY COAL ASH AND SEWAGE SLUDGE

我国西北地区荒漠化土壤的一个重要特征是严重缺磷。粉煤灰和城市污水沉淀物均有较高的磷含量。但是,如果将城市污水沉淀物单独加入土壤,在强淋雨条件下其有效磷将会再度流失。为研究如何提高有效磷的利用率,特设计了粉煤灰和污水沉淀物复合土壤添加剂中磷的有效化实验。实验表明:多孔的粉煤灰颗粒对污水沉淀物中的有效磷有强烈的吸附、存储,并缓慢解吸、释放的作用。同时,粉煤灰颗粒中的磷也会在污水的生物化学等综合作用下缓慢溶出。因此,在植被覆盖率低、干旱且易遭受集中强淋雨条件的西北荒漠化土壤中,添加由粉煤灰和污水沉淀物组成的复合添加剂,能够有效恢复植被,加快改善西北地区荒漠化的步伐。

One of the characteristics of desertificated soil in the northwestern part of China is the bad lack of phosphorus. But the contents of phosphorus in coal ash and sewage sludge are high. So the coal ash and sewage sludge can be added into desertificated soil for supplying phosphorus. The effect would be better if the coal ash or sewage sludge is added separately, because phosphorus can be lost again under the condition of strong rain leaching in Northwest China. The experiment was carried out on how to enhance the validity of phosphorus in the additive. The results showed that there is a strong adsorption and slow release process of phosphorus in the experiment. It is indicated that porous coal ash particles can adsorb a large amount of available phosphorus from sewage sludge. And then the available phosphorus can release again, though slowly. This means that by mixing coal ash and sewage sludge, the available phosphorus can be stored firstly, then some of it will release slowly and absorbed by plants. Moreover, phosphorus in coal ash also can be released by breaking the particles under complex physical, chemical and biochemical processes. The experimental results show that: improvement of the desertificated soil in Northwest China is a way of mixing coal ash and sewage sludge to complement phosphorus, especially for desertificated soil in arid, less vegetation and strongly rain leaching areas. The way can increase greatly the validity of phosphorus.