Emergy Analysis Of Comprehensive Utilization Project Of Wastewater Treatment—concurrently On Coastal Area Model

Sewage treatment systems will cause the consumption of energy and resources while sewage discharge,disinfection,coagulation,flocculation agent in the process.In order to evaluate the effect of sewage treatment system for comprehensive utilization efficiency and sustainable development of natural economic system,the Qiqihaer sewage treatment plant was chosen as an example,fours models were contrasted by using application of emergy analysis principle and method.Model A includes sewage treatment system and boiler heating system model;Model B includes sewage treatment system,boiler heating system and step by step PV power station system;Model C includes sewage treatment system and water source heat pump heating system.Model D includes sewage treatment plant,water source heat pump heating system,step by step photovoltaic power plant.The emergy flow of four models were counted,three emergy evaluation indexes,including emergy yield ratio(emergy yield ratio,EYR),environmental load ratio(ratio,ELR)and emergy sustainable development index(emergy sustainable index study on the comparative analysis,ESI)were calculated.The paper gets the following results and cognition:(1)By analysis and comparison,after adding water source heat pump heating system and step type photovoltaic power station equipment,the operating cost of the comprehensive energy consumption of sewage treatment plant is is better than a single operating system.Therefore,to explore the convergence of different industries will not only produce economic benefits,but also optimize the industrial structure and improve the ecological benefits.The environmental load rate of the four models is below 1,the environmental pressure is small,and the sustainable development index is between 1 and 10,which can be promoted from the ecological point of view.(2)From the point of view of emergy flow,the C and D models can be considered optimal with regard to nonrenewable resources only.Considering the capital input,the C model is the best,and the B and D models are the best with regard to output only.The A and B models rely more on nonrenewable resources,and C and D models are appropriate for resource scarcity areas.B and D models are more suitable for energy shortage and developed areas.A and C models are suitable for resource rich and economically underdeveloped areas.(3)From the three aspects of emergy output rate,environmental load rate and sustainable development index,the model D is optimized.Ranked is a model C,its emergy output rate is close to model A,but environmental load rate and sustainability index were higher than model A;Model A is the highest in efficiency,but the pressure on the environment is the dangerest;Considering the environmental pressure,Model B is better than A,but its output rate is decline,the comprehensive sustainable development index is drop compared with model A,so model B is not recommended derived from economy and ecological point of view.