Phosphorus management and recovery from sewage sludge on an international scale - potentials and limitations

Abstract

Phosphorus (P) is an important nutrient and essential for life. It is being mainly applied in agriculture as mineral fertiliser for food and feed production. The agricultural products which contain phosphorus are being consumed and eventually end up in waste such as sewage sludge. Since phosphorus is a non-renewable resource phosphate mines are getting depleted and thus imposing a serious challenge on future food security. One way of moving towards a more sustainable management of phosphorus is through recycling it from sewage sludge.Many countries have recognised the importance of managing and using phosphorus on a sustainable way. However, they differ in their patterns of phosphorus consumption, in their political approaches on recovering phosphorus from sewage sludge and their state of development in the implementation of P recovery technologies.This thesis analyses endeavours concerning P recovery from sewage sludge in Austria, Germany, the Netherlands, Sweden and Switzerland. The analysis consists of an examination of current legal frameworks and national strategies on P recovery in those five countries. Further, the thesis looks at the national P balances of the five countries to discern the main phosphorus flows in a country and consequently make statements on current P management at the national level. Based on the P balances current and potential P recycling rates are being identified. In addition to that, this thesis includes investigations on whether technologies for P recovery from sewage sludge have been already implemented in those five countries. Since four of the five countries are members of the European Union regulations and strategies on P recovery on the EU level are being examined as well. The results of the analysis of the domestic regulations and the national P balances are being compared and differences among the countries regarding P recovery and P management are listed.The results from the comparison show that Austria, Germany, the Netherlands, Sweden and Switzerland have similar approaches concerning P management, but they slightly differ in their state of development in the implementation of technologies for P recovery from sewage sludge. However, none of the five countries is currently recovering phosphorus from sewage sludge on a large scale. Thus there is still work need to be done to attain the goal of sustainable P management and circular economy.