Parichat Suknark, Sasidhorn Buddhawong*, Sirintornthep Towprayoon, Soydoa Vinitnantharat, Awassada Phongphiphat, Isaree Jirajariyavech and Komsilp Wangyao

Abstract: This study evaluates the refuse-derived fuel (RDF) production potential from a thin-layer landfill in Thailand. Unmanned aerial vehicle (UAV) photogrammetry was used to estimate the waste volume. Electrical resistivity tomography (ERT) measurements were performed to estimate the proportion of RDF in the waste pile using the relationship between resistivity and waste composition. Then, an economic cost–benefit analysis was performed. Disposal zones C and D at Chanthaburi landfill were used as the study site. The results showed that zones C and D's total waste volume and weight were 219,163 m³ and 170,947 tons, respectively. ERT results imply that the potential of RDF production from plastic waste in zone C was between 27.01% and 35.57%, and between 29.96% and 55.64% in zone D. Thus, the spatial average of RDF production potential from both zones was approximately 30.97%. As a result, the RDF produced during this study was approximately 55,666 tons. The economic cost–benefit analysis observed that the total financial cost of construction and operation was 97,642,554 THB, while the benefits from selling RDF, soil-like material for waste covering, and regaining the landfill volume was a totally 131,734,704 THB. The net present value was 50,754,800 THB, indicating that the project was worthwhile.

Keywords: Electrical resistivity topography, landfill mining, refuse-derived fuel, thin-layer landfill.

Nutchapon Horakul and Navadol Laosiripojana

Abstract: Lignin, a biopolymer which can be found in lignocellulosic materials, is the second most abundant from cellulose. Unlike cellulosic compounds, lignin has an equivocal structure which is the limitation for the industrial applications. Since lignin has a great antioxidative property, it has a capability to incorporate with the conventional plastics for the purpose of shelf-life extension as packaging materials. In this work, Ethanol organosolv lignin (EOL), a sulfur-free lignin, was extracted from eucalyptus sawdust by using ethanol as an organic solvent. The profiling of EOL was done via gel permeation chromatography (GPC), Scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). EOL from eucalyptus was undergone the partial depolymerization via mild ethanolysis (160, 200 °C for 1 h) to homogenize the lignin by lowering molecular weight (MW) and increasing radical scavenging activity (RSA). Eucalyptus organosolv lignin (EL) has Mw of 1758 Da and 1.48 for Pd while the product at 160 °C (ESL160) and at 200 °C (ESL200) has Mw of 1643 Da, 1.42 for Pd and Mw of 1613 Da, 1.41 for Pd. Lignin samples including EL, ESL160, and ESL200 were then blended with LDPE and produced film, which was tested toward antioxidant activity. DPPH (2,2- diphenyl-1-picrylhydrazyl) assay was used to evaluate the antioxidant activity of LDPE/lignin films and reported in the value of %RSA. It was found that, at 1%wt of lignin in LDPE, %RSA of LDPE/EL, LDPE/ESL160, and LDPE/ESL200 were 17.83, 27.65, and 27.54, respectively.

Keywords: Lignin, mild ethanolysis, depolymerization, LDPE, antioxidant activity.

Pannathorn Thammabut, Sudarut Tripetchkul*, Komsilp Wangyao and Sirintornthep Towprayoon

Abstract: This study investigates the feasibility of the co-composting process of night-soil sludge and yard waste using the solar greenhouse reactor to reduce the composting time. Changes in physicochemical and biological properties were monitored during the co-composting processes: solar greenhouse composting with natural ventilation and static pile composting with natural ventilation. Furthermore, the biodegradation of organic matter was evaluated. The physicochemical analysis showed that the solar greenhouse composting could significantly expedite a rising temperature to the thermophilic temperature range within the first day of the composting process and maintain the thermophilic phase for at least 7 days. On the other hand, the static pile composting treatment could not reach the thermophilic stage. Moreover, the solar greenhouse composting system could enhance the composting process during the first two weeks, as evidenced by higher accumulated temperature integration (145.00 °C), organic matter reduction (7.60 %), and OM reduction rate constant (k, 0.0243 k day-1 , R²=0.84), and the GI value (130.29 %). Twenty-eight days of composting are sufficient to produce compost that meets Thai agricultural standards and is free of Salmonella typhi. The results concluded the success of the thermophilic composting using the solar greenhouse reactor for enhancing the biodegradation of organic matter, thus, reducing the composting process time.

Keywords: Composting solar greenhouse, thermophilic temperature, night-soil sludge, organic matter degradation, yard waste.