Environmental implications of stored cattle slurry treatment with sulphuric acid and biochar: A life cycle assessment approach.

With the increase of animal slurry produced from livestock production, the monitoring and mitigation of greenhouse gas (GHG) and ammonia (NH3) emissions represent a major issue. Life cycle assessment (LCA) has been used to evaluate the long-term environmental effects of applied strategies and technologies on cattle slurry management for mitigation of environmental harmful gases. This study was carried on two main aims: first, the effect of the addition of sulphuric acid (SA), biochar (SBi) or A + Bi to liquid cattle-slurry (treated systems) on gas emissions during storage compared to the untreated system (S) was investigated in a laboratory-controlled experiment; second, the environmental implications of each treated or untreated system were assessed through a LCA approach according to ISO 14040/44. Five CML 2001 impact categories were used: eutrophication potential (EP), acidification potential (AP), global warming potential (GWP), human toxicity potential (HTP) and Ozone Layer Depletion Potential (ODP). Comparisons were based on 1 ton fresh dairy cattle slurry. The environmental profile of untreated system showed lower efficiency in mitigation of total GHG and NH3 emissions (0.0312 and 0.0001 kg CO2-eq respectively), during storage period and greater impact on GWP and HTP categories. The electricity consumption in mechanical separation dominated the environmental impacts. From the three proposed treated systems, SA showed the highest efficiency on mitigation of gas emissions compared to the other treatments, reducing NH3, CH4 and CO2 emissions respectively in 61%, 98% and 15%, when compared to the SBi system. In all categories, acidified slurry also showed the lowest environmental impact relative to other treated systems and the benefit was more evident when the impacts were expressed per kilogram of nitrogen in the slurry. Therefore, LCA methodology was of great importance to assess the environmental implications of the treatments and acidification can be considered as an effective technique on the mitigation of environmental implications of livestock production and cattle-effluent valorization. Optimization and uniformity of performed studies are essential to validate new strategies to improve the sustainability of this sector in the management of animal wastewater.

Impact of different treatments on Escherichia coli during storage of cattle slurry.

There are different types of effluents from farming operations including untreated slurry (a mixture of manure, urine, split feed, and water), and treated slurry that normally is filtered to separate the solid fraction from the liquid fraction. With the amount of slurry applied on the soils as fertiliser every year, there are necessary to measure the leaching of microbial capable of transmitting infective agents that can be normally on slurry, because slurry can be a potential biohazard capable of transmitting infective agents. The aim of this study was to investigate the presence and survival of Escherichia coli (E. coli) on liquid fraction of dairy slurry, with the addition of different treatments during storage, such as addition of Biochar, beneficial microorganisms, sulphuric acid and the combinations of them. All the applied treatments to slurry show statistically significant differences (P < 0.001), according to the different sampling dates. Results showed that there are conditions and treatments that benefit the survival probability of E. coli, the treatments that include the acidification of slurry have the highest averages of CFU/ml (243288.3 at 37 °C; 136584 at 44 °C). These results can contribute to the improvement of the quality of slurry applied on soils, beneficiating agriculture but also public health.

Life cycle analysis of a new modular greening system.

The construction and use of buildings represent about half of the extracted materials and energy consumption, and around one third of the water consumption and waste produced in the European Union. Therefore it is becoming more important to use sustainable materials that reduce the environmental impacts of construction, by conserving and using resources more efficiently. Green walls can be used as a sustainable strategy to reduce the environmental impact of buildings. The aim of this study is to evaluate the environmental impact of a new modular system for green roofs and green walls (Geogreen) which uses waste and sustainable materials in its composition. A life cycle analysis (LCA) is used to evaluate the long term environmental benefits of this system. The life cycle analysis (LCA) is carried according to ISO 14040/44 using GaBi software and CML 2001 impact category indicators. The adopted functional unit is the square meter of each material required to assemble the Geogreen system. This study also compares the environmental performance of the Geogreen system with other living wall systems and other cladding materials using data from the literature. This LCA study of the Geogreen system became relevant to identify a curing process with a major impact on GWP due to the energy consumed in this process. A change on this process allowed reducing 74% of the overall GWP. After this change it can be noticed that the Geogreen System presents one of the lowest environmental burden when compared to other construction systems.

Assessment strategies for municipal selective waste collection schemes.

An important strategy to promote a strong sustainable growth relies on an efficient municipal waste management, and phasing out waste landfilling through waste prevention and recycling emerges as a major target. For this purpose, effective collection schemes are required, in particular those regarding selective waste collection, pursuing a more efficient and high quality recycling of reusable materials. This paper addresses the assessment and benchmarking of selective collection schemes, relevant to guide future operational improvements. In particular, the assessment is based on the monitoring and statistical analysis of a core-set of performance indicators that highlights collection trends, complemented with a performance index that gathers a weighted linear combination of these indicators. This combined analysis underlines a potential tool to support decision makers involved in the process of selecting the collection scheme with best overall performance. The presented approach was applied to a case study conducted in Oporto Municipality, with data gathered from two distinct selective collection schemes.

Statistical analysis in MSW collection performance assessment.

The increase of Municipal Solid Waste (MSW) generated over the last years forces waste managers pursuing more effective collection schemes, technically viable, environmentally effective and economically sustainable. The assessment of MSW services using performance indicators plays a crucial role for improving service quality. In this work, we focus on the relevance of regular system monitoring as a service assessment tool. In particular, we select and test a core-set of MSW collection performance indicators (effective collection distance, effective collection time and effective fuel consumption) that highlights collection system strengths and weaknesses and supports pro-active management decision-making and strategic planning. A statistical analysis was conducted with data collected in mixed collection system of Oporto Municipality, Portugal, during one year, a week per month. This analysis provides collection circuits' operational assessment and supports effective short-term municipality collection strategies at the level of, e.g., collection frequency and timetables, and type of containers.