The use of 'waste' Mn oxides as contaminated land remediation products

土地是一种宝贵但有限的资源。环境署估计，英国约有30万公顷土地在一定程度上受到工业活动遗留污染的影响，而在世界范围内，由于受污染的土地与贫困密不可分，问题的程度要大得多。在英国，对新住房的需求不断增加，加上政府在布朗菲尔德土地上实现60%或更多的新住房的目标，使得污染土地修复的原位技术成为优先领域。目前的主要补救技术往往既不能处理含有金属和持久性有机污染物混合物的“混合”场地，也不能成为具有成本效益和可持续的技术。如果被证明是可行的，所提出的技术没有这些缺点。因此，它可以在国际土地补救部门占有非常强大和有利可图的市场份额。商业可行性是复杂的事实，我们正在使用一种材料，目前被视为“废物”作为补救产品。欧盟最近出台的《垃圾填埋指令》也对欧洲污染土地的补救产生了巨大影响，人们越来越关注开发新的成本效益高的原地方法来补救布朗菲尔德。锰（Mn）氧化物自然存在于土壤中，部分解释了土壤降解和隔离污染物的自然能力。锰氧化物是一种强有力的氧化剂，既能固定两种金属，又能促进持久性有机污染物的原位降解。在这个项目中，我们将研究是否可以通过添加额外的氧化锰来增强这种自然防御机制，以及这对土壤的任何积极和消极影响。由于锰氧化物也刺激土壤中的腐殖化率，因此有可能增强碳固存和改善一般土壤健康。本项目将通过一系列工厂设计的实验，研究锰氧化物的潜在有益作用（金属固定化、持久性有机污染物固定化和土壤有机质腐殖化）如何相互作用。光谱分析技术的使用将为评估锰氧化物修复污染土地的长期潜力以及天然锰氧化物在土壤中的作用提供机理信息。达勒姆大学已经确定了数十万吨目前没有市场的高活性锰氧化物“废物”（约翰逊等人，2006年）。最近在达勒姆的工作已经产生了非常有前途的结果，这些纯锰氧化物吸附特定的持久性有机污染物（多环芳烃）的潜力。该项目建议在这项工作的基础上，深入调查这些天然矿物表面的基本过程，以及这些过程如何在真实的土壤和不同的环境条件下竞争活性矿物表面。我们的目标是研究这些机制的污染物分解和固定使用光谱技术。这项工作的新奇在于研究锰氧化物作为修复产品的潜在用途，能够处理具有挑战性的“鸡尾酒”网站。如果该项目证明锰氧化物可以为这些“鸡尾酒”场地提供单一解决方案，则该技术的应用市场相当可观，仅英国的污染土地修复市场价值就超过10亿美元。

Land is a valuable but finite resource. The Environment Agency estimates that there are approximately 300,000 hectares of land in the UK affected to some extent by contamination left by industrial activity and worldwide, the extent of the problem is much greater as contaminated land is inextricably linked to poverty. In the UK, the increasing demand for new housing coupled with the Government targets of achieving 60% or more of new homes on brownfield land have made in situ techniques for contaminated land remediation a priority area. Current leading remediation technologies often fail either to deal with 'cocktail' sites where there are mixtures of metals and Persistent Organic Pollutants (POPs) and/or be cost-effective and sustainable technologies. If demonstrated to be viable, the technology proposed has none of these failings. As such it could command a very powerful and lucrative market share of the international land remediation sector. Commercial viability is compounded by the fact that we are using a material currently considered as a 'waste' as a remediation product. The recent introduction of the EU Landfill Directive also has huge implications for the remediation of contaminated land in Europe and there is increasing interest in the development of new cost effective in situ methods to remediate brownfield sites. Manganese (Mn) oxides occur naturally in soils and explain in part soil's natural ability to degrade and sequester contaminants. Mn oxides are powerful oxidising agents capable of both immobilising both metals and enhancing the degradation of POPs in situ. In this project we will investigate if this natural defence mechanism can be enhanced by adding extra Mn oxide and any positive and negative effects this has on the soil. Since Mn oxides also stimulate humification rates in soils there is the potential for enhancing carbon sequestration and improving general soil health. This project will investigate how the potential beneficial actions of Mn oxides (metal immobilisation, POP immobilisation and humification of Soil Organic Matter, SOM) interact via a series of factorially designed experiments. The use of spectroscopic analytical techniques will provide mechanistic information to assess the long term potential for Mn oxides to remediate contaminated land and therefore the role of natural Mn oxides in the soil.Durham University have identified hundreds of thousands of tonnes of highly reactive Mn oxide 'wastes' which currently have no market (Johnson et al, 2006). Recent work at Durham has produced very promising results on the potential of these pure Mn oxides to sorb specific POPs (PAHs). This project proposes building on this work with a thorough investigation into the fundamental processes operating at the surface of these natural minerals and how these processes compete for reactive mineral surface in real soils and under different environmental conditions. We aim to study these mechanisms of contaminant breakdown and immobilisation using spectroscopic techniques. The novelty in the work lies in investigating the potential use of Mn oxides as remediation products capable of treating the challenging 'cocktail' sites. If this project proves that Mn oxide could provide a single solution for these 'cocktail' sites, the markets for application of this technology are considerable with the contaminated land remediation market in the UK alone valued at >1bn.