Hydrolysis characteristics and kinetics of waste hay biomass as a potential energy crop for fermentable sugars production using autoclave parr reactor system

The use of the organic fraction of municipal solid waste crops has received considerable attention as a sustainable feedstock that can replace fossil fuels for the production of renewable energy. Therefore, municipal bin-waste in the form of hay was investigated as a potential energy crop for fermentable sugars production. Hydrolysis of hay by dilute phosphoric acid was carried out in autoclave parr reactor, where reactor temperature (135-200 degrees c) and acid concentration (2.5-10% (w/w)) were examined. Analysis of the decomposition rate of hemicellulosic biomass was undertaken using HPLC of the reaction products. Xylose production reached a maximum value of 13.5 g/100 g dry mass corresponding to a yield of 67% at the best identified conditions of 2.5 wt% H3PO4, 175 degrees C, 10 min reaction time, and at 5 wt% H3PO4, 150 degrees C, and 5 min reaction time. For glucose, an average yield of 25% was obtained at 5 wt% H3PO4, 175 degrees C and 30 min. Glucose degradation to HMF was achieved at 10 wt% H3PO4 and 200 degrees C. The maximum yield for produced arabinose was an average of 3 g/100 g dry. mass corresponding to 100% of the total possible arabinose. The kinetic study of the acid hydrolysis was also carried out using the Saeman and the Two-fraction models. It was found for both models that the kinetic constants (k) depend on the acid concentration and temperature. For xylose and arabinose it was found that the rate of formation was more favoured than the rate of degradation. By contrast, for glucose it was found that glucose degradation was occurring faster than glucose formation. It can be concluded that dilute phosphoric acid hydrolysis of hay crop is feasible for the production of fermentable sugars which are essential for bioethanol synthesis. 

Dilute phosphoric acid-catalysed hydrolysis of municipal bio-waste wood shavings using autoclave parr reactor system

The visibility of using municipal bio-waste, wood shavings, as a potential feedstock for ethanol production was investigated. Dilute acid hydrolysis of wood shavings with H3PO4 was undertaken in autoclave parr reactor. A combined severity factor (CSF) was used to integrate the effects of hydrolysis times, temperature and acid concentration into a single variable. Xylose concentration reached a maximum value of 17 g/100 g dry mass corresponding to a yield of 100% at the best identified conditions of 2.5 wt.% H3PO4, 175 degrees C and 10 min reaction time corresponding to a CSF of 1.9. However, for glucose, an average yield of 30% was obtained at 5 wt.% H3PO4, 200 degrees C and 10 min. Xylose production increased with increasing temperature and acid concentration, but its transformation to the degradation product furfural was also catalysed by those factors. The maximum furfural formed was 3 g/100 g dry mass, corresponding to the 24% yield. (C) 2011 Elsevier Ltd. All rights reserved.

Acid-catalyzed hydrolysis of cellulose and cellulosic waste using a microwave reactor system

A microwave reactor system was investigated as a potential technique to maximize sugar yield for the hydrolysis of municipal solid waste for ethanol production. Specifically, dilute acid hydrolysis of a-cellulose and waste cellulosic biomass (grass clippings) with phosphoric acid was undertaken within the microwave reactor system. The experimental data and reaction kinetic analysis indicate that the use of a microwave reactor system can successfully facilitate dilute acid hydrolysis of cellulose and waste cellulosic biomass, producing high yields of total sugars in short reaction times. The maximum yield of reducing sugars was obtained at 7.5% (w/v) phosphoric acid and 160 degrees C, corresponding to 60% of the theoretical total sugars, with a reaction time of 5 min. When using a very low acid concentration (0.4% w/v) for the hydrolysis in the microwave reactor, it was found that 10 g of total sugars/100 g dry mass was produced, which is significant considering the low acid concentration. When hydrolyzing grass clippings using the microwave reactor, the optimum conditions were an acid concentration of 2.5% (w/v), 175 degrees C with a 15 min reaction time, giving 18 g/100 g dry mass of total sugars, with xylose being the sugar with the highest yield. It was observed that pentose sugars were more easily formed but also more easily degraded, these being significantly affected by increases in acid concentration and temperature. Kinetic modeling of the data indicated that the use of microwave heating may account for an increase in reaction rate constant, k(1), found in this study in comparison with conventional systems described in the literature.

