The effects of using reprocessable material on the durability and mechanical properties of landfill leachate collection HDPE pipes

This paper investigated the durability and mechanical properties of landfill leachate collection HDPE pipes which had been made of different weight percent amounts of virgin and reprocessable HDPE compounds (VC and RC). Durability is reported base on the chemical properties, obtained through oxidative induction time (OIT) and melt flow index (MFI) measurements, at the temperature of 50 °C and over a period of 12 months immersion in a synthetic leachate. Mechanical properties are also described according to tensile and pressure tests which had been conducted on the pipes samples. All of the factors were examined had been affected by the addition of RC, but for the special combination the antioxidant depletion was significantly affected by the experimental aging condition and no important changes had been observed in the other pipe properties. The results from OIT tests indicate that the rate of antioxidant depletion is reduced by an increase in the weight percent amounts of RC, during the experimental aging condition. This reduction is probably attributed to the extraction of antioxidants from RC in their recovery process. Finally, although these results are related to the particular HDPE compound, antioxidant formulation and condition examined, but it can be said that the use of clean own reprocessable material for the production of landfill leachate pipes shall be permitted without limitations.     

Quality control for coal combustion products in South Korea through assessed pozzolanic-activity index with long-term property tests

In South Korea, nine million tons of fly ash (FA) are annually produced and approximately 70 % is reutilized for industrial demand. For the prompt reuse and insufficient reclamation site, quality control of FA which is main productive construction material from coal ash is very important. Assessed Pozzolanic-activity Index (API) test which needs only 2 days for evaluation of pozzolanic reaction is currently considered as an alternative of activity index measurement. This paper aims for an applicability of API test for prompt quality control and investigation of domestic FA properties. For the work, FAs from two different power plant types are prepared, and quality tests are carried out based on Korean Standards (KS) methods and API method. Lots of test results are compared with those from API and K-value test for FA with age of 7 days–1 year. From the test results for FA aged 1 year, API results are evaluated to be closely related with those from activity index and K-value, and the correlations are improved with increasing ages regardless of plant types. The applicability of API test is verified and the reduced period of FA quality evaluation can accelerate prompt use and the related process of FA.     

Leaching behavior of some demolition wastes

Demolition wastes may be used in different civil engineering applications as road constructions, concrete, and embankments or landfill. Regardless its application, leaching tests of the waste should be carried out to assess concentrations of pollutants. Concrete, brick and mixture of concrete, bricks, tiles and ceramics wastes were subject to percolation test—CEN/TS 14405, and batch test—SR EN 12457. The leachates were analyzed with respect to concentration of inorganic elements—arsenic, barium, cadmium, chromium, copper, mercury, molybdenum, nickel, lead, selenium, zinc, fluoride, chloride and sulfate, and organic compounds (phenol index). The concentrations of elements in leachates were compared with the limit values of European regulation for the acceptance of inert wastes at landfills. Generally, the releases of inorganic species in leachates were below limits values. Some waste leachates obtained by percolation and batch test had high values for phenol index.     

Solubility parameters for determining optimal solvents for separating PVC from PVC-coated PET fibers

Poly(vinyl chloride) (PVC) in PVC-coated poly(ethylene terephthalate) (PET) fabrics can be separated through dissolution in a suitable solvent, leaving only the PET fibers. We investigated the solubility of PVC in 30 solvents using swelling tests. The results were compared with those obtained using the Hansen, Gutmann, Swain, E _T(30), and Kamlet–Taft parameters. For this purpose, Gaussian plots of the PVC swellability versus solubility parameter were used to decide the applicability of the solubility parameter system. Only Gutmann’s electron acceptor–donor parameter (AN + DN) and the Kamlet–Taft parameters β and π* could describe the PVC-solvent system satisfactorily. Tetrahydrofuran (THF), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF), cyclohexanone, and cyclopentanone were tested for separating PVC from PET at different temperatures. THF dissolved PVC at 20 °C, while cyclohexanone and cyclopentanone did so at 40 °C. Traces of PVC remained on the PET fibers when DMF was used. Complete dissolution of PVC was not achieved at any temperature with MEK. The present work shows that solubility parameters are a helpful tool for the search for suitable solvents. It shows also that solubility parameters have to be selected carefully, since their usefulness depends strongly on the polymer properties.     

