Essay: Waste management

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  • Waste management
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Abstract
Waste management is a successful instrument to minimize generated wastes, and improve environmental conditions. In spite of the large share of developing countries in the textile industry, limited information is available concerning the waste management strategies implemented for textiles on those countries and their environmental impacts. In the current study two waste management approaches for hazardous solid waste treatment of acrylic fibers (landfill and incineration) were investigated. The main research questions were: What are the different impacts of each waste management strategy? Which waste management strategy is more eco-friendly?.
Life cycle assessment was employed to in order to model the environmental impacts of each waste streaming approach separately then compare them together. Results revealed that incineration was the more eco-friendly approach. Highest impacts of both approaches were on ecotoxicity and carcinogenic potentials due to release of metals from pigment wastes. Landfill had an impact of 46.8% on human health as compared to 28 % by incineration. Incineration impact on ecosystem quality was higher than landfill impact (68.4% and 51.3%, respectively). As for resources category, incineration had a higher impact than landfill (3.5 % and 2.0%, respectively). Those impacts could be mitigated if state of the art landfill or incinerator were used and could be reduced by applying waste to energy approaches for both management systems
In Conclusion, shifting waste treatment from landfill to incineration would decrease the overall environmental impacts and allow energy recovery. The potential of waste to energy approach by incineration with heat recovery could be considered in further studies. Future research is needed in order to assess the implementation of waste management systems and the preferable waste management strategies in textile industry on developing countries.
Keywords: Waste handling, Incineration, Impact Assessment, Landfill, Textile, Acrylic Fiber.
1. Introduction
1.1. Potential Environmental Impacts of Textile Waste
Textile industry emits large quantities of pollutants in form of liquid discharge, solid wastes and air pollutants to the environment. The industry has been always regarded as a water-intensive sector, the main environmental concern is the amount of large amount of effluent discharged and the chemicals within that effluent. Energy consumption and air emissions are another two important issues as well (IPPC 2001). The industry requires as many as 2,000 different chemicals from dyes to transfer agents, which are used at various steps of the process. Additionally, large amounts of water are used to convey these chemical and wash them out. The output of these processes are expelled wastewaters full of chemical which sink into the environment (HSRC 2006). Textile mills discharge millions of gallons of effluent each year. The effluent contains natural impurities extracted from the fibers and a mixture of process chemicals such as inorganic salts, dyes and heavy metals. The effluent is usually high in both temperature and pH because it’s saturated with dyes, and many chemicals used during the process. In general, the effluent is highly-coloured, high in BOD and COD, has a high conductivity and is alkaline in nature. This effluent represents a threat to the aquatic life if it is not properly treated before disposal (Lawrence 1996, HSRC 2006 and Badani et al. 2005).
Chemicals that evaporate into the air became air pollutants. Some of them may be breathed or absorbed through the skin. Others are carcinogenic, they may cause harm to children or may trigger allergic reactions in some people. These air pollutants can fall out to become surface water or groundwater pollutants and water pollutants can infiltrate into the ground or volatilize into the air (Woodard 2001, HSRC 2006, Lo et al., 2012).
Hazardous solid wastes from the industry and disposed in the ground can influence the quality of groundwater and surface waters by way of leachate entering the groundwater and traveling with it through the ground (Lo et al. 2012 and Woodard 2001). Waste treatment processes can also transfer substances from one of the three waste categories to one or both of the others. Waste treatment or disposal systems themselves can directly impact the quality of air, water or ground. The total spectrum of industrial wastes must be managed as substances resulting from a system of interrelated activities (Woodard 2001).
The environmental concerns with the waste resulting from the textile industry have been increasing (Briga-Sá et al. 2013). Yacout et al (2016) recommended the development of ecofriendly technologies for minimize the negative impacts of this industry. Several studies were conducted in order to determine the environmental impacts of the industry and reduce its negative impacts. Ren (2000) developed environmental performance indicators for textile process and product. Pollution prevention and waste minimization techniques in the textile industry were illustrated by Lawrence (1996) and Barclay & Buckley (2000). Additionally, Environmental management systems (EMS) are implemented in order to reduce redundant production procedures, packaging, raw materials needed, energy and water consumption and toxics release to the environment. EMS adopted by firms monitor waste and pollution levels, and take corrective actions to reduce them. Effective implementation of EMS enhance the utilization of raw materials, water and energy, leads to cost reduction, quality improvement and waste reduction (Vandevivere et al. 1998, ECE 2003 and Melnyk et al. 2003). Brito et al. (2008) and Lo et al. (2012) studied the impact of EMS in textiles industries and stated that the dyeing process in textiles processing could produce huge amount of toxic emissions that impacts on the environment which will lead to high restoration costs. In spite of that, the environmental issue in the textiles industry has received little attention from both academics and practitioners. Most environmental researches are technology-oriented.
