There exist numerous ecotechnologies for recovery and reuse of carbon and nutrients from various waste streams before they are lost to runoff. However, it remains largely unknown how growing implementation of such ecotechnologies affect nutrient emissions to surface waters at catchment scale. Here, this knowledge gap is addressed by application of SWAT model in three case study catchments draining to the Baltic Sea: Vantaanjoki (Finland), Fyrisån (Sweden) and Słupia (Poland). Sustainability analysis with Multi-Criteria Analysis was applied in the stakeholder workshops in the case study areas to assess different ecotechnology alternatives. The following ecotechnologies received the highest sustainability scores: in Vantaanjoki anaerobic digestion, based on mostly agricultural residues; in Fyrisån source-separation of wastewaters; in Słupia nutrient extraction within the wastewater treatment process. The effect of application of digestate on agricultural soils in the Vantaanjoki catchment was simulated by adjusting the model parameters describing the organic carbon content and physical properties of soil. The results showed small reductions of nutrient loads to the Gulf of Finland. Larger reductions of nutrient loads to Lake Mälaren in Sweden and the Baltic Sea in Poland were achieved as a result of the wastewater treatment upgrades. In the Fyrisån catchment, higher relative reductions were simulated for TN than TP, and in dry years than in wet years. Although the studied ecotechnologies did not show as high effectiveness in nutrient load reduction as combinations of traditional Best Management Practices reported in literature, they do have other multiple benefits including crop yield increase, electricity, heat and bio-based fertilizer production.

在将各种废物流中的碳和养分流失至径流之前，存在许多用于回收和再利用碳和养分的生态技术。然而，人们仍然不知道这种生态技术的不断实施如何影响流域规模的地表水养分排放。在这里，通过在排入波罗的海的三个案例研究流域中应用SWAT模型来解决这一知识差距：Vantaanjoki（芬兰），Fyrisån（瑞典）和Słupia（波兰）。在案例研究领域的利益相关者研讨会上应用了具有多准则分析的可持续性分析，以评估不同的生态技术替代方案。以下生态技术在可持续性方面得分最高：在Vantaanjoki厌氧消化中，主要基于农业残留物；在费里森的废水源分离中；废水处理过程中Słupia的营养提取。通过调整描述有机碳含量和土壤物理性质的模型参数，模拟了在万塔若基河流域施用消化液对农业土壤的影响。结果表明，到芬兰湾的养分含量略有减少。由于废水处理技术的升级，瑞典的Mälaren湖和波兰的波罗的海的养分负荷大大减少。在Fyrisån流域，模拟得出TN的相对减少量高于TP，而干旱年份的相对减少量要高于湿年份。尽管所研究的生态技术并未像文献中报道的传统最佳管理实践相结合，在减少营养负荷方面显示出很高的效果，