Plastic Solid Waste Research Articles

Transformation of Plastic Solid Waste into Liquid Fuel

The study being reported here was conducted to convert plastic waste,a major source of solid pollution in Pakistan, into liquid fuel by application of Thermal Pyrolysis. A pyrolysis reactor consisting of high strength Pyrex round bottom flask was constructed in the laboratory and used for converting plastic waste into liquid fuel. A 280g sample of plastic waste was pyrolyzed and the resultant products were 120g liquid oil, 100g solid residueand 60g gas.Thus, the yield of liquid fuel from the plastic waste was 43% wt. along with solid mass 36%wt. and gas 21 % wt. The results clearly indicate that there is a significant potential of producing liquid fuel from plastic waste in Pakistan andthe world.

Pyrolysis oil for diesel engines from plastic solid waste: a performance, combustion and emission study

Demand of energy and global warming aggravates the search of green alternate renewable resources. Furthermore, conversion of solid waste into the useful energy has huge potential. This study analyses the effect of pyrolysis plastic oil into the water-cooled diesel engine. Besides, the nanoparticle TiO2 was sonicated at 100 ppm at 25 kHz. A series of test was conducted at various engine loads to examine the effect of pyrolysis oil. From the results it is evident that addition of the pyrolysis plastic oil is possible without executing major modifications to the engine. On the contrary, the brake thermal efficiency was slightly lower than that of conventional diesel engine. However, addition of the nanoparticles showed a profound change in BTE and BSEC. At higher speed the emission of NOx is higher in both testing fuels than that of diesel. However, HC and CO2 emission levels are lower.

Characteristics and mechanical properties changes due to incorporation of aloe vera in polyethylene-based film

Non-degradable properties of polyethylene (PE) films due to long-chain structure cause increment of solid waste plastic. Many researchers, with different purposes, have studied the incorporation of functional materials to PE. Studying the impact of incorporation of aloe vera (AV) into PE films in terms of its characteristic and mechanical properties is the main objective of this paper. The films were prepared using melt-blending and hot press technique. The characterization assessed for the PE and PE-AV films were spectroscopy, crystalline phase, thermal analysis and performance of mechanical properties of the sample. The functional group detected in spectroscopy studied did not show any changes for PE film or PE with the presence of AV. Lower thermal degradation temperature (Td) obtained for PE-AV3 while others film found no significant changes of Td value and only one peak of thermal degradation occurred for all film. The same goes to the analysis obtained from differential scanning calorimetry (DSC) data. However, the crystalline structure displayed momentous peak changes for PE with AV. The highest tensile strength (TS) obtained by PE-AV3, at once developing highest value of Young’s modulus (YM), modulus of resilience (UE) and modulus of toughness (UT). A certain amount of AV has substantial effect on changing the polymeric structure especially improving the mechanical properties of PE film. Therefore, AV has potential to become an additive for developing a new partially degradable PE film.

An Investigation into the Impacts of Climate Change on Anthropogenic Polluted Coastal Lagoons in Ghana

This paper discusses the impacts of Climate Change and anthropogenic activities on coastal lagoons in Ghana. Ghana’s coastal lagoons provide unique ecosystem services. However, they are highly fragile and vulnerable to natural processes and anthropogenic activities. Climate Change impacts, such as increased temperatures, sea-level rise, storm surge and increased precipitation are likely to have ecological damage to lagoon ecosystems as a result of erosion, submergence of lagoon barriers, flooding and drying of the surrounding wetlands. Field observation, Geographic Information System modeling were among the methodology applied. The paper identified that anthropogenic activities and Climate Change would combine to have a serious future impact on lagoon ecosystems. Particularly, increased rainfall-induced flooding from the hinterland may be very injurious to the lagoon ecosystem, since the flood water may carry not only nutrients but also various contaminants and solid plastic waste generated by human activities around lagoons catchment into the lagoon channels. Besides, due to the barriers across most lagoon inlets, such polluted runoff water may not be able to flush out to sea, thus impacting negatively on the water quality of the lagoons. The paper proposes some adaptation strategies and recommends the early implementation of Climate Change adaptation strategies, coastal lagoon management measures to prevent potential future destructive impacts.