A comparison of refrigerant management policies and suggestions for improvement in South Korea

HFCs (hydrofluorocarbons) emerged as alternative refrigerants after the production of chlorofluorocarbons was banned and hydrochlorofluorocarbons were phased out, under the Montreal Protocol on Substances that Deplete the Ozone Layer. However, because the Kyoto Protocol considered HFCs as greenhouse gases, and their impact on climate change has been increasing, major developed countries have been strengthening existing regulations on the use of HFCs as refrigerants. South Korea has also passed various legislations related to refrigerant management. However, reports indicate that implementation of these regulations has been ineffective, due to the absence of a specific system for managing the production, use, and disposal phases of refrigerants. To identify and resolve these issues, this study investigates the current state of refrigerant management in South Korea for those three phases. Refrigerant management policies are compared between different legislatures, using the examples of the European Union, United States, and Japan. Based on the findings, five types of measures are suggested to reduce the production and consumption of refrigerants, and to improve refrigerant management regulations in ways that are most appropriate to the South Korean context.     

Preparation of biochar catalyst with saccharide and lignocellulose residues of corncob degradation for corncob hydrolysis into furfural

This paper presented a novel process for production of furfural by hydrothermal degradation of corncob over biochar catalyst, in which it was prepared with the recycling degradation solution and lignocellulosic solid residues. The biochar catalyst was papered by lignocellulose residues and concentrated saccharide solution, and then impregnated in 0.5 mol/L sulphuric acid at room temperature for 24 h assisted by the ultrasonic vibration. In the system of recycling, 8.8 % lignocellulose residues and 100 % concentrated saccharide solution from corncob hydrolysis have been recycled. Hydrolysis of corncob was carried out at 180 °C for duration of 170 min over the biochar catalyst. The experimental results have shown that the furfural yield of up to 37.75 % and overall corncob conversion rate of 62.00 % could be achieved under optimum operating conditions for the catalysts preparation and the corncob hydrolysis. It is believed that the acid density of 4.27 mmol/g of biochar catalyst makes the SO₃H groups cleave β-1,4 glycosidic linkages effectively and hydrolyze the cellulose and hemicellulose to water-soluble sugars, as well as to facilitate dehydration of xylose to give the product of furfural.     

Demonstrating Contaminant Degradation at an MGP Site With Metabolic Gas Flux and Radio Carbon Dating

Obtaining lines of evidence indicating that contamination in sediment environments is degrading and being transformed to less toxic forms is an important component of building support for a monitored natural recovery remedy for contaminated sediments. This project was a field demonstration of manufactured gas plant contaminant degradation in river sediments using metabolic gas flux and was performed in an urban area section of a river in northeastern Indiana. CO₂ sorbent traps were deployed to measure CO₂ flux from the river sediments. Sediment samples were collected and analyzed for polycyclic aromatic hydrocarbon (PAH) concentrations and for microbial community composition using molecular techniques. The results showed that the deployment was successful, measuring CO₂ flux at all sediment locations and demonstrating that microbial contaminant degrading activity was occurring in the sediments. Radio carbon dating showed a significant portion of the CO₂ being generated (approximately 19–27 percent) was the result of fossil fuel degradation. Molecular results showed that the microbial community consisted of phylotypes known to be associated with monocyclic aromatic and PAH degradation. ©2017 Wiley Periodicals, Inc.     

Life-cycle greenhouse gas emissions and economic analysis of alternative treatments of solid waste from city markets in Vietnam

We utilize life cycle assessment to trace conversion of degradable organic carbon (DOC) contained in organic waste from city markets in Da Nang, Vietnam. Our methodology makes explicit the process of conversion of DOC under aerobic and anaerobic conditions, as well as the balance of nutrients. Greenhouse gas emissions were calculated for six alternative scenarios: (i) anaerobic landfilling (current situation); (ii) semi-aerobic landfilling; (iii) landfill gas capture; (iv) composting; (v) pre-composting before landfill; and (vi) biogas production. We calculate that 1 t of waste in anaerobic landfilling emits 1.70 t CO₂-eq. with life-cycle perspective. Lowest emission occurs in biogas scenario with 0.26 t CO₂-eq./t. Composting occupies an intermediate position with 0.39 t CO₂-eq./t. Likewise, we estimate that cost of emission reduction in solid waste sector of Vietnam is 15.13 US$/t CO₂-eq., given by alternative of composting and taking anaerobic landfilling as reference. On the other hand, if social cost of carbon (SCC) is incorporated lowest cost to treat 1 t of waste is given by composting and semi-aerobic landfilling at discount rate of 5 %. However, using lower discount rates, and consequently higher values of SCC, composting and biogas production become the alternatives with lowest treatment costs.