The study of ultrasound-assisted oxidative desulfurization process applied to the utilization of pyrolysis oil from waste tires

In recent years, the increasing world population and rapid industrial development has increased the consumption of fossil fuel-derived oils. In response to the resulting exhaustion of fossil fuel energy, many countries around the world are investigating methods of waste energy recovery and reuse, including oil recovery from the pyrolysis process of waste tires. This study investigates the efficiency of an ultrasound-assisted oxidative desulfurization (UAOD) process in sulfur reduction from diesel oil and the pyrolysis oil from waste tires treatment. The results indicate that the oxidation efficiency increases as the doses of transition metal catalyst are increased. Longer sonication time also enhances the oxidation process, apparently through the biphasic transfer of oxidants, which results in a high yield of organic sulfur oxidation products. The best desulfurization efficiency was 99.7% (2.67 ppm sulfur remaining) and 89% (800 ppm sulfur remaining) for diesel and pyrolysis oils, respectively, via a process executed by two UAOD units connected in series and combined with solid adsorption using 30 g of Al₂O₃ in 6 cm columns. These batch experiment results demonstrate clean waste energy recovery and utilization, while fulfilling the requirements of Taiwan EPA environmental regulations (sulfur concentrations less than 5000 ppm).     

Minimizing greenhouse gas emissions through the application of solar thermal energy in industrial processes

The analysis of industrial energy usage indicates that low temperature processes (20 ≈ 200 °C) are used in nearly all industrial sectors. In principle there is the potential to use solar thermal energy in these lower temperature processes thus, reducing the environmental impact of burning fossil fuels. Using the model of an Austrian dairy plant, this research investigated the potential for, and the economic viability of, using solar energy heat processes in industry.Some industrial sectors such as food, chemistry, plastic processing, textile industry, building materials industry and business establishments can be identified as potential sectors for the application of solar energy heat processes. When assessing the (economic) feasibility of solar thermal energy, the investigation of these industries’ energy systems has to focus on an integrated analysis of cooling and heating demands and to take into account competing technologies. Amongst these are heat integration, cogeneration, new technologies and heat pumps. Pinch analysis was used to investigate industrial energy systems and heat integration possibilities and proved to be a viable tool. Working from the basis of energy balances, Sankey diagrams, pinch analysis and environmental cost accounting, a newly developed investigation tool was applied in the case study of an Austrian dairy plant. This enabled a fast optimization of the system. Two different options for the integration of solar thermal energy into the production line were calculated, option 1 with a solar field of 1000 m² and option 2 with a solar field of 1500 m². Natural gas savings of 85,000 for option 1 and 109,000 m³/a for option 2 can be achieved, resulting in a reduction of 170 tons of CO₂ per year, or 218 tons for options 1 and 2 respectively. Based upon option 1, return on investment is realised after less than three years of implementation. This research thus, indicates promising technical and economical feasibility of using solar thermal energy for industrial processes and provides an important step towards sustainable zero emission production in industry.     

Effects of different diets on utilization of nitrogen from cattle slurry applied to grassland on a sandy soil in The Netherlands

Dietary adjustments have been suggested as a means to reduce N losses from dairy systems. Differences in fertilizing value of dairy slurry as a result of dietary adjustments were evaluated in a 1-year grassland experiment and by long-term modelling. Slurry composition of non-lactating dairy cows was manipulated by feeding diets with extreme high and low levels of dietary protein and energy. C:N_total ratio of the produced slurries ranged from 5.1 to 11.4. To evaluate their short-term fertilizer N value, the experimental slurries (n = 8) and slurries from commercial farms with variable composition (n = 4), were slit-injected in two grassland fields on the same sandy soil series in the north of The Netherlands (53°10′N, 6°04′E), with differences in sward age and ground water level. The recently established grassland field (NEW) was characterized by lower soil OM, N and moisture contents, less herbs and more modern grass varieties compared to the older grassland field (OLD). Slurry was applied in spring (100 kg N ha⁻¹) and after the first cut (80 kg N ha⁻¹) while in total four cuts were harvested. Artificial fertilizer N treatments were included in the experiment to calculate the mineral fertilizer equivalent (MFE) of slurry N. The OLD field showed a higher total N uptake whereas DM yields were similar for the two fields. Average MFE of the slurries on the OLD field (47%) was lower than on the NEW field (56%), probably as a result of denitrification of slurry N during wet conditions in spring. Slurries from high crude protein diets showed a significantly higher MFE (P < 0.05) compared to low crude protein diets. No significant differences in MFE were observed between slurries from high and low energy diets. On both fields, MFE appeared to be positively related to the ammonium content (P < 0.001) and negatively to the C:N_total ratio of the slurry DM (P = 0.001). Simulation of the effect of long-term annual application of 180 kg N ha⁻¹ with highest and lowest C:N_total ratio suggested that both slurries would lead to an increase in annual soil N mineralization. Both soil N mineralization and SOC appeared to be substantially higher in equilibrium state for the slurry with the highest C:N_total ratio. It is concluded that in a situation with slit-injection, the reduced first-year N availability of slurry with a high C:N_total ratio as observed in the grassland experiment will only be compensated for by soil N mineralization on the very long term.     