Thermal degradation kinetics of real-life reclaimed plastic solid waste (PSW) from an active landfill site: The mining of an unsanitary arid landfill

Landfilling is viewed nowadays as a serious threat associated with various burdens and stressors on the urban environment. To date, there is little information available on actual value of landfilled waste namely plastic solid waste (PSW) resulting from mining operations. In this work, PSW reclaimed from an active unsanitary landfill site (MAB) has been studied with the aim of determining its thermal profile and degradation behaviour for future utilisation in thermo-chemical conversion (TCC) processes. The materials were characterised by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) in accordance with internationally approved test methods in a simulated pyrolytic environment. In addition, chemical analysis using Fourier Transform Infrared Spectroscopy (FTIR) was applied to study the nature of the materials reclaimed. The degradation kinetics of the reclaimed PSW were studied with the aim of determining the apparent activation energy (Ea) of the pyrolytic reactions. The Ea values determined ranged from 199 to 266 kJ mol−1 which is in-line with pyrolytic reactions applicable for future use in fuel recovery units. TGA showed a clear shift in thermograms indicating a clear change in the degradation mechanism. The physico-chemical studies conducted on the materials also favours TCC treatment over other conventional end of life options such as physical (mechanical) recycling or incineration. The degradation mechanism was also determined from the Criado method showing that Avarami-Erofeve was the model that best represents PSW degradation. Overall, this work points towards future intervention schemes for reclaimed municipal solid waste (MSW) and in particular PSW favouring TCC technologies.

Clean Energy from Plastic: Production of Hydroprocessed Waste Polypropylene Pyrolysis Oil Utilizing a Ni–Mo/Laponite Catalyst

This research demonstrates a process to convert polypropylene pyrolysis oil (PPO) into diesel. The hydroprocessing of PPO (HPPO-B) utilizing a Ni–Mo/Lap bimetal catalyst has been attempted in this study. Hydroprocessing of plastic pyrolysis oil had been attempted earlier, but the hydroprocessing of PPO utilizing a bimetal catalyst and the corresponding validation suites consisting of physicochemical tests, composition comparison with diesel, and diesel engine trials have not yet been reported. The physicochemical properties of the produced HPPO-B matched EN590 standard (European diesel standards) requirements. The hydroprocess conditions (70 bar and 350 °C) and the synthesized Ni–Mo/modified Lap catalyst have been responsible for producing n-alkanes, isoalkanes, and aromatics in proportions that gave a 95% match with diesel. Diesel engine combustion and emissions of HPPO-B matched those of diesel. HPPO-B provides the opportunity to utilize plastic solid waste (PSW) as a transport fuel. The results of HPPO-B inspire and encourage pursuance of the hydroprocess path for protecting the environment from hazardous plastic solid waste (PSW).

On recyclability of thermosetting polymer and wood dust as reinforcement in secondary recycled ABS for nonstructural engineering applications

The management of thermosetting plastic solid waste has become serious issue worldwide due to its highly stable long-chain molecular structure and its recycling is the only way to reduce harmful effects. Also, depletion of natural resources like wood at alarming rate creates worldwide environment issues. In this article, feedstock filament for three-dimensional printing (in nonstructural engineering applications) of thermoplastic composite based on secondary (2°) recycled acrylonitrile butadiene styrene (ABS) as matrix reinforced with waste bakelite powder (BP) (thermosetting) and wood dust (WD) with twin-screw extrusion (TSE) process has been prepared (to impart desired mechanical/thermal/rheological and morphological properties).The results indicated that reinforcement of BP/WD initially increases the melt flow rate (MFR) of composite filament as compared to 2° recycled ABS. However, with increase in percentage of reinforcement beyond a certain limit, the MFR of the composite filaments starts decreasing. The mechanical, rheological, morphological, and thermal properties related to fused filaments prepared by TSE process have been explored in this research work and it has been observed that ABS composite filaments reinforced with 10% by weight of BP possess high peak strength (PS), high energy carrying capacity, more thermal stability, and contains low porosity. Based upon combined optimized extrusion parameter settings for maximizing the PS and percentage break elongation, 10 kg load, 225°C processing temperature, and 70 r min−1 are the best settings for both the composite filaments (ABS + BP, ABS + WD), and the corresponding values for ABS + BP and ABS + WD composite filament are 30.58 MPa (5.15%) and 25.65 MPa (6.05%), respectively.

