Xavier Gabarrell

Roof selection for rainwater harvesting: Quantity and quality assessments in Spain

Roofs are the first candidates for rainwater harvesting in urban areas. This research integrates quantitative and qualitative data of rooftop stormwater runoff in an urban Mediterranean-weather environment. The objective of this paper is to provide criteria for the roof selection in order to maximise the availability and quality of rainwater. Four roofs have been selected and monitored over a period of 2 years (2008-2010): three sloping roofs - clay tiles, metal sheet and polycarbonate plastic - and one flat gravel roof. The authors offer a model for the estimation of the runoff volume and the initial abstraction of each roof, and assess the physicochemical contamination of roof runoff. Great differences in the runoff coefficient (RC) are observed, depending mostly on the slope and the roughness of the roof. Thus, sloping smooth roofs (RC>0.90) may harvest up to about 50% more rainwater than flat rough roofs (RC=0.62). Physicochemical runoff quality appears to be generally better than the average quality found in the literature review (conductivity: 85.0 ± 10.0 μS/cm, total suspended solids: 5.98 ± 0.95 mg/L, total organic carbon: 11.6 ± 1.7 mg/L, pH: 7.59 ± 0.07 upH). However, statistically significant differences are found between sloping and flat rough roofs for some parameters (conductivity, total organic carbon, total carbonates system and ammonium), with the former presenting better quality in all parameters (except for ammonium). The results have an important significance for local governments and urban planners in the (re)design of buildings and cities from the perspective of sustainable rainwater management. The inclusion of criteria related to the roofs slope and roughness in city planning may be useful to promote rainwater as an alternative water supply while preventing flooding and water scarcity.

LCA of selective waste collection systems in dense urban areas

This paper presents research concerning the environmental analysis of the selective collection management of municipal solid waste. The main goal of this study is to quantify and to compare, by means of Life Cycle Assessment (LCA), the potential environmental impacts of three selective collection systems modelled on densely populated urban areas. These systems are: the mobile pneumatic, the multi-container and the door-to-door. Impact assessment method based on CML 2 baseline 2000 is applied to the different systems. The study separates and analyzes the collection systems in substages: two urban substages and one inter-city substage. At the urban level, the multi-container system has the least environmental impact of all systems. The mobile pneumatic system has greater environmental impacts in terms of global warming, fresh water aquatic ecotoxicity, terrestrial ecotoxicity, acidification and eutrophication. In this system, the pipes and the pneumatic transport have the greatest impacts. The door-to-door system has a greatest environmental impact in terms of abiotic depletion, ozone layer depletion and human toxicity. An overall evaluation of the three substages, with a sensitivity analysis, indicates that the mobile pneumatic system at an inter-city distance of 20 km shows the greatest environmental impacts and the greatest energy demand. Inter-city transport is key; the results show that from an inter-city distance of 11 km onwards, this becomes the substage which most contributes to global warming impact and energy demand, in all the systems.

The use of life cycle assessment for the comparison of biowaste composting at home and full scale.

Environmental impacts and gaseous emissions associated to home and industrial composting of the source-separated organic fraction of municipal solid waste have been evaluated using the environmental tool of life cycle assessment (LCA). Experimental data of both scenarios were experimentally collected. The functional unit used was one ton of organic waste. Ammonia, methane and nitrous oxide released from home composting (HC) were more than five times higher than those of industrial composting (IC) but the latter involved within 2 and 53 times more consumption or generation of transport, energy, water, infrastructures, waste and Volatile Organic Compounds (VOCs) emissions than HC. Therefore, results indicated that IC was more impacting than HC for four of the impact categories considered (abiotic depletion, ozone layer depletion, photochemical oxidation and cumulative energy demand) and less impacting for the other three (acidification, eutrophication and global warming). Production of composting bin and gaseous emissions are the main responsible for the HC impacts, whereas for IC the main contributions come from collection and transportation of organic waste, electricity consumption, dumped waste and VOCs emission. These results suggest that HC may be an interesting alternative or complement to IC in low density areas of population.