Integrating petrography, mineralogy and hydrochemistry to constrain the influence and distribution of groundwater contributions to baseflow in poorly productive aquifers: Insights from Gortinlieve catchment, Co. Donegal, NW Ireland

Identifying groundwater contributions to baseflowforms an essential part of surfacewater body characterisation. The Gortinlieve catchment (5 km2) comprises a headwater stream network of the Carrigans River, itself a tributary of the River Foyle, NW Ireland. The bedrock comprises poorly productive metasediments that are characterised by fracture porosity. We present the findings of a multi-disciplinary study that integrates new hydrochemical and mineralogical investigations with existing hydraulic, geophysical and structural data to identify the scales of groundwater flow and the nature of groundwater/bedrock interaction (chemical denudation). At the catchment scale, the development of deep weathering profiles is controlled by NE-SW regional scale fracture zones associated with mountain building during the Grampian orogeny. In-situ chemical denudation of mineral phases is controlled by micro- to meso-scale fractures related to Alpine compression during Palaeocene to Oligocene times. The alteration of primary muscovite, chlorite (clinochlore) and albite along the surfaces of these small-scale fractures has resulted in the precipitation of illite, montmorillonite and illite/montmorillonite clay admixtures. The interconnected but discontinuous nature of these small-scale structures highlights the role of larger scale faults and fissures in the supply and transportation of weathering solutions to/from the sites of mineral weathering. The dissolution of primarily mineral phases releases the major ions Mg, Ca and HCO3 that are shown to subsequently formthe chemical makeup of groundwaters. Borehole groundwater and stream baseflow hydrochemical data are used to constrain the depths of groundwater flow pathways influencing the chemistry of surface waters throughout the stream profile. The results show that it is predominantly the lower part of the catchment, which receives inputs from catchment/regional scale groundwater flow, that is found to contribute to the maintenance of annual baseflow levels. This study identifies the importance
of deep groundwater in maintaining annual baseflow levels in poorly productive bedrock systems.

The 'human revolution' in lowland tropical Southeast Asia:the antiquity and behavior of anatomically modern humans at Niah Cave (Sarawak, Borneo)

Recent research in Europe, Africa, and Southeast Asia suggests that we can no longer assume a direct and exclusive link between anatomically modern humans and behavioral modernity (the 'human revolution'), and assume that the presence of either one implies the presence of the other: discussions of the emergence of cultural complexity have to proceed with greater scrutiny of the evidence on a site-by-site basis to establish secure associations between the archaeology present there and the hominins who created it. This paper presents one such case study: Niah Cave in Sarawak on the island of Borneo, famous for the discovery in 1958 in the West Mouth of the Great Cave of a modern human skull, the 'Deep Skull,' controversially associated with radiocarbon dates of ca. 40,000 years before the present. A new chronostratigraphy has been developed through a re-investigation of the lithostratigraphy left by the earlier excavations, AMS-dating using three different comparative pre-treatments including ABOX of charcoal, and U-series using the Diffusion-Absorption model applied to fragments of bones from the Deep Skull itself. Stratigraphic reasons for earlier uncertainties about the antiquity of the skull are examined, and it is shown not to be an `intrusive' artifact. It was probably excavated from fluvial-pond-desiccation deposits that accumulated episodically in a shallow basin immediately behind the cave entrance lip, in a climate that ranged from times of comparative aridity with complete desiccation, to episodes of greater surface wetness, changes attributed to regional climatic fluctuations. Vegetation outside the cave varied significantly over time, including wet lowland forest, montane forest, savannah, and grassland. The new dates and the lithostratigraphy relate the Deep Skull to evidence of episodes of human activity that range in date from ca. 46,000 to ca. 34,000 years ago. Initial investigations of sediment scorching, pollen, palynomorphs, phytoliths, plant macrofossils, and starch grains recovered from existing exposures, and of vertebrates from the current and the earlier excavations, suggest that human foraging during these times was marked by habitat-tailored hunting technologies, the collection and processing of toxic plants for consumption, and, perhaps, the use of fire at some forest-edges. The Niah evidence demonstrates the sophisticated nature of the subsistence behavior developed by modern humans to exploit the tropical environments that they encountered in Southeast Asia, including rainforest. (c) 2006 Elsevier Ltd. All rights reserved.

A lysimeter experimental study and numerical characterisation of the leaching of incinerator bottom ash waste

Incinerator bottom ash (IBA) is a residual produced from incinerating municipal solid waste. In the past, IBA presented a big waste disposal problem; however, various recycling approaches have been adopted in recent years to mitigate this problem, as well as to provide a useful alternative to using primary aggregate resources. The use of IBA as an alternative to conventional aggregates in different civil engineering construction applications helps to conserve premium grade aggregate supplies; however, when IBA is in contact with water in the field, as a consequence of precipitation events or changes in water table, elements, such as salts and heavy metals, may be released to the soil and ground water. In this work, IBA waste was mixed with limestone aggregate to produce a blend with acceptable mechanical properties and minimum environmental risks for use as road foundation. The study focused on evaluating potential environmental impacts of some constituents, including sulphate, chloride, sodium, copper, zinc and lead in IBA blends using a lysimeter as a large scale leaching tool. Moreover, a specific scenario simulating field conditions was adopted in the lysimeter to assess the potential impact of changing conditions, such as IBA content in the blend, liquid to solid ratio (L/S) and pH value, on long-term release of heavy metals and salts. Then, numerical modelling was used to predict the release of the aforementioned constituents from IBA based on initial measurement of intrinsic material properties and the kinetic desorption process concept. Experimental results showed that zinc and lead were released in very low concentrations but sodium and sulphate were in high concentrations. The control limestone only blend also demonstrated low release concentrations of constituents in comparison to IBA blends, where constituent concentrations increased with increase in IBA content. Experimental results were compared with numerical results obtained using a non-equilibrium desorption model. Good agreement was found between the two sets of data. 

