Life Cycle Evaluation Of Fermentation Wastewater Treatment System Based On ANAMMOX Process

At present,fermentation wastewater treatment industry is generally characterized by high energy consumption,high material consumption and high carbon emission,which has great potential for energy conservation and emission reduction.However,the direction of energy conservation and emission reduction transformation in the whole fermentation wastewater treatment industry is not clear enough.This study selected a typical fermentation wastewater treatment system as a case study.Firstly,the operation efficiency of the whole process analysis was analyzed.Secondly,the environmental impact contribution factors of each unit were analyzed based on life cycle assessment.Then combined with the sensitivity analysis results to find out the pain points of energy conservation and emission reduction.The most suitable process combination for fermentation wastewater treatment industry was put forward from the perspectives of technology,environment and economy,which pointed out the direction of transformation and provided theoretical support for energy conservation and emission reduction in the future.The main conclusions were as follows.（1）After 1#AO tank was transformed into CANON process,the long-term data monitoring results of the core treatment units showed that the COD removal rate of the UASB unit was more than 78%.The COD removal rate of CANON unit was72%～80%,with the TN removal rate of 70%～80%.And the COD removal rate of the AO unit was 73%～81%,with the TN removal rate of 87%～92%.The analysis results of mass flow and energy flow shown that,compared with the AO unit,the amount of Na OH in the ANAMMOX unit was reduced by 100%（mass fraction 30%）,the power consumption was reduced by 89%,and the amount of residual sludge was reduced by65%,indicating that the ANAMMOX process has great advantages in energy saving and consumption reduction.（2）In this study,Recipe 2016 Midpoint method was adopted to treat 1 m³wastewater as a functional unit.According to operation data,the life cycle evaluation of the fermentation wastewater treatment system after partial Anammox modification was carried out.The results shown that AO was the most influential unit among the six process units,the contribution to ozone depletion was the largest,followed by global warming potential.ANAMMOX was an energy saving and environment-friendly process.In addition,the CHP unit could reduce environmental impact indicators such as global warming potential,photochemical smog,land acidification and fossil resource consumption.The CHP unit not only neutralized the direct and indirect CO₂ emissions from the production process,but also achieved a carbon surplus of 1.74 kg per m3of wastewater.It shown that CHP was an ideal way to achieve carbon neutrality in wastewater treatment industry.（3）Based on sensitivity analysis,this study obtained the pain point factors of carbon neutrality in fermentation wastewater treatment system,namely direct greenhouse gas emission and power consumption.Then demonstrated the sustainability of the comprehensive application of integrated ANAMMOX process to replace AO process from multiple perspectives of technology,environment and economy.The results shown that if the AO process was completely transformed into ANAMMOX process,the total power consumption of the system could be reduced by53%,CH₄ emissions could be reduced by 83%,and N₂O emissions could be reduced by 60%,which was equivalent to reducing system carbon emission by 41%.The ozone loss index was only 18%of the pre-modification scenario（UASB+AO）.In addition,the economic advantages were also very superior.For the treatment of 1 m³fermentation wastewater,the cost of UASB+ANAMMOX（S3）was only 54%of that of the current process route（S1）,and the treatment benefits increased by 16%.The S3process route could achieve positive economic benefits,and the income per unit wastewater treatment was 1.45 yuan.To sum up,this study deeply analyzes the various impacts of process selection on the environment and society.In the process design stage of fermentation wastewater in the future,it should not only consider the single goal of pollutant removal,but also comprehensively design the most sustainable process system based on the concept of energy saving and emission reduction and circular economy.