Research on recycling channel selection of closed-loop supply chain considering consumer preference and fairness concern

This paper studied the influence of consumer preference and fairness concern on recycling and pricing decisions of closed-loop supply chain (CLSC) under different recycling channels. The results show that consumers' fairness concern cannot affect the manufacturer's decisions and profit; consumers' fairness concern is benefit to consumers, and it can improve the recycle rate. The channel selection strategy is depend on consumers' fairness attitude.

Sustainable utilization of recycled aggregates: robust construction and demolition waste reduction strategies

PurposeDue to the high demand of concrete, significant volume of natural resources is required, including virgin aggregates. Many studies have shown that the production of concrete has one of the highest CO2 levels. Although efforts are in place to recycle, enormous effects on landfill and the wider environment remain. Research has suggested the importance of reusing construction and demolition waste such as aggregate for use in recycled concrete. However, robust construction and demolition waste reduction strategies are required. There have been numerous researches on the use of recycled concrete and its management in the construction industry. This paper further consolidates this position.Design/methodology/approachThis paper exhibits the barriers and benefits of using recycled aggregates for construction industry. This is achieved via reviewing the current construction and demolition waste reduction strategies used mainly in three countries: the UK, Australia and Japan. These countries were selected since they seemingly have similar construction industry and environment. Subsequently, evolving barriers and benefits of using recycled aggregates for construction industry are also reviewed and discussed. And to support such focus, robust construction and demolition waste reduction strategies will be advocated.FindingsThe findings are summarized as follows. The recycling construction and demolition waste could have a positive net benefit compared to the procurement and production of virgin aggregate materials with the same properties. This is not only financially beneficial but also environmentally viable, as fewer resources would be required to produce the same aggregate material. There are effective ways to achieve a high recycle rate target, as demonstrated by Japan. The implementation of a similar recycling process could be implemented globally to achieve a more effective recycle rate through the help of governments at all levels. By creating awareness about the financial and environmental benefits of using recycled aggregate products, large recycling companies can be also enticed to follow suit.Practical implicationsThe findings from this paper can ultimately support the construction industry to further consolidate and advocate the use of recycled aggregates.Originality/valueTo achieve the research aim, this paper reviews some of the main sustainability factors of recycled aggregates (including coarse and fine aggregates) and provides comparison to virgin aggregates.

Production of Biocrude and Charcoal from Fast Oxidative Pyrolysis of Cassava Pulp Residue Using a Fluidized Bed Reactor

Cassava pulp (Manihot esculenta Crantz) residue (CPR) is the solid waste generated from the cassava processing industry. In the bench-scale experiments, fast oxidative pyrolysis of CPR was carried out in a fluidized bed reactor, using uncondensed recycled pyrolysis gas as carrier medium to produce charcoal and biocrude. The influence of three gas recycle rates, ranging from 0.60 to 2.3 Sm3 h –1 , on the product yields and characteristics was investigated. Results suggest that an increase in the recycle rate will lead to an increase in biocrude yield and a decrease in the charcoal yield. The product yields of biocrude and charcoal were 15.68 ± 2.08 percent and 24.29 ± 3.31 percent, respectively. The biocrude product was mainly composed of alcohols, phenols, ldehydes, ketones, alkanes, and alkynes. The charcoal obtained has a heating value that is around 85 percent higher than that of the CPR feedstock. It has a high fixed carbon content of around 67 percent, but a low volatile matter content of only around 28 percent. At the pyrolysis temperature of around 500 °C, the uncondensed pyrolysis gas compounds consisted primarily of N2 and C2 H6, with small amounts of H2, and higher hydrocarbon compounds. Results suggest the potential for generating biofuel products from the fast oxidative pyrolysis of CPR.

Multi-Objective Production Programming to Systematic Sorting and Remanufacturing in Second-Hand Clothing Recycling Industry

This study proposes a multi-objective production programming model which is established for systematic sorting and remanufacturing second-hand clothes and the objectives are twofold: (1) minimizing the remanufacturing cost to maintain the competitiveness of second-hand clothing industry and (2) maximizing the recycle rate to reduce the environmental impact from the disposed clothes. Previous studies are lacking to involve the features of second-hand clothing recycled from reuse to recycle in optimizing both the remanufacturing costs and recycle rate. The consequential final destination of consumers’ second-hand clothes is either resold, donated, or disposed of. This study applied sensitivity analysis by varying production cost and new material cost are conducted to evaluate the suitability of three different types of sorting methods for second-hand clothes before let them entering the remanufacturing processes on (1) categories the used clothes; (2) worn-out conditions (high, medium, low), and (3) clothes materials (cotton, linen, wool, silk, artificial fiber). The results show that the first sorting method by clothing categories outperforms the other two methods in maximizing the recycling rate. The second sorting method by worn-out condition generates a minimal remanufacturing cost. The recycling scenarios are simulated to verify the applicability of the proposed programming model with respect to the three sorting methods. The results show that Taiwan exhibited superior the recycle rates and Bangladesh had lower remanufacturing costs by adopting the sorting method by clothes materials.

