Recycling and Reuse Approaches for Better Sustainability

Various studies have been executed for the aim of obtaining new products via reused waste materials or to use such materials as admixture materials in already available products. The widespread, worldwide popularity of automobile traffic and increasing quantity of PET (polyethylene terephthalate) pose risks for human health, environmental safety and aesthetical concerns, etc. However, the reuse of waste tires and plastic materials in various applications has been encouraged and increased globally.

The objective of the present study is to analyze not only the usability of such wastes by adding waste tire and waste PET materials into the soil but also to determine their effects on the soil characteristics. Sieve analysis, hydrometer test, pycnometer, and compaction and CBR (California bearing ratio) tests have been conducted on a sample soil from Corlu region. In optimum water content, CBR tests have preliminarily been conducted on a natural soil sample, which was then ensued by adding into the soil sample 2% ratio of tire, 2% ratio of PET, 4% ratio of PET + 0.5% ratio of tire, and 0.5% ratio of PET + 4% ratio of tire (by weight), respectively. The results of the laboratory tests performed revealed that a significant change was not observed in the CBR values of the waste tire, while the PET admixture led to an increase in the CBR values.

One recent sustainable alternative for domestic wastewater management is stream segregation at the source to recover, recycle, and reuse valuable materials embedded in each stream. Gray water may be treated to remove organic matter and pathogens to return the reclaimed water to almost any point in the water cycle as an alternative source of water including toilet flushing and irrigation. Yellow water may be used as a significant source of nitrogen, phosphorus, and potassium as plant nutrients to be recycled as fertilizers through direct or indirect routes. Finally, organic matter in brown and black water may be used as a source of energy or as a soil conditioner after composting. Regardless of the form of segregation, each stream presents a new concept/route in terms of recycling and reuse to enable revaluation of this “waste” stream, i.e., domestic wastewater, as a beneficial source.

Beneficial use of sediments is known as a sustainable and environmentally friendly alternative to confined disposal facilities and open water disposal. Since most of the geotechnical engineering applications such as roads, backfills, berms, and in situ capping require a large amount of material in their construction, the beneficial use of dredged materials in geotechnical engineering applications is a promising implementation. In this study, sediment dredging and management are introduced. The beneficial use of dredged materials in geotechnical engineering applications is reviewed, and the necessary requirements for their beneficial use in these applications are addressed.

This study aims to determine the methods used by the university students for the disposal of potentially recyclable wastes (paper and cardboard, glass, metal cans, etc.) and assess university students’ recycling behavior. For this purpose, a survey was conducted on students at Istanbul University, Turkey. Depending on the survey results, suggestions on how to improve recycling of package wastes, spent batteries, and waste electrical and electronic equipments in the university campus are presented. The effect of gender on recycling behavior of university students and attitudes toward the disposal of potentially recyclable wastes were also discussed.

The aim of this study is to evaluate the environmental impacts of high-density polyethylene (HDPE) packaging materials with the help of life cycle methodology. The production of HDPE plastics has two consecutive steps of granulate production and blow molding. When production of HDPE and transportation stages are considered, highest shares in global warming potential (GWP), photochemical ozone creation potential (POCP), acidification potential (AP), and eutrophication potential (EP) are due to granulate production. On the other hand, blow molding is the main contributor to ozone depletion potential (ODP) with regard to production and transportation stages. Incineration is observed to exert positive impacts on POCP, AP, and EP. Recycling has positive effect on all impact categories except EP. Besides, as landfilling elevates environmental impacts, it is not recommended as an end-of-life fate for HDPE packaging wastes.

Resource management, akin to hazardous waste management, must adopt a cradle-to-grave perspective for key resources. One good reason is that substance flows go unnoticed in the regional metabolism and the global trade of all goods (im Güterfluss). This in turn conceals causality in depletion and pollution, or hinders an effective conservation of resources and the environment, leaving its management symptomatic. Phosphorus (P) is a key nonrenewable resource, which must be imported to almost all countries, and its use as fertilizer cannot be substituted posing a constraint on the global food production and for the long term. This paper shows the P-flows used and lost abroad (the Hinterland) to produce the goods imported into one country, as a continuum of our earlier study and for the cases of Turkey and Austria. These Hinterland flows represent the actual and total raw material consumption of a country and can in some cases dominate the overall system belittling front-end or country-wide recycling and conservation efforts. In particular, losses in global agriculture as well as the magnitude of mining wastes must be considered for effective decisions on P-management. Taking the Hinterland into account will link those global and regional P-flows and help in setting the right priorities for P-management. Implication for recycling and the circular economy is the potential shown for recovery, which shall only take place alongside with reducing big losses and the inefficiencies within one country and elsewhere.

