高校实验室废气治理工艺选择及生命周期评价OA

[Objective]Volatile organic compounds(VOCs)are key precursors of particulate matter 2.5 and ozone.Although industrial emissions have significantly decreased under the ongoing Blue Sky Protection Campaign,exhaust gases from university laboratories near residential areas have become a critical concern for environmental quality and public health management.University labs typically use many volatile organic and inorganic reagents and feature numerous exhaust-collection points.This results in characteristics such as high total emissions,complex chemical composition,large air volumes,and low concentrations of laboratory exhaust gases.Currently,research on the effectiveness of treatment methods for university laboratory exhaust gases and the assessment of their full life cycle environmental impacts is lacking,limiting evidence-based guidance for selecting appropriate treatment strategies.[Methods]This study focuses on university laboratory exhaust gases and their treatment processes,evaluating treatment efficiency through pilot-scale and bench-scale tests.For bench-scale tests,xylene with varying humidity levels was used as the simulated exhaust gas,while for pilot-scale tests,a mixture of xylene,ethanol,and hydrochloric acid heated in a water bath inside a fume hood served as the simulated exhaust.Three combined treatment processes—"alkali washing+activated carbon adsorption,""activated carbon adsorption+alkali washing,"and"SDG(acidic exhaust adsorbent)adsorption+activated carbon adsorption"—were examined to thoroughly assess resource and energy consumption and environmental impacts throughout their entire life cycle.[Results]Under dry conditions with an inlet xylene concentration of 400 mg/m3,the saturated adsorption capacity of activated carbon for xylene was 226 mg/g.At 50%relative humidity(RH),capacity decreased to 114 mg/g,and at 90%RH,it dropped further to 89 mg/g.The"SDG adsorption+activated carbon adsorption"system showed the highest removal efficiency for mixed VOCs(xylene and ethanol),reaching 83%,along with 91%efficiency for hydrochloric acid mist.Although the"activated carbon adsorption+alkali washing"setup performed slightly lower,both systems significantly outperformed the"alkali wash+activated carbon adsorption"process in VOC removal.This difference is largely due to the high humidity(～100%RH)introduced by front-stage alkali washing,which promotes competitive water vapor adsorption and reduces activated carbon effectiveness.Life cycle assessment indicated that the"SDG adsorption+activated carbon adsorption"method has the lowest overall environmental impact.Additionally,performing alkali washing after adsorption resulted in better environmental outcomes regarding global warming potential and photochemical ozone creation potential compared to front-stage alkali washing.[Conclusions]Environmental impact analysis showed that moving alkaline washing to after the adsorption stage,which increases exhaust humidity,reduced global warming potential by 1.4%and photochemical ozone creation potential by 41.2%.Moreover,replacing wet alkaline washing with dry acidic exhaust adsorbent decreased global warming potential,photochemical ozone creation potential,acidification potential,and human health hazards by 4.5%,41.3%,9.9%,and 2.2%,respectively.