Composting of spent pig litter in turned and forced-aerated piles

A study was carried out to compare the compositing efficiency of spent litter (a mixture of partially decomposed pig manure and sawdust) in turned and forced-aerated piles. Duplicate piles were built with manual turning (every 4 days) during composting, and duplicate piles were set up with forced aeration using an air pump. The present study demonstrated that the efficiency of composting in the turned and forced-aerated piles was similar. Spent litter in these piles reached maturity at the same time (60 days). The forced-aerated piles went through similar physical, chemical, and microbial changes with the turned piles during composting. The forced-aerated composting system was also as effective as the turned system in eliminating Salmonella sp. in the spent litter. These results suggest that a forced-aerated composting system could be used as an alternative method in composting spent litter. The similarities in temporal changes in temperature, chemical, and microbiological properties of the forced-aerated piles, compared with the turned piles, indicate that addition of a bulking agent under forced aerated composting of spent litter is not necessary. The partially decomposed sawdust in the spent litter provided enough free air space, allowing the delivery of oxygen for the microorganisms in the spent litter piles.     

Composting of vegetable waste in subtropical climates

This experiment examined the possibility of using composting as a method of waste disposal in subtropical countries, such as the United Arab Emirates (UAE), where temperatures are high and humidity is low. In order to simulate conditions in the UAE, a representative mixture of wastes generated in the UAE was prepared and tested at ambient temperatures resembling those of subtropical countries. The mixture consisted of tomatoes, cabbage, eggplant and grass. The addition of grass (40% of the mixture by weight) adjusted the carbon/nitrogen ratio and the moisture content of the compost to the necessary level for initiating decomposition. To maintain the moisture content of the compost under severe dry hot weather, a saturated insoluble polymer (IP) was added at 20% and 60% concentration (wet weight). The mixture was then composted at three different temperatures. Results showed that the mixture requires about two weeks for stabilisation. High temperature is an advantage to the compost process; at temperatures between 40 and 60°C, the waste mixture (regardless of IP concentration) decomposed quicker than at low temperature (25°C). The addition of 20% saturated IP to the compost increases the moisture content and decomposition rate. It also increases the organic chemical content of the compost, which will be reflected by microbial activity.     

Effects of composting on phytotoxicity of spent pig-manure sawdust litter

The phytotoxicity of spent pig-manure sawdust litter (spent litter) was evaluated during further composting. Aqueous extracts of the spent litter were prepared by shaking the sample with water (1:10 w/v), and the toxicity of these extracts was determined on relative seed germination, relative root elongation and germination index (GI, a factor of relative seed germination and relative root elongation). The sensitivity of six plant species, namely Brassica parachinensis (Chinese cabbage), Brassica albogalera (Chinese kale), Allium sativum (onion), Cucumis sativus (cucumber), Amaranthus espinosus (Chinese spinach), and Lycopersicon esculentum (tomato) were compared. The effect of different moisture levels during composting on the phytotoxicity of the spent litter was also examined. Phytotoxicity of the spent litter was only evident during the earlier stage of composting (first 14 days) and, that seed germination and root elongation reached 100% (same as the control) towards the end of the composting. The concentrations of the major inhibitors, water-extractable Cu and Zn, and NH4(+)-N of the spent litter, declined during composting, indicating that these inhibitors were gradually eliminated as composting proceeded. Multiple regression analysis showed that the NH4(+)-N content of the spent litter was the most important chemical factor affecting phytotoxicity of the plant species selected for this study. Relative root elongation and GI were more sensitive indicators of phytotoxicity than seed germination. In the present study, the GI's of all plant species were >80% at day 60, indicating that the spent litter had reached its maturation by day 60. The responses of different plant species to the water-extracts of the spent litter were different. Among the six species, Chinese cabbage and Chinese spinach were the most sensitive species, and tomato and cucumber were the least sensitive species to indicate phytotoxicity of the spent litter. Moisture adjustment during the composting process did not affect the results of the phytotoxicity test.     