Life cycle assessment of biogas upgrading technologies

This article evaluates the life cycle assessment (LCA) of three biogas upgrading technologies. An in-depth study and evaluation was conducted on high pressure water scrubbing (HPWS), as well as alkaline with regeneration (AwR) and bottom ash upgrading (BABIU), which additionally offer carbon storage. AwR and BABIU are two novel technologies that utilize waste from municipal solid waste incinerators - namely bottom ash (BA) and air pollution control residues (APC) - and are able to store CO(2) from biogas through accelerated carbonation processes. These are compared to high pressure water scrubbing (HPWS) which is a widely used technology in Europe. The AwR uses an alkaline solution to remove the CO(2) and then the solution - rich in carbonate and bicarbonate ions - is regenerated through carbonation of APC. The BABIU process directly exposes the gas to the BA to remove and immediately store the CO(2), again by carbonation. It was determined that the AwR process had an 84% higher impact in all LCA categories largely due to the energy intensive production of the alkaline reactants. The BABIU process had the lowest impact in most categories even when compared to five other CO(2) capture technologies on the market. AwR and BABIU have a particularly low impact in the global warming potential category as a result of the immediate storage of the CO(2). For AwR, it was determined that using NaOH instead of KOH improves its environmental performance by 34%. For the BABIU process the use of renewable energies would improve its impact since accounts for 55% of the impact.

Environmental analysis of rainwater harvesting infrastructures in diffuse and compact urban models of Mediterranean climate

PurposeAt present, many urban areas in Mediterranean climates are coping with water scarcity, facing a growing water demand and a limited conventional water supply. Urban design and planning has so far largely neglected the benefits of rainwater harvesting (RWH) in the context of a sustainable management of this resource. Therefore, the purpose of this study was to identify the most environmentally friendly strategy for rainwater utilization in Mediterranean urban environments of different densities.Materials and methodsThe RWH systems modeled integrate the necessary infrastructures for harvesting and using rainwater in newly constructed residential areas. Eight scenarios were defined in terms of diffuse (D) and compact (C) urban models and the tank locations ((1) underground tank, (2) below-roof tank, (3) distributed-over-roof tank, and (4) block tank). The structural and hydraulic sizing of the catchment, storage, and distribution subsystems was taken into account using an average Mediterranean rainfall, the area of the harvesting surfaces, and a constant water demand for laundry. The quantification of environmental impacts was performed through a life cycle assessment, using CML 2001 Baseline method. The necessary materials and processes were considered in each scenario according to the lifecycle stages (i.e., materials, construction, transportation, use, and deconstruction) and subsystems.Results and discussionThe environmental characterization indicated that the best scenario in both urban models is the distributed-over-roof tank (D3, C3), which provided a reduction in impacts compared to the worst scenario of up to 73% in diffuse models and even higher in compact ones, 92% in the most dramatic case. The lower impacts are related to the better distribution of tank weight on the building, reducing the reinforcement requirements, and enabling energy savings. The storage subsystem and the materials stage contributed most significantly to the impacts in both urban models. In the compact density model, the underground-tank scenario (C1) presented the largest impacts in most categories due to its higher energy consumption. Additionally, more favorable environmental results were observed in compact densities than in diffuse ones for the Global Warming Potential category along with higher water efficiencies.ConclusionsThe implementation of one particular RWH scenario over another is not irrelevant in drought-stress environments. Selecting the most favorable scenario in the development of newly constructed residential areas provides significant savings in CO2 emissions in comparison with retrofit strategies. Therefore, urban planning should consider the design of RWH infrastructures using environmental criteria in addition to economic, social, and technological factors, adjusting the design to the potential uses for which the rainwater is intended.Recommendations and perspectivesAdditional research is needed to quantify the energy savings associated with the insulation caused by using the tank distributed over the roof. The integration of the economic and social aspects of these infrastructures in the analysis, from a life cycle approach, is necessary for targeting the planning and design of more sustainable cities in an integrated way.

LCA comparison of container systems in municipal solid waste management

The planning and design of integrated municipal solid waste management (MSWM) systems requires accurate environmental impact evaluation of the systems and their components. This research assessed, quantified and compared the environmental impact of the first stage of the most used MSW container systems. The comparison was based on factors such as the volume of the containers, from small bins of 60-80l to containers of 2400l, and on the manufactured materials, steel and high-density polyethylene (HDPE). Also, some parameters such as frequency of collections, waste generation, filling percentage and waste container contents, were established to obtain comparable systems. The methodological framework of the analysis was the life cycle assessment (LCA), and the impact assessment method was based on CML 2 baseline 2000. Results indicated that, for the same volume, the collection systems that use HDPE waste containers had more of an impact than those using steel waste containers, in terms of abiotic depletion, global warming, ozone layer depletion, acidification, eutrophication, photochemical oxidation, human toxicity and terrestrial ecotoxicity. Besides, the collection systems using small HDPE bins (60l or 80l) had most impact while systems using big steel containers (2400l) had less impact. Subsequent sensitivity analysis about the parameters established demonstrated that they could change the ultimate environmental impact of each waste container collection system, but that the comparative relationship between systems was similar.