Alkali (NaOH) hydrolysis and low-temperature thermal treatment were applied to digested sludge for the recovery and release of PO₄ ³⁻ and NH₄ ⁺. The Box-Behnken design was applied in the hydrolysis using 0.5M NaOH for the optimization of the conditions that affect the nutrients and metal release from digested sludge. PO₄ ³⁻ release was positively associated with decreasing liquid/solid ratio and increasing temperature. Moreover, Ca, Fe, and Zn releases also increase with increasing temperature. However, the temperature did not have any effect on NH₄ ⁺ release. An optimal condition for the release of nutrients and metals was obtained at a liquid/solid ratio of 10/1 (mL/g), a temperature of 40 °C, and a reaction time of 40 min. In this optimal condition, the concentrations of PO₄ ³⁻ and NH₄ ⁺ released were 921.00 and 819.15 mg/L, respectively. The removal rates of PO₄ ³⁻ and NH₄ ⁺ from hydrolyzed sludge liquid by struvite crystallization were 95.27% and 77.95% in this condition. Struvite obtained had low Ca, Fe, and Al content. The produced struvite meets the legal limits for fertilizer use in terms of Cd, Cu, Ni, Pb, Zn, Hg, and Cr content specified by Turkish regulations.

One-dimensional (1D) advection–dispersion transport modeling was conducted as a conceptual approach for evaluation of organic (phenolic compounds) contaminant transport through alternative liner systems from leachate to groundwater. In this study, ten identical pilot-scale landfill reactors with different alternative composite liners were simultaneously operated for a period of about 290 days. The results of 1D transport model showed that the highest molecular diffusion coefficients for 2,3,4-TCP and 2,3,4,5-TeCP and PCP were determined to be with the average values of 54.25 × 10⁻⁹, 44.17 × 10⁻⁹, and 15.19 × 10⁻⁹ m²/sn and the lowest molecular diffusion coefficients for 2,4-DCP and 2,3,5-TCP were obtained to be with the average values of 1.107 × 10⁻⁹ and 1.115 × 10⁻⁹ m²/sn approximately in all reactor systems. The results indicate that liner systems have no significant effect on organic contaminant migration from leachate to groundwater and the dominant mechanism in transportation of organic contaminant is molecular diffusion and geomembrane layer is ineffective in organic contaminant transport through composite liners.

As a result of social and economic activities of people, materials that completed useful life that should be removed from the environment we live in are classified as waste. Nowadays, except for local uses (burning, warming, etc.), there are few uses for general purposes (alternative fuel, etc.). Energy usage and waste amount are increasing rapidly with the increase of the population in the world and the development of industry and technology. Control of energy consumption and waste is crucial for a sustainable future. In this study, the use of pyrolysis for agriculture and forest wastes was investigated based on the literature. For this purpose, many studies on pyrolysis of organic wastes such as agriculture and forest wastes have been compiled and presented on a common basis. The methods followed in the selected studies are examined and given in the form of tables under the common headings in order that different researchers can reach easily. It has been generally agreed that the pyrolysis process, which is considered as an alternative waste management method, is an energy and environmentally friendly application for waste and that this application can be used to reduce waste and recycle waste.

Pressure management is one of the most effective methods for water loss reduction. Pump used in turbine mode (pump as turbine, PAT) is a viable option for reducing excess water pressure, water losses, and pipe failures in water distribution networks in addition to energy production at microscale. In this study, a PAT system recently installed in Antalya City of Turkey is presented, and its performance is evaluated for its initial operational period of approximately 5 months. This full-scale PAT system was implemented in a parallel pipeline with a pressure-reducing valve (PRV). The operation of the PAT system was continuously monitored online for flow rate, power, and pressure levels. The PAT system proved to work efficiently in a wide range of inflows (130–300 m³/h) where the produced energy varied between 0.7 and 8.4 kWh for a reduction of approximately 1 bar pressure head with an average efficiency of 60%. Environmental benefits of green energy production, reduction in physical water losses, and carbon dioxide emissions were evaluated. The payback period of the PAT application was computed as 53 days based on the costs and revenues of the PAT application.