Physicochemical properties of chars at different treatment temperatures

In this study, the physicochemical properties of the char of Indonesian SM coal following heat treatment at various temperatures were evaluated using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and morphological and specific surface area analysis. Based on these analyses, heat treatment of coal was determined to be the most effective in increasing the coal rank. In the XPS analysis, the C-O and C-O-C groups and quaternary-N species were found to be of a lower grade coal when the pretreatment temperature decreased, meanwhile the C-C group and pyridinic species increased. In the FT-IR analysis, the collapse of the C-O and C-O-C group was observed due to the collapse of the ether group. In SEM and Brunauer-Emmett-Teller (BET) analysis, a decrease in the ether group was shown to be accompanied with the formation of micropores.     

Physicochemical properties of chars at different treatment temperatures

In this study, the physicochemical properties of the char of Indonesian SM coal following heat treatment at various temperatures were evaluated using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and morphological and specific surface area analysis. Based on these analyses, heat treatment of coal was determined to be the most effective in increasing the coal rank. In the XPS analysis, the C–O and C–O–C groups and quaternary-N species were found to be of a lower grade coal when the pretreatment temperature decreased, meanwhile the C–C group and pyridinic species increased. In the FT-IR analysis, the collapse of the C–O and C–O–C group was observed due to the collapse of the ether group. In SEM and Brunauer–Emmett–Teller (BET) analysis, a decrease in the ether group was shown to be accompanied with the formation of micropores.

Implications Recently, XPS analyses have been reported as coal surface analysis. Usually, they have reported the analysis of the coals with different rank. This study investigated the coal surface characteristics of the coals pretreated at different temperature using various analyses (BET, SEM, XPS, FT-IR), and this study can be the basis for other research and applications.     

Pyrolysis behavior of tire-derived fuels at different temperatures and heating rates

Pyrolytic product distribution rates and pyrolysis behavior of tire-derived fuels (TDF) were investigated using thermogravimetric analyzer (TGA) techniques. A TGA was designed and built to investigate the behavior and products of pyrolysis of typical TDF specimens. The fundamental knowledge of TGA analysis and principal fuel analysis are applied in this study. Thermogravimetry of the degradation temperature of the TDF confirms the overall decomposition rate of the volatile products during the depolymerization reaction. The principal fuel analysis (proximate and ultimate analysis) of the pyrolytic char products show the correlation of volatilization into the gas and liquid phases and the existence of fixed carbon and other compounds that remain as a solid char. The kinetic parameters were calculated using least square with minimizing sum of error square technique. The results show that the average kinetic parameters of TDF are the activation energy, E = 1322 +/- 244 kJ/mol, a pre-exponential constant of A = 2.06 +/- 3.47 x 10(10) min(-1), and a reaction order n = 1.62 +/- 0.31. The model-predicted rate equations agree with the experimental data. The overall TDF weight conversion represents the carbon weight conversion in the sample.     

不同温度下猪粪厌氧发酵的氨胁迫效应

为了明确不同温度下氨胁迫对猪粪厌氧发酵性能的影响,以猪粪为底物,通过添加外源氯化铵逐步提高氨氮质量浓度,在3种温度下开展了半连续厌氧发酵实验。结果表明,在3种温度下,当总氨氮质量浓度达到4 000 mg·L⁻¹时,VS甲烷产率明显降低。VS甲烷产率半抑制时,44 ℃发酵体系中的总氨氮质量浓度达到6 845 mg·L⁻¹,对应游离氨质量浓度为1 257 mg·L⁻¹;在7 000 mg·L⁻¹左右的总氨氮质量浓度下,44 ℃发酵体系表现出更好的耐受性。氨胁迫导致了35、44 ℃下丙酸、丁酸和戊酸等3种脂肪酸的积累;在55 ℃下,该3种脂肪酸生成和分解的过程和速率与35、44 ℃存在明显差异。Pearson相关性分析结果表明,35、44 ℃下通过氨抑制影响甲烷产率的主要因素为游离氨(NH₃),而55 ℃下的主要因素为总氨氮。该研究结果可为养殖粪污厌氧发酵的工艺优化提供参考。     

