Identification of the key factors affecting composting of a weathered hydrocarbon-contaminated soil

The batch culture degradation of NASA wastewater containing mixtures of citric acid, methylhydrazine, and their reaction product was studied. The organic contaminants present in the NASA wastewater were degraded by Achromobacter sp., Rhodococcus B30 and Rhodococcus J10. While the Achromobacter sp. showed a preference for the degradation of the citric acid, the Rhodococcus species were most effective in reducing the methylhydrazine and the reaction product. Removals of more than 50% were observed for citric acid, methylhydrazine and the reaction product when the NASA wastewater was inoculated with the microbes in batch cultures. Simulation and chemical characterization of citric acid and hydrazine mixtures show that the interaction is partly of a chemical nature and leads to the formation of a conjugated UV/Visible absorbing compound. An 'azo' carbonyl derivative of the citric acid, consistent with the spectral data obtained from the investigation, has been proposed as the possible product.     

葡萄籽对猪粪秸秆高温堆肥中微生物群落与碳氮含量的影响

以猪粪与秸秆(鲜质量10.5∶1)为基础,在自制的强制通风静态堆肥反应箱中进行堆肥化试验,研究添加8%葡萄籽对猪粪秸秆高温堆肥中微生物群落演替和碳氮转化的影响.在堆肥化的30 d里,分7次采集不同时期的堆肥样品,测定堆肥中微生物区系、微生物生理群的数量及堆肥碳氮含量.结果表明：添加葡萄籽使堆肥中细菌数量略高、放线菌数量显著增加、真菌数量明显降低,细菌/放线菌下降;氨化细菌和反硝化细菌数量降低;而硝化细菌、固氮菌和纤维素分解菌数量增多;铵态氮和有机碳含量下降,而硝态氮含量明显提高.堆肥中硝态氮含量与放线菌数量呈极显著正相关关系.添加葡萄籽使堆体升温快且高温期稳定,堆肥含水率波动较小,从而使堆肥高温期放线菌和亚硝化细菌的波动较小,数量较高,有利于堆肥中硝态氮含量的增加.     

环境条件对猪粪好氧堆肥过程的影响

禽畜粪便的大量排放给环境造成了巨大污染,其中猪场粪便和污水是最主要的污染源。为了实现猪粪的无害化、减量化和资源化,好氧堆肥是目前普遍应用和效果良好的实用技术。为了探明堆肥过程的生物学和化学过程,论本文主要从几个影响因素如温度、调理剂、含水率、通风方式、微生物菌剂等对猪粪好氧堆肥技术方面进行了综述。     

畜禽粪便堆肥过程中各种氮化合物的动态变化及腐熟度评价指标

对不同畜禽粪便在堆肥过程中各种含氮化合物的动态变化进行了研究,结合综合性腐熟度评价指标——种子发芽指数（GI）,探讨了畜禽粪便堆肥过程中与氮有关的腐熟度评价指标.结果表明：随着堆肥的进行,除奶牛粪外,其它畜禽粪便的全氮（TN）含量均呈先下降而后平稳变化趋势,奶牛粪则呈先增加而后平稳变化趋势;各种畜禽粪便中,碱解性氮（HN）含量先增后降;NH₄⁺-N含量先下降而后保持平稳;NO₃^- -N含量则持续增加;NH₄⁺ -N/NO₃^- -N迅速降低.堆肥腐熟度指标中,除综合性评价指标GI值外,HN/TN和NH₄⁺ -N/TN也可作为评价畜禽粪便腐熟程度的优选指标,而NO₃^- -N/TN只能作为一般性评价指标.根据综合性评价指标GI值达到腐熟要求的标准（GI>0.50）,除仔猪粪外,其它畜禽粪便在HN/TN<20.77％、NH₄⁺ -N/TN<10.06％及NO₃^- -N/TN>0.38％时基本达到腐熟要求.     