Briga-Sá et al. (2013) investigated the potential of reusing textile wastes. They illustrated that in the European Union, around 5.8 million tons per year of textiles are discarded, only 1.5 million tons (25%) of these textiles are recycled. The remaining 4.3 million tons goes to landfill or to municipal waste incinerators. Additionally there is also the textile waste from the textile industry. This shows that there is an enormous source of secondary raw material that is not used, but can be re-injected into the market Briga-Sá et al. (2013).
Landfill and incineration
1.2. Waste management LCA in Textile Industry
Nakamura and Kondo (2002) studied the different models of waste management assessment, they illustrated that the main concerns of waste management LCA are the economic and environmental impacts that result from the introduction of alternative waste-recycling and waste treatment methods. Ekvall et al. (2007) investigated the importance of LCA on waste management assessments. They declared that in assessments of the environmental impacts of waste management, LCA helps expanding the perspective beyond the waste management system. LCA makes it possible to consider the environmental benefits that can be obtained through different waste management processes. For example, material from recycling processes replaces production of virgin material. Udo de Haes and Heijungs (2007) also studied LCA applications regarding waste hierarchy and integrated waste management. They stated that a fixed order for waste management starts from most to least preferable: product reuse, materials recycling, incineration and finally land fill. A step down on this ladder is only to be taken if the higher step appears to be impossible.
Cherubini et al. (2009) illustrated that there is an increasing interest in resources and waste management in order to design proper strategies for sustainable resource and waste management policies. LCA methodologies can be used in this context as an input to decision-making regarding the choice of strategic decisions for resource use and waste management approaches. Their research focused on LCA of four waste management strategies: landfill without biogas utilization, landfill with biogas for electricity generation, splitting inorganic waste in a sorting plant and waste incineration. Their results revealed that landfill systems was the worst waste management options and significant environmental savings at global scale are achieved from energy recycling Cherubini et al. (2009).
In the current investigation, LCA methodology was used to determine the different impacts of two waste management strategies. Then, compare the environmental impacts of the two waste streaming approaches for handling hazardous solid wastes of the acrylic fiber manufacturing: landfill and incineration, in order to identify which approach is more environmental friendly.
2. Analysis of Waste Management System
In the current study data was collected from one of the biggest plants for acrylic fiber production in MENA (Middle East and North Africa) region, located at Alexandria, Egypt. The plant was established with a designed production capacity of 18,000 Ton per year. An inventory of generated waste was done: air emissions, liquid discharge and solid wastes were included. Two sources of air emissions were found: water vapors and chemical vapors. Both emissions were absorber and recycled back to the process. As for liquid discharge the total raw effluent generated is 3,600 m3/day. Two major streams are generated from process plant areas and inflow generated from utilities (El-Raey 2007). Liquid waste sources and generated amount are presented in Table (1). Both steams are treated through an effluent treatment plant, table (2) shows the water quality parameters of process effluent to the Effluent Treatment Plant. Effluent samples are taken every shift (3 shifts/day) in order to analyze the different parameters (COD, BOD, Monomers of acrylic fiber and Sodium Thiocyanate). pH and temperature of effluent were constantly monitored by on-site meters. COD ranged from 50 -100 ppm and BOD values were around 60 ppm. It was noticed from the analysis records that before discharge to the environment the treated effluent was within acceptable environmental limitations according to the Egyptian standards concerning wastewater discharge to non-fresh water drains (EEAA, 1994).
As for solid wastes, different source of solid waste are shown in table (3). The filter pads and waste water treatment sludge are being disposed off by government recognized sites for toxic material. Wet and dry fiber waste from the production line, were recovered and utilized again as dope solution. The fiber with lowest grade was liquefied in the gel dissolving unit using sodium thiocyanate (Yacout et al. 2015).