Although carbon dioxide (CO₂) in the air is at a low level (between 0 and 0.03%), the concentration of it is significantly higher in industrial regions. The CO₂ concentration in the atmosphere increases 2–3 ppm every year because of the burning of fossil fuels. Global studies have focused on reducing the carbon dioxide level to the minimum limit (450 ppm) by reducing CO₂ emissions 50–80% by the year 2050. In this study, in order to minimize the CO₂ levels in the Aliağa and Atatürk industrial districts in Izmir, Turkey, S. elongatus from cyanobacteria were isolated from the Gölcük Lake in Ödemiş, Izmir, and were used to produce 1-butanol from CO₂ via photosynthesis as a fuel source, instead of gasoline, for cars. The maximum 1-butanol concentration produced was 79 mg/L, and the 1-butanol_produced/CO_2utilized efficiency was 87.6% in the S. elongatus species isolated from the Gölcük Lake at a temperature of 30 °C, at 60 W light intensity, at pH = 7.1, at 120 mV redox potential, at a flow rate of 0.083 m³/min using CO₂ from the Aliağa industrial region, and at 0.5 mg/L dissolved O₂ concentration. The maximum 1-butanol concentration produced was 59 mg/L, and the 1-butanol_produced/CO_2utilized efficiency was 67.9% in the Atatürk industrial district due to low levels of polluted air in this region. In order to produce 10.000 m³ 1-butanol from 1000 g/L CO₂, the cost was calculated as 0.13 euro, while the addition of plasmid increased the cost to 0.66 euro to produce 10.000 m³ 1-butanol.

Although energy sources on the environment are limited, in all parts of life, energy requirement increases rapidly which depends on the increasing technology and population. This problem enforces researchers to study on energy efficiency, performance, and optimization. This paper presents artificial intelligence-based (AI) prediction models to estimate energy loads for residential buildings. The model was developed by using eight input parameters (relative compactness, surface area, wall area, roof area, overall height, orientation, glazing area, glazing area distribution) related to two output parameters (heating and cooling loads).

The dataset contains 768 residential building information. In the proposed model, advanced machine learning (ML) regression algorithms (tree-based and lazy learning algorithms) compared with multilayer perceptron (MLP) and support vector regression (SVR) algorithms. According to coefficient of determination (R ²), mean absolute error (MAE), and root mean squared error (RMSE) values best prediction model obtained for energy-efficient building design.

As the population coming to the cities increases, the surface textures of the natural landscapes around the city deteriorate and are quickly transformed into urban areas. At the local level, ecosystem and climate change also occur when materials such as concrete and asphalt with higher thermal capacities and thermal conductivity replace plant cover and water masses. As a result, the continuity of urban life becomes dangerous. Sustainable cities make the city more efficient and provide people with a high-quality living environment, without consuming too much natural resources. These local effects can be limited by city-level harmonization policies such as cool plots in cities, cool and green roofs, and expanding vegetation. In this study, the effects of the presence of green roofs instead of the traditional roof on the sustainability of life in the cities were examined.

Cement is a composite material and it consists of different raw materials. The raw materials which are used in the cement production industry are commonly obtained from rocks such as limestone, gypsum, clay, and iron ore. In addition, the cement raw materials may also include natural radionuclides such as ²²⁶Ra, ²³²Th, and ⁴⁰K, which may have an adverse effect on human health. Hence, determination of natural radioactivity level is very important for human health safety. In this study, natural activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K are investigated in cement and cement raw materials in Turkey as a case study. In addition, eight different radiological parameters and indices were calculated from activity concentrations. The natural radioactivity due to the presence of ²²⁶Ra, ²³²Th, and ⁴⁰K was measured using the gamma spectrometer coupled with HPGe detector. The mean measured activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in the raw materials were 38.14, 92.66, and 636.63 Bq kg⁻¹, respectively, with higher activity concentrations in coal for ²²⁶Ra and trass for ²³²Th and ⁴⁰K. Mean activity concentrations of natural radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) in cement samples were found as 34.26, 58.2, and 512, respectively. The results showed that coal and fly ash are the principal contributors for the presence of ²²⁶Ra activity concentration, trass and iron ore materials for the presence of ²³²Th, and clay and trass raw materials for the presence of ⁴⁰K in cements.