Environmental consequences of different beef production systems in the EU

The aim of this paper is to examine the environmental consequences of beef meat production in the EU, using a life cycle approach. Four beef production systems were studied – three from intensively reared dairy calves and one from suckler herds. According to the results of the analysis, the contributions from the production of 1 kg beef meat (slaughter weight) to global warming, acidification, eutrophication, land use and non-renewable energy use were lower for beef from dairy calves than from suckler herds (16.0–19.9 versus 27.3 kg CO₂e, 101–173 versus 210 g SO₂e, 622–1140 versus 1651 g NO₃e, 16.5–22.7 versus 42.9 m²year, and 41.3–48.2 versus 59.2 MJ, respectively). The breakdown analysis helped identify the key areas in the “cradle to farm gate” beef production system where sustainable management strategies are needed to improve environmental performance. The study also included a sensitivity analysis to preliminarily estimate GHG emissions from beef production systems if land opportunity cost and land use change related to grazing and feed crop production for beef were taken into account. If so, the contribution from the production of 1 kg beef to global warming would increase by a factor of 3.1–3.9, based on a depreciation period of 20 years. This highlights the importance of taking into account the impacts of land use in assessing the environmental impacts of livestock production.     

Economic evaluation of optional recycling processes for waste electronic home appliances

This paper presents an economic evaluation of three typical recycling processes for the five main types of waste electronic home appliances (EHA) (TV set, refrigerator, washing machine, air conditioner and personal computer) in Beijing, the capital of China. The main purpose is to identify the formal management framework with economic feasibility for the waste EHA generated in large municipalities of China. It is found that the advanced technologies, which have mechanical processing units, should be introduced to recover more valuable materials from the waste appliances. Net revenues with a range of 90–240 RMB (Chinese currency unit, 1.0 USD ≈ 8.0 RMB) per unit, depend on the type of appliance, could be expected in case of using the most complicated procedures which can separate both metals and plastics from the shredded mixtures. However, the recycling of waste refrigerator and waste washing machine will, respectively, spend about 100 and 6 RMB per unit if solely by simple manual dismantling. Revenues from recycling of the other three types of appliances are positive but quite low in this case. Although positive revenues could be achieved from the isolated evaluation of recycling, the entire management system, which also covers the phases of collection and transportation, is economically infeasible if the waste appliances are bought from the households still at current prices. Based on a survey of the householder's attitude to the cost for waste EHA management, which was conducted earlier, the practical way to construct a formal management system for waste EHA in Beijing is to reduce the citizen's traditional expectation to the values of waste appliances and encourage their transfer to the formal collection system at lower prices.     

Market-based approaches and tools for improving water and air quality

Nitrogen (N) losses from agriculture are negatively impacting groundwater, air, and surface water quality. National, state, and local policies and procedures that can mitigate these problems are needed. Market-based approaches where waste treatment plants (point sources) can purchase nutrient credits from upstream agricultural operations (non-point sources) to meet their National Pollutant Discharge Elimination System permit requirements within the Clean Water Act are being explored. This paper reviews these market-based approaches for enhancing air and water quality at a lower cost than simple command-and-control regulation, and describes new tools that are being developed, such as Nitrogen Trading Tool (NTT), that can be used to assess nitrogen losses to the environment under different management scenarios. The USDA-NRCS, EPA and several other state and local agencies are interested in these new tools. The NTT, though primarily designed for water quality markets, also estimates savings in nitrous oxide (N₂O) emissions that can be traded in carbon markets. For example, an analysis using NTT shows that for 100 ha of crop land, a C sequestration equivalent of approximately 25–38 Mg C y^?1 for a farm in Ohio, and 13–21 Mg C y^?1 for a farm in Virginia could be achieved with better nitrogen management practices. These numbers across a watershed could be much larger with improved N and conservation management practices that contribute to better water quality and lower global warming potential. There is a need to further develop, calibrate, and validate these tools to facilitate nitrogen and carbon trading future markets around the globe to increase environmental conservation across agro-ecosystems worldwide.     

