Evaluation of operational parameters in thermophilic acid fermentation of kitchen waste

In this study, the effect of operational parameters, such as solids retention time (SRT), pH, and substrate total solids (TS) concentration, on acid fermentation efficiency was investigated. From batch tests, it was shown that the appropriate pH range for thermophilic acidogens was around 6–7 and that the optimum pH condition was 6. From the continuous experiment, pH and SRT were shown to be the most important operational parameters for solubilization and organic acid production. In contrast, TS concentration did not show any obvious effect on chromium chemical oxygen demand (CODcr) solubilization when TS was in the range 3.5%–10%. The optimum operational conditions for thermophilic acid fermentation were an SRT of 2 days and a pH of 6. This research was carried as a part of the CREST project of Japan Science and Technology Agency.     

气相色谱-质谱联用法测定水中卤代乙酸类化合物

采用气相色谱-质谱联用法测定水中9种卤代乙酸类化合物,通过优化试验条件,使方法在5.00μg/L~200μg/L范围内线性良好。当取样量为40 m L时,方法检出限在0.7μg/L~1.0μg/L之间,3种实际水样的加标回收率为81.2%~98.0%,6次平行测定结果的RSD≤12%。     

碱性条件促进太湖蓝藻厌氧发酵产挥发性脂肪酸

采用批式研究实验,考察了酸性(pH 5)、中性(pH 7)和碱性(pH 9)条件下,太湖蓝藻厌氧发酵产挥发性脂肪酸(volatile fatty acids,VFAs)过程中的产酸指标,酸分布及蓝藻有机成分降解的效果。结果表明,pH为9时VFAs产率最高,为0.274 g VFAs/g VS,VS降解率达到51.91%。蓝藻有机成分中蛋白质、碳水化合物、脂类降解率也在pH为9时达到最高,分别为53.2%、30%和40.6%。实验对蓝藻产酸效果与其他固废产酸效果进行了比较,比较结果说明,太湖蓝藻作为厌氧发酵原料生产挥发性脂肪酸具有可行性。     

高效木质纤维素分解复合菌系降解稻草特性的研究

以1%稻草为惟一碳源,利用间歇实验,在50℃的静置培养条件下,对特异驯化获得的一组高效木质纤维素复合菌系的生长及降解特性进行了深入的探讨。实验结果表明,复合菌系的优势菌是杆菌,其生长曲线显示典型的3阶段,即0~108 h的对数生长期、108~144 h的稳定期、144~216 h的衰亡期。当发酵结束时,稻草的降解效率达到75%,90%以上的产物是乙酸,其次是少量的乙醇、丁酸和丙酸,这种发酵类型为下游两相厌氧消化的产甲烷相的稳定、高效运行提供重要物质基础。     

Isolates identification and characteristics of microorganisms in biotrickling filter and biofilter system treating H2S and NH3

A combination system of biotrickling filter （BTF） and biofilter （BF）, adopting surfactant-modified clinoptilolite and surfactant- modified wood chip as the media respectively, was applied to treat H2S and NH3 simultaneously. The identification and sole carbon sources utilization patterns of isolates in the combination system were studied by Biolog system. The isolates were identified as Bacillus sphaericus, Geobacillus themoglucosidasius （55℃） and Micrococcus luteus （ATCC 9341） in BTF, and Aspergillus sydowii （Bainier ＆ Sartory） Thom＆ Church in BE Among 95 substrate classes supplied by Biolog system, the carboxylic acids and methyl esters had the highest utilization extent for the four species, followed by the amino acids and peptides. The descending sequence of carbon sources utilization capability of isolates was A. sydowii （52.6%）, M. luteus （39.5%）, B. sphaericus （21.6%）, and G. thermoglucosidasius （17.7%）.     

