湿热水解处理餐厨垃圾氮素转化规律

为了研究餐厨垃圾湿热水解过程中氮素的变化规律，设计了10、30、60、90和120℃5个温度水平以及30、60、90、120、150和180min6个加热时间水平，进行了30组完全实验，对不同湿热条件下餐厨垃圾粗蛋白、TN、NH4＋-N、NO3-N、有机氮及氨基酸等氮的不同存在形式的变化规律进行实验研究。结果表明，10、30及60℃条件下蛋白质的高级结构不会改变，利于粗蛋白的积累，且在温度120℃，加热时间90min条件下粗蛋白百分含量最高，占干物质的31．34％；随温度的升高和加热时间的延长TN、NHf-N和有机氮含量均上升；当温度达到120℃，由于水解反应，各温度处理下NHf．N浓度超过有机氮浓度，而NO3-N始终维持较低水平。氨基酸总量随温度的升高和水解时间的延长呈上升趋势，当温度达90％，加热时间达180min时，处理后餐厨垃圾总氨基酸百分含量最高，达164％，但温度达到120℃时，随着处理时间的延长，餐厨垃圾总氨基酸含量明显降低。     

湿热水解预处理对餐厨废弃物液相厌氧发酵产氢潜力的影响

为研究湿热水解预处理方法对餐厨废弃物液相厌氧发酵效果的影响,选取不同温度(80、120、150和200℃)、处理时间(40、50、60和70 min)和加水比例(40%、60%、80%和100%)条件下对餐厨废弃物进行预处理,并在中温(37±1)℃条件下对液相进行厌氧发酵潜力实验。结果表明:湿热水解预处理可有效提高餐厨废弃物液相的生物可利用性,进而提高厌氧发酵的产气效率,其中加水比例40%,150℃处理60 min条件下可浮油脱出量最高为67.7 m L/kg,与原样相比提高了2.65倍;氢气含量最高为62%,最高产氢速率为15.57 m L/h,累积产氢最高达194.28 m L/g VS,与原样相比分别提高了3.6、5.4和20倍,说明湿热水解预处理可有效提高餐厨废弃物液相的产氢潜力。     

城市污水厂污泥的浸泡油炸

提出了一种利用餐厨废油为热交换介质，在常压下对城市污水厂污泥进行油炸干化制成固体燃料，以实现城镇两大废弃物一污泥和餐厨废油综合处置的方法。以大豆油模拟餐厨废油，研究了污泥油炸干燥特性及过程影响参数。实验结果表明，污泥经油炸干化后，干基含水率从初始的4．56kg／kg降低至0．05kg／kg，干基含油率升为0．37～0．47kg／kg，干污泥热值达到21．551～24．082MJ／kg，是一种高热值固体燃料。油温对污泥油炸干化过程影响显著，当油温从120℃升至180℃时，污泥干燥时间从28min缩短至4min。实验条件下，1t餐厨废油可处理约8．3t湿污泥。     

预处理沼液与餐厨废弃物的厌氧产气发酵特性

为了实现对餐厨废弃物能源化的梯度利用,将沼液进行水浴加热、超声波和曝气等预处理后与餐厨废弃物混合,在中温(35±1)℃条件下进行产氢和产甲烷梯度厌氧发酵实验。考察了不同预处理沼液对产氢率、产氢相缓冲能力、产氢过程可溶性代谢产物成分以及其进行产甲烷发酵的潜力。结果表明,未经处理的沼液与餐厨废弃物混合发酵的产氢率很低,并且相分离不彻底有甲烷产生;各预处理组的产氢率均明显高于未处理组,并很少或几乎没有甲烷产生,其中超声波处理组产氢率最高为52.3 m L·g~(-1)VS。水浴加热和超声波处理组的产氢流出液经产甲烷发酵,可以获得与餐厨废弃物直接进行产甲烷发酵相当的甲烷产率。这表明,将餐厨废弃物进行产氢和产甲烷梯度厌氧发酵可获得更高的能源化效率。     

茅草添加与温度变化对餐厨垃圾厌氧水解产酸的影响

比较了茅草添加在温度变化条件下对餐厨垃圾厌氧水解过程小分子有机酸产量的影响，提出一种新型餐厨垃圾的资源化方式。研究结果显示，餐厨垃圾在55℃条件下厌氧水解主要产物为乳酸，达到25．7g／L，其干物质转化率可以达到32．1％（gTS），而餐厨＋茅草处理在同样条件下的乳酸产量为20．1g／L，干物质转化率为25．1％。温度下降为37℃后继续进行的的厌氧水解，得到的主要产物是乙酸、丙酸和丁酸，餐厨处理和餐厨＋茅草处理这两者的峰值分别为6．5、2．8、8．0和6．1g／L、2．7g／L和5．9g／L。结果显示茅草添加可以在一定程度上调节水解产物的比例，而温度变化可以调控小分子有机酸的产量。本研究结果表明，厌氧水解是一种有潜力的小分子有机酸生产与餐厨垃圾资源化处理途径。     

