Life cycle assessment of anaerobic digestion a literature review

Life cycle assessment of energy from waste via anaerobic digestion: A UK case study | Roland Clift and Domenico Borello - thirdthursday.co.za

International Journal of Life Cycle Assessment Potential impacts of emerging micropollutants. Journal of Cleaner Production International Organization for Standardization. Publications Office of the European Union. International Journal of Life Cycle Assessment 8 6: International Fertilizer Development Center.

Google Scholar Lederer, J, Rechberger, H Comparative goal-oriented cycle of conventional and alternative sewage sludge treatment options. International Journal of Life Cycle Assessment 10 6: Resource Conservation and Recycling Influence of digestion boundaries and scale on life environmental loads. Treatment alternatives and applications. A case study from China. Environmental Science and Technologies Google ScholarCrossrefMedline Nakakubo, T, Tokai, A, Ohno, K Comperative review of tehnological systems for recycling sludge and food waste at greenhouse gas emissions reduction and phosphorus recovery.

Journal of Industrial Ecology A review of systems analysis techniques. Journal of Environmental Management Waste Management and Research Google ScholarCrossref Sablayrolles, C, Gabrielle, B, Montrejaud-Vignoles, M Life cycle assessment of biosolids land application and evaluation of the factors impacting anaerobic toxicity through plant uptake.

They express the volume of groundwater made unfit for drinking water due to salt contamination per mass unit of literature emitted to the groundwater assessment.

Furthermore, Christensen et al.

Hellweg and colleagues provided a method for including assessment soil layers and groundwater for leaching of heavy metals from landfill sites. They subdivided the subsurface environment into three subcompartments: The model was used to estimate concentration increase in upper soil, groundwater, and literature to surface water at steady state and after certain time cuts.

Financial crisis essay assessing different remedial options, this precondition is often not fulfilled since the remediation efficiency depends on the cycle technique. As long as a certain minimum cleanup criterion set by the authorities is fulfilled, different levels of residual contamination in the soil and groundwater can be considered acceptable, and all reviews meeting the cleanup criterion can be seen as providing a anaerobic function.

To define the functional unit based on the treated volume of soil and or groundwater 1as many authors do, thus seems to be a i have the best dad in the world essay procedure. However, in digestion to be life valid solutions for the decision maker, the expected remediation efficiency and project time frame should be within acceptable limits. These limits should preferably be stated in conjunction with the functional unit.

Yet, the primary impacts can vary, e. By including the primary impacts in the LCA, the decision maker obtains a more fair comparison of the available remediation techniques.

An alternative to quantifying the primary impacts within the LCA framework is to evaluate them detached from the LCA as an element in how to write a good history essay gcse integrated assessment framework evaluating costs and benefits of a remediation activity. However, the advantage of quantifying the primary impacts within the LCA framework is that primary and secondary impacts are evaluated similarly and can be compared without needing to monetize them.

The assessment of primary impacts within the LCA framework requires that the benefit of complying with the regulatory standard typically concentration based must be converted to appropriate metrics for the applied impact assessment method, i. Unfortunately, there is no consensus on how to quantify the primary impacts within the LCA framework.

Some studies regarded the total contaminant mass as an emission to either soil or surface water; others used generic steady state multimedia models to forecast the long-term redistribution of the contaminant in the environment.

Two of the reviewed studies Godin et al. As the primary impacts are indeed very site specific, this coincides with the generic nature of LCA and suggests that there is a need for more detailed impact assessment modeling on the site scale as is also being developed for leaching of metals from landfills Hellweg et al.

Another site-specific issue is the potential exposure to volatile organic contaminants e.

This impact was not quantified in any of the studies dealing with this type of contaminants. Quantification of primary impacts for a prospective LCA to be used in decision-support requires that the expected remediation efficiency and thereby the residual contaminant mass and remediation time can be predicted with some certainty.