Growth potential of faecal bacteria in simulated psychrophilic/mesophilic zones during composting of organic waste

Aim: This study investigated the growth potential of Salmonella serotype Typhimurium and faecal indicator organisms in compost materials and the correlation between bacterial growth potential and the physico‐chemical composition of the compost substrate and temperature. Methods and Results: Survival of Salm. Typhimurium, Enterococcus spp. and total coliforms at 14, 24 and 37°C was determined in material of different degrees of maturity collected from composting plants for household waste and manure. All three micro‐organisms showed the potential for growth in the material from active composts (Solvita index 4) but inactivation generally occurred over time in mature compost material (Solvita index 7–8). Conclusions: Salm. Typhimurium had the potential for growth in psychrophilic/mesophilic (P/M) zones of immature compost material and its growth potential correlated negatively with the maturity of the compost and the temperature within the simulated P/M zone. Significance and Impact of the Study: The risk of pathogen regrowth in P/M zones during organic waste composting further emphasizes the importance of good management practices and of avoiding P/M zones in combination with low compost maturity.     

静态好氧高温牛粪堆肥中nirK型反硝化细菌群落动态变化

【背景】堆肥过程中,不同反硝化微生物相互作用产生大量气态氮,不仅导致氮素流失使得堆肥肥效降低,而且造成环境污染。但是目前关于堆肥中反硝化细菌群落结构变化,尤其是群落结构与堆肥理化因子间相关性方面的报道较为欠缺。【目的】对堆肥中反硝化细菌进行研究,旨在揭示反硝化细菌群落动态变化,为深入理解堆肥氮循环机理提供科学数据。【方法】设计一种静态好氧高温堆肥技术处理牛粪和水稻秸秆,利用高通量测序技术研究堆肥中nirK型反硝化细菌群落组成的动态变化,并分析优势反硝化细菌菌属与理化指标之间的相关性。【结果】堆肥全程共17d,各项堆肥理化指标以及生物学指标表明堆肥已经基本腐熟。高通量测序结果表明,在堆肥的不同阶段nirK型反硝化细菌群落结构差异显著。门水平上,堆肥中反硝化细菌属于变形菌门(Proteobacteria)和一未分类门;目水平上,优势类群主要属于根瘤菌目(Rhizobiales)、红杆菌目(Rhodobacterales)和伯克氏菌目(Burkholderiales),其中根瘤菌目(Rhizobiales)的种类最多,而伯克氏菌目(Burkholderiales)的相对丰度最高。Spearman相关性分析表明未分类门的反硝化细菌和未分类科根瘤菌目的反硝化细菌与全碳、碳氮比、含水率以及pH呈显著负相关(P0.05),与凯氏氮和硝态氮呈显著正相关(P0.05);其他优势菌属与全碳、碳氮比、含水率以及pH呈显著正相关(P0.05),与凯氏氮和硝态氮呈显著负相关(P0.05);未分类科伯克氏菌目的反硝化细菌、未分类纲变形菌门的反硝化细菌、产碱杆菌科的Pusillimonas属和副球菌属(Paracoccus)与铵态氮显著相关(P0.05)。【结论】静态好氧高温堆肥技术可以缩短堆肥周期。在堆肥的不同阶段nirK型反硝化细菌群落结构差异显著,并且该菌群落结构的变化受到堆肥理化因子的显著影响。本研究有助于揭示堆肥中氮素转化规律,并为改进堆肥工艺提供理论依据。     

微生物接种技术应用于堆肥化中的研究进展

简述了自然发酵在堆肥化处理中的作用,综合介绍了接种有机物腐熟剂的研究情况及添加特定微生物菌剂在堆肥处理固体废物方面的应用现状;并结合微生物接种动力学的理论分析,对其应用于堆肥处理方面的广阔前景作出了展望。     

Environmental impact of two aerobic composting technologies using life cycle assessment

