热处理时间对餐厨垃圾高温干式厌氧发酵的影响

餐厨垃圾中有机物大部分以大分子的形式存在,对其进行热处理,破坏大分子有机物的存在形式,将会影响其干式厌氧发酵的过程。实验对餐厨垃圾进行了热处理(100℃),处理后将其在含固率(TS)20%、接种率25%的条件下进行高温55℃厌氧发酵。实验结果表明,热处理后,餐厨垃圾的理化性质发生显著变化,累计产气量、TS和VS的去除率均增大。当热处理时间为15 min时,餐厨垃圾的SCOD值最高,为59.49 g/L,比未处理时提高了3.3倍。同样该条件下,累计产气量也最高,为2 782.8 mL,与未处理相比累积产气量提高58.30%,第二产气高峰比未处理提前3天。各发酵瓶发酵前后TS、VS去除率的变化趋势与累计产气量的变化基本一致,累计产气量越大,TS、VS的去除率越大。     

腐植酸强化苯酚厌氧发酵降解

在无外加电子受体的条件下,首次研究了腐植酸对活性污泥厌氧降解苯酚的影响。研究结果表明,腐植酸Suwannee River Humic Acid Standard(SR-HA)、Leonardite Humic Acid Standard(L-HA)和Pahokee Peat Humic Acid(PP-HA)作为氧化还原介体能够提高苯酚的厌氧发酵降解效率。其中腐植酸PP-HA对苯酚的厌氧降解表现出了最为明显的强化效果,反应进行36 h后,苯酚去除率提高了18.5%。当单独投加的PP-HA浓度在0至100 mg/L范围内,苯酚的厌氧降解效率随着腐植酸浓度增加而逐渐提高,而浓度大于100 mg/L后,腐植酸对苯酚降解效率的促进作用随着PP-HA浓度的增加逐渐减缓。除此之外,当低浓度的蒽醌-2-磺酸钠(AQS)(0.02 mM)和PP-HA(20 mg/L)在反应体系中共存时,相比于无介体存在的对照组,苯酚厌氧降解效率提高了约1.4倍。产物分析结果表明,乙酸和CH4作为苯酚发酵降解的重要产物被检测出来。最后,在氧化还原介体腐植酸的存在下,初步探讨了苯酚厌氧发酵降解的代谢途径。     

城市生活垃圾和污水处理厂剩余污泥混合发酵的原料配比优化研究

以城市生活垃圾和污水处理厂的剩余污泥为混合原料,研究了混合原料的不同配比对厌氧发酵过程及产气的影响。结果表明:城市生活垃圾与剩余污泥以挥发性固体(VS)质量比为2∶1混合后,厌氧发酵效果最好,累计产气量最高,达到8 721mL,发酵后的总固体(TS)、VS、COD去除率分别达43.65%、35.98%、47.88%;各实验组在发酵过程中的pH、氨氮浓度和碱度均在合理范围内,未对厌氧发酵反应造成影响;以适当配比的城市生活垃圾和剩余污泥为混合原料,进行中温联合厌氧发酵是可行的,联合厌氧发酵可以弥补单一原料的缺陷,在一定程度上改善厌氧发酵效果。     

利用三七渣固态发酵灵芝菌的研究

以川芝6号为发酵菌种,对三七渣固态发酵灵芝菌的培养基制备条件进行了研究和优化。结果表明,优化的培养基制备条件为采用过60目筛的三七渣,酵母粉添加量5%(质量分数,下同),磷酸二氢钾添加量0.025%,培养基含水量70%,不调节初始pH。在此条件下进行灵芝发酵,发酵培养物中灵芝菌丝体的质量分数最高可达31.27%。     

Factors affecting the quantitative uncertainty of the estimated short-term intake. Part I—Calculation methods

ABSTRACT

The calculation of the combined uncertainty of the international estimated short-term intake (IESTI) of ethephon residues in apples is shown as an example. The ethephon residues in apples were reported by the Joint FAO (Food and Agriculture Organization of the United Nations)/WHO (World Health Organization) Meeting on Pesticide Residues (JMPR). The apple consumption data were taken from the IESTI (international short-term intake) calculation template used by the JMPR. The IESTI was calculated with the currently used method (case 2a) and a proposed one recommended by the EFSA (European Food Safety Authority)/RIVM (Dutch National Institute for Public Health) Scientific Workshop co-sponsored by FAO and WHO. In this example, the ratio of IESTI_proposed/IESTI_current and their combined relative uncertainty are about 2.8, and 1.7, respectively. The larger IESTI and uncertainty obtained with the proposed equation are the consequence of calculation only with the large portion (LP) instead of its combination with unit mass, and the MRL instead of the highest residue (HR). The LP is the major contributor to the combined uncertainty. Both the calculated IESTI and its combined uncertainty depend on the actual food – pesticide residue combination, and should be calculated for each case.     

甲烷氧化菌在填埋场覆盖层中的工程应用(Ⅱ):基质选择性及长效性

针对已筛选获得的甲烷氧化混合菌,选取填埋场覆盖土(LCS)、矿化垃圾(AR)和塘渣(TZ)3种填埋场周边易得的材料为供试生存基质,从基质选择性及长效性角度进行了甲烷减排应用条件的探究及使用效能评估.结果表明,在TZ、LCS、AR、TZ-AR和LCS-AR这5种生存基质中,TZ-AR最适合甲烷氧化混合菌的生长,且TZ与AR的复配比例以5∶5为最佳.甲烷氧化混合菌在TZ-AR的粒径≤4 mm和含水率为20%时具有最高甲烷氧化能力.一次性接种甲烷氧化混合菌在静态体系中的最佳使用有效期为31 d.其在接种量为0.08、0.16、0.20 m L·g-1和0.25m L·g-1时甲烷氧化速率无明显差异,从工程应用角度而言,8%的接种量为最佳.     