Development and application of a multiple linear regression model to consider the impact of weekly waste container capacity on the yield from kerbside recycling programmes

The paper describes the development and application of a multiple linear regression model to identify how the key elements of waste and recycling infrastructure, namely container capacity and frequency of collection affect the yield from municipal kerbside recycling programmes. The overall aim of the research was to gain an understanding of the factors affecting the yield from municipal kerbside recycling programmes in Scotland. The study isolates the principal kerbside collection service offered by 32 councils across Scotland, eliminating those recycling programmes associated with flatted properties or multi occupancies. The results of a regression analysis model has identified three principal factors which explain 80% of the variability in the average yield of the principal dry recyclate services: weekly residual waste capacity, number of materials collected and the weekly recycling capacity. The use of the model has been evaluated and recommendations made on ongoing methodological development and the use of the results in informing the design of kerbside recycling programmes. The authors hope that the research can provide insights for the ongoing development of methods to optimise the design and operation of kerbside recycling programmes.

A comparison of biodegradable municipal waste (BMW) management strategies in Ireland and the Czech Republic and the lessons learned

In order to meet the recycling and recovery targets set forth by the European Union's (EU) Waste and Landfill Directives, both the Irish and Czech governments’ policy on waste management is changing to meet these pressures, with major emphasis being placed upon the management of biodegradable municipal waste (BMW). In particular, the EU Landfill Directive requires reductions in the rate of BMW going to landfill to 35% of 1995 values by 2016 and 2020 for Ireland and the Czech Republic, respectively. In this paper, the strategies of how Ireland and the Czech Republic plan to meet this challenge are compared. Ireland either landfills or exports its waste for recovery, while the Czech Republic has a relatively new waste management infrastructure. While Ireland met the first target of 75% diversion of BMW from landfill by 2010 and preliminary 2012 data indicate that Ireland is on track to meet the 2013 target, the achievement of the 2016 target remains at risk. Indicators that were developed to monitor the Czech Republic's path to meeting the targets demonstrate that it did not meet the first target that was set for 2010 and will probably not meet its 2013 target either. The evaluation reports on the implementation of Waste Management Plan of Czech Republic suggest that the currently applied strategy to divert biodegradable waste from landfill is not effective enough. For both countries, the EU Waste Framework and Landfill Directives will be a significant influence and driver of change in waste management practices and governance over the coming decade. This means that both countries will not only have to invest in infrastructure to achieve the targets, but will also have to increase awareness among the public in diverting this waste at the household level. Improving environmental education is part of increased awareness as it is imperative for citizens to understand the consequences of their actions as affluence continues to grow producing increased levels of waste.

Graphical abstract
Despite the differences in the levels of waste generation in both the Czech Republic and Ireland, each country can learn from each other in order to meet the recycling and recovery targets set by the European Union's (EU) Waste and Landfill Directives. Both countries will not only have to invest in infrastructure to achieve the targets, but will also have to increase awareness among the public in diverting this waste at the household level. In addition, there needs to be minimum safe standards when land-spreading organic agricultural and organic municipal and industrial materials on agricultural land used for food production, as well as incentives to increase BMW diversion from landfill such as the increased landfill levy implemented in Ireland and the acceptance of MBT and/or incineration as a means of treating residual waste.

An overview of waste crime, its characteristics, and the vulnerability of the EU waste sector

While waste is increasingly viewed as a resource to be globally traded, increased regulatory control on waste across Europe has created the conditions where waste crime now operates alongside a legitimate waste sector. Waste crime,is an environmental crime and a form of white-collar crime, which exploits the physical characteristics of waste, the complexity of the collection and downstream infrastructure, and the market opportunities for profit. This paper highlights some of the factors which make the waste sector vulnerable to waste crime. These factors include new legislation and its weak regulatory enforcement, the economics of waste treatment, where legal and safe treatment of waste can be more expensive than illegal operations, the complexity of the waste sector and the different actors who can have some involvement, directly or indirectly, in the movement of illegal wastes, and finally that waste can be hidden or disguised and creates an opportunity for illegal businesses to operate alongside legitimate waste operators. The study also considers waste crime from the perspective of particular waste streams that are often associated with illegal shipment or through illegal treatment and disposal. For each, the nature of the crime which occurs is shown to differ, but for each, vulnerabilities to waste crime are evident. The paper also describes some approaches which can be adopted by regulators and those involved in developing new legislation for identifying where opportunities for waste crime occurs and how to prevent it.