填埋场好氧修复过程碳排放特征及削减研究

填埋场是温室气体的主要人为排放源之一。由于历史原因我国目前存在着大量到期填埋场及非正规堆场,面临着严峻的存量垃圾问题,亟需进行修复,而好氧修复技术因其能够有效加速垃圾稳定化而得到了广泛应用,但修复过程中其碳排放特征尚且未知。因此,以某大型垃圾填埋场为对象,考察其在不同的修复状态下,填埋场有机质垃圾和二次污染物的变化特征,揭示其在好氧修复下的稳定化进程,并核算该过程中的甲烷(CH₄)减排效果。结果表明:该填埋场在曝气量和注水量分别为322.34 m3/min及25.65 m3/d的操作状态下,通过间歇注气方法(注气3 h,停3 h,每日运行9 h),垃圾中有机质平均含量从47.66%降至17.86%;填埋气CH₄含量从0.02%~46.48%下降至4.23%,满足导气管排放口CH₄浓度<5%的要求;渗滤液中ρ(COD)、ρ(氨氮)及ρ(总氮)分别降低至800.8,680.9,897.8 mg/L;在修复过程中,该填埋场CH₄实际排放量从24.57 t降低至2.47 t,减少了22.10 t CH₄排放,同时由于填埋场稳定化的加速,其CH₄排放潜力减少了1.75 kg/t垃圾。该研究成果中好氧修复可做为填埋场CH₄减排的重要支撑。

CARBON EMISSION CHARACTERISTICS AND REDUCTION FROM LANDFILL THROUGH FORCED AEROBIC STABILIZATION PROCESS

Landfill is one of the main anthropogenic emission sources of greenhouse gases. Due to historical reasons, there are a large number of expired landfills and informal storage yards in China facing a severe problem of waste stock that needs to repair urgently. Aerobic remediation technology has been widely used because it can effectively accelerate waste stabilization, but its carbon emission characteristics in the remediation process are still not clear. Taking a large-scale landfill as the object, this paper investigated the change characteristics of landfill organic waste and secondary pollutants under different repairing states, revealed its stabilization process under aerobic repair, and calculated the effect of methane emission reduction in this process. The results showed that under the aeration and water injection of 322.34 m3/min and 25.65 m3/d respectively, by intermittent gas injection method (opening for 3 hours and stopping for 3 hours, running for 9 hours per day), the content of organic matter in garbage decreased from 47.66% to 17.86%; the proportion of methane in landfill gas decreased from 0.02%~46.48% to 4.23%, reaching the requirement that the methane concentration at the outlet of air duct was less than 5%; the concentrations of COD, ammonia nitrogen and total nitrogen in leachate decreased to 800.8 mg/L, 680.9 mg/L and 897.8 mg/L respectively; during the restoration process, the actual methane emission of the landfill was reduced from 24.57 tons to 2.47 tons, cut by 22.10 tons. At the same time, due to the acceleration of the stabilization of the landfill, its methane emission potential was reduced by 1.75 kg/t waste. In conclusion, aerobic remediation could provide important support for methane emission reduction in landfill sites.