湿热预处理对北京市典型餐厨垃圾生物制氢潜力的影响

采用北京市2种典型餐厨垃圾,研究不同湿热预处理温度(40、80、120和160℃)和时间(30、60、90和120 min)对2种典型餐厨垃圾理化性能的影响。在此基础上,阐明餐厨垃圾厌氧产氢潜力。结果表明,湿热预处理温度、时间对餐厨垃圾可浮油脱出量具有显著影响,ρ(SCOD)、ρ(TOC)与VS/TS呈负相关。餐厨垃圾处理厂的厨余垃圾经120℃湿热预处理30 min后,可浮油脱出量最大达17 m L·kg-1,ρ(SCOD)、ρ(TOC)分别为150.99、57.91 g·L-1;食堂的餐饮垃圾经160℃湿热预处理30 min后效果最佳,可浮油脱出量最高达99 m L·kg-1,ρ(SCOD)、ρ(TOC)分别为120.69、62.58 g·L-1。餐饮垃圾经160℃湿热预处理30 min,在中温(35±1℃)、高温(55±1℃)厌氧制氢,高温比产氢率和最大产氢速率分别可达40.58 m L·g-1VS、29.20 m L·h-1,与未经预处理组比提高0.78、2.02倍,中温产氢启动时间缩短1倍以上。可见,湿热预处理能显著改善餐厨垃圾理化性质,提高微生物的底物利用效率,提高餐厨垃圾厌氧制氢量及产氢效率。     

响应面法优化黄粉虫幼虫处理餐厨垃圾饲养条件的研究

研究了黄粉虫幼虫处理餐厨垃圾的方法.首先在饲养温度、饲料含水量和饲养密度等条件下进行单因素实验,然后,以利用率为指标,运用响应面法优化了黄粉虫幼虫处理餐厨垃圾的饲养条件,结果表明,最佳饲养条件为饲养温度26.7℃、饲料含水量14.5％、饲养密度4.1头/cm2.在此饲养条件下,黄粉虫对餐厨垃圾利用率理论值为38.72％,实际餐厨垃圾利用率为38.88％,相对误差为0.41％,说明利用黄粉虫幼虫处理餐厨垃圾具有较好的效果.     

餐厨垃圾和绿化废弃物换向通风好氧堆肥

以某高校餐厨垃圾和绿化废弃物为原料,利用一种换向通风的堆肥降解装置对其进行好氧堆肥处理,研究了2个进气温度(35℃、45℃)和3个通风速率(1.5、2.5和4 m3/h)6个处理组对堆肥原料理化性质(堆体温度、含水率、pH值、有机质含量、C/N、种子发芽指数)的影响。餐厨垃圾和绿化废弃物进行15 d好氧堆肥后,pH值上升到7左右,有机质含量达到20%~80%,C/N都降到20以下,种子发芽指数均大于50%。经过1个月腐熟,其含水率≤30%。上述指标符合有机肥料标准(NY525-2011)的要求,该堆肥产物可用于园林绿地,具有显著的经济效益和生态效益。本研究结果表明,将城市餐厨垃圾和绿化废弃物混合后进行好氧堆肥是废弃物处理的高效工程,具有良好的发展前景。     

含油量对餐厨垃圾厌氧发酵的影响

在35℃条件下，研究了不同含油量（0％、1％、2％、3％、4％、5％）餐厨垃圾中温厌氧消化过程中日产气量、甲烷含量、总固体（TS）、挥发性固体（VS）、干物质产气率等的变化，为后续餐厨垃圾连续发酵的预处理提供参考。结果表明：5％含油量餐厨厌氧发酵周期最长，累计产气量最大，为5800mL。在消化过程中，沼气中甲烷含量先上升后下降，最高可达76％；于物质产气率随含油量增大而增大，依次为497．4、506．1、543．8、554．4、590．7和600．1mL／gTS；5％含油餐厨垃圾的TS和VS去除率最大，分别为34．4％和42．9％。     

接种比例和温度对餐厨废弃物厌氧发酵特性的影响

为提高餐厨废弃物厌氧发酵的甲烷转化率和挥发性固体降解率,分别在35℃和55℃条件下,采用批式发酵工艺,考察了接种物与底物的挥发性固体量之比对餐厨废弃物厌氧发酵挥发性固体甲烷产率、挥发性固体降解率、液相末端产物组成和pH值等发酵特性的影响。结果表明,温度和接种比例共同决定厌氧发酵停留阶段,在35℃发酵时接种比例大于50∶50的处理和55℃发酵时接种比例大于30∶70的处理以产甲烷发酵为主,其余以酸化发酵为主;游离氨抑制导致高温组的甲烷含量、挥发性固体甲烷产率和甲烷转化率均低于中温组;发生酸化处理组底物的挥发性固体降解率均低于40%,产甲烷发酵处理组挥发性固体降解率均高于80%。     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

Knowledge transfer initiative between molecular biologists and environmental researchers and regulators

A Natural Environment Research Council (NERC) funded Knowledge Transfer (KT) workshop was held in the United Kingdom (UK) to identify the needs and opportunities in the application of molecular biology and ‘omics’ techniques to environmental monitoring and risk assessment. Attendees highlighted a lack of effective communication between end-users and researchers as well as difficulties with data interpretation as reasons behind the slow uptake of molecular biology and omics techniques. A number of promising areas in which new techniques could be implemented at a practical level in the very near future were identified, thereby raising the profile of these recent technologies and providing vital proof of concept work. Molecular taxonomy, bacterial source tracking and pre-screening of chemicals for potential toxicities were all viewed as areas in which omics and molecular techniques could have immediate value, with the aim of reducing cost, increasing efficiency and providing more comprehensive data of improved quality.