Werner David, Ghosh Upal, Luthy Richard G
School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, NE1 7RU Newcastle, United Kingdom.
Environ Sci Technol. 2006 Jul 1;40(13):4211-8. doi: 10.1021/es052215k.
The sorption kinetics and concentration of polychlorinated biphenyls (PCBs) in historically polluted sediment is modeled to assess a remediation strategy based on in situ PCB sequestration by mixing with activated carbon (AC). We extend our evaluation of a model based on intraparticle diffusion by including a biomimetic semipermeable membrane device (SPMD) and a first-order degradation rate for the aqueous phase. The model predictions are compared with the previously reported experimental PCB concentrations in the bulk water phase and in SPMDs. The simulated scenarios comprise a marine and a freshwater sediment, four PCB congeners, two AC grain sizes, four doses of AC, and comparison with laboratory experiments for up to 540 days of AC amendment slowly mixed with sediment. The model qualitatively reproduces the observed shifts in the PCB distribution during repartitioning after AC amendment but systematically overestimates the overall effect of the treatment in reducing aqueous and SPMD concentrations of PCBs by a factor of 2-6. For our AC application in sediment, competitive sorption of the various solutes apparently requires a reduction by a factor of 16 of the literature values for the AC-water partitioning coefficient measured in pure aqueous systems. With this correction, model results and measurements agree within a factor of 3. We also discuss the impact of the nonlinearity of the AC sorption isotherm and first-order degradation in the aqueous phase. Regular mixing of the sediment accelerates the benefit of the proposed amendment substantially. But according to our scenario, after AC amendment is homogeneously mixed into the sediment and then left undisturbed, aqueous PCB concentrations tend toward the same reduction after approximately 5 or more years.
对历史污染沉积物中多氯联苯（PCBs）的吸附动力学和浓度进行建模，以评估基于与活性炭（AC）混合进行原位多氯联苯封存的修复策略。我们通过纳入仿生半透膜装置（SPMD）和水相的一级降解速率，扩展了基于颗粒内扩散模型的评估。将模型预测结果与先前报道的水体和SPMD中多氯联苯的实验浓度进行比较。模拟场景包括海洋和淡水沉积物、四种多氯联苯同系物、两种活性炭粒度、四种活性炭剂量，并与长达540天的活性炭与沉积物缓慢混合的实验室实验进行比较。该模型定性地再现了活性炭添加后重新分配过程中多氯联苯分布的观测变化，但系统地高估了处理对降低多氯联苯水体和SPMD浓度的总体效果，高估系数为2至6倍。对于我们在沉积物中应用活性炭的情况，各种溶质的竞争吸附显然需要将在纯水体系中测得的活性炭 - 水分配系数的文献值降低16倍。经过这种校正后，模型结果与测量值在3倍的范围内相符。我们还讨论了活性炭吸附等温线的非线性和水相中的一级降解的影响。沉积物的定期混合大大加速了所提议的添加的益处。但根据我们的模拟场景，在活性炭添加均匀混合到沉积物中然后保持原状后，大约5年或更长时间后，水体中多氯联苯的浓度趋于相同程度的降低。