不同焚烧温度下开发区污泥焚烧渣分析

在不同焚烧温度条件下采用可控温管式炉焚烧开发区干污泥,对污泥焚烧渣中微观形貌、元素分布、矿物组成以及重金属总量及其形态进行了分析研究。实验结果表明,污泥焚烧渣在焚烧温度为900℃出现明显的结焦现象,在焚烧温度为1 100℃时焚烧渣结焦的微观表面致密。XRD分析发现温度的升高使污泥烧渣中出现NaA lS iO4等性质相当稳定的物质。不同重金属在底渣中的总量分布及其形态特征受焚烧温度的影响程度不同。焚烧温度的提高使污泥中重金属的残渣态比例增高,使污泥焚烧对环境的影响减小。     

Sorption of simazine to corn straw biochars prepared at different pyrolytic temperatures

Simazine sorption to corn straw biochars prepared at various temperatures (100-600 °C) was examined to understand its sorption behavior as influenced by characteristics of biochars. Biochars were characterized via elemental analysis, BET-N₂ surface area (SA), FTIR and ¹³C NMR. Freundlich and dual-mode models described sorption isotherms well. Positive correlation between log K_oc values and aromatic C contents and negative correlation between log K_oc values and (O + N)/C ratios indicate aromatic-rich biochars have high binding affinity to simazine (charge transfer (π-π*) interactions) and hydrophobic binding may overwhelm H-bonding, respectively. Dual-mode model results suggest adsorption contribution to total sorption increases with carbonization degree. Positive correlation between amounts of adsorption (Q_ad) and SA indicates pore-filling mechanism. Comparison between our results and those obtained with other sorbents indicates corn straw biochars produced at higher temperature can effectively retain simazine. These observations will be helpful for designing biochars as engineered sorbents to remove triazine herbicides.     

不同温度下有机负荷对厌氧折流板反应器污泥颗粒化的影响

采用2个相同的厌氧折流板反应器（ABR）研究不同温度、有机负荷对ABR启动过程中胞外聚合物（EPS）产生的影响,以及各隔室优势菌种。结果表明,高温和较高的有机负荷（OLR）促进EPS的产生,而EPS有利于颗粒污泥的形成。较高温度也有利于反应器承受更高的有机负荷。启动结束后,沿着水流方向,隔室中的污泥发生变化,由水解酸化菌演替为产甲烷优势菌。     

Composting of wastewater treatment sludge with different bulking agents

The main objectives of this study were to investigate the compostability of wastewater treatment sludge (WTS) containing different bulking agents (BAs) and to determine the most efficient BA. Four different compost trials consisting of mixtures of wheat straw (WS), plane leaf (PL), corncob (CC) and sunflower stalk (SS) with WTS were performed in laboratory reactors. In all experiments, a mixture of 60% WTS and 40% BA (wet basis) was used. The temperature, dry matter (DM), organic matter (OM), pH, electrical conductivity (EC) and C/N ratio were monitored during the composting process. Evaluation of the operational parameters showed that the highest organic matter degradation (i.e. 37.6%), loss of dry matter (i.e. 29.6%) and temperature (i.e. 64 °C) were achieved for the WTS-CC mixtures. Results also showed that the WTS-SS mixture was also successful in terms of these operational parameters. Use of bulking agents for the treatment of wastewater treatment sludge in composting process is an important issue with regards to process efficiency, economy and disposal of agricultural waste. Corncob and sunflower stalk that were previously not used for the composting of WTS from food industry were shown to be highly successful BA materials in this study.

Implications: The compostability of wastewater treatment sludge from the food industry with different bulking agents was studied. Wheat straw, plane leaf, corncob, and sunflower stalk were used as bulking agents. The required microbial stabilization and degree of mineralization were achieved with corncobs and sunflower stalks.     