1. Goal and Scope Definition of LCA
The investigation compared the environmental impacts of two waste streaming approaches: landfill and incineration of the generated hazardous waste from 1000 kg production of acrylic fiber. The aim was to analyze and evaluate their environmental impacts based on the current case study plant and find out which approach has less negative impacts on the environment. The used method in the current study was “Eco-indicator 99”. Twelve impact categories were taken into consideration: Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Carcinogens Potential (CP), Ecotoxicity Potential (ETP), Respiratory Inorganic Formation Potential (RIFP), Respiratory Organic Formation Potential (ROFP), Radiation Potential (RP), Ozone Layer Depletion (OLD), Minerals Depletion (MD), Land Use (LU), and Fossil Fuels Depletion (FFD). These impact categories are grouped in three groups: impact on human health, impact on ecosystem quality and impact on resources. Cumulative Energy Demand (CED) was also used as a single indicator for fossil fuels depletion. The life cycle assessment was realized by software SimaPro7.
2. Inventory Analysis
2.1. Data collection and uncertainty
Data were obtained from the case study facility, They were collected from the process manuals, utility manuals, data sheets and daily reports of 2012 (Table 1). The validity period for the LCA results of the current study will be till 2017 as the acceptable time coverage of used data for LCA studies should be within the last 5 years (European Environment Agency 1997). Results of this inventory are presented in a list of consumed resources and emissions following the system of Goedkoop and Spriensma (2000). All input/output data used in the study are presented in Table (4) (Yacout el al 2016). Impacts on human health and ecosystem were estimated and generated using the software modeling program SimaPro (Table 5).
Regarding data uncertainty, several uncertainties are present in the used data. First of all, the available data in the LCA database used does not always reflect the reality of the product being studied due to the geographical/regional location of the case study (Baker and Lepech 2009). There is no available database, to date, that represents the regional location in Egypt or the Middle East, and few data on the current databases represents Africa (Yacout et al. 2016).
Data for basic materials used in the study is considered for the region of Europe (Ecoinvent v2 database), which will represent the case study only if all the used raw materials are imported from Europe. Energy data for both electricity and steam generation may vary as well based on the used database. The electrical data used in this case study was the generated electricity in Africa (IDEMAT 2001database). This data represents the average fuel use and emissions for total energy generation for the whole continent. As for steam, on-site steam source average was used (Industry data 2.0 database). This steam source is suitable for the current case study as it represents the purchased steam from a nearby generator. However, this may not be the case on other case studies (Yacout et al 2016). The treatment of hazardous and non-hazardous materials in textile industry, in this case the chosen waste streams is another uncertainty (Van der Velden et al. 2014). The waste management approaches and waste handling strategies may diverse according to the used practice in the case study area.
2.2. Background data and waste approaches
LCA was applied on two waste streaming scenarios: the first scenario was based on 100% hazardous solid waste incineration and the second scenario was 100% hazardous solid waste landfill. The generated wastes was from 1000 kg production of acrylic fiber. Background data was created utilizing eco-profiles from the Eco-Invent database for all the necessary input materials and processes. In compliance with ISO14044:2006 Section 4.2.3.3., a cut-off criteria of 0.1% was chosen. Eco-indicator 99 methodology was used for LCA single score and weighting of the eleven impact categories taken into consideration (Goedkoop and Spriensma, 2000) and (Frischkneckt et al. 2007). The used LCA simulation model considered the impacts of “worse – case scenario” in both landfilling and incineration. For landfill, short term leaching to wastewater treatment plant was considered and long term leaching to ground water in case of base lining failure. Regarding incineration, short term emissions to rivers was assumed as well as long term emissions to ground water from slag bottom.
5. Results of Life Cycle Assessment
Results in Tables (5-7) and Figures (1-2) present the overall environmental impacts of the waste streaming approaches: landfill and incineration. In worse – case scenario leachate takes place in the landfill, accordingly as assessed by the model, a high ecotoxicity and carcinogenic potential were detected due to the release of cadmium and arsenic. In order to avoid/minimize the environmental impacts, a landfill needs to be constantly monitored (Cherubini et al. 2009). As for incineration, if the incinerator does not control the emissions properly as assumed, various impacts could be detected as presented in Figures (1-2). In accordance with previous results reported by Arena et al. (2003), Mendes et al. (2004), Finnveden et al. (2005), Cherubini et al. (2009), Assamoi and Lawryshyn (2012) and Lettieri et al. (2014), Fig (2) indicates that incineration is more environmentally friendly, shifting waste treatment from landfilling to incineration would decrease the overall environmental impacts and will allow energy recovery.
