生物流化床处理垃圾渗滤液的硝化强化实验研究

采用厌氧/好氧/硝化耦合生物流化床反应器处理高浓度难降解垃圾渗滤液,通过摇瓶富集与开放体系扩大培养得到高浓度的硝化菌液,用于硝化生物流化床反应器的挂膜启动、驯化与动态运行实验。结果表明,扩培菌液中亚硝化细菌与硝化细菌的浓度分别达到9 .0×107 和3. 5×107 MPN/mL。硝化生物流化床的强化挂膜启动与驯化约历时30d,实际废水动态运行的结果显示,当进水垃圾渗滤液平均氨氮浓度为284 .4mg/L时,出水氨氮浓度为14. 3mg/L,达到了GB16889 1997一级排放标准,经过硝化生物强化的流化床反应器处理高浓度垃圾渗滤液的硝化速率高达28. 1gNH+4 N/m3·h,与未经生物强化的同类系统相比高出近1倍。     

厌氧折流板反应器处理生活污水的运行特性

以厌氧消化污泥作为厌氧折流板反应器ABR的接种污泥,研究恒温(35℃)条件下ABR处理生活污水的启动和运行特性。实验结果表明,ABR反应器仅用了39 d就完成初次启动,COD去除率一直稳定在60%左右。在以后运行的5个阶段里,即当水力停留时间为4~10 h,容积负荷为1.17~2.9 kg COD/m3.d,反应器对COD的平均去除率基本稳定在70.49%~80.2%;并且当HRT=7 h,VRL=1.612 kg COD/m3.d时,反应器对COD的去除率平均高达80.2%,平均COD出水低于100 mg/L。在实验过程中(除启动阶段外),反应器出水碱度均远远大于进水碱度,VFA均在1.5 mmol/L以下。     

新型循环流化床硝化-反硝化启动试验研究

利用新型循环流化床进行清水实验及硝化、反硝化启动试验研究,考察了系统对有机物和氮的去除效果,并分析了曝气量对系统启动的影响。结果表明,将输送床和传统流化床工艺进行有机结合,技术上可行,可以在系统内不同区建立缺氧、好氧条件,通过硝化和反硝化作用完成脱氮。     

共基质模式下铁盐脱氮反应器的运行性能及微生物学特征

铁盐作为自养反硝化电子供体时,被氧化产生的高价铁易于沉淀,使得反硝化微生物表面产生"铁壳",其抑制微生物的活性,甚至导致微生物死亡.为解决自养铁盐脱氮反应器因"铁壳"包被而导致的反应器效能下降问题,本文采用共基质模式培养铁盐脱氮反应器,即在反应器进水中适量添加少量乙酸钠,作为有机电子供体,以期实现铁盐脱氮反应器的高效、稳定运行.结果表明,添加适量有机物可使得铁盐脱氮反应器高效稳定运行,效能(以N计)达0. 51 kg·(m3·d)-1,稳定运行约30d.共基质模式下,反应器运行期间始终可以检测到异养菌.结合污泥的TEM检测结果,发现在铁盐脱氮反应器稳定运行期间,异养菌是铁盐脱氮主力军,其独特的铁盐代谢方式可有效避免铁壳形成.本项研究有效解决了铁盐脱氮过程中微生物"铁壳"包被难题,将助力于自养脱氮技术的研发及应用.     

常温下加装脱硫装置的MCAnMBR处理高硫酸盐有机废水试验

研究了加装脱硫装置的沼气循环厌氧膜生物反应器对含高硫酸盐有机废水的处理效能.在26~34℃的室温下,历时63d成功地启动了加装脱硫装置的MCAnMBR反应器.调试初期,通过调节气路平衡和采用甲醇驯化的方法有效解决了MCAnMBR反应器在处理高硫酸盐有机废水时存在的跑泥和pH上升问题.结果表明,当控制HRT为120 h,有机负荷(以COD计)为3.61~4.36 kg·(m~3·d)~(-1),pH为7.18~7.61时,在23.3~25.4℃的室温下,对含SO_4~(2-)浓度为650~5 800 mg·L~(-1)的有机废水处理效果极佳,出水COD浓度最低可至23 mg·L~(-1),COD总去除率稳定在96.23%~99.77%,SO_4~(2-)还原率可达83.83%~95.51%.说明加装脱硫装置可有效解决硫化物的次级抑制作用问题,且通过梯度试验发现本反应器处理高硫酸盐有机废水的上限为:COD浓度18 000~21 000mg·L~(-1)、SO_4~(2-)浓度9082~9600 mg·L~(-1),COD/SO_4~(2-)为2.     

Nitrous oxide emissions from black soils with different pH

N₂O fluxes as a function of incubation time from soil with different available N contents and pH were determined. Cumulative carbon dioxide (CO₂) emissions were measured to indicate soil respiration. A 144-hr incubation experiment was conducted in a slightly acidic agricultural soil (pH_H2O 5.33) after the pH was adjusted to four different values (3.65, 5.00, 6.90 and 8.55). The experiments consisted of a control without added N, and with NH₄⁺-N and NO₃^--N fertilization. The results showed that soil pH contributed significantly to N₂O flux from the soils. There were higher N₂O emissions in the period 0-12 hr in the four pH treatments, especially those enhanced with N-fertilization. The cumulative N₂O-N emission reached a maximum at pH 8.55 and was stimulated by NO₃^--N fertilization (70.4 μg/kg). The minimum emissions appeared at pH 3.65 and were not stimulated by NO₃^--N or NH₄⁺-N fertilization. Soil respiration increased significantly due to N-fertilization. Soil respiration increased positively with soil pH (R² = 0.98, P < 0.01). The lowest CO₂-C emission (30.2 mg/kg) was presented in pH 3.65 soils without N-fertilization. The highest CO₂-C emissions appeared in the pH 8.55 soils for NH₄⁺-N fertilization (199 mg/kg). These findings suggested that N₂O emissions and soil respiration were significantly influenced by low pH, which strongly inhibits soil microbial nitrification and denitrification activities. The content of NO₃^--N in soil significantly and positively affected the N₂O emissions through denitrification.     