Application of Binding-Bonding technique for Plastic Solid Waste

Plastic solid waste management is amongst the most menacing issue covered across the globe. Plastic is the material with multiple usages, replacement of plastic is a solution to reduce plastic based pollution but this is not possible in order to gather the needs of humans. Natural resources are depleting worldwide at the same time the generated wastes are expanding substantially. The usage of plastic when looking to its degradation rate has calamitous difference, at present the conversion of plastic into cement can provide an upgrade to environment as well as economic benefits. In this present study the Plastic waste management was done at educational institution in order to manage the huge amount of plastic waste generated everyday by the affiliates.Utilization of plastic waste in preparation of paved blocks originated from the known mechanisms for production of bricks and fly ash blocks. Plastic serves as a bonding agent when heated. Soil serves as binding agent when mixed with melted plastic. Properties of sandy soil shows that after heating it changes the colour, becomes non-sticky, has no effect of weather, compressive strength increases and surface becomes hard. The method used in this study for preparation of blocks from plastic was hypothesized form the technique of production of bricks in which soil is mixed with bonding clay. Sandy soil and clay mixture serves good quality by providing less shrinkage. The aim of this study is to manage plastic waste from depleting the environment.

Application of Instrumental in the Identification of Solid Waste Characteristic of Imported recycled ABS Plastic

The content of carbon, hydrogen and nitrogen in imported recycled ABS plastics was determined by Instrumental, and the content of three monomer units (acrylonitrile, butadiene and styrene) in ABS was calculated. The influence of sample quantity and combustion time was discussed. The precision of carbon, hydrogen and nitrogen was 0.08% - 1. 32%, and the content of three monomer units was 0.08% - 1.32%. The precision of the method was 0.72% - 8.22%, and the recovery rate of the method was 90.7% - 114.8%. The precision and recovery rate of the method are good. It can quickly determine the content of each monomer unit in ABS plastics, and provide technical support for the property identification of related imported plastic solid waste.

Use of recycled materials as mid layer in three layered structures-new possibility in design for recycling

Challenges of using recycled polymer materials in food packaging are related both to the properties of the material and demanding safety issues for food contact materials. The aim of this research was to detect possible risks using recycled post-consumer plastic waste in three-layered polyethylene (PE) films produced with virgin outer layers and a mid-layer from recycled flexible PE material. Migration tests were performed as risk assessment for identifying possible migrating substances from the mid-recycled layer. Overall migration was determined on various 3-layered structures made from virgin low-density PE (LDPE) and virgin linear low-density PE (LLDPE), respectively, with two different recycled PE from post-consumer waste (R1 and R2). 95% ethanol was used as a simulant for screening at 20, 40 and 60 °C for 10 days. Specific migration was performed using sophisticated analytical techniques (liquid and gas chromatography). Overall migration values for all temperatures were from < 2 mg/dm2 at lowest and 5.6 ± 0.1 mg/dm2 at highest temperature, thus well below the overall migration limit (OML) of 10 mg/dm2. Specific migration of intentionally and non-intentionally added substances were detected, identified and quantified. Similarly, specific migration values were under specific migration limit (SML) defined in legislation. Optical properties of the reference samples were significantly different in appearance and on cross section for samples with recycled materials R1 compared to recycled material R2 which caused only slight changes in the appearance of both reference films. This research presents a valuable study on migration from recycled flexible PE films and use of recycled materials in food packaging applications. Use of virgin materials as outer layer in combination with commercially available recycled material can increase the use of recycled materials in packaging as well as reduce the total amount of flexible plastic solid waste.

