Anil Kumar*, R.P. Saini and J.S. Saini

Abstract: An experimental investigation was carried out to study the effect of artificial roughness, in the form of multi v-shaped ribs with gap on one heated wall of a rectangular solar air heater duct, on heat transfer (Nusselt number) and friction loss (friction factor). The artificially roughened duct had a width to height ratio (W/H) of 12, relative roughness width ratio (W/w) of 6, relative roughness pitch (P/e) of 10, relative roughness height (e/D) of 0.0433, relative gap width (g/e) of 1.0, relative gap distance (Gd/Lv) of 0.69, while the angle of attack (α) was varied from 30° to 75°. The heat transfer and friction characteristics of the duct were compared with those of a smooth duct under similar experimental conditions. It was found that there was a significant effect on the Nusselt number and friction factor when the angle of attack was changed.

Keywords: Angle of attack, Friction factor, Gap distance, Gap width, Nusselt number.

Shewin Attasat*, Piyabutr Wanichpongpan and Wiwat Ruenglertpanyaku

Abstract: In this study, an integrated aquaculture system, based on shrimp-fish-seaweed, was designed and tested for its ability to treat shrimp pond effluent. Marine shrimp (Penaeus vannamei), herbivorous fish (Oreochromis sp.) and seaweed (Entermorpha sp.) were co-cultured in a recirculation system. The experimental results indicated that the integrated aquaculture, that included water-recirculation, could reduce nitrogenous-waste accumulation in shrimp ponds by retaining some nitrogen content in fish and seaweed biomass. 88% of the nitrogen introduced by feeding was collected through this system. Most nitrogen content (45%) was found in the form of pond sediment. 24% of the original nitrogen was retained in the form of aquaculture biomass, i.e. 15%, 6% and 3% for shrimp, fish and seaweed respectively.

Keywords: shrimp pond effluent; integrated aquaculture system

Narissara Kaewphan and Shabbir H. Gheewala*

Abstract: Due to the huge amount of feedstock availability, bioplastic products have chance to penetrate in Thailand’s plastic market, as most of the plastic products are relying on fossil fuels. Thus, this paper illustrates greenhouse gas emissions from bioplastic bags are manufactured from cassava. This could replace percent conventional plastic bags share by 10% of total plastic bag product in Thailand. The study also focuses on market opportunity for bioplastic by using interview questionnaire. The opportunity can be predicted by analyzing the consumer behavior result and give recommendations for future support to bioplastic products. The results show that on the basis of global warming effects, plastic bags perform better than bioplastic bags. On the other hand, bioplastic bags help to reduce fossil fuel use and offer advantages vis-à-vis less emissions from disposal stage. Consumer behavior analysis revealed that on average a person receives about 140 bags per year from shopping at the supermarket. About 60% of the people interviewed said that they are willing to pay a small extra amount for bioplastic bags.

Keywords: Bioplastic bag, consumer behavior,greenhouse gas, market opportunity,plastic bag.

Sudjit Karuchit* and Jetiya Kwanma

Abstract: This research studied the relationship among important factors of cement production – namely, raw materials, fuels, and manufacturing processes – and gaseous and particulate emissions. Two types of statistical prediction models, multiple regression (MR) and artificial neural network (ANN), were developed and compared. The recorded daily average data of raw materials, coal fuels, alternative (hazardous waste) fuels, production processes, and gaseous and particulate emissions in 2007 were used in the analysis. Results show that the MR and ANN models for predicting NO₂, SO₂, CO₂, HCl and TSP, have the Adjusted R2 values in the range of 0.25-0.57 and 0.44-0.66, respectively. It is also found that the independent variables that have significant effect on the of models are quantity of clay, quantity of limestone, raw mill running time, alternative fuels used, kiln running time, and quantity of clinker. Overall, the ANN models perform slightly better than the MR models.

Keywords: Cement, artificial neural network, multiple regression, air pollution, model.

Suneerat Fukuda

Abstract: This study investigated the effect of temperature, heating rate and particle size on the yields of pyrolysis products from palm empty fruit bunch (EFB). Experiments were carried out in a lab-scale fixed bed pyrolysis system under vacuum condition. Under all conditions studied, the liquid product or known as bio-oil appeared to be dominating. The total liquid (organic + water) yield reached its maximum at 550°C with around two-third being organic and the rest being water. Increasing the particle size generally increased gas yield and decreased liquid yield. However, the catalytic effect of inorganic matters could also have some role during pyrolysis. Higher heating rates increased the yield of organic fraction and overall pyrolysis conversions. The mass and energy balance analysis showed that about two-third of the energy from biomass was concentrated in the liquid product. If not being able to utilize the product char due to the high content of alkalis and only the product gas was used to provide energy for pyrolysis reactions, the net efficiency of the process will largely be affected by the required process energy consumption and the import of external energy may be needed.

Keywords: Bio-oil; Vacuum pyrolysis; Palm empty fruit bunch; Energy balance.

Satoshi Soda,*, Takashi Arai, Daisuke Inoue, Tomonori Ishigaki, Michihiko Ike and Masato Yamada

Abstract: Treatment performance and greenhouse gas emissions of various biological sewage treatment processes in Japan were evaluated. Data related to energy consumption, effluent water quality, and sludge production of various treatment processes were obtained from “Sewage Statistics” published by the Japan Sewage Works Association. The conventional activated sludge (CAS) process and modified processes for nutrient removal were selected for analysis, such as anaerobic–oxic, recycled nitrification–denitrification, anaerobic-anoxic–oxic, nitrification/endogenous denitrification, and step-feed nitrification–denitrification processes. Performance of the treatment processes was evaluated as the eutrophication potential (EP) calculated from the BOD, total nitrogen, and total phosphorus concentrations in treated effluent and NO_X emission by electricity consumption. The global warming potential (GWP) of treatment processes was calculated from CO₂, CH₄, and N₂O emissions by electricity consumption, and N₂O and CH₄ emissions from the biological processes and water environment where effluent is discharged. The EP values of the nutrient removal processes (1.0–6.4 g-PO₄eq/m³) showed negative correlation with the GWP values (0.22–0.68 kg-CO₂eq/m³) as a general trend. The sole exception to this tradeoff was the step-feed nitrification–denitrification process, which can reduce the EP value of sewage with a considerably smaller increase of the GWP value than that of the CAS process. Sludge yields of treatment processes (0.01–0.032 m³/m³) also showed negative correlation with GWP values.

Keywords: Eutrophication potential, global warming potential, life cycle assessment, sludge production, wastewater treatment plant.