6- Discussion of Life Cycle Assessment
Table (5) shows that the highest impact of both approaches is on ecosystem quality due to their ecotoxicity potential from copper, zink and nickel emissions. Overall impact of incineration on ecosystem quality is higher than overall impact of landfill, reaching 68.4% and 51.3%, respectively. At the same time, due to the high potential of cadmium release into the effluent, the human health indicator is the second highest impact. Landfill has an overall impact of 46.8% on human health as compared to 28 % overall impact by incineration. As for resources it is evident that the impact of incineration approach is higher than the impact of landfill with, 3.5 % and 2.0%, respectively. The amount of fossil fuels (coal and natural gas) used by incineration is higher than the used in a landfill. Fossil fuels are mainly consumed during incineration through the combustion process and during landfill by transportation and handling processes.
LCA results in Figures (1-2) show that ecotoxicity is the highest category affected by both waste streams, followed by carcinogens potential, climate change, human respiratory system due to inorganic substances. Fossil fuels depletion and acidification/eutrophication potential came next. Smallest impact of both waste streams was on land use which could be attributed to the occupation of road network during transfer of the hazardous solid wastes from the plant area to the landfill or incineration area and occupation of the dump site itself. Additionally, land use potential in case of landfill is higher than incineration due to the large dump site area required for landfilling. No impacts were detected on radiation, ozone layer depletion, minerals depletion or human respiratory system due to organic substances.
6.1. Global Warming Potential (GWP)
In accordance with Cherubini et al. (2009) the calculated GWP through the life cycle assessment indicates that landfill is more preferable in terms of climate change impact as shown in Tables (5-6) and Figures (1-2). The footprint landfill approach is mainly constituted by the generated methane from the anaerobic digestion. As for incineration, the combustion step strongly affects final results: CO2 from fossil carbon and NOx emissions. Similar results were reported by Cherubini et al. (2009). In this case, it is suggested to consider the possibility of waste to energy recovery of both waste streams. The generated methane from landfill can be used for electricity generation, as for the generated CO2 emissions from incineration it can be used as a source of heating. The recycling of these emissions could reduce the overall impact of the textile industry on the environment, in addition to save a significant amount of energy.
6.2. Acidification Potential (AP)
LCA results indicate that landfill is also more preferable in terms of acidification potential Tables (5-7) and Figures (1-2). Assamoi and Lawryshyn (2012) and Lettieri et al. (2014) reported similar results. Responsible gases of rain acidification are SO2, NOx, HCl, H2S and NH3. The main attributors to this impact category are the air emissions from the combustion process in incineration approach, the released SO2 from incineration is higher than the released from landfill.
6.3. Eutrophication Potential (EP)
Nitrogen and phosphorous levels released to waterways contribute to eutrophication potential. Tables (5-6) present the eutrophication potential due to the treatment of hazardous solid wastes generated from 1 kg production of acrylic fiber. NO2 emissions from incineration are almost five times higher than NO2 emissions from landfill. NO2 emissions from incineration are generated from the combustion process of acrylic fiber hazardous wastes and from the used fossil fuels through the incineration process. Assamoi and Lawryshyn (2012) reported in their environmental comparison between landfilling and incineration that the landfilling option has a noticeably smaller eutrophication impact on the environment. Continues monitoring of the incinerator as well as proper control of it, could minimize the release of these emissions to waterways and mitigate this impact.
6.4. Carcinogens Potential (CP)
The carcinogens potential of acrylic fiber hazardous solid waste treatment is presented in Tables (5-6) and Figures (1-2). The CP of landfill approach is almost ten times higher than the CP of incineration. The effects of polluted surface run-off and leachate on surface water and ground water are the most serious pollution in the mid and long term perspective brought by landfills (Law-wai 2001 and Doka 2003). LCA results indicated that CP by landfill of hazardous solid wastes generated from acrylic fiber industry is a result of arsenic, zink and cadmium emissions reaching the effluent. These elements can be found in pigments and dyes (Laing 1991 and Barclay & Buckley 2000). It was reported that in textile industry the loss of dyes to effluent ranges from 2% to 10% of the overall used dyes depending on the type of dye used in the dying process. Different dyes containing these emissions are applied to acrylic fibers including: a) acid dyes, b) basic dyes which require preparation as a double salt of zinc, dichromates to oxidize and c) disperse dyes and phenol compounds used with disperse dyes (Laing 1991; Knackmuss 1996; Slokar and Le Marechal 1998; Barclay & Buckley 2000; Shenai 2001; Kolekar 2010). In order to minimize the carcinogenic potential of both landfill and incineration waste streams, proper treatment for process effluent must be done before discharge to environment.