Potential Use of Earthworms to Enhance Decaying of Biodegradable Plastics

Biosolid application, wastewater irrigation, and plastic mulching technologies are major sources of plastic pollution in agroecosystems. Microplastics may interact with soil physicochemical properties and organisms and negatively affect plant growth. To alleviate environmental plastic pollution, synthetic and biobased biodegradable polymers are replacing nonbiodegradable polymers, but their biodegradation rate in the field is frequently lower than that estimated from standardized biodegradation testing. Plastic polymer biodegradation is a multistep process that involves plastic deterioration, microbial colonization, production of polymer-degrading exoenzymes, and mineralization. However, these physicochemical and biological processes are not always efficient because of unfavorable environmental conditions (e.g., temperature, soil moisture). We propose to use earthworms to increase the biodegradable polymer biodegradation rate by creating optimal habitats for microbial proliferation. Earthworm-induced processes that lead to soil alteration (bioturbation) and solid organic wastes decomposition (vermicomposting) are described to understand how earthworms may favor biodegradable plastic mineralization. Therefore, we suggest two practical sustainable bioengineering strategies: (1) enhancing bioturbation by inoculating agricultural soils with soil-dwelling earthworms, which is viable for horticulture where using biodegradable mulching films increases plastic debris in the soil and (2) vermicomposting with blended biodegradable plastic debris and solid organic wastes, which is complementary to industrial or home composting of single-use biodegradable plastics.

Estimation of plastic waste inputs from land into the Caspian Sea: A significant unseen marine pollution

It has been proven that there is an extensive bulk of plastic debris in marine ecosystems. The present study analyzed solid waste generation, its management and final disposal methods in Caspian Sea coastal countries, and the amount of plastic waste entering the Caspian Sea. The results showed that, on average, more than 90% of waste in the Caspian Sea coastal countries is mismanaged. According to our estimates, 425 kilotons (Kt) of plastic waste was generated by Caspian Sea coastal countries in 2016, of which, with high probability, 58–155 Kt find their way to the Caspian Sea. It is estimated that without improved waste management infrastructures, the amount of plastic waste entering the Caspian Sea will increase to 68–182 Kt by 2030, an increase of about 15%. Accordingly, the related cumulative environmental and health problems could be more severe. All countries located in the coastal areas of the Caspian Sea should revise their solid waste and plastic waste management programs to protect that sensitive marine ecosystem.

Rheological property analysis of pyrolytic liquid fuel (PLF) using ASTM and APHA standards

In this paper expounds, to apply the pyrolysis impact on plastic solid wastes (PSW) to pyrolytic liquid fuel and characterize the potential and rheological properties of produced pyrolytic liquid fuel was explored from the view point of energy vitality and waste minimization. Fundamentally, the plastic solid wastes such as high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) were pyrolyzed in a pyrolytic reactor which operated at optimum temperature 450 °C under atmospheric pressure. Subsequently, the rheological properties of pyrolytic liquid fuel such as pH, relative density, kinematic viscosity, flash point, cloud point, pour point and calorific value are analyzed by standard American society for testing and materials (ASTM) and American public health association (APHA) methods. The comparison of pyrolytic fuel with conventional fuels can avowing that the produced pyrolytic liquid fuel as an alternative liquid fuel which can supplant the fuel shortage and providing an enthusiasm to the researcher to concentrating on plastic thermal cracking. Hence, the pyrolytic liquid fuel has been proved that could be the suitable replacement of conventional fuel in terms of calorific value.

Using solid household plastic waste in the construction of soil embankments

The article analyzes innovative ways of using crushed solid plastic in a mixture with soil for arrangement of soil embankments for various purposes. Using a mixture of loam loess and crushed plastic, on the one hand, solves the environmental problem of plastic recycling, and on the other hand, creates technological material for the erection of the embankment. In order to determine the suitability of the material, laboratory studies of the characteristics of the mixture were carried out. For each sample of the mixture, the optimal humidity and density of the skeleton were determined by dynamic compaction in the MDU-1. The modulus of deformation of the compacted specimens is determined. The article investigates the characteristics for the composition of the loam loess and crushed plastic containers in the ratio of 80:20 %.

Experimental investigation to identify the type of waste plastic pyrolysis oil suitable for conversion to diesel engine fuel

