Recent developments in Life Cycle Assessment.

The interest in using Jatropha curcas L. (JCL) as a feedstock for the production of bio-diesel is rapidly growing. The properties of the crop and its oil have persuaded investors, policy makers and clean development mechanism (CDM) project developers to consider JCL as a substitute for fossil fuels to reduce greenhouse gas emissions. However, JCL is still a wild plant of which basic agronomic properties are not thoroughly understood and the environmental effects have not been investigated yet. Gray literature reports are very optimistic on simultaneous wasteland reclamation capability and oil yields, further fueling the Jatropha bio-diesel hype. In this paper, we give an overview of the currently available information on the different process steps of the production process of bio-diesel from JCL, being cultivation and production of seeds, extraction of the oil, conversion to and the use of the bio-diesel and the by-products. Based on this collection of data and information the best available practice, the shortcomings and the potential environmental risks and benefits are discussed for each production step. The review concludes with a call for general precaution and for science to be applied. (C) 2008 Elsevier Ltd. All rights reserved.

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Jatropha bio-diesel production and use

The safe disposal of human excreta is of paramount importance for the health and welfare of populations living in low income countries as well as the prevention of pollution to the surrounding environment. On-site sanitation (OSS) systems are the most numerous means of treating excreta in low income countries, these facilities aim at treating human waste at source and can provide a hygienic and affordable method of waste disposal. However, current OSS systems need improvement and require further research and development. Development of OSS facilities that treat excreta at, or close to, its source require knowledge of the waste stream entering the system. Data regarding the generation rate and the chemical and physical composition of fresh feces and urine was collected from the medical literature as well as the treatability sector. The data were summarized and statistical analysis was used to quantify the major factors that were a significant cause of variability. The impact of this data on biological processes, thermal processes, physical separators, and chemical processes was then assessed. Results showed that the median fecal wet mass production was 128 g/cap/day, with a median dry mass of 29 g/cap/day. Fecal output in healthy individuals was 1.20 defecations per 24 hr period and the main factor affecting fecal mass was the fiber intake of the population. Fecal wet mass values were increased by a factor of 2 in low income countries (high fiber intakes) in comparison to values found in high income countries (low fiber intakes). Feces had a median pH of 6.64 and were composed of 74.6% water. Bacterial biomass is the major component (25-54% of dry solids) of the organic fraction of the feces. Undigested carbohydrate, fiber, protein, and fat comprise the remainder and the amounts depend on diet and diarrhea prevalence in the population. The inorganic component of the feces is primarily undigested dietary elements that also depend on dietary supply. Median urine generation rates were 1.42 L/cap/day with a dry solids content of 59 g/cap/day. Variation in the volume and composition of urine is caused by differences in physical exertion, environmental conditions, as well as water, salt, and high protein intakes. Urine has a pH 6.2 and contains the largest fractions of nitrogen, phosphorus, and potassium released from the body. The urinary excretion of nitrogen was significant (10.98 g/cap/day) with urea the most predominant constituent making up over 50% of total organic solids. The dietary intake of food and fluid is the major cause of variation in both the fecal and urine composition and these variables should always be considered if the generation rate, physical, and chemical composition of feces and urine is to be accurately predicted.

/pdf/the-characterization-of-feces-and-urine-a-review-of-the-48jlbpxv0z.pdf

The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1012&context=wffdocs

The challenges of wastewater irrigation in developing countries

Energy balances are analysed from a life-cycle perspective for biogas systems based on 8 different raw materials. The analysis is based on published data and relates to Swedish conditions. The results show that the energy input into biogas systems (i.e. large-scale biogas plants) overall corresponds to 20–40% (on average approximately 30%) of the energy content in the biogas produced. The net energy output turns negative when transport distances exceed approximately 200 km (manure), or up to 700 km (slaughterhouse waste). Large variations exist in energy efficiency among the biogas systems studied. These variations depend both on the properties of the raw materials studied and on the system design and allocation methods chosen. The net energy output from biogas systems based on raw materials that have high water content and low biogas yield (e.g. manure) is relatively low. When energy-demanding handling of the raw materials is required, the energy input increases significantly. For instance, in a ley crop-based biogas system, the ley cropping alone corresponds to approximately 40% of the energy input. Overall, operation of the biogas plant is the most energy-demanding process, corresponding to 40–80% of the energy input into the systems. Thus, the results are substantially affected by the assumptions made about the allocation of a plant's entire energy demand among raw materials, e.g. regarding biogas yield or need of additional water for dilution.

Assessment of energy performance in the life-cycle of biogas production

http://kth.diva-portal.org/smash/get/diva2:14398/FULLTEXT01

Municipal solid waste management from a systems perspective

A simulation model, ORWARE (ORganic WAste REsearch) is described. The model is mainly used as a tool for researchers in environmental systems analysis of waste management. It is a computer-based mo ...

ORWARE - a simulation tool for waste management.

Biomass produced on farm land is a renewable fuel that can prove suitable for small-scale combined heat and power (CHP) plants in rural areas. However, it can still be questioned if biomass-based energy generation is a good environmental choice with regards to the impact on greenhouse gas emissions, and if there are negative consequences of using of agricultural land for other purposes than food production. In this study, a simplified life cycle assessment (LCA) was conducted over four scenarios for supply of the entire demand of power and heat of a rural village. Three of the scenarios are based on utilization of biomass in 100 kW (e) combined heat and power (CHP) systems and the fourth is based on fossil fuel in a large-scale plant. The biomass systems analyzed were based on 1) biogas production with ley as substrate and the biogas combusted in a microturbine, 2) gasification of willow chips and the product gas combusted in an IC-engine and 3) combustion of willow chips for a Stirling engine. The two first scenarios also require a straw boiler. The results show that the biomass-based scenarios reduce greenhouse gas emissions considerably compared to the scenario based on fossil fuel, but have higher acidifying emissions. Scenario 1 has by far the best performance with respect to global warming potential and the advantage of utilizing a byproduct and thus not occupying extra land. Scenario 2 and 3 require less primary energy and less fossil energy input than 1, but set-aside land for willow production must be available. The low electric efficiency of scenario 3 makes it an unsuitable option.

Biomass from agriculture in small-scale combined heat and power plants : A comparative life cycle assessment

When analysing new types of sewage systems, knowledge is needed on the composition of the different wastewater fractions. The computer model URWARE, developed from the model ORWARE, is intended to analyse and compare different wastewater system structures, e.g. to compare wastewater systems where urine and/or faeces are source separated with conventional wastewater systems, where the different wastewater fractions are mixed with each other. To use URWARE for this purpose, knowledge was needed on the composition of the wastewater fractions urine, faeces and household greywater. Sometimes the compostable household waste is mixed into the wastewater by use of a food waste disposer and thus also the composition of the solid compostable household waste is needed. Thus, the objective of the present report was to collect the knowledge on the mass and composition of urine, faeces, greywater and compostable household waste in Sweden. (Less)

https://www.iea.lth.se/publications/Reports/LTH-IEA-7222.pdf

Andras Baky

Papers

Municipal solid waste management from a systems perspective

ORWARE - a simulation tool for waste management.

Biomass from agriculture in small-scale combined heat and power plants : A comparative life cycle assessment

Composition of Urine, Feaces, Greywater and Biowaste for Utilisation in the URWARE Model

Use of on-farm produced biofuels on organic farms - evaluation of energy balances and environmental loads for three possible fuels.