Influence of agricultural activities, forest fires and agro-industries on air quality in Thailand

Annual and monthly-based emission inventories in northern, central and north-eastern provinces in Thailand, where agriculture and related agro-industries are very intensive, were estimated to evaluate the contribution of agricultural activity, including crop residue burning, forest fires and related agro-industries on air quality monitored in corresponding provinces. The monthly-based emission inventories of air pollutants, or, particulate matter (PM), NOx and SO₂, for various agricultural crops were estimated based on information on the level of production of typical crops: rice, corn, sugarcane, cassava, soybeans and potatoes using emission factors and other parameters related to country-specific values taking into account crop type and the local residue burning period. The estimated monthly emission inventory was compared with air monitoring data obtained at monitoring stations operated by the Pollution Control Department, Thailand (PCD) for validating the estimated emission inventory. The agro-industry that has the greatest impact on the regions being evaluated, is the sugar processing industry, which uses sugarcane as a raw material and its residue as fuel for the boiler. The backward trajectory analysis of the air mass arriving at the PCD station was calculated to confirm this influence. For the provinces being evaluated which are located in the upper northern, lower northern and northeast in Thailand, agricultural activities and forest fires were shown to be closely correlated to the ambient PM concentration while their contribution to the production of gaseous pollutants is much less.     

仲钨酸铵生产中钨渣的污染特性分析

采集了14家仲钨酸铵（APT）生产企业生产过程中产生的钨渣,分别采用HJ/T299—2007《固体废物 浸出毒性浸出方法 硫酸硝酸法》和GB 5085.3—2007《危险废物鉴别标准 浸出毒性鉴别》附录S推荐的方法分析了钨渣中重金属的浓度及浸出浓度,并研究了钨渣的污染特征。结果表明,钨渣中重金属浓度服从正态分布,浓度较高的重金属为Cu、Zn和类金属As,其最大值分别为6 260、25 000和26 900 mg/kg,平均值分别为3 510、4 560和5 640 mg/kg;浸出浓度较大的是Pb、As和Hg,其最大值分别为33.6、26.2和0.85 mg/L,超出GB 5085.3—2007中规定的相应限值的6.72、5.24和8.5倍,超标率分别为14.3%、21.4%和42.9%;钨渣中As、Mo和Hg是特征污染物,应作为危险废物进行管理。     

pH和发酵时间对厨余垃圾发酵产乳酸及光学特性的影响

通过间歇实验探讨了在中温、非灭菌条件下,pH和发酵时间对厨余垃圾发酵产乳酸及其光学特性的影响.结果表明,采用非灭菌的厨余垃圾发酵产乳酸,发酵液中还原糖浓度低,pH调节到近中性和偏碱性（pH为6～8）的各组还原糖浓度高于偏酸性组（pH=5和pH=4的对照组）;在控制pH为7时,总乳酸产生速率达到0.59 g·(L·h)^-1,单位挥发性固体的乳酸产量达到0.62 g·g^-1;控制pH为7和8时,以有机碳表示的乳酸分别占发酵液总有机碳的78%和89%;控制pH为8时,L-乳酸是主要的异构体形式,单位挥发性固体L-乳酸产量达到0.48 g·g^-1;响应面分析结果表明,发酵时间在120 h前,随着pH升高和发酵时间的延长,发酵液中L-乳酸浓度增大,120 h后则下降;pH和发酵时间对L-乳酸占总乳酸的比例有明显影响：偏酸性条件(未调pH及pH=5),发酵前120 h,该比例随发酵时间逐渐增大,L-乳酸在总乳酸中的比例达到0.9,其后,则逐渐下降;偏碱性条件下(pH=8),L-乳酸在总乳酸中的比例在整个发酵时间段内都保持在0.86以上,在发酵时间48 h时达到0.93,而在pH中性条件下,该比例在发酵后期显著下降;控制pH为8时,可以同时获得高的乳酸产量和光学纯度.     

Residual dynamics of thiacloprid in medical herbs marjoram, thyme, and camomile and in soil

Thiacloprid is a new insecticide of the chloronicotinyl family. To assess its risk after application, residual characteristics of thiacloprid in marjoram, thyme, and camomile and in soil were studied under field conditions. The active ingredient was extracted from the plant material using a mixture of acetone-water. After filtration, the extract was concentrated to the aqueous phase, diluted with water, and portioned against ethyl acetate on a matrix solid phase dispersion column. Thiacloprid was extracted from soil using a mixture of methanol-water, filtered, and re.extracted （clean up） with dichloromethane. The residues were quantified using HPLC-MS-MS. The methods were validated by recovery experiments. Thiacloprid residues in marjoram, thyme, and camomile and in soil persisted beyond 10, 14, 14, and 21 d but no residues were detected after 14, 21, 21, and 28 d, respectively. The data obtained in this study indicated that the biexponential model is more suitable than the first-order function to describe the decline of thiacloprid in fresh marjoram, fresh thyme, and dried camomile flowers with half-life （t1/2） of 1.1, 0.7, and 1.2 d, respectively. However, both the first-order function and biexponential model were found to be applicable for dissipation of thiacloprid in soil with almost the same t1/2 values of 3.5 and 3.6 d. The results indicated that thiacloprid dissipates rapidly and does not accumulate in the tested herbs and in soil.