Home composting versus industrial composting: Influence of composting system on compost quality with focus on compost stability

Stability is one of the most important properties of compost obtained from the organic fraction of municipal solid wastes. This property is essential for the application of compost to land to avoid further field degradation and emissions of odors, among others. In this study, a massive characterization of compost samples from both home producers and industrial facilities is presented. Results are analyzed in terms of chemical and respiration characterizations, the latter representing the stability of the compost. Results are also analyzed in terms of statistical validation. The main conclusion from this work is that home composting, when properly conducted, can achieve excellent levels of stability, whereas industrial compost produced in the studied facilities can also present a high stability, although an important dispersion is found in these composts. The study also highlights the importance of respiration techniques to have a reliable characterization of compost quality, while the chemical characterization does not provide enough information to have a complete picture of a compost sample.

Olive oil mill waste waters decoloration and detoxification in a bioreactor by the white rot fungus Phanerochaete flavido-alba.

Olive oil mill wastewater (OMW) is produced as waste in olive oil extraction. With the purpose of treating this highly polluting waste, a number of experiments were conducted in a laboratory‐scale bioreactor with the white rot fungus Phanerochaete flavido‐alba ( P. flavido‐alba). It is known that this fungus is capable of decolorizing OMW in static or semistatic cultures at Erlenmeyer scale and at 30 °C. The objective of this work was to prove that P. flavido‐alba could decolorize OMW in submerged cultures and that it is capable of reducing OMW toxicity at room temperature (25 °C) and in a laboratory‐scale bioreactor. In the experiments conducted, manganese peroxidase (MnP) and laccase enzymes were detected; however, unlike other studies, lignin peroxidase was not found to be present. Decoloration obtained after treatment was 70%. The reduction of aromatic compounds obtained was 51%, and the toxicity of the culture medium was reduced by up to 70%. We can therefore state that P. flavido‐alba is capable of reducing important environmental parameters of industrial effluents and that prospects are positive for the use of this process at a larger scale, even when working at room temperature.

Service Sector Metabolism: Accounting for Energy Impacts of the Montjuic Urban Park in Barcelona

This article evaluates, from an industrial ecology (IE) perspective, the energy performance of the services inside an urban system and determines their global environmental impact. Additionally, this study determines which are the most energy demanding services and the efficiency of their energy use per visitor and per surface area unit. The urban system under study is the Montjuic urban park in Barcelona, Catalonia, Spain, which can be considered a services system. In this case study we distinguished the different patterns of consumption among the service fields and, by studying each field individually, found the most efficient facilities and identified the most critical services based on energy use per visitor or per square meter. These findings are based on the use of energy flow accounting (EFA), life‐cycle assessment (LCA), and the energy footprint to analyze the Parks technical energy consumption. Electricity consumption represents nearly 70% of the total energy consumed by the services at Montjuic Park. The forest surface area required to absorb the CO2‐equivalent emissions produced by the life cycle of the energy consumed at Montjuic Park represents 12.2 times the Parks surface area. We conclude this article by proposing the incorporation of the methods of IE within the study of parks containing multiple services to improve energy management, and as a result, to raise the global environmental performance of the service sector.

Eco-innovation of a wooden childhood furniture set: An example of environmental solutions in the wood sector

The environmental profile of a set of wood furniture was carried out to define the best design criteria for its eco-design. A baby cot convertible into a bed, a study desk and a bedside table were the objects of study. Two quantitative and qualitative environmental approaches were combined in order to propose improvement alternatives: Life Cycle Assessment (LCA) and Design for Environment (DfE). In the first case Life Cycle Assessment (LCA) was applied to identify the hot spots in the product system. As a next step, LCA information was used in eco-briefing to determine several improvement alternatives. A wood products company located in Catalonia (NE Spain) was assessed in detail, dividing the process into three stages: assembly, finishing and packaging. Ten impact categories were considered in the LCA study: abiotic depletion, acidification, eutrophication, global warming, ozone layer depletion, human toxicity, fresh water aquatic ecotoxicity, marine aquatic ecotoxicity, terrestrial ecotoxicity and photochemical oxidant formation. Two processes can be considered the key environmental factors: the production of the wooden boards and electricity, with contributions of 45-68% and 14-33% respectively depending on the impact categories. Subsequently, several improvement alternatives were proposed in the eco-design process (DfE) to achieve reductions in a short-medium period of time in the environmental impact. These eco-design strategies could reduce the environmental profile of the setup by 14%. The correct methodological adaptation of the concept of eco-briefing, as a tool for communication among environmental technicians and designers, the simplification of the analytical tool used and the LCA, could facilitate the environmental analysis of a product. The results obtained provide information that can help the furniture sector to improve their environmental performance.