接种比例对酒糟与餐厨垃圾混合厌氧发酵产沼气的影响

采用酒糟与餐厨垃圾作为混合发酵物料,并接种消化污泥进行厌氧干式发酵,比较接种比例(inoculum to substrate ratios,ISRs)(VS质量比)分别为0.5、0.8、1.0、2.0时的甲烷产率和产量、体系VFA、碱度、游离氨等指标。结果表明:接种比例的提高可有效提高甲烷产生速率,缩短发酵周期,减弱较高浓度VFA引起的抑制作用。当ISRs=1.0时产甲烷效果较好,累计产甲烷率为222.58mL/g,VS去除率达83.4%,继续增加接种比例对发酵效果影响不显著。此外,试验中适宜的VFA/碱度值为0.3～1.2,过大或过小都有可能抑制产甲烷过程。     

Absolute dominance of hydrogenotrophic methanogens in full-scale anaerobic sewage sludge digesters

Anaerobic digestion （AD） is gaining increasing attention due to the ability to covert organic pollutants into energy-rich biogas and, accordingly, growing interest is paid to the microbial ecology of AD systems. Despite extensive efforts, AD microbial ecology is still limitedly understood, especially due to the lack of quantitative information on the structures and dynamics of AD microbial communities. Such knowledge gap is particularly pronounced in sewage sludge AD processes although treating sewage sludge is among the major practical applications of AD. Therefore, we examined the microbial communities in three full-scale sewage sludge digesters using qualitative and quantitative molecular techniques in combination： denaturing gradient gel electrophoresis （DGGE） and real-time polymerase chain reaction （PCR）. Eight out of eleven bacterial sequences retrieved from the DGGE analysis were not affiliated to any known species while all eleven archaeal sequences were assigned to known methanogen species. Quantitative real-time PCR analysis revealed that, based on the 16S rRNA gene abundance, the hydrogenotrophic order Methanomicrobiales is the most dominant methanogen group （〉 94% of the total methanogen population） in all digesters. This corresponds well to the prevailing occurrence of the DGGE bands related to Methanolinea and Methanospirillum, both belonging to the order Methanomicrobiales, in all sludge samples. It is therefore suggested that hydrogenotrophic methanogens, especially Methanomicrobiales strains, are likely the major players responsible for biogas production in the digesters studied. Our observation is contrary to the conventional understanding that aceticlastic methanogens generally dominate methanogen communities in stable AD environments, suggesting the need for further studies on the dominance relationship in various AD systems.     

锯末+乙醇作为混合碳源去除地下水中硝酸盐的影响因素研究

本试验采用室内试验装置,研究了 pH、温度、硝酸盐浓度对锯末+乙醇作为混合碳源去除地下水中硝酸盐的影响结果表明,pH值在5～10内变化时对锯末+乙醇混合碳源体系的硝酸盐去除率影响较大,pH ＞7时的硝酸盐去除率明显高于pH ＜7时的去除率;并且随着pH值的增加,亚硝酸盐的积累量越多,锯末+乙醇混合碳源体系最佳的pH值范围是7～8.锯末+乙醇混合碳源体系受温度的影响较大,温度为8.5、15℃时的反硝化速率显著低于25℃时的速率,25℃时的反硝化速率分别是8.5、15℃时的3倍和1.5倍,锯末+乙醇混合碳源体系适宜的温度范围为25 ～35℃进水硝酸盐浓度也会影响锯末+乙醇混合碳源体系的反硝化效果,硝酸盐氮浓度在67.8 ～113 mg·L-1范围内变化时,反应体系的硝酸盐去除效果较好反应初期,硝酸盐浓度越大混合碳源体系的反硝化速率就越低,可能较大的硝酸盐负荷对反硝化细菌产生毒害作用而不利于硝酸盐的去除.     

Response of anaerobes to methyl fluoride, 2-bromoethanesulfonate and hydrogen during acetate degradation

To use the selective inhibition method for quantitative analysis of acetate metabolism in methanogenic systems,the responses of microbial communities and metabolic activities,which were involved in anaerobic degradation of acetate,to the addition of methyl fluoride(CH3F),2-bromoethanesulfonate(BES)and hydrogen were investigated in a thermophilic batch experiment.Both the methanogenic inhibitors,i.e.,CH3F and BES,showed their effectiveness on inhibiting CH4 production,whereas acetate metabolism other than acetoclastic methanogenesis was stimulated by BES,as reflected by the fluctuated acetate concentration.Syntrophic acetate oxidation was thermodynamically blocked by hydrogen(H2),while H2-utilizing reactions as hydrogenotrophic methanogenesis and homoacetogenesis were correspondingly promoted.Results of PCR-DGGE fingerprinting showed that,CH3F did not influence the microbial populations significantly.However,the BES and hydrogen notably altered the bacterial community structures and increased the diversity.BES gradually changed the methanogenic community structure by affecting the existence of different populations to different levels,whilst H2 greatly changed the abundance of different methanogenic populations,and induced growth of new species.