Dissipation and leaching of (14)C-monocrotophos in Soil Columns under subtropical climate

Dissipation and leaching behavior of 14C-monocrotophos was studied for 365 days under field conditions using PVC cylinders. The first set (24 cylinders) was spiked with 1.0 microCi 14C-labeled monocrotophos along with 1.06 mg unlabeled monocrotophos to give a concentration of 2 mg kg -1 in the soil up to 15 cm depth. The second set (24 cylinders) received 14C-labeled monocrotophos along with other non-labeled insecticides viz., dimethoate @ 300 g a.i ha-1, deltamethrin @ 12.5 g a.i ha-1, endosulfan @ 750 g a.i ha-1, cypermethrin @ 60 g a.i ha-1, and triazophos @ 600 g a.i ha-1 at an interval of 15 days each as recommended for the cotton crop. 14C-monocrotophos dissipated faster, up to 45% in first 90 days in columns treated with only monocrotophos compared to 25% in columns that received monocrotophos along with other insecticides. However, both the columns showed similar residues 180 days onward. After 180 days of treatment, 46% radiolabeled residues were observed, which reduced up to 39.6% after 365 days. Leaching of 14C-monocrotophos to 15-30 cm soil layer was observed in both the experimental setups. In the 15-30 cm soil layer of both soil columns, up to 0.19 mg 14C-monocrotophos kg-1d. wt. soil was detected after 270 days.     

筒仓式堆肥反应器不同通风量对堆肥效果的影响

使用筒仓式堆肥反应器,利用含水率为70%的鸡粪作为堆肥原料,分别向堆料中通入12、6和2.4 m3·min-13种不同的通风量,研究不同的通风量对堆肥效果的影响。研究表明,合理的通风量对于堆肥的快速发酵非常重要,通风量为12 m3·min-1时堆肥效果最佳。当通风量为6 m3·min-1和2.4 m3·min-1时,堆体的全氮含量最终都有所下降,说明其通风量不能满足堆体快速发酵对氧气的需求,所以堆体内发生了部分厌氧反应。而6 m3·min-1的通风处理全磷的增加量最大,说明此处理减少了物料中磷的损失,增加了有效磷的含量。当通风量为12 m3·min-1时,与其他2个处理相比,高温期持续时间更长,有机质降解量更大,氮磷等养分的增加量更大,种子发芽率也更高,这些都说明了通风量为12 m3·min-1时堆肥效果最佳。     

不同氮源对常中温条件下麦秆厌氧发酵的影响

通过自行设计的厌氧发酵装置,研究不同氮源对常温（20℃）和中温（35℃）条件下麦秆厌氧发酵的影响。结果表明,在常温和中温条件下进行麦秆沼气厌氧发酵时,适量添加外部氮源可加快产气速率,增加产气量,缩短产气停滞时间,其中添加牛粪效果最好,分别在182 d和84 d时发酵完全,总累积产气3 486.80 mL和4 210.70 mL,干物质累积产气量为217.93 mL/g和263.17 mL/g,且在实验期间未出现产气停滞。添加尿素处理次之,分别在累积产气215.70 mL和238.00 mL时进入61 d和20 d的产气停滞期,在196 d和143 d时发酵完全,在实验结束时,累积产气2 784.20 mL和3 454.00 mL,干物质累积产气量为174.01 mL/g和215.88 mL/g。可见,在以秸秆为原料的沼气发酵过程中,可通过添加适量的外部氮源和提高发酵温度来提高沼气产量,而且在条件允许的情况下,应尽量添加畜禽粪便等有机氮源。     

Differential sorption behaviour of aromatic hydrocarbons on charcoals prepared at different temperatures from grass and wood