Background, aim, and scope  Composting is a viable technology to treat the organic fraction of municipal solid waste (OFMSW) because it stabilizes biodegradable organic matter and contributes to reduce the quantity of municipal solid waste to be incinerated or land-filled. However, the composting process generates environmental impacts such as atmospheric emissions and resources consumption that should be studied. This work presents the inventory data and the study of the environmental impact of two real composting plants using different technologies, tunnels (CT) and confined windrows (CCW). Materials and methods  Inventory data of the two composting facilities studied were obtained from field measurements and from plant managers. Next, life cycle assessment (LCA) methodology was used to calculate the environmental impacts. Composting facilities were located in Catalonia (Spain) and were evaluated during 2007. Both studied plants treat source separated organic fraction of municipal solid waste. In both installations the analysis includes environmental impact from fuel, water, and electricity consumption and the main gaseous emissions from the composting process itself (ammonia and volatile organic compounds). Results and discussion  Inventory analysis permitted the calculation of different ratios corresponding to resources consumption or plant performance and process yield with respect to 1 t of OFMSW. Among them, it can be highlighted that in both studied plants total energy consumption necessary to treat the OFMSW and transform it into compost was between 130 and 160 kWh/t OFMSW. Environmental impact was evaluated in terms of global warming potential (around 60 kg CO₂/t OFMSW for both plants), acidification potential (7.13 and 3.69 kg SO₂ eq/t OFMSW for CT and CCW plant respectively), photochemical oxidation potential (0.1 and 3.11 kg C₂H₄ eq/t OFMSW for CT and CCW plant, respectively), eutrophication (1.51 and 0.77 kg /t OFMSW for CT and CCW plant, respectively), human toxicity (around 15 kg 1,4-DB eq/t OFMSW for both plants) and ozone layer depletion (1.66 × 10⁻⁵ and 2.77 × 10⁻⁵ kg CFC⁻¹¹ eq/t OFMSW for CT and CCW plant, respectively). Conclusions  This work reflects that the life cycle perspective is a useful tool to analyze a composting process since it permits the comparison among different technologies. According to our results total energy consumption required for composting OFMSW is dependent on the technology used (ranging from 130 to 160 kWh/t OFMSW) as water consumption is (from 0.02 to 0.33 m³ of water/t OFMSW). Gaseous emissions from the composting process represent the main contribution to eutrophication, acidification and photochemical oxidation potentials, while those contributions related to energy consumption are the principal responsible for global warming. Recommendations and perspectives  This work provides the evaluation of environmental impacts of two composting technologies that can be useful for its application to composting plants with similar characteristics. In addition, this study can also be part of future works to compare composting with other OFMSW treatments from a LCA perspective. Likewise, the results can be used for the elaboration of a greenhouse gasses emissions inventory in Catalonia and Spain.     

Survival kinetics of faecal bacterial indicators in spent broiler litter composting

Aims:  The objective of this study was to deduce and analyse equations that best describe the behaviour of faecal bacterial indicators and two decomposition parameters during broiler litter composting. Mathematical models were fitted and the order of rate equations were identified.
Methods and Results:  The Levenburg-Marquardt algorithm was used to fit nonlinear mathematical models to total coliforms (TC), faecal coliforms (FC), Escherichia coli (EC), faecal enteroccocci (FE), organic-C and volatile solids reduction, VS_Red, by the least squares procedure. The rate equations showed that TC, FC and EC reductions were expressed by second-order decay kinetics. FE reduction followed first-order decay. Temperature dependency of decomposition rate was effectively verified by applying empirically derived rate equations.
Conclusions:  The governing mathematical models critically compare the inactivation kinetics of faecal indicators. TC, FC and EC were rapidly destroyed while FE was more resistant. Temperature elevation, organic-C and VS_Red dynamics provide an accurate understanding of composting-induced decomposition of the broiler litter.
Significance and Impact of the Study:  The conservative performance of FE with respect to the other indicators has been established. Hence, FE presents better opportunities to encompass the totality of the composting process in terms of attainment of hygiene efficacy compared with EC.