Linkages between land management activities and water quality in an intensively farmed catchment in southern New Zealand

Linkages between land management activities and stream water quality are reported for a 2480 ha catchment used for dairy farming, sheep–beef farming and forestry in Southland, New Zealand. Our approach was to reconcile measured loads of nutrients exported from the catchment with those estimated based on characterisation of farming practices within the catchment. The latter was based upon detailed surveys of farm practices and soil quality. Monthly stream monitoring showed that median nutrient (N and P), sediment and faecal bacteria concentrations exceeded guidelines recommended for surface waters. Measured specific yields for suspended sediment (SS), total N (TN) and phosphorus (P) discharged from the catchment were 58, 8.2 and 0.43 kg ha⁻¹ year⁻¹, respectively, for the 2001–2005 monitoring period. In comparison, model estimates of N and P losses in drainage and overland flow from farms in the catchment were 10.1 and 0.59 kg ha⁻¹ year⁻¹, respectively. Field measurements, farm management surveys and farm systems modeling have identified some land management practices that appear to be key sources of many of these pollutants. These sources include subsurface drainage systems (including the preferential flow of irrigated effluent through these soils), overland flow from the heavy soils used for dairy farming in the catchment and the practice of intensively wintering cows on forage crops. Modeling suggests that a significant improvement in catchment water quality could be achieved through the implementation of targeted best management practices (BMPs) on dairy farms in the catchment. These include (i) covered feedpad wintering systems for controlling N losses, (ii) nitrification inhibitor use on milking platforms, (iii) deferred irrigation and low rate application of farm dairy effluent and (iv) limiting soil Olsen P to economically optimum levels. The adoption of these BMPs will, in part, depend on their economic viability. This paper therefore presents a double-bottom-line analysis (i.e. environmental and economic) of some of these BMPs and discusses their potential to cost-effectively deliver improved water quality in the Bog Burn catchment.     

Modelling greenhouse gas emissions from European conventional and organic dairy farms

Agriculture is an important contributor to global emissions of greenhouse gases (GHG), in particular for methane (CH₄) and nitrous oxide (N₂O). Emissions from farms with a stock of ruminant animals are particularly high due to CH₄ emissions from enteric fermentation and manure handling, and due to the intensive nitrogen (N) cycle on such farms leading to direct and indirect N₂O emissions. The whole-farm model, FarmGHG, was designed to quantify the flows of carbon (C) and nitrogen (N) on dairy farms. The aim of the model was to allow quantification of effects of management practices and mitigation options on GHG emissions. The model provides assessments of emissions from both the production unit and the pre-chains. However, the model does not quantify changes in soil C storage.Model dairy farms were defined within five European agro-ecological zones for both organic and conventional systems. The model farms were all defined to have the same utilised agricultural area (50 ha). Cows on conventional and organic model farms were defined to achieve the same milk yield, so the basic difference between conventional and organic farms was expressed in the livestock density. The organic farms were defined to be 100% self-sufficient with respect to feed. The conventional farms, on the other hand, import concentrates as supplementary feed and their livestock density was defined to be 75% higher than the organic farm density. Regional differences between farms were expressed in the milk yield, the crop rotations, and the cow housing system and manure management method most common to each region.The model results showed that the emissions at farm level could be related to either the farm N surplus or the farm N efficiency. The farm N surplus appeared to be a good proxy for GHG emissions per unit of land area. The GHG emissions increased from 3.0 Mg CO₂-eq ha⁻¹ year⁻¹ at a N surplus of 56 kg N ha⁻¹ year⁻¹ to 15.9 Mg CO₂-eq ha⁻¹ year⁻¹ at a N surplus of 319 kg N ha⁻¹ year⁻¹. The farm N surplus can relatively easily be determined on practical farms from the farm records of imports and exports and the composition of the crop rotation. The GHG emissions per product unit (milk or metabolic energy) were quite closely related to the farm N efficiency, and a doubling of the N efficiency from 12.5 to 25% reduced the emissions per product unit by ca. 50%. The farm N efficiency may therefore be used as a proxy for comparing the efficiencies of farms with respect to supplying products with a low GHG emission.     

Life cycle assessment of sub-units composing a MSW management system

This paper summarises the results of a number of life cycle evaluations that we have carried out in recent years about some of the sub-units (in particular, the recycling of the packaging materials, the treatment of the bio-waste, and the energy recovery from the residual waste) that compose a municipal solid waste management system (MSWMS) and about the MSWMS as a whole.The range of values estimated for cumulative energy demand (CED), global warming (GWP₁₀₀), human toxicity, acidification, and photochemical ozone creation indicators according to the different analyses are presented in the paper for each sub-unit. The assumptions influencing the results have been identified, too. The proper aggregation of sub-units has allowed the estimation of the impacts associated with two integrated MSWMSs implemented in Italy and of the order of magnitude of those associated with a generic MSWMS, similar to those of the two case studies.The results show that the assumptions that most influence the environmental indicators are those about selection efficiencies and quality deterioration in the recycling of the packaging materials, about process emissions and avoided products in the composting, about the biogas yield and its way of utilisation in the anaerobic digestion, and about the efficiency of the plant and the kind of avoided energy in the energy recovery. All the indicators, except GWP₁₀₀ under certain assumptions, are negative in sign, thus indicating a benefit for the environment thanks to the avoided impact associated with the production of material and energy during the waste management. The estimated order of magnitude of the CED and GWP₁₀₀ indicators turns out to be respectively thousands of MJ eq. and tens of kg CO₂ eq. per tonne of managed waste.     

The basis of a policy for minimizing and recycling food waste

The life cycle of basic food items was studied in order to discover the reasons for low landfill diversion rates of this material. Management failures at key points of the cycle were identified. Subjects of study were commercialization procedures of fruit and vegetables before consumption, consumption proper and after-consumption disposal procedures for food scraps in the Brazilian context. Before consumption, the rate of lost fruit and vegetables stood at 16 wt.% of the total quantity commercialized. During consumption by residents, the waste rate of food amounted to 9 wt.% of all collected household garbage. In the after-consumption sector of the cycle, biodegradables represented 72 wt.% of all household garbage collected by official means in a typical Brazilian town. The numbers produced clearly identified landfill diversion of biodegradables as a management problem. The authors experimented with original proactive administrative procedures designed to set landfill diversion targets. The occurrence of wasted fruit and vegetables at the wholesaler and retailer levels was identified. Remedies were proposed and tested to reduce this waste by at least 50%. In the after-consumption sector, the notion of divided garbage collection was developed and applied to test communities. It was shown that biodegradables may be collected separately from the rest of household waste. This resulted in a diversion potential of 100% for biodegradables alone and 77 wt.% for all collected household waste. The study produced a formal policy proposal to municipal administrations to avoid the need for tipping of biodegradable material.     

The holistic impact of integrated solid waste management on greenhouse gas emissions in Phuket

Continually increasing amounts of municipal solid waste (MSW) and the limited capacity of the existing waste management system in Phuket have led to the consideration of integrated waste management system (IWMS). Life cycle assessment (LCA) was employed to compare the greenhouse gas emissions expressed as global warming potential (GWP) of the existing waste management system (the base scenario) and other three IWMSs for Phuket MSW. Besides incineration and landfilling, the proposed scenarios include 30% source separation for recycling (scenario 2), anaerobic digestion (scenario 3) and both (scenario 4).The functional unit is set as 1 t of Phuket MSW treated. Results from the impact assessment of the base scenario shows that the net GWP is 1006 kg CO₂ equivalent. Landfilling contributes to the highest potentials of this impact. The results from a holistic comparison show that scenario 4 is the best option among all the scenarios, contributing GWP of 415 kg CO₂ eq., whereas the base scenario is the worst. The emission of greenhouse gas from landfilling is reduced by the introduction of landfill gas recovery and utilization for electricity production. By assumption, 50% recovery of landfill gas leads to the GWP reduction around 58% by total GWP of landfilling and 36% by the net GWP of the whole system in the base scenario. The study suggests that a policy that promotes source separation should be pursued, preferably combined with the application of landfill gas recovery for electricity. Policy promoting recycling is favorable over anaerobic digestion in the situation that both treatment systems could not be established at the same time. The major conclusion from the study is that results from the LCA can support Phuket Municipality for decision-making with respect to planning and optimizing IWMS. It can benefit other municipalities or policy makers to apply in their waste management projects.     

Energy sector reform in Eritrea: initiatives and implications

The Government of Eritrea gave priority status to the energy sector immediately after the country's independence in May 1991, as manifested by the rapid improvement in electricity and oil supplies. Electricity generation capacity has increased from a total of 30 MW in 1991 to over 130 MW at present. The lengths of transmission and distribution lines have similarly increased from 150 km to 400 km and from 800 to 1300 km respectively. However, as in most Sub-Saharan Africa, this public utility is characterised by inefficient managerial, technical and financial performances, an inability to mobilize the funds needed for expansion, low repair and maintenance capacity, inappropriate tariff rates, and inadequate revenue collection mechanisms. This has led the government to take appropriate reform measures in recent years, including the restructuring of the Eritrea Electric Corporation (EEC) to operate on commercial principles, setting tariffs based on real costs and reasonable profits, effective collection of revenues, the minimization of wastage and loss in the delivery of energy services, facilitating the private sector participation, and ring-fencing the interests of the poor by setting up a Rural Electrification Fund. A Regulatory body has been established to enforce these reform measures. Recognising the role of modern energy in poverty reduction and achieving the Millennium Development Goals (MDGs), the Government with the support of its development partners is expanding energy services to rural areas in an innovative manner. The Government's commitment to diversify energy sources is exemplified by its agreement with the Global Environment Facility (GEF) to share the costs of an on-going pilot wind energy project. It has also established an Energy Research and Training Centre to promote the application of renewable energies and improved biomass stoves throughout Eritrea.     

Ultrasound-accelerated enzymatic hydrolysis of solid leather waste

The leather industry is a heavy pollution industry and looking for clean technology. The utilization of enzyme and ultrasound in the industry are potential eco-friendly technologies.Enzymes can degrade the untanned solid leather waste. According to our investigation, ultrasound (40 kHz, 0.64 W/cm²) has little effect on the activity of one alkaline protease from Bacillus licheniformis. It is the first time to use ultrasound to accelerate the enzymatic hydrolysis of the untanned solid leather waste. With the application of ultrasound, the value of k_A for the enzymatic hydrolysis of the untanned solid leather waste increases 18% and K_M is almost unchanged, compared with that obtained without ultrasound. Ultrasound improves the ultimate conversion ratio from 57.6% to 84.1%. The reason is that ultrasound can facilitate the protease through the pores of skin and impair the integrity of collagen. Amino acid analysis indicated that ultrasound can promote the breakdown of helical regions of collagen which are difficult to attack by proteases.In view of environment protection, the use of enzyme and ultrasound in combination is a promising clean technology for the disposal of the untanned solid leather waste.     

Degradation and re-emergence of the commons: The impacts of government policies on traditional resource management institutions in China

In the vast majority of cases studied to date, rapid changes in indigenous resource management institutions and traditional ecological knowledge (TEK) have been reported with profound implications for indigenous livelihoods, biodiversity, and system resilience worldwide. In this case study, we examined how policy changes in China over the past 60 years have influenced indigenous resource management institutions designed to manage common pool pastoral systems in eastern Inner Mongolia. Based on semi-structured interviews (n = 91), focus group discussions (64 participants involved), and participant observation, we found that for over half a century rescaling efforts by the Chinese government shifted the focus to national level development planning, which led to the degradation of indigenous institutions that managed common pool pastoral systems in the region. However, we also highlight how local actors have used recent changes in government policies to revitalize traditional herding institutions. This provides a rare glimpse at the re-emergence of the commons from the bottom up.     

Mitigation of greenhouse gas emissions by anaerobic digestion of cattle slurry

Biogas treatment of animal manures is an upcoming technology because it is a way of producing renewable energy (biogas). However, little is known about effects of this management strategy on greenhouse gas (GHG) emissions during fermentation, storage, and field application of the substrates compared to untreated slurries. In this study, we compared cattle slurry and cattle slurry with potato starch as additive during the process of fermentation, during storage and after field application. The addition of potato starch strongly enhanced CH₄ production from 4230 l CH₄ m⁻³ to 8625 l CH₄ m⁻³ in the fermenter at a hydraulic retention time (HRT) of 29 days. Extending the HRT to 56 days had only a small effect on the CH₄ production. Methane emissions from stored slurry depended on storage temperature and were highest from unfermented slurry followed by the slurry/starch mixture. Gas emissions from untreated and fermented slurry during storage were further analyzed in a pilot-scale experiment with different levels of covering such as straw cover, a wooden lid and no cover. Emissions of greenhouse gases (CH₄, N₂O, NH₃) were in the range of 14.3–17.1 kg CO₂ eq. m⁻³ during winter (100 day storage period) and 40.5–90.5 kg CO₂ eq. m⁻³ during summer (140 day storage period). A straw cover reduced NH₃ losses, but not overall GHG emissions, whereas a solid cover reduced CH₄ and NH₃ emissions. After field application, there were no significant differences between slurry types in GHG emissions (4.15–8.12 kg CO₂ eq. m⁻³ a⁻¹). GHG emissions from slurry stores were more important than emissions after field application. Co-digestion of slurry with additives such as starch has a large potential to substitute fossil energy by biogas. On a biogas plant, slurry stores should be covered gas-tight in order to eliminate GHG emissions and collect CH₄ for electricity production.     

Operational change as a profitable cleaner production tool for a brewery

The development and implementation of new procedures and operational changes in the production processes constitutes a powerful tool for the practical application of Cleaner Production in industries. In this work an operational change (new procedure) was developed for the elaboration of a type of beer which uses sugar as malt adjunct. The change consists in processing separately the three main components of the beer wort: malt extract, sugar and water, and use them properly in a different sequence than that used up to date in the traditional process. The new procedure was successfully assayed on industrial scale in Tínima brewery, located in Camagüey, Cuba, obtaining a good quality beer, technological and economical advantages with benefits for the environment, registering significant savings in energy (49%), sugar (4%), water (7%) and caustic soda (3%) consumption; and diminishing the surplus hot water (74%), waste generation (11%) and greenhouse gases emission (21%). Beer production capacity is increased also almost three times. With the application of the new technology to the Cuban beer type of 8 °P, it was achieved a total saving of US$ 481.83/1000 hL of beer produced.     

The water footprint of food waste: case study of fresh mango in Australia

In many parts of the world, freshwater is already a scarce and overexploited natural resource, raising concerns about global food security and damage to freshwater ecosystems. This situation is expected to intensify with the FAO estimating that world food production must double by 2050. Food chains must therefore become much more efficient in terms of consumptive water use. For the small and geographically well-defined Australian mango industry, having an average annual production of 44,692 t of marketable fresh fruit, the average virtual water content (sum of green, blue and gray water) at orchard gate was 2298 l kg^?1. However, due to wastage in the distribution and consumption stages of the product life cycle, the average virtual water content of 1 kg of Australian-grown fresh mango consumed by an Australian household was 5218 l. This latter figure compares to an Australian-equivalent water footprint of 217 l kg^?1, which is the volume of direct water use in Australia having an equivalent potential to contribute to water scarcity. Nationally, distribution and consumption waste in the food chain of Australian-grown fresh mango to Australian households represented an annual waste of 26.7 Gl of green water and 16.6 Gl of blue water. These findings suggest that interventions to reduce food chain waste will likely have as great or even greater impact on freshwater resource availability as other water use efficiency measures in agriculture and food production.     

Effects of grazing intensity and prescribed fire on soil physical and hydrological properties and pasture yield in the savanna woodlands of Burkina Faso

In West Africa policies for prescribed early fire and livestock grazing in the savanna woodlands are rarely based on long-term experimental studies. The inherently different management characteristics and their effects on the vegetation dynamics make landscape degradation a contentious issue. The effects of grazing intensity were investigated by a comparison of non-grazed areas, lightly grazed areas, moderately grazed areas, heavily grazed areas and very heavily grazed areas that received one of two fire treatments: early burning and fire protection in a long-term 12-year study. The parameters assessed reflected changes in herbaceous plant cover, biomass as well as soil physical and hydrological properties. The main findings were by and large specific for the grazing level. This supports the argument for devolution of management responsibility to the local level where there is indigenous site-specific knowledge but at the same time insufficient management capacity.A comparison of composite soil samples taken at a depth of 0–10 cm did not differentiate significantly between treatments. This is probably because the composite soil sampling procedure hid the properties of the top first few centimeters. Grazing pressure had a tendency to reduce total above ground biomass (p = 0.081). This was related to increased biomass removal and the trampling pressure (static load) exerted by the animals. The infiltration measurements indicated that the deleterious impact of cattle trampling increased as stocking rate increased. Livestock grazing significantly (p = 0.038) lowered the infiltrability. Prescribed early fire had a tendency (p = 0.073) to reduce the soil water infiltration rate. The subplots subjected to prescribed burning had a lower steady state infiltration rate compared to unburnt areas (means of 49.2 ± 27.5 mm h⁻¹ versus 78 ± 70.5 mm h⁻¹ for burnt and unburnt subplots, respectively). A partial least squares projection to latent structures showed that 34% of the steady state infiltrability was explained by the stocking rate and soil organic matter. Also all soil characteristics were significantly connected to steady state infiltrability suggesting that they are related to the soil hydrological response to trampling.From a management perspective, adoption of a short duration grazing system should avoid high stocking rates because they may adversely affect soil infiltrability, increase susceptibility to erosion in the savannas and decrease biomass productivity.     

Material flows in the life cycle of leather

This paper presents a study on the resource and environmental profile of leather for communicating to the consumers about the environmental burdens of leather products. The results indicate that significant environmental impacts were caused during the tanning and finishing of leather as well as the electricity production and transportation required in the life cycle. The use of fossil fuels in the production of energy has greater impact with increased emissions leading to about 15190 kg CO₂ equivalent of global warming and about 73 kg SO₂ equivalent of acidification while producing 100 m² of leather for shoe uppers. Further resource use of 174 kg of coal, 6.5 kg of fuel oil, 17.4 m³ of water and 348 kg of chemicals of which about 204 kg are hazardous are consumed, and wastewater of about 17 m³, BOD of 55 kg, COD of about 146 kg, TDS of 732 kg and solid waste of about 1445 kg are generated during the life cycle for the production of 100 m² of leather. The total solid waste generated is 1317 kg, out of which about 80% is biodegradable contributed by slaughtering, tanning and finishing stage, 14% is non-biodegradable contributed by tanning, finishing and electricity production stages and 6% is hazardous mainly from tanning and finishing stage of leather.     

Biogas production from maize and dairy cattle manure—Influence of biomass composition on the methane yield

There is an increasing world wide demand for energy crops and animal manures for biogas production. To meet these demands, this research project aimed at optimising anaerobic digestion of maize and dairy cattle manures. Methane production was measured for 60 days in 1 l eudiometer batch digesters at 38 °C. Manure received from dairy cows with medium milk yield that were fed a well balanced diet produced the highest specific methane yield of 166.3 Nl CH₄ kg VS⁻¹. Thirteen early to late ripening maize varieties were grown on several locations in Austria. Late ripening varieties produced more biomass than medium or early ripening varieties. On fertile locations in Austria more than 30 Mg VS ha⁻¹ can be produced. The methane yield declined as the crop approaches full ripeness. With late ripening maize varieties, yields ranged between 312 and 365 Nl CH₄ kg VS⁻¹ (milk ripeness) and 268–286 Nl CH₄ kg VS⁻¹ (full ripeness). Silaging increased the methane yield by about 25% compared to green, non-conserved maize. Maize (Zea mays L.) is optimally harvested, when the product from specific methane yield and VS yield per hectare reaches a maximum. With early to medium ripening varieties (FAO 240–390), the optimum harvesting time is at the “end of wax ripeness”. Late ripening varieties (FAO ca. 600) may be harvested later, towards “full ripeness”. Maximum methane yield per hectare from late ripening maize varieties ranged between 7100 and 9000 Nm³ CH₄ ha⁻¹. Early and medium ripening varieties yielded 5300–8500 Nm³ CH₄ ha⁻¹ when grown in favourable regions. The highest methane yield per hectare was achieved from digestion of whole maize crops. Digestion of corns only or of corn cob mix resulted in a reduction in methane yield per hectare of 70 and 43%, respectively. From the digestion experiments a multiple linear regression equation, the Methane Energy Value Model, was derived that estimates methane production from the composition of maize. It is a helpful tool to optimise biogas production from energy crops. The Methane Energy Value Model requires further validation and refinement.