Multi-sectoral analysis of urban nitrogen metabolism and study on impacts of recycling technologies

Abstract

Based on the multi-sectoral system analysis (MSA) model, the present study firstly simulated the nitrogen metabolism flows involving the water sector, the food sector, the forestry department, the energy sector and the waste management department in Suzhou. Secondly, the key sectors and steps of urban nitrogen metabolism were recognized. Thirdly, four targeted recycle technologies of nitrogen were selected: Urine Source Separation Technology, Pyrolysis of Separated Sludge Technology, Livestock Manure Pyrolysis Technology and Algal Water Purification. The impacts of these technologies together with their combined scenarios on the urban nitrogen metabolism were discussed. The intention of this analysis is to provide decision support for the optimization control of urban nitrogen. The main conclusions are as follows: The nitrogen input of Suzhou was 1.6' 10⁶t/y, 90% of which was from coal and natural gas. The energy sector, food sector and water sector contained steps which were crucial to the recycling of nitrogen. Better effects for the optimization of nitrogen metabolism can be produced by increasing the number of combination circumstance. This could potentially lead to a 52% increase of nitrogen metabolic efficiency at most. Such an increase would be a great contribution to the construction of a low nitrogen society.