Jurnal Reaktor

179-186

Authors: Opy Kurniasari, Tri Padmi, Edwan Kardena, Enri Damanhuri

Municipal solid waste (MSW) handling in Indonesia is currently highly dependent on landfilling at the final disposal facility (TPA), which generally operated in layer-by-layer basis, allowing the anaerobic (absent of oxygen) process. This condition will certainly generate biogas in the form of methane (CH4) and CO2. Methane is a greenhouse gas with a global warming potential greater than CO2, and can absorb infrared radiation 23 times more efficient than CO2 in the period of over 100 years. One way that can be done to reduce methane gas from landfills that escape into nature is to oxidize methane by utilizing landfill cover material (biocover) as methane-oxidizing microorganism media. Application of compost as landfill cover material is a low-cost approach to reduce emissions so are suitable for developing countries. The compost used in this study was compost landfill mining, which is degraded naturally in landfill. The purpose of this study was to evaluate the ability of biocover to oxidize the methane on a certain layer thickness with a continuous flow conditions. Three column reactors were used, which were made of flexy glass measuring 70 cm in high and 15 cm in diameter. The methane flowed from the bottom of the reactor continuously at a flow rate of 5 ml/minute. The columns were filled with biocover compost landfill mining with layer thickness of 5, 25, 35 and 60 cm. The results showed that the thicker layer of biocover, the higher the efficiency of methane oxidation. The oxidation efficiency obtained in each layer thickness of 15, 25, 35 and 60 cm was 56.43%, 63.69%, 74.58% and 80, 03% respectively, with the rate of oxidation of 0.29 mol m-2 d-1 and the fraction of oxidation of 99%. The oxidation result was supported by the identification of bacteria isolated in this experiment, namely metanotrophic bacteria that have the ability to oxidize methane through the form of methanol metabolite.

193-198

Authors: Luqman Buchori, Mohamad Djaeni, Laeli Kurniasari

The main problem in corn drying process is the low of energy efficiency (50%) and quality products. Consequently, operating costs in large for fuel consumption and the short shelf life of corn. Zeolite adsorption dryers have the potential to overcome this problem. This research aims to study composition of corn-zeolite and the effect of temperature on drying speed and protein and fat content in corn. