Life Cycle Assessment of Membrane System for Wastewater Treatment: a Review and Further Research

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1 Applied Mechanics and Materials Online: ISSN: , Vol. 315, pp doi: / Trans Tech Publications, Switzerland Life Cycle Assessment of Membrane System for Wastewater Treatment: a Review and Further Research Salwa Mahmood, Muhamad Zameri Mat Saman a, Noordin Mohd Yusof Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, UTM Skudai Malaysia a zameri@fkm.utm.my Keywords: Life Cycle Assessment (LCA); Membrane System; Wastewater Treatment Abstract. Membrane technology has received increasing attention for the treatment of wastewaters lately. The use of membrane system showed high demand in industries. The Life Cycle Assessment (LCA) will be used to evaluate the environmental impacts of membrane system from raw materials, continues with product development and manufacturing, and finally ends when all materials are returned to earth. This paper presents a review of researchers on LCA, membrane manufacture and application to suggest corresponding further research direction. A methodology for sustainable assessment will be developed for membrane system for wastewater treatment for small and medium enterprise (SME). Introduction In recent years, sustainability issue became a high priority for wastewater treatment process. There is therefore a need to improve the sustainability of the industrial practice by taking sustainability elements; environmental, economical and social as important consideration. By 2025, nearly one third of the population will suffer from a water stress situation [1]. That is why membrane system is playing an important role for treatment of wastewaters and is particularly drawing attention on water recycling schemes [2]. The rapidly growing research works and awareness in this technology together with the declining trend in membrane costs further promotes the adoption of membrane treatment to deliver efficient water processing. Sustainable development has become an important environmental benchmark for wastewater treatment plants in chemical process industry. In this context, membrane system has been the method of choice in water treatment industry due to it is potential to deliver high quality water, thus the use of membrane technology for water supply, including reclamation, needs to be scrutinized in terms of ecological sustainability. This is in line with the government s newly introduced National Green Technology as to provide direction and motivation for Malaysians to continuously enjoy good quality living and a healthy environment [3]. In order to achieve sustainable membrane system, measurement of sustainability related to whole life cycle is needed. It is important to assess the emission through life cycle, reduce the environmental impact and maintain the quality and safety of the membrane system. This paper reviews the researches in the area of LCA of membrane system for wastewater treatment in order to develop a new methodology more effective. Literature Review LCA is a tool for the analysis of the environmental burdens of products or services at all stages of production, consumption and end of use. It is cover from cradle-to-grave [4]. The environmental burden includes all types of impacts to the environment including depletion of natural resources, energy consumption and also emission to land, water and air. Use of LCA could ensure that all environmental impacts are assessed within a consistent LCA framework to minimize the possibility of problem shifting. LCA can assist in: Identifying opportunities to improve the environmental performance of products at various points in their life cycle, Informing decision-makers in industry, government or non-government organizations (e.g. for the purpose of strategic planning, priority setting, product or process design or redesign), All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-05/03/16,21:46:08)

2 Applied Mechanics and Materials Vol Selection of relevant indicators of environmental performance, including measurement techniques and marketing (e.g. implementing an eco-labelling scheme, making an environmental claim, or producing an environmental products declaration). Previous studies of LCA as a tool for measuring environmental impact in various processes and system is shown in Table 1. One of the advantages of LCA is that LCA makes it possible to analyse different entities by a common yardstick so that the total energy and material inputs in construction, operation and demolition phases of the system can be analysed. It is often the case that an entity consists of multiple products and components and thus it is not possible to breakdown and adds all the parameters in each component of the entity [5]. Meanwhile, Table 2 also presents the previous studies of LCA but researchers had focused on filtration process and system for wastewater treatment. Based on these tables, it is can see that most of the researchers are focused purification of membrane application instead of life cycle on membrane system as a whole that could be higher source of environmental burdens. There are few studies on treatment for wastewater directly from manufacturing industry. But, majority of the researchers only focus on the application performance of the membrane application. Also some of the researchers only focus on the environmental impact without concerning the cost involved and society impact. Stated to date, a few studies have investigated the environmental effect of direct and indirect exposure and no clear guidelines exist to quantify these effects [21]. Table 1 Summary of the previous studies of LCA in general aspects Author/s Findings Joshi [6] LCA analyses and assesses environmental impacts over the entire life cycle of a product. LCA involves tracing out the major stages and processes involved over life cycle of a product / process/system covering raw materials extraction, manufacturing, product use, recycling and final disposal, identifying and quantifying relevant environmental impact at each stage. In addition, LCA aims to facilitate a system view in product and process evaluation. Ishii [7] The target of LCA varies from a single product to a system that consists of several processes, the final analysis depends largely on what have been counted in the analysis and what have been left out. LCA requires clarifying the boundaries of the analysis in order to avoid any misunderstandings. Since the original scope of LCA looks at holistic environmental impacts, it requires the consideration of many aspects (i.e. parameters) when it is used as a decision making tool. Sombekke LCA is one of the instruments for analysing the effect of activities on the environment. et al. [8] LCA deals with the environmental impact of a product in it are entire life cycle, comprising all the extraction from emission into the environment. LCA generates an environmental profile based on environmental themes such as global warming potential, SETAC [9] Olsen et al. [10] Pillay et al. [11] acidification, nitrification, and aquatic ecotoxity. LCA is an objective process to evaluate the environmental burdens associated with a product process or activity by identifying and quantifying energy and materials used and wastes released to the environment, to assess the impact of those energy and materials uses and releases on the environment, and to evaluate and implement opportunities to affect environmental improvements. LCA is environmental management tools that gains more and more ground and which often thought of as universal due to it is fundamental holistic philosophy to reduce environmental impact of product during their entire life cycle. LCA can be overlaps with other environmental management tools because they may benefits from each other in an overall environmental effort. LCA is a systematic way to evaluate the environmental impact of products or processes by following a cradle-to-grave approach. LCA is the process of evaluating the effects that a product has on the environment over the entire period of it is life cycle. It can be used through product design and process selection, to purchasing decisions and final disposal routes. In addition, LCA provides objectives answers to environmental questions while suggesting more sustainable forms of production and consumption.

3 188 Mechanical & Manufacturing Engineering Table 2 Summary of the previous studies of LCA on filtration process and system for wastewater treatment Author/Year Discussion/Findings Mahgoub et al. [12] This study focused on the assessment of environmental impact of Alexandria s urban water system and on the identification of option to improve the sustainability of the system by using LCA. The results show that the highest impact in today s system is generated by the disposal of primary treated wastewater and by high energy consuming water treatment plants. But only the operational phase of the infrastructure is taken into consideration in the LCA because it has the highest contribution to the total environment impact of the life cycle. Biswas [13] The analysis found that the equivalent of 3890 tons of CO2 could be emitted from the production of I GL of desalinate water. This LCA analysis has also identified that the reverse osmosis process would cause the most significant greenhouse emissions as a result of the electricity used if this is generated from fossil fields. The use of microfiltration and a split hybrid system has been found to provide significant environmental benefits. Vince et al. [14] Fane [15] Fujiwara [16] Tangsubkul et al. [17] Sala et al. This study presented of some potable water supply scenarios (groundwater treatment, ultrafiltration, nanofiltration, seawater reverse osmosis and thermal distillation associated to water transfer) in order to illustrate the environmental information drawn from Life Cycle Assessment (LCA) as a tool. From the studies, electricity production for plant operation shows the main source of impact. Improvement levers are presented for impact reduction and comparison between alternative and conventional water treatment process. This paper aims at developing a tool based on the LCA approach which could be used systematically for the environment evaluation of potable water production alternatives. This study discussed sustainability and membrane processing for wastewater reuse, at three levels from the macro to micro. Firstly the existing and potential role of membrane technology in sustaining water supplies, consider how technology stands up scrutiny in terms of sustainable development and address the concept of long term sustainable flux in application such as membrane bioreactors, where the challenges is to maintain operation in the presence of membrane fouling. This study covered the life cycle of a purification facility (i.e. materials, construction, operation, maintenance and control), and involved the calculation of lifecycle energy (LC-E) and lifecycle CO2 (LC-CO2) based on the application of inventory analysis as an element of LCA. Researchers found that it is necessary to consider the particular conditions, for these systems have different features and ambient environments e.g. the raw water quality and purification method. LCA offers the following benefits to the membrane industry when determining the optimal operating mode of a membrane microfiltration (MF) process: Allows environmental considerations to be incorporated into the technical planning and development of an MF process. The breakdown of the environmental impact contributions helps to identify factors that significantly contribute to each impact category. The LCA study explores different chemical cleaning scenarios and their associated environmental consequences. It was found that at low flux, the choice of chemical cleaning frequency can affect the overall environmental performance of the process. Quantitative environmental trade off found using LCA can help to justify options in membrane development that involve qualitative environmental concerns. For example, it has been found that operating MF at low flux tends to enhance the treatment performance of the process, however, the drawback is that at low flux (10-30 L/m2 h), more membrane modules are required hence incurring environmental cost. When a cleaner source of energy is used, operation at high fluxes becomes attractive. This study discussed issues as goals in water reuse and influence on water demands,

4 Applied Mechanics and Materials Vol [18] ecological analysis of the cycle of the main pollutants, health aspects and treatment requirements, energy consumption and measurable environmental benefits, in order to provide a set of criteria to assess sustainability in water recycling projects and to decrease the impact of the cultural water cycle on the environment. Pillay et al. [11] Parameshwar an et al. [2] Culaba et al. [19] Sombekke. et al. [20] This study conducted LCA studies to assess the environmental burdens of an industrial water recycling plants in Durban, South Africa. This study found that electricity generation is the dominant overall process for all impact categories considered. Therefore, it is important to look at electricity use and identify processes that have the highest consumption. The overall reduction of the electricity used in the system will reduce the environmental burdens of the system and will result in an improved environmental performance as measured by the LCA. The overall life cycle impacts of the membrane treatment process for different operating conditions need deliberate assessment as a step of optimization of membrane treatment operation. The environmentally optimum flux is shown to be much lower than the economic optimum flux. Researchers narrowed the idea behind modelling for sustainability is to use the methodology for LCA described in ISO and to incorporate procedures to assess the influences of waste minimization and materials recovery on the environmental performance of manufacturing systems. The methodology by using expert system that can operate on the basis of quantitative and qualitative information and may apply heuristic method (rules based on practical experience) to arrive at decision. Then, the software is structured and controls the flow of information in the Crystal software and linkage with the spread sheet. This study compared two groundwater treatment schemes for removing hardness and colour. First scheme is the conventional treatments by using pellet softening and granular activated carbon (GAC) and second by using nanofiltration. Specific decisions will only be accepted when choices are transparent and are based not only on quality and health aspects and costs, but also on environmental aspects (use of energy, chemicals),impact on landscape, political and public support. According to the panel, nanofiltration has more environmental impact, mainly because of the higher use of energy and the waste of groundwater (10%) in the form of membrane concentrate. Research Direction In membrane system for wastewater treatment, varieties of process take place. Therefore, it is necessary to analyse the whole life cycle to determine the overall pollution associated to these activities. Since the manufacturing process of hollow fibers membrane and system for wastewater treatment involves varieties of chemical, so LCA is needed to access the environmental burdens. The aims of overall environmental effort in chemical area is to reduce environmental and health hazardous effect of chemical substances and to maintain an acceptable standard for the environment [10]. The proposed research direction will be focus on developing a methodology for assessing the sustainability of membrane system for wastewater treatment. LCA will be used as a tool to classify and assess impact categories contributed in membrane system as a whole. From the system boundary, the sustainability parameters can be identified and classified in environmental, economy and social aspects. Parameters involved in the entire product life cycle will be obtained from primary and secondary data. Based on ISO 14040:2006, LCA standard framework can be divided into 4 major stages; goal and scope definition, inventory analysis, impact assessment, and interpretation. When performing an LCA, the requirement of ISO shall apply in this research. Table 3 shows the four major stages required. The purpose of the new methodology is to assess the environmental sustainability of the membrane system in order to improve the system sustainability. It is means balanced the sustainability for environmental, economical and social aspects. Conclusion This paper is aimed to propose the research direction for assessing the sustainability of membrane system as a whole. While literature on membrane technology is plenteous and growing, only few studies have explored on measurement of sustainability. There is no research done in measurement of sustainability for membrane system for wastewater treatment that considering sustainability elements; environmental, economical and social aspect in LCA analysis.