Plastics for various applications is increasing every year due to outstanding advantages, but after use recycling and disposal have remained a challenge. In this paper, through experiments, we compare properties of pyrolysis oil derived from after use HDPE (High-density polyethylene), LDPE (Low-density polyethylene), PP (Polypropylene)and styrene for their suitability as diesel engine fuel. This experimental study is to identify which type of plastic is suitable for blending with diesel. The physicochemical properties of pyrolysis oil of HDPE, LDPE, PP, and styrene were tested, tabulated and compared with diesel. The physicochemical properties of polypropylene pyrolysis oil (PPO) were found to be superior to the produced pyrolysis oil of HDPE, LDPE, and styrene. The GC-MS(Gas chromatography-mass spectrometry)and FT-IR (Fourier transform-infrared spectroscopy) were taken for pyrolysis oil of HDPE, LDPE, PP, and styrene and compared with diesel. PPO showed lower carbon number chain compounds compared to the other three waste plastics. We selected PPO for diesel engine performance and emission trials based on the results of the above tests. PPO was blended in the ratios of 5%, 10% and 15% with diesel. Combustion analysis showed a increase in cylinder pressure in comparison to diesel values. The heat release rates (HRR) were sharply higher than diesel. Both cylinder pressure and HRRvalues for PPO increased as the blend ratios increased. The emission results showed an increase in carbon monoxide (CO), hydrocarbon (HC)and oxides of Nitrogen (NO x )emissions. The multiple times increase in emissions is due to the presence of unsaturated hydrocarbons and higher carbon number of saturated compounds in PPO. GC-MS tests confirmed the presence of such compounds in PPO. To reduce the unsaturation to negligible levels, we will take up future experiments in hydrogenating PPO with various catalysts and test the performance and emissions in diesel engines. The experiment and analysis plan for conversion of solid waste plastics to diesel fuel. • Four types of plastics selected to determine which plastic has a diesel like quality. • Physicochemical properties, FTIR, GCMS results showed Polypropylene had diesel like qualities. • Diesel Engine trials done with polypropylene pyrolysis oil blended with diesel as fuel. • Engine trial results showed delayed combustion, high heat release rate and higher emission.

An anthropology of waste

ABSTRACTThis article discusses plastic and other solid household waste in both rural and urban Daerah Istimewa Yogyakarta (Special Region of Yogyakarta) and integrates several practical and theoretical perspectives in its analysis. An exploration of the everyday littering practices of the Javanese people is combined with analysis of their particular ways of relating to the environment. This study reveals that an abstract notion of nature is not seen as crucial by most actors. Rather, what counts for individuals is their immediate social environment. Government officials are increasing efforts to raise awareness of the issues at hand, and to encourage citizens to sort household waste and to recycle. However, bottom-up initiatives such as community-based ‘waste banks’, communal clean-ups and ‘recycle fashion’ street carnivals that address various social, economic, and emotional aspects of waste have proven much more efficient. Thus, a tentative path to transform the waste problem that, in the authors’ perspective, challenges the notions of growth, modernisation, and human-nonhuman relations is seen in Java in the mobilisation of the local, social and moral world. However, it is not certain that this will generate a less consumptive lifestyle leading to the much needed reduction of waste.

Use of recycled polypropylene/poly(ethylene terephthalate) blends to manufacture water pipes: An industrial scale study

Poly(ethylene terephthalate) (PET) and polypropylene (PP) are two major polymeric materials that constitute many single-use plastic products. A common strategy to reduce polymeric waste is via mechanical recycling, a low cost and efficient process. However, from an industrial point of view, the reliability of this process is more easily achieved by a downgrade in the final properties of these materials, which limits the usage of recycled-based materials to less demanding applications. Furthermore, due to the intrinsic heterogeneity of the PP or PET waste, the use of these materials in industrial processing, tuned and developed for virgin neat materials, poses serious integrity problems. This aspect is particularly relevant in the case of plastics originating from the food packaging industry. This work explores the possibility of incorporating either PP or PET originated from plastic solid waste (PSW), in pipe manufacturing, with competitive mechanical properties compared to those prepared from virgin materials. To achieve this industrial solution, a process was developed using PP/PET 70/30 wt% formulations and the impact of replacing the virgin material by the different PSW in the microstructure, thermal and mechanical properties of the final material was analyzed. The impact of using a compatibilizer able to counteract the natural immiscibility between the PP and PET domains was also assessed. The developed formulation with recycled PET is a good example of the applicability of work developed at a laboratory scale into industrial-scale production.

