Proceedings

The recycling of biosolids to land has seen rapid evolution of constraints, regulations and voluntary schemes in a short space of time, with the Biosolids Nutrient Management Matrix in 2014 and the Biosolids Assurance Scheme towards late 2016, and with future constraints yet to be fully defined such as the NEP and the unknowns of Brexit. Ultimately, a water company has to understand the implications of all the potential risks and opportunities arising from these. For Yorkshire Water, one rising constraint has been the start of the shift from nitrogen to nitrogen & phosphorous-limited recycling to land. YWS also finds itself in a catch 22 situation, where it holds both an interest in catchment management to reduce P release while at the same time wanting to apply more to land. Arup has assisted YWS in understanding the availability and costs associated with disposal to land for the range of potential scenarios, enabling an evaluation of risk exposure to the business and the identification of mitigation plans. This work, also intends to challenge whether we should consider all the phosphorous to be the same as the proportion of chemically-bound phosphate increases to meet tighter effluent consents.