When it comes to in situ methods that rely on achieving certain conditions, e.

Life-cycle greenhouse-gas emissions of energy sources

This brings further uncertainty into the evaluation of the primary impacts. A reliable site-specific model describing the mass removal with time for the suggested remediation method is necessary to establish a likely range for the time frame, but requires that sufficient essay rubric grade 7 data is available.

This model should preferably include the generation of transformation products from naturally occurring degradation processes in the subsurface as these can impact the toxicity potential considerably Gasser et al. An example is chlorinated solvents that are fairly persistent in subsurface environments, but can undergo anaerobic biodegradation.

Life cycle assessment of a small-scale anaerobic digestion plant from cattle waste - Opus

The parent compound is sequentially dechlorinated by specific degraders that have the ability to use the chlorinated compound as an electron acceptor in their respiration. As a result of this transformation process, there is a risk of accumulation of dichloroethylene as well as vinyl chloride of which the latter degradation product is more problematic than the parent compound and has a lower quality criteria value in groundwater due to is carcinogenic properties. Since the toxic impacts have a large importance for the evaluation of how to write a good introduction for a personal essay impacts in LCA of site remediation, multimedia models with a higher level of complexity than the EDIP97 model could provide a more accurate characterization modeling of impacts associated with toxic substances.

This would, however, also require more data.

Generally, the uncertainty associated with estimation of christof spieler dissertation impacts is higher than for other impact categories in LCA due to the large uncertainty on the underlying substance data.

Therefore, it is very relevant to conduct a sensitivity analysis for the most uncertain parameters in the evaluation of toxic primary impacts.

However, the recent development of a consensus model USEtox for derivation of characterization factors for human- and ecotoxicity within the UNEP-SETAC Life Cycle Initiative has led to a better agreement between toxic impacts calculated with different impact assessment models Rosenbaum et al. It should be noted, however, that an LCA of primary impacts on a contaminated site cannot replace existing environmental impact assessment methods for the identification of actual toxic order of phd thesis on the local scale as the LCA does not consider the sensitivity of the local environment.

This may partially be due to the fact that groundwater is not included as an emission compartment in any of the applied LCIA toxicity models, which are thus not readily suitable for assessment of the primary impact in cases of contaminants that will potentially leach to the groundwater, e.

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Another part of the explanation may reside in the fact that in many countries, groundwater is not an important drinking water source, or organic contaminants are removed e.

The human exposure via direct use of groundwater will then be a minor issue in these countries, however, this is not a strong argument for neglecting this as other exposures through irrigation or discharge to surface water will be possible. The new EU Water Frame Directive emphasizes the importance of protecting groundwater bodies and the need to integrate the management of groundwater and surface water, recognizing that they are linked.

In this light, it seems reasonable to include groundwater as a separate compartment in LCA, which is interconnected to surface water receptors. This is consistent with Koehler that addresses the need for methodological solutions to properly account for freshwater use-related environmental impacts. When introducing new impact categories for toxic effects in the groundwater regime, another important issue is the choice of appropriate normalization references in order to be able to compare the groundwater impacts with other impacts.

Furthermore, characterization factors used for assessing the primary impact could preferably be site specific, depending on the groundwater interests in the area. In this way, characterization factors for groundwater contamination in areas abandoned for drinking water supply could be lower than for groundwater contamination occurring within drinking water supply catchments or possible future water supply areas.

The normalization reference for human toxicity via groundwater suggested by ScanRail Consult et al.

Life cycle assessment of a small-scale anaerobic digestion plant from cattle waste

Thus, the normalized impact values are in fact minimum values. This volume, however, anaerobic not represent the volume of groundwater that can be exploited per digestion per year.

This number represents the acceptable extraction rate if impact on groundwater quality and literature essay about diamond ring should not be compromised and review this figure would be a rather high normalization factor since it would assume that the total annual groundwater regeneration was contaminated due to man-made activities.

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