6.5. Ecotoxicity Potential (ETP)
Effect of the ecotoxicity potential by landfill and incineration in Tables (5-6) and Figures (1-2), indicated that ecotoxicity has the highest impact of both approaches on environment, moreover, landfill has a higher ecotoxicity potential than incineration. In worse – case scenario, leachate takes place in landfill, high ecotoxicity potential is expected due to the surface run-off, leachate reaching surface water and ground water containing copper, zink, nickel, cadmium, lead and mercury released from the pigment wastes. As for incineration, cadmium and arsenic emissions could be released from pigment wastes which would cause the ecotoxicity potential. Minimizing the potential of this impact category can be done by using state of the art landfill and monitoring it continuously. In addition, reduce the generated waste of pigment and dyes from the process by proper control machinery and treatment of these wastes before final discharge to environment. Usage of more ecofriendly dyes can be considered as well.
6.6. Respiratory Inorganic Formation Potential (RIFP)
Analysis results in Tables (5-7) and Figures (1-2) show that the respiratory inorganic formation potential generated by incineration approach is almost two and half times the RIFP generated by landfill, due to the emissions of NOx, SO2, NH3, CO, Particulates < 2.5 µm and Particulates > 2.5 and < 10 µm released to air. In agreement with Buonanno et al.,(2008) the most significant negative outcome of incineration is the emissions that result from combustion. This air pollution has both a harmful effect on the local area and on the climate in general. As indicated before in the GWP section, the combustion step during incineration, which releases NOx emissions, strongly affects the final results. Similar results were reported by Cherubini et al. (2009). Proper filtration of generated air emissions from incineration will reduce the potential of this impact. In addition, the implementation of waste to energy approach by reusing these emissions as a heating source could reduce its potential impact.
6.7. Fossil Fuels Depletion
As shown in Tables (5-7) and Figures (1-2) incineration consumption of fossil fuels is higher than landfill consumption. LCA results indicated that 95% of the fossil fuels used in the incineration approach are consumed within the combustion process. On the other hand, 94% of the used fossil fuels by landfill are consumed during landfill operations including: transportation, waste spreading and landfill shaping. Finnveden et al. (2005) stated that debates are currently ongoing regarding how to reduce the use of fossil fuels and increase the use of renewable fuels, waste is sometimes regarded as a renewable fuel. Waste to energy technologies hold the potential to create sustainable renewable energy. Consequently, it is recommended to investigate the potential of applying waste to energy approaches in both waste streams. In case of landfill, the generated methane can be used for electricity generation, as for the generated CO2 emissions from incineration it can be used as a source of heating. The recycling of these emissions not only will reduce the overall impact of the textile industry on the environment, but also it will save a significant amount of energy.
7. Further research needs
In spite of the large contribution of developing countries in the textile industry, limited studies were conducted analyzing the current waste management applications in these countries. Future investigations are required in order to assess the implementation of waste management systems and recommend the preferable waste management strategies in textile industry on developing countries. Further LCA studies are also needed in order to identify the environmental impacts of the different processes and approaches used in textile manufacturing on developing countries at local and global scale. Arab countries and African continent, in particularly Egypt have thus far engaged in few life cycle assessment studies (Ali et al. 2014, Yacout et al. 2016). Furthermore, for the production of more eco-friendly textiles the environmental impacts of more waste management strategies such as waste to energy approach by incineration with heat recovery could be determined at local and global scale.
8. Conclusion
In the current study two waste streaming approaches for hazardous solid waste treatment (landfill and incineration) were investigated to identify which approach was more eco-friendly. The study confirms previous results in recommending waste treatment by incineration. Shifting waste treatment from landfilling to incineration would decrease the overall environmental impacts and will allow energy recovery. Incineration has a better environmental performance in terms of human health impact especially carcinogenic and ecotoxicity potentials. If a the landfill is not properly designed or if a long term leachate to ground water occurs due to base lining failure, high ecotoxicity and carcinogenic potential would be expected. The high ecotoxicity and carcinogenic potentials in both landfill and incineration can be attributed due to the release of metals from pigment and dye wastes to surface and ground waters. Those impacts could be mitigated if state of the art incinerator or landfill were used.
Further research is needed in analyzing and identifying more eco-friendly waste management strategies especially in developing countries. Waste to energy approaches in textile industry could be considered as a potential for both waste minization and development of sustainable renewable energy.

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