Francesc Castells

Environmental assessment of urban wastewater reuse: treatment alternatives and applications.

The main function of a Wastewater Treatment Plant is to minimize the environmental impact of discharging untreated water into natural water systems. Also a Wastewater Treatment Plant may get a resource from wastewater carrying out a tertiary treatment on the treated wastewater which can be reused in non-potable applications. Water reuse strategies are intended to address the problem of water scarcity without aggravating other environmental problems, thus reflecting the need of their environmental assessment. In this paper we used Life Cycle Assessment to evaluate different disinfection treatments (chlorination plus ultraviolet treatment, ozonation and ozonation plus hydrogen peroxide) and to assess the environmental advantages and drawbacks of urban wastewater reuse in non-potable applications. To do so, we compared the environmental impacts of producing 1m(3) of water for non-potable uses from reclaimed water, potable water and desalinated water sources. The calculation has used current operating data from a Wastewater Treatment Plant located in the Mediterranean area, although the results can be applied to any other plant with similar technology. The ozonation and ozonation plus hydrogen peroxide disinfection treatment technologies have similar environmental profiles. However most of the indicators are about 50% higher than the ultraviolet disinfection except for the acidification (100% higher) and photochemical oxidation (less than 5%). Non-potable uses (both agricultural and urban uses) of reclaimed water have environmental and economical advantages. Reuse of treated wastewater is particularly beneficial when it can replace desalinated water. Consequently, reclaimed water should be promoted for non-potable uses, when there is scarcity of freshwater.

Environmental performance of construction waste: Comparing three scenarios from a case study in Catalonia, Spain

The main objective of this paper is to evaluate environmental impacts of construction wastes in terms of the LIFE 98 ENV/E/351 project. Construction wastes are classified in accordance with the Life Program Environment Directive of the European Commission. Three different scenarios to current waste management from a case study in Catalonia (Spain) have been compared: landfilling, recycling and incineration, and these scenarios were evaluated by means of Life Cycle Assessment. The recommendations of the Catalan Waste Catalogue and the European Waste Catalogue have been taken into account. Also, the influence of transport has been evaluated. Results show that in terms of the Global Warming Potential, the most environmentally friendly treatment was recycling, followed by incineration and lastly landfilling. According to the influence of treatment plants location on the GWP indicator, we observe that incineration and recycling of construction wastes are better than landfilling, even for long distances from the building site to the plants. This is true for most wastes except for the stony types, than should be recycled close to the building site. In summary, data from construction waste of a Catalan case study was evaluated using the well established method of LCA to determine the environmental impacts.

LCA and tomato production in mediterranean greenhouses

LCA is used to analyse and evaluate the environmental impact associated with the process of greenhouse cultivation of a tomato crop. Tomato production in kg is selected as a functional unit. Three different tomato production processes were compared: soil cultivation and open and closed hydroponic systems. Three different waste management scenarios were also analysed. The most significant negative environmental impacts were identified, enabling the application of the most suitable technology in order to mitigate their effects. The main negative impact of greenhouse tomato production derives from the waste of biomass and plastics, therefore suitable waste management is the best practicable environmental option to reduce this. The composting of biodegradable matter is the best way of managing this kind of waste. Improving the material composition of structures and auxiliary materials is also advised. Lastly, more rational management criteria for the supply of nutrients to the crop will have to be found.

Life cycle assessment of two dwellings: one in Spain, a developed country, and one in Colombia, a country under development.

The main objective of this paper is to study and quantify the differences in energy consumption and environmental impacts of two dwellings during the full building life cycle: one in Spain, a developed country, and one in Colombia, a country under development. In both scenarios, we assessed the construction, use and end-of-life phases. Results show that the use phase in the Pamplona house (Colombia) represents a lower percentage for all impacts in the total than in the Barcelona house (Spain). The findings of this study showed that the difference in consumption in Colombia and Spanish dwellings analysed is not only due to the variation in results for bio-climatic differences but also because of the consumption habits in each country. The importance of consumption habits of citizens and the need to decouple socio-economic development from energy consumption are sought for achieving sustainability from a life cycle perspective. There is a crucial necessity to provide satisfaction to basic needs and comfort requirements of population with reasonable and sustainable energy consumption. Then, the type of standard dwelling varies substantially depending on the geographic location where it is built. Climate, technological, cultural, socio-economical differences clearly define the standard of a building in any context and in any region. However, the function is always the same, to provide protection and housing for its habitants.

Uptake and persistence of pesticides in plants: measurements and model estimates for imidacloprid after foliar and soil application.

The uptake and persistence behaviour of the insecticide imidacloprid in tomato plants treated by (i) foliar spray application and (ii) soil irrigation was studied using two plant uptake models. In addition to a pesticide deposition model, a dynamic root uptake and translocation model was developed, and both models predict residual concentrations of pesticides in or on fruits. The model results were experimentally validated. The fraction of imidacloprid ingested by the human population is on average 10(-2) to 10(-6), depending on the time between pesticide application and ingestion, the processing step, and the application method. Model and experimentally derived intake fractions deviated by less than a factor of 2 for both application techniques. Total imidacloprid residues were up to five times higher in plants treated by foliar spray application than by soil irrigation. However, peeling tomatoes treated by spray application reduces the human intake fraction by up to three orders of magnitude. Model calculations suggest that drip-irrigation in a closed hydroponic system minimizes worker and consumer exposure to pesticides and prevents runoff of pesticide by spray drift and leaching into the environment.