Ecological footprint is a method that was created to calculate the load for nature of a specific population, and it also calculates the biological effective and water-containing areas which are required to obtain renewable sources for the use of people. The data obtained by the ecological footprint resource accounting provides guidance for strategic decisions on resource management. Many studies exist in the web area in order to calculate the ecological footprint automatically after entering the data. In this study, the questions in a web site were asked to people living in Istanbul in different age intervals. It was observed that the percentages of the components constituting the ecological footprints calculated for three different age ranges (three different age ranges between individuals aged 50 and below) varied according to the age ranges. In addition, the values of ecological footprints according to the education and income levels were examined for the male and the female individuals. For all the age ranges, it can be said that the ecological footprints of individuals with high economic income are higher than those with low economic income. Also, the ecological footprint of the males of the same income level is higher than the ecological footprints of the females.

Black carbon (BC) is one of the key atmospheric aerosol components of locomotive air quality and climate change. BC has the capacity to absorb light across all visible wavelengths; it reradiates solar radiation as heat, inducing a climate warming effect. Due to its shorter lifetime in the atmosphere compared to carbon dioxide, it is an excellent target for emission reductions. BC is a specific marker of primary combustion of fossil fuel and biomass. BC concentrations in urban areas are variable; in developed countries, motorized transport vehicles are considered to be the most important source of BC, whereas in developing countries, biomass burning may be important. The interest of policy makers in BC was rise up owing to arising evidence on health effects and the impact of BC on global warming. The authors present here a general knowledge on BC to clarify its sources, concentration levels, effect on climate change, and adverse health effect.

Within the course of significant changes in the history of humankind, the Industrial Revolution, together with the developments in science and technology, resulted in increases in the world population, which led to increases in anthropogenic greenhouse gas emissions and concerns for human welfare. As a result, the composition of the atmosphere has changed, creating a change in the global climate. According to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, this change will severely diminish the impact of the struggles for sustainable development. Turkey is located in the Mediterranean Basin, which will be the region affected most from climate change, the first impact of which will be severe drought. Climate change will significantly influence water, agriculture, and energy sectors. Because of steady population growth and intensive industrialization, total greenhouse gas (GHG) emissions in Turkey steadily increased from 1990 through 2015. The energy sector in Turkey accounted for 67.8% of total GHG emissions, followed by industrial processes at 15.7%, agriculture at 10.8%, and waste at 5.7%. According to the modeling results covering between 2016 and 2099 in Turkey, especially in summer, an increase in the mean temperature between 1 and 4 °C is expected throughout different areas of the country.

In this study, geo-accumulation index (I _geo), enrichment factor (EF), potential ecological risk (E _r), and risk index (RI) of five metals (Cu, Pb, Zn, Hg, and Cd) and Sc (as reference element for enrichment factor calculation) in soil samples were applied for assessing the pollution pattern and possible sources of heavy metals. Soil samples were collected from 27 different locations in Avcilar in the European part of Istanbul, Turkey. The mean I _geo values of Cu, Pb, Zn, Hg, and Cd were found between 0.12 and 0.96, which means that the soil contamination levels of these metals were uncontaminated to moderately contaminated. The EF mean values of Cu, Pb, Zn, Hg, and Cd were 1.70, 1.30, 1.30, 2.29, and 1.26, respectively. These EF results indicated that Cu, Pb, Zn, and Cd in the study area soil were affected by natural sources, whereas Hg was mainly caused by nature and partly influenced by human activities. The order of the mean values of E _r in the soil samples was in the following descending order of Hg > Cd > Cu > Pb > Zn. Most of the soil samples showed low and moderate ecological risks.

