NTPlus - developing the circular economy in agriculture

该项目展示了从水中回收养分，减少农业对哈伯法生产氮肥和曼海姆法生产硫酸盐肥料的依赖，帮助农业走向净零。这有可能彻底改变硝酸盐的去除，这是在硝酸盐水平高于安全水平的情况下进行的。地下水硝酸盐污染发生在集约化农业和污水处理使用大量盐分的地区，产生了盐水硝酸盐废流，经常不得不将其运到大型废水处理厂。盐再生用于去除硝酸盐的离子交换树脂，但该过程通常效率约为10%。这是一个昂贵的过程：在英国，水务行业的结构使工厂的资本和运营成本能够分散到庞大的客户群中，但在世界其他地区，水务行业分散，禁止更广泛地使用硝酸盐去除。例如，在加利福尼亚州的中央山谷，超过200个小型社区供水系统十多年来一直超过最高硝酸盐水平，而没有安装一个处理系统。大多数硝酸盐处理地点都有邻近的农田--农民使用反季节的钾肥氯化钾，以便在种植作物之前冲走氯化物。该项目将展示离子交换树脂的再生效率接近100%，生产含有钾、硫酸盐、硝酸盐、钙和镁的低氯肥料产品，以及天然黄腐酸(通过离子交换系统清除)，这些产品改善了土壤条件，并参与了土壤中微量矿物质的运输。这些技术可以被附近的农场用于智能(变量施肥)灌溉，并可能成为现有化肥制造商的新产品，使他们能够运输固体补充添加剂，并在农场补充液体产品。通过鼓励英国采用智能灌溉，作物产量将经常实现10%的增长，同时更有效地利用化肥和水。英国的灌溉使用量正在增加，以确保提高对气候变化的适应能力，特别是在使用灌溉蓄水的情况下，促进冬季抽水和利用此类设施缓解洪水的可能性。已经存在于渗流层中的硝酸盐的数量是巨大的(英国地质勘探局估计为600-1800米TE)，被视为水源的“定时炸弹”。这个项目将这个问题变成一个可持续的解决方案。所生产的产品具有比原材料投入更大的价值，这使得有可能实现指数级增长。全球每年有9000万吨钾肥用于农业。如果其中10%用于从水中回收养分，这将减少土壤和淡水系统的氯输入超过20Mte，并减少超过30Mte的二氧化碳排放，并在额外的作物生产中捕获近1000Mte的二氧化碳。

This project demonstrates the recovery of nutrients from water, decreasing agriculture's dependence on the Haber process for nitrogen fertilisers and the Mannheim process for sulphate fertilisers, helping agriculture move towards net zero. This has the potential to revolutionise nitrate removal, which is carried out where nitrate levels are above safe levels. Nitrate pollution of ground water occurs in regions of intensive agriculture and treatment uses large quantities of salt, producing a brine nitrate waste stream which often has to be tankered to a large waste water treatment works. The salt regenerates the ion exchange resin used to remove nitrate, but the process is typically ~10% efficient. This is an expensive process: in the UK, the structure of the water industry enables the capital and operational costs of plants to be spread over a large customer base, but, in other parts of the world, the water industry is fragmented, prohibiting the wider use of nitrate removal. For example, in the Central Valley in California, over 200 small community water systems have consistently exceeded the maximum nitrate level for over a decade, without a single treatment system being installed.Most nitrate treatment sites have adjacent farmland - and the farmer applies potash fertiliser, potassium chloride, out of season so the chloride is washed away before the crops are planted. This project will demonstrate regeneration of the ion exchange resin at close to 100% efficiency, producing low-chloride fertigation products containing potassium, sulphate, nitrate, calcium and magnesium, as well as natural fulvic acids (scavenged by the ion exchange system) which improve soil condition and are involved in the transportation of trace minerals in soils. These could be used by a nearby farm in smart (variable rate fertilisation) irrigation, and could become a new product for existing fertiliser manufacturers, enabling them to ship solid complementary additions and make up the liquid products on the farm.By encouraging the uptake of smart irrigation in the UK, crop yield gains of 10% would be regularly achieved, along with more efficient use of both fertilisers and water. Irrigation use is increasing in the UK to ensure increased resilience to climate change, particularly where irrigation water storage is used, facilitating winter abstraction and the potential to use such facilities for flood mitigation. The amount of nitrate already present in the Vadose layer is substantial (BGS estimate 600 - 1,800M te) and is seen as a 'timebomb' for water sources.This project turns this problem into a sustainable solution. The products produced have a greater value than the raw material inputs, which enables the potential for exponential growth. Globally, 90 M te of potash is used annually in agriculture. If 10% of this were used to recover nutrients from water, this would reduce chloride inputs to soil and fresh water systems by over 20 M te and reduce CO2 emissions by over 30 M te, with nearly 1,000 M te of CO2 captured in additional crop production.