Combustion and emission analysis of hydrogenated waste polypropylene pyrolysis oil blended with diesel

Petroleum-based plastic pyrolysis oil contains unsaturated compounds, and the presence of these compounds makes the produced fuel unsuitable for combustion in diesel engines. Hydrogenation of pyrolysis oil is performed to convert unsaturated compounds to saturated compounds. Past studies have shown that hydrogenation of petroleum-based plastic pyrolysis oil is viable; however, its combustion and emissions analysis in diesel engines has not yet been reported. In this study, we investigated the combustion, performance, and emissions of hydrogenated polypropylene pyrolysis oil (HPPO) blended with diesel. Polypropylene (PP) was converted to pyrolysis oil using ZSM-5 as the catalyst. The hydrogenation of polypropylene pyrolysis oil (PPO) was conducted at pressure of 70 bar, and the reaction temperature was maintained at 350 °C. Ni metal impregnated on the ZSM-5 base support was used as the catalyst of choice. The produced HPPO possessed physicochemical properties that match the EN590 standards(European diesel fuel standards). Gas chromatography-mass spectrometry (GC–MS) studies of PPO and HPPO showed the effectiveness of hydrogenation for the complete conversion of alkenes to alkanes, and hydrocracking resulted in cracking higher carbon number alkanes to lower values. HPPO was blended with diesel in ratios of 10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.%. The diesel engine performance results for the blended fuel showed combustion, performance, and emissions on par with pure diesel fuel for blending ratios up to 20 wt.%. As is known, plastic solid waste (PSW) materials pose serious hazards to the environment. Our HPPO physicochemical properties matched the EN590 standards for diesel fuel. The combustion of HPPO in diesel engines can provide an option for environmentally cleaner disposal of PSW.

Modelling the chemical recycling of crosslinked poly (methyl methacrylate): Kinetics of depolymerisation

Whereas increasing plastic solid waste production constitutes one of the main challenges of modern society, mainly due to the lack of suitable recycling technologies, chemical recycling represents an attractive solution for the conversion of plastic solid waste into valuable chemical intermediates. Herein, a kinetic model for the pyrolysis of a dental industry waste, ethylene glycol dimethacrylate (EGDMA) crosslinked poly (methyl methacrylate) (PMMA), is presented for the first time. Kinetics parameters and their statistical significance have been estimated from eight non-isothermal thermogravimetric analysis (TGA) experiments with heating rates varying between 5 and 50 °C·min−1 by using nonlinear regression. Our analysis indicates that the mechanism of depolymerisation of EGDMA crosslinked PMMA is likely to involve a consecutive reaction pathway involving two steps. The developed kinetic model - containing five kinetic parameters only - was able to predict well all non-isothermal TGA runs, and was validated against isothermal TGA experiments at 400 °C.

Thermal investigation of plastic solid waste pyrolysis via the deconvolution technique using the asymmetric double sigmoidal function: Determination of the kinetic triplet, thermodynamic parameters, thermal lifetime and pyrolytic oil composition for clean energy recovery

Pyrolysis is widely used as a waste treatment technology (thermal recycling), which can be an alternative to disposal in landfills. To investigate the applicability of pyrolysis of plastic solid waste (PSW) to recovery energy from plastic solid waste (PSW), the pyrolysis of PSW was performed in a thermogravimetric analyzer under an inert condition. The PSW samples were heated under dynamic conditions from 25 °C to 1000 °C at four low heating rates (5, 10, 20, and 30 °C min−1). The decomposition behavior of pseudo-components was characterized by the deconvolution method using the asymmetric double sigmoidal function (Asym2Sig), and the data obtained were used to determine the kinetic parameters. The kinetic parameters were evaluated by isoconversional methods, the compensation effect factor and master plot. The thermodynamic parameters (ΔG, ΔH and ΔS) and lifetime were estimated based on the thermogravimetric and kinetic data. In addition, a fixed-bed reactor and GC–MS were employed to identify some valuable products in pyrolytic oil. Three pseudo-components were identified, which had the main influence on pyrolytic performance. The kinetic parameters suggested the suitability of PSW pyrolysis, where the reaction models were found to be suitable for describing the thermal behavior of PSW pyrolysis. The simulation profile curves from the simplified kinetic expression based on the kinetic triplet and deconvolution results had a satisfactory agreement with experimental conversion curves. The thermodynamic parameters were consistent with other wastes used as a bioenergy feedstock. Plastic solid waste presents attractive characteristics for pyrolytic oil production. The main highlights achieved for this study indicate that the pyrolysis of plastic solid waste can be an important step for the development of a recycling system that can recover energy from these wastes in a clean and environmentally friendly process.