5 190 Mechanical & Manufacturing Engineering Acknowledgements The authors wish to thank the Ministry of Science, Technology and Innovation (MOSTI), UTM and Research Management Center, UTM for the financial support to this work through the Long Term Research Grant Scheme (LRGS) funding number R.J L804. Stages Goal and scope definition Inventory analysis Impact assessment Table 3 Four major stages required to apply ISO 14040:2006 Requirements Purpose of this study is to estimate the environmental aspects and potential impacts associates to membrane system as a whole view of the technology less aggressive and harmful for the environment. A system boundary of this study begins from extraction materials, manufacturing process, transportation, usage and end of life. Inventory analysis performing mass and energy balances to quantify all the material and energy inputs, wastes and emissions from the system, energy inputs and raw material inputs for hollow fibers membrane module is identified. Parameters involved will be obtained from primary and secondary data. From the whole process of hollow fibers membrane module manufacturing process, environmental burdens categories will be quantified. The damages cause on various environmental impacts will be measured. To date, there are available numerous approaches towards the life cycle Impact assessment (LCIA) which can be used including with the help of software programs that enable users to develop, store, analysed and exchange vast amounts of data related to products, services, processes, and their respective impacts. Interpretation Environmental potential impacts associated with membrane system for wastewater treatment will be reduced by looking at the result from Impact Assessment. References [1] Postel S. L. and Wolf A. T, Dehydrating conflict. Foreign Policy, Sept/Oct 2001, (2001) [2] Parameshwaran, K., Fane, A.G., Cho, B.D., Kim, K.J, Analysis of Microfiltration Performance with Constant Flux Processing of Secondary Effluent. Water Research. 35, (2001) [3] KeTTHA National Green Technology Policy, Malaysia: Ministry of Energy, Green Technology and Water. (2009) [4] British Standard Institution (2006). BS EN ISO London: British Standard Institution. [5] Levan S. L. (1995) Life Cycle Assessment : Measuring Environmental Impact Life Cycle Environmental Impact Analysis for Forest Products. Paper presented at 49 th Annual Meeting of the Forest Product Society, Portland, Oregon. (pp. 7-16). [6] Joshi, S. (1999). Product Environmental Life-Cycle Assessment Using Input-Output Techniques. Journal of Industrial Ecology, 3(2-3), [7] Ishii, S. (2007) Environmental system analysis of urban water system. Department of Urban Engineering, the University of Tokyo. [8] Sombekke, H. D. M., Voorhoeve, D. K., & Hiemstra, P. Environmental impact assessment of groundwater treatment with nanofiltration. Desalination, 113[2 3] (1997) [9] Fava J. A., Denison R., Jones B. et al., A technical framework for life cycle assessment. Society of Environmental Toxicology and Chemistry, Washington D. C. (1991) 134 [10] Olsen, S. I., Christensen, F. M., Hauschild, M., Pedersen, F., Larsen, H. F., & Tørsløv, J.. Life cycle impact assessment and risk assessment of chemicals a methodological comparison. Environmental Impact Assessment Review, 21[4] (2001)

6 Applied Mechanics and Materials Vol [11] Pillay S. D., Friedrich E., Buckley C. A., Life cycle assessment of an industrial water recycling plant. Paper presented at the Biennal Conference of the Water Institute of Southern Africa (WISA) held on May 2002 at the Durban, South Africa. [12] Mahgoub El-Sayed Mohamed M., van der Steen, N. P., Abu-Zeid, K., & Vairavamoorthy, K. Towards sustainability in urban water: a life cycle analysis of the urban water system of Alexandria City, Egypt. Journal of Cleaner Production, 18[10 11] (2010) [13] Biswas, W.K. (2009). Life cycle assessment of seawater desalination in Western Australia. World Academy of Science, Engineering and Technology, 56. [14] Vince, F., Aoustin, E., Bréant, P., & Marechal, F., LCA tool for the environmental evaluation of potable water production. Desalination, 220[1-3] (2008) [15] Fane, A.G.,Sustainability and membrane processing of wastewater for reuse. Desalination, 202 (2007) [16] Fujiwara, M.,Hayashi, N., Kanai, K., Kiyozuka, M.,Matsui, Y.,Mori, K. and Sakakibara, Y., Application of Life Cycle Assessment (LCA) to water Purification Facilities: Inventory Analysis for Comparison between Coagulation Sedimentation + Sand Filtration and Membrane Filtration. Japan Water Research Centre (2006). [17] Tangsubkul, N., Parameshwaran, K., Lundie, S., Fane, A. G., & Waite, T. D., Environmental life cycle assessment of the microfiltration process. Journal of Membrane Science, 284[1-2] (2006) [18] Sala L., Serra M., Towards sustainability in water recycling. Water Science and Technology, 50[2] (2004) 1-7. [19] Culaba A. B. & Purvis M.R.I., A methodology for the life cycle and sustainability analysis of manufacturing processes. Journal of Cleaner Production, 7 (1999) [20] Sombekke, H. D. M., Voorhoeve, D. K., & Hiemstra, P., Environmental impact assessment of groundwater treatment with nanofiltration. Desalination, 113[2 3] (1997) [21] Colvin V. L., The potential environmental impact of engineered nanomaterial. Nature Publishing Group. 21[10] (2003)

7 Mechanical & Manufacturing Engineering / Life Cycle Assessment of Membrane System for Wastewater Treatment: A Review and Further Research / DOI References [6] Joshi, S. (1999). Product Environmental Life-Cycle Assessment Using Input-Output Techniques. Journal of Industrial Ecology, 3(2-3), /