回灌渗滤液VFA浓度对填埋层甲烷化代谢的影响

处于稳定产甲烷阶段的填埋层具有降解回灌渗滤液有机物的能力,但高浓度渗滤液的主要组分(挥发性脂肪酸(VFA))可能影响填埋层的甲烷化代谢,导致填埋层对回灌渗滤液有机物降解效率恶化.采用实验室模拟填埋柱回灌不同ρ(VFA)模拟渗滤液的方法,研究不同VFA负荷对稳定产甲烷阶段填埋层甲烷化代谢的影响.结果表明:稳定产甲烷填埋层具有处理高ρ(VFA-C)渗滤液的能力,其有机碳的转化能力小于1.0 g/(kg·d);当回灌渗滤液中的ρ(VFA-C)大于14.8g/L(有机负荷为2.2 g/(kg·d))时可抑制填埋层的甲烷化代谢,但这种抑制可随着回灌渗滤液中ρ(VFA-C)的降低而得到解除;为保证填埋层内垃圾的降解,应控制回灌渗滤液的有机负荷不超过1.0g/(k·d).      

Characterization of haloacetic acid precursors in source water

Raw water from the Bangkok (Thailand) main municipal water supply canal was examined for its natural organic composition by fractionation with adsorption resins. DAX-8 resin was the first resin employed to fractionate the hydrophobic fractions. Fractionation at neutral pH resulted in the separation of the hydrophobic neutral components; at a high pH level (approx. 10) separation of the hydrophobic base components occurred; and at a low pH level (approx. 2) the hydrophobic acid components were separated. AG-MP-50 cationic resin was then used to separate the hydrophilic base components, and WA-10, a weak anionic resin, was applied finally to fractionate the hydrophilic acid and neutral components. Subsequently, each fraction was tested for its chlorine disinfection by-product (DBP) formation potential. The HAA formation tests demonstrated that the various organic fractions had different reactivity levels for the formation of haloacetic acids (HAAs). For this source water, the hydrophilic neutral fraction dominated over the other five fractions in being the main organic component and the most significant precursor of HAAs formation. On the other hand, in terms of specific HAA formation potential (FP), the hydrophobic and hydrophilic base fractions were the most reactive precursors to the formation of HAAs. In all cases, the quantity of HAAs formed depended linearly upon the amount of organic constituents in the water sample.     

固定化酶酸化/UASB两相厌氧有机酸代谢特征

以固定化酶酸化相和UASB产甲烷相为两相厌氧系统进行连续流实验,研究了酸化相和产甲烷相中的有机酸和乙醇的变化特征、变化速率,挥发性有机酸组成,发酵类型以及对COD去除率的影响.结果表明:酸化相的酸化率为28.2%,水解产物组成中乙醇>乙酸>丁酸>丙酸,其中乙醇占44.8%,乙酸占38.4%,丙酸为6.9%,丁酸为9.8%,为乙醇型发酵类型.在产甲烷相中乙醇被去除99.8%,乙酸为92.0%,丙酸为59.1%,丁酸为46.2%,呈乙醇>乙酸>丙酸>丁酸;比较有机酸和乙醇的去除速率呈乙醇>乙酸>丁酸>丙酸,其中乙醇在产甲烷相中去除速率最快为0.21h^-1.系统运行稳定,COD去除率达到90%以上,其中对COD去除贡献率顺序为乙醇>乙酸>丁酸>丙酸,     

Partial least square modeling of hydrolysis: analyzing the impacts of pH and acetate

Introduction Environm ental and econom ic advantages highlight anaerobic digestion as a sustainable technology for solid w aste treatm ent (Edelm ann etal., 2000). A naerobic digestion could be described as four sequential steps: hydrolysis, acidogenesis, aceto- genesis and m ethanogenesis, am ong w hich the hydrolysis is recognized as the rate-lim iting step for particulate organic w aste (Jain et al., 1992; M ata-A lvarez, 2000). H ydrolysis occurs com m only together w ith the acidogenesi…     

新农药环境化学行为研究──除草剂绿草定（Triclopyr）在土壤－水环境中的吸附和光解

研究土壤、腐殖酸、粘土矿对绿草定的吸附及溶液中的光降解的结果表明：吸附强弱与土壤理化特性密切相关,Freundlich常数Kf与（3·OM%＋Clay％）pH3有较好的相关性（r＝0.997）;腐殖酸较粘土矿的吸附容量大;绿草定在土壤中的吸附可能有离子键、氢键、配位键及偶极－偶极作用等。太阳光中小于330nm波长的光对降解有效,波长254nm的光对绿草定的降解作用是波长300nm光的3.5倍。