pH对污水污泥中污染物浸出的影响

研究pH对污泥中污染物浸出的影响可以为投海过程中海洋水体酸碱性变化对污泥中污染物浸出的影响及其变化规律提供理论依据。为了得出不同pH值对污泥中污染物浸出的影响，采用CEN/TS 14429：2005浸出实验对上海5个污水处理厂脱水污泥中重金属、溶解性有机碳、溶解性硫化物和主要离子的浸出情况进行了研究，同时分别以超纯水和海水为浸提剂研究在相应pH范围内盐度对上述指标浸出的影响。结果表明，Zn、Cd、Pb和As在酸性和碱性条件下浸出量较高，在中性或接近中性条件下浸出量则最低，且海水中Zn和Cd的浸出量比超纯水中高；Cu在碱性条件下的浸出量明显比酸性条件高；在所研究的pH范围内，5个污泥样品中溶解性有机碳的浸出量均随pH的升高而增高；仅酸挥发性硫含量最高的S5在海水中有较明显的溶解性硫化物浸出；部分污泥样品中的氮在酸性纯水中有较高的浸出量，海水中浸出量较少；而无论海水或纯水中，磷在强酸和强碱条件下均有明显浸出。

Influence of pH on leaching of pollutants from sewage sludge

The study on the impact of pH can provide a theoretical basis for the ocean-dumping disposal of sewage sludge. The leaching processes of heavy metal,dissolved organic carbon,dissolved sulfide and main ions from 5 dehydrated sewage sludge samples at different pH values with CEN/TS 14429:2005 were mainly designed. At the same time,two different leaching agents,ultrapure water and seawater, were selected as separate leachants to explore the effect of salinity on the above leaching processes. The results showed that leached amount of Zn,Cd,Pb and As was high under acid and alkaline conditions,but low under neutral conditions,and the leached amount of Zn and Cd in seawater was much more than that in ultrapure water. Alkaline condition was preferred to acid condition in the Cu leached process. With the pH increasing,the leaching amount of dissolved organic carbon increased. The obvious leaching of dissolved sulfide was observed only from the sample S5 with the highest level of acid volatile sulfide. Nitrogen could be leached from some samples only in the acid pure water,whereas phosphorous could be leached from all samples under highly acid and alkali conditions no matter what the leaching agent was.