Kinetic evaluation of an acidogenic completely stirred tank reactor (CSTR) treating a chemical synthesis-based pharmaceutical wastewater was investigated. For kinetic modeling of the acidogenic reactor (Monod, Contois, Grau, et al.), first-order kinetic models were used. These models have high correlation coefficients in this study. Monod models have shown high correlation coefficients (99%) which were used in describing the process kinetics of the anaerobic acidogenic reactor. Kinetic studies showed that sludge yield (Y) and decay rate (K _d ) were 0.25 mg VSS/mg COD and 0.79 1/day, respectively.

Reuse of greywater for non-potable purpose such as irrigation, toilet flushing and groundwater recharge has been evaluated and applied widespread after advanced treatment processes. Specifically advanced oxidation processes present alternative option to integrate with biological treatment as prior or post-treatment to remove recalcitrant organic matters of emerging concern in greywater. This study focuses on the efficiency assessment of heterogeneous photocatalysis (PC) for oxidative degradation of real greywater samples collected at a hotel in Antalya, Turkey, by means of dissolved organic carbon (DOC) and UV₂₅₄ absorbance removals that correspond the mineralization and degradation rates, respectively. Increasing TiO₂ dose from 0.1 to 1 g/L enhanced DOC removal rates. Reduction of suspended solids from greywater using 0.45 microfilters increased DOC removal from 27 to 35% during PC treatment.

Gray water is a segregated domestic wastewater stream, which may be returned to almost any point in the water cycle after pertinent treatment. It is a reliable and renewable source of water. The experience of ITU’s segregated streams and ECOSAN research group has revealed/confirmed some issues/facts about gray water management based on Turkish case studies. Characterization of gray water and/or its sub-streams to be recycled and reused is a key factor in determining final uses as well as selecting the most appropriate treatment schemes and feasible layouts. Pathogens may be as significant a parameter as the predominantly mentioned organic matter. Carefully performed water balances regarding the amount which is to be supplied by reclaimed gray water and the amount of gray water that may possibly be produced within an area are critical in the success and feasibility of the process. Proximity of the gray water source to the location of end use is yet another significant determinant. Economic analysis for reclaimed gray water use for toilet flushing in the Turkish megacity Istanbul has shown that the suggestion is feasible with payback periods of less than 5 years with optimal number of units in developments. Social acceptance surveys indicate that there is a considerable approval for the use of reclaimed gray water. All in all, the idea of recycling and reuse of reclaimed gray water makes a lot of sense, and the conclusions drawn in terms of technical/environmental, economic, and social tiers of sustainability have provided motivating results.

Advanced oxidation process treatment method has been adapted to olive oil mill wastewater (OMW) for treatability in conventional plants by the aim of sludge minimization. Lots of olive oil mills have facilities in the Aegean Region, Turkey. Wastewater, used in this study, was collected from these factories. Because of the advanced and expensive treatment methods of this wastewater, regulations and limitations are ignored. 95 °C temperature and 10 bar pressure conditions were used with H₂O₂ as an oxidant in wet oxidation method. Over 96% of oil-grease and 48% of chemical oxygen demand (COD) removal were achieved using wet air peroxidation in conditions with 2.5 mL H₂O₂/100 mL in 1 h. The influence of hydrogen peroxide with temperature and pressure makes the oil in wastewater soluble and in that way can be treatable in conventional plants.

In the present study, the biosorption of Astrazon Blue FGRL (AB) which is one of the cationic dyes most commonly used in nylon and acrylic textiles from aqueous solution was studied onto tea waste (tea dust discharged after using), a waste lignocellulosic material. The effects of different parameters including biosorbent dosage, initial pH, contact time, initial dye concentration, and temperature were studied. Tea waste was characterized by Brunauer-Emmett-Teller (BET) surface area, FTIR, and SEM. The experimental equilibrium data were fitted to the Langmuir and Freundlich isotherms. The Freundlich isotherm model fitted to the experimental data better than the Langmuir isotherm. The maximum biosorption capacity, q _max, was found to be 263.16 mg/g. The experimental data were discussed in detail comparing with some other low-cost adsorbents reported for AB removal in the previous literature, considering q _max, adsorbent surface area, experimental conditions, isotherm models, and thermodynamics of the AB adsorption. The thermodynamic data indicated that AB biosorption was feasible but nonspontaneous, endothermic, and a chemisorption reaction.