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村镇承载着我国约40%的人口和农副食品的初级加工[1],厨余垃圾对村镇环境影响较大[2]。由于厨余垃圾易腐败酸化,因此,必须进行及时处理,才能减少厨余垃圾腐败酸化带来的环境影响,这同时也限制了村收集-镇转运-县处理模式的正常运转。基于此,依托农村现有沼气工程[3],就地厌氧处理利用,探索可行有效的技术路线,具有重要现实意义。
厨余渗滤液中易降解COD含量较高,极易导致厨余废水的酸化,从而对厌氧工艺的稳定运行带来较大风险[4],并会进一步影响厌氧微生物的产甲烷和产乙酸过程,导致甲烷产量降低乃至反应器酸化崩溃。已有研究[5]表明,加碱调pH、重新接种和混合厌氧发酵是常用的控制酸化方法,这些方法在村镇应用时存在药剂投加量大、运行维护复杂等缺点,造成运行成本上升15%~37%[6-8],因此,制约了上述方法在村镇处理厨余垃圾渗滤液过程中的推广应用。在酸化崩溃的早期,厌氧体系内CO2大量溢出,不仅使氢营养型产甲烷菌底物浓度下降,限制氢营养型产甲烷途径,还会导致系统中碱度出现损失[9],影响系统运行稳定性。因此,通过沼气循环曝气,促进沼气中CO2在厌氧体系中的再溶解,强化CO2气液传质,提升厌氧系统中CO2浓度,从而促进氢营养型产甲烷反应,可在酸化早期控制过度酸化现象。内循环(IC)厌氧反应器具有二次气液循环系统,通过循环管路增强反应器内气液混合,无需额外加压沼气曝气[10],有利于实现村镇厨余渗滤液废水的就地处理和利用;通过该系统与外置膜系统组合,克服IC反应器出水水质不稳定缺点,有望一步满足工程排放需求,扩大厌氧工艺在处理类似高浓度废水中的应用范围。
本研究针对我国村镇厨余渗滤液处理需求,构建了IC-AnMBR内循环厌氧膜生物反应器,通过反应器构型的设计和过程控制的优化,缓解由VFAs累积造成的酸化抑制,以短流程工艺实现厨余渗滤液的稳定处理,并考察沼气循环曝气对膜污染的缓解效果,以期为AnMBR工艺的高效运行提供参考。
IC-AnMBR处理村镇厨余渗滤液废水稳定运行调控机制
Regulation mechanism for steady operation of IC-AnMBR treating high strengh organic rural leachate from food waste
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摘要: 村镇厨余垃圾渗滤液等高浓度有机废水的高效处理是提升村镇环境卫生水平的一个重要方面。为满足村镇厨余垃圾渗滤液低能耗有机物排放达标的处理需求,构建了内循环厌氧膜生物反应器 (internal circulation anaerobic membrane bioreactor,IC-AnMBR),并用来处理厨余渗滤率废水,重点分析了反应器的COD去除性能和调控机制;根据pH、VFAs/碱度、容积产气率、膜通量和出水有机污染物组分等指标,考察了COD在水解酸化、产甲烷和膜截留过程中的转移转化特征。结果表明:通过耦合膜擦洗曝气和沼气曝气循环,将VFAs/碱度和容积产气率分别从1.5和0.1优化到0.02和1.0;优化了COD稳定达标性能和去除负荷,将COD去除率和负荷从59%和0.3 kg·(m3·d)−1分别提高到了97.7%和1.8 kg·(m3·d)−1;采用沼气循环曝气擦洗陶瓷膜,控制了滤饼层积累,并将膜通量从0.6 L·(m2·h)-1提高到2.1 L·(m2·h)−1。IC-AnMBR短流程工艺能够实现村镇厨余垃圾渗滤液的稳定处理。
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关键词:
- 厨余垃圾渗滤液 /
- 内循环厌氧膜生物反应器(IC-AnMBR) /
- COD去除率 /
- 膜通量
Abstract: Efficient handling high strength organic wastewater such as food waste leachate is an important aspect for improving rural environmental sanitation level. An internal circulation anaerobic membrane bioreactor (IC-AnMBR) was constructed to treat the wastewater from rural food waste leachate and meet its organic discharge requirements with low energy consumption. The COD removal performance and regulation mechanism of the reactor were mainly analyzed. According to the indexes of pH, VFAs/ alkalinity, volumetric gas production rate, membrane flux and effluent organic pollutants, the migration and transformation characteristics of COD during hydrolysis and acidification, methane production and membrane separation were also investigated. The results show that by coupling membrane scouring aeration and biogas aeration cycle together, VFAs/ alkalinity and volumetric gas production rates were optimized from 1.5 and 0.1 to 0.02 and 1.0, respectively. The performance of stably meeting the discharging standard for effluent COD and COD removal loading were also optimized, the COD removal rate and loading increased from 59% and 0.3 kg·(m3·d)−1 to 97.7% and 1.8 kg·(m3·d)−1, respectively, achieving the short-cut compliance of IC-AnMBR for the food waste leachate. Adopting biogas circulation to scour the ceramic membrane mitigated the accumulation of the filter cake layer and increased the membrane flux from 0.6 L·(m2·h)−1 to 2.1 L·(m2·h)−1. So IC-AnMBR short process can achieve the stable treatment of rural food waste leachate. -
表 1 废水水质
Table 1. Water quality of wastewater
阶段 运行时间/d pH COD/(mg·L−1) NH3-N/(mg·L−1) HRT/d Ⅰ 1~35 3.56±0.17 24 322±9 845 77.1±36.5 30 Ⅱ 35~108 3.53±0.77 18 998±3 479 47.9±35.8 45 Ⅲ 108~210 3.47±0.57 34 512±5 602 113.26±73.5 20 表 2 出水水质
Table 2. Water quality of effluent
阶段 运行
时间/dHRT/d 容积负荷/
(kg·(m3·d)−1)COD去除
率/%COD/
(mg·L−1)pH TIC/
(mg·L−1)NH3−N/
(mg·L−1)容积产气率/
(L·(L·d)−1)Ⅰ 1~35 30 0.61±0.40 59.1±26.4 7 440±2 121 8.23±0.39 2 555.8±522.0 2 936.5±448.0 — Ⅱ 35~108 45 0.30±0.14 84.1±9.5 3 064±2 168 8.17±0.14 1 456.1±358.6 1 531.0±451.6 0.111±0.100 Ⅲ 108~210 20 1.17±0.51 97.8±0.70 675±283 7.71±0.37 705.1±78.9 885.2±120.8 0.350±0.266 -
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