Life cycle inventory analysis of hydrogen production by the steam-reforming process: comparison between vegetable oils and fossil fuels as feedstock

A life cycle inventory analysis has been conducted to assess the environmental load, specifically CO2 (fossil) emissions and global warming potential (GWP), associated to the production of hydrogen by the steam reforming of hydrocarbon feedstocks (methane and naphtha) and vegetable oils (rapeseed oil, soybean oil and palm oil). Results show that the GWPs associated with the production of hydrogen by steam reforming in a 100 years time frame are 9.71 and 9.46 kg CO2-equivalent/kg H2 for natural gas and naphtha, respectively. For vegetable oils, the GWP decreases to 6.42 kg CO2-equivalent/kg H2 for rapeseed oil, 4.32 for palm oil and 3.30 for soybean oil. A dominance analysis determined that the part of the process that has the largest effect on the GWP is the steam reforming reaction itself for the fossil fuel-based systems, which accounts for 56.7% and 74% of the total GWP for natural gas and naphtha, respectively. This contribution is zero for vegetable oil-based systems, for which harvesting and oil production are the main sources of CO2-eq emissions.

Environmental assessment of the milk life cycle: The effect of packaging selection and the variability of milk production data

Milk is a very important part of our diet, which is why there is a wide variety of packaging alternatives with considerable local variants on the market. This study assesses the environmental impact of the commonest packaging options on the Spanish market and evaluates (from the point of view of global warming and acidification) the production of the various packaging materials and sizes and their final disposal (landfilling, incineration and recycling). For the two indicators studied (global warming and acidification) larger aseptic carton packages and recycling disposal have the best environmental impact. The global warming and acidification potential of the milk life cycle were also studied: milk production, transport (local conditions), packaging production and packaging disposal. Of the two indicators studied, the milk production stage has the largest impact on the milk life cycle. It should be taken into account that the impact of the milk production stage can vary considerably and has a significant influence on the global warming and acidification potential of the milk life cycle.

Alternatives for Reducing the Environmental Impact of the Main Residue from a Desalination Plant

One of the most important problems today is the scarcity of fresh water safe enough for human, industrial, and agricultural use. Desalination is an alternative source of fresh water supply in areas with severe problems of water availability. Desalination plants generate a huge amount of brine as the main residual from the plant (about 55% of collected seawater). Because of that, it is important to determine the best environmental option for the brine disposal. This article makes a global environmental analysis, under Spanish conditions, of a desalination plant and an environmental assessment of different final brine disposals, representing a range of the most common alternatives: direct disposal, wastewater treatment plant (WWTP) outflow dilution, and dilution with seawater. The environmental profile of the plant operation and a comparison of the brine final disposal alternatives were established by means of the life cycle assessment (LCA) methodology. From an analysis of the whole plant we observed that the highest environmental impact was caused by energy consumption, especially at the reverse osmosis stage, while the most relevant waste was brine. From an analysis of brine final disposal we have elaborated a comparison of the advantages and detriments of the three alternatives. As all of them might be suitable in different specific situations, the results might be useful in decisions about final brine disposal.

Geographical and technological differences in life cycle inventories shown by the use of process models for waste incinerators part I. technological and geographical differences

Goal and BackgroundGeographical and technological differences in Life Cycle Inventory data are an important source for uncertainty in the result of Life Cycle Assessments. Knowledge on their impact on the result of an LCA is scarce, and also knowledge on how to manage them in an LCA case study.ObjectiveGoal of this paper is to explore these differences for municipal solid waste incinerator plants, and to develop recommendations for managing technological and geographical differences.MethodologyThe paper provides a definition of technological and geographical differences, and analyses their possible impacts. In a case study, the differences are caused intentionally in ‘games’, by virtually transplanting incineration plants to a different location and by changing parameters such as the composition of the waste input incinerated. The games are performed by using a modular model for municipal solid waste incinerator plants. In each case, an LCA including an Impact Assessment is calculated to trace the impact of these changes, and the results are compared.ConclusionsThe conclusions of the paper are two-fold: (1) reduce the differences in inventory data where their impact on the result is high; where it is possible reducing them to a great extent, and the effort for performing the change acceptable; in the case of incineration plants: Adapt the flue gas treatment, especially a possible DeNOx step, to the real conditions; (2) make use of modular process models that allow adapting plant parameters to better meet real conditions, but be aware of possible modelling errors. The paper invites the scientific community to validate the model used for a waste incinerator plant, and suggest putting up similar models for other processes, preferably those of similar relevance for Life Cycle Inventories.

Economic and environmental effects of CO 2 taxation: an input-output analysis for Spain

The aim of this work is to investigate the direct and indirect effects of an environmental tax on Spanish products, based on their CO2 emission intensities. For this purpose, we apply environmental input-output (EIO) and price models. The short-term price effects of the introduction of tax on consumption prices, and its influence on consumers’ welfare, are determined. We also quantify the environmental impacts of such taxation in terms of the reduction in CO2 emissions. The results, based on the Spanish economy for the year 2007, show that sectors with a relatively poor environmental profile are subjected to high environmental tax rates. As a consequence, applying a CO2 tax on these sectors increases production prices and induces a slight increase in the Consumer Price Index, and a decrease in private welfare. In general, our analysis highlights that the environmental and economic goals cannot both be met at the same time with the environmental taxation, unless there is a way in which the public revenues could be used to compensate those who are negatively affected by the tax.