Recycle Evaluation using System Dynamics for Solid Waste Management in Malaysia

Solid waste management gained the highest significant attention globally. In Malaysia, the generation of solid waste has increased 4% approximately year by year and an average from 0.8 kg/cap/day to 1.12 kg/cap/day. This trend is in line with the increasing population density in Malaysia especially in urban areas. The exponential growth of economic, urbanization, demographics and changing lifestyles are the key reasons behind the increase in the generation of solid waste. The objective of this research is to develop a system dynamic model for solid waste management in peninsular Malaysia and analyze the recycle evaluation. This method has an ability to handle a complex system and dynamic behavior over time. The result show that model imitate the real system with the validation less than +10% and -10% of acceptance range. This model can assist the decision maker in making efficient decision. The management of solid waste department may holistically measure the alternative action in cost effective and save time. As a result, the recycle rate in Malaysia relatively low and lack of participation from public. Enforcement and engagement from all parties are needed in order to achieve a sustainable environment in future.

MODEL OPTIMASI AGRO ECO-INDUSTRIAL PARK BERBASIS INDUSTRI TAHU DENGAN PENDEKATAN GOAL PROGRAMMING

Industri tahu di Kabupaten Sumedang menghadapi beberapa permasalahan terkait limbah, inefisiensi penggunaan air, dan ketergantungan terhadap bahan baku (kedelai) impor. Konsep Agro Eco-industrial Park (AEIP) berbasis industri tahu dapat menjadi alternatif solusi untuk memperbaiki kinerja industri tahu dan agroindustri terkait lainnya. Pengembangan AEIP perlu mempertimbangkan keseimbangan kapasitas untuk mengoptimalkan kinerja sistem. Penelitian ini bertujuan membangun suatu model optimasi AEIP berbasis industri tahu yang didukung agribisnis ternak sapi, usaha tani kedelai, produksi pupuk organik, dan unit biodigester. Penelitian dilakukan di sentra industri tahu Giriharja, Kabupaten Sumedang dengan menggunakan metode Goal Programming untuk memodelkan pertukaran material antar agroindustri. Model memasukkan lima variabel keputusan yaitu jumlah produksi tahu, jumlah produksi ternak sapi, jumlah produksi kedelai, jumlah produksi pupuk organik, dan jumlah produksi biogas. Kinerja model diukur dari sisa pertukaran material dan derajat daur ulang. Hasil penelitian menunjukkan bahwa model yang dibangun mampu memberikan solusi optimal berupa jumlah produksi untuk masing-masing agroindustri. Model juga menunjukkan kinerja yang lebih baik dibanding sistem yang sedang berjalan yang diindikasikan dengan penurunan sisa limbah dan peningkatan Recycle Rate.

Effect of Hg in Jiaozhou Bay Waters-Settling Process

Being a close bay, vertical settling was the dominant transfer process of Hg Jiaozhou Bay. Based on the investigation data of mercury (Hg) in bottom waters in Jiaozhou bay in 1979 to 1985 (in absence of 1984), this paper tried to analysis both of the settling processes and settling mechanisms of Hg. Results showed that that Hg in Jiaozhou Bay was settling continually over year, therefore a continued accumulation of Hg contents in bottom waters appeared, especially in spring and summer. Sediments in sea bottom could be both of source and sink of pollutants, especially for persistence pollutants such as Hg. Based on the both of the settling processes and settling mechanisms, the improve of recycle rate and the emission reduction of Hg should be the major pollution control strategies in Jiaozhou Bay.

Anaerobic fermentation of organic solid wastes: volatile fatty acid production and separation

Anaerobic fermentation of organic municipal solid waste was investigated using a leach-bed reactor (LBR) to assess the volatile fatty acid (VFA) production efficiency. The leachate recycle rate in the LBR affected the VFA composition of the leachate. A six-fold increase in the recycle rate resulted in an increase of the acetic acid fraction of leachate from 24.7 to 43.0%. The separation of VFAs via leachate replacement resulted in higher total VFA production. VFA separation from synthetic VFA mix and leachate of a fermented organic waste was assessed via a counter-current flow polytetrafluoroethylene (PTFE) membrane contactor. Acetic and propionic acid permeation fluxes of 13.12 and 14.21 g/m2.h were obtained at low feed pH values when a synthetic VFA mix was used as a feed solution. The highest selectivity was obtained for caproic acid compared to that of other VFAs when synthetic VFA mix or leachate was used as a feed solution. High pH values and the presence of suspended solids in the leachate adversely affected the permeation rate.