Naturally occurring charcoals are increasingly being recognized as effective sorbents for organic compounds. In this study we investigated the sorption of benzene and toluene in single-sorbate and bi-sorbate systems on different types of charcoals produced in laboratory, employing the batch sorption technique. Air dried plant materials from Phalaris grass (Phalaris tuberosa) and Red Gum wood (Eucalyptus camadulensis) were combusted under limited oxygen supply at 250 degrees C, 450 degrees C, and 850 degrees C. The resulting charcoals were characterized for their specific surface areas, total cation content, and pore size distributions (pore size distribution only for wood combusted at 450 degrees C and 850 degrees C). For the materials treated at 850 degrees C not only the surface area, microporosity, and total amount of sorbed sorbate increased markedly, but also the non-linearity of the sorption isotherm. The pore size distributions and surface areas as well as an indifferent sorption behaviour and competition effects for both sorbates indicated that pore filling mechanisms were the dominating processes governing the sorption on these microporous, high temperature treated materials. For the materials treated at lower temperatures the affinity of toluene was higher compared to that of benzene. In the bi-sorbate system the overall uptake of benzene increased. These phenomena might be due to the stronger hydrophobicity of toluene, and to a varying potential for swelling of the matrix and pore deformation by the two sorbates. The significantly lower sorption capacity of the Phalaris-derived material compared to the Red Gum charcoal correlated with its smaller surface area and higher cation content.     

不同温度条件水解酸化-好氧工艺处理高矿化度采油废水

采用不同温度组合的水解酸化-好氧工艺对胜利油田某联合处理站经过"隔油-混凝-过滤"处理的高矿化度采油废水进行处理.结果表明:水解酸化反应器内的微生物能够适应高温(55℃)的环境,而好氧反应器中微生物的活性会受到高温较大的抑制;"高温水解酸化-中温好氧工艺"和"中温水解酸化-中温好氧工艺"可以使出水COD达到低于80 mg/L的外排要求,停留时间分别为15 h和7.5 h.采用水解酸化-好氧工艺处理高矿化度油田采油废水足可行的.     

Impact of climate change and seasonal trends on the fate of Arctic oil spills

We investigated the effects of a warmer climate, and seasonal trends, on the fate of oil spilled in the Arctic. Three well blowout scenarios, two shipping accidents and a pipeline rupture were considered. We used ensembles of numerical simulations, using the OSCAR oil spill model, with environmental data for the periods 2009–2012 and 2050–2053 (representing a warmer future) as inputs to the model. Future atmospheric forcing was based on the IPCC’s A1B scenario, with the ocean data generated by the hydrodynamic model SINMOD. We found differences in “typical” outcome of a spill in a warmer future compared to the present, mainly due to a longer season of open water. We have demonstrated that ice cover is extremely important for predicting the fate of an Arctic oil spill, and find that oil spills in a warming climate will in some cases result in greater areal coverage and shoreline exposure.     

Temperature and nutrients are significant drivers of seasonal shift in phytoplankton community from a drinking water reservoir,subtropical China

Reservoirs are an important source of water supply in many densely populated areas in southeast China. Phytoplankton plays an important role in maintaining the structure and function of these reservoir ecosystems. Understanding of seasonal succession in phytoplankton communities and its driving factors is essential for effective water quality management in drinking-water reservoirs. In this study, water samples were collected monthly at the surface layers of riverine, transitional, and lacustrine zones from May 2010 to April 2011 in Tingxi Reservoir, southeast China. The phytoplankton showed distinct seasonal shifts in community structure at both taxonomic and functional levels. Cyanophyta was the dominant group in summer, especially species of Raphidiopsis in May and Aphanizomenon in June, and cyanobacterial dominance was promoted by both warmer conditions and excessive nutrients loading. Cyanophyta was gradually replaced by Cryptophyta (e.g., Chroomonas caudata) in abundance and by Bacillariophyta (Fragilaria sp. or Synedra sp. and Melosira sp.) in biomass with decreasing temperature. It appeared that seasonal shifts in phytoplankton composition were closely related to climate, nutrient status, and hydrology in this reservoir. Our partial RDA results clearly showed that water temperature and nutrients (TN and TP) were the most critical factors driving phytoplankton community shift in the abundance and biomass data, respectively. Further, with the global warming, cyanobacterial blooms may increase in distribution, duration, and intensity. In our study, the abundance and biomass of cyanobacteria had significant and positive correlations with temperature and phosphorus. Therefore, a stricter limit on nutrient input should be a priority in watershed management to protect drinking water from the effects of cyanobacterial blooms, especially in high-temperature period.