垃圾渗滤液原位反硝化研究

场外硝化–原位反硝化是垃圾填埋场氮管理的新途径.本文利用垃圾柱模拟生物反应器填埋场,研究了硝化渗滤液在填埋场内部的变迁及其对垃圾降解的影响.结果表明,硝化渗滤液回灌促进了填埋场垃圾降解,回灌的总氧化态氮(TON)被完全还原,反硝化为主要作用反应,最大TON负荷为28.6mg(N)kg(TS)-1d-1.当负荷大于11.4mg(N)kg(TS)-1d-1时,垃圾产甲烷受到抑制,抑制作用随负荷的增加而加强.在此过程中,反硝化逐渐代替产甲烷作用成为填埋场内垃圾降解的主要反应,产生气体以氮气为主,而非甲烷;硝化渗滤液与垃圾的长期作用也改变了填埋场的菌群结构.

硝化渗滤液回灌对填埋垃圾反硝化、产甲烷及稳定化的影响

垃圾填埋场是重要的甲烷释放源,其有效管理是减缓温室效应的重要环节.通过硝化渗滤液回灌模拟垃圾填埋柱,研究硝化渗滤液在新鲜垃圾和老龄垃圾填埋柱中的脱氮及对垃圾稳定化和产甲烷的影响.结果表明,回灌的硝化渗滤液在不同填埋龄垃圾柱中,均可实现总氧化态氮(Total oxidation nitroge,TON)完全还原.当回灌TON负荷分别达到14.19 g t-1(TS)d-1和10.45 g t-1(TS)d-1时,新、老垃圾柱中甲烷产生开始受到抑制.实验后期,回灌TON负荷增至38.78 g t-1(TS)d-1和30.62 g t-1(TS)d-1时,新、老垃圾填埋柱产甲烷相对抑制率分别达54.10%和95.77%.同时,回灌反硝化对新、老垃圾柱中垃圾降解贡献率(Rd)分别达85%和93%,能有效促进垃圾稳定.

Nitrogen Release Kinetics and Nitrification-Denitrification on Surface Sediments under Aerating Disturbance Condition

[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.

Nitrite Accumulation during the Denitrification Process in SBR for the Treatment of Pre-treated Landfill Leachate

The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.

硝酸盐连续回灌对生物反应器填埋场N_2O产生的影响

异位硝化-原位反硝化是实现填埋场渗滤液脱氮处理的一种有效措施,但硝化反硝化过程中会产生强温室气体N2O.实验构建了3个新鲜垃圾生物反应器填埋场模拟装置,分别回灌NO-3-N浓度为50、100和300 mg·L-1的渗滤液,考察垃圾原位反硝化过程中N2O产生规律及其影响因素.结果表明,回灌不同浓度硝酸盐,N2O产生量均表现为初期浓度较大-下降-后期升高的规律;N2O产生量与回灌NO-3-N量正相关,其累积产生量分别为36 481、44 241、86 264μg,但反硝化消耗单位硝酸盐氮产生的N2O量(以N计)以及N2O转化率与回灌硝酸盐氮量呈负相关,N2O平均转化率分别为8.84‰、5.68‰和2.34‰.分析认为,各反应器垃圾降解后期反硝化碳源不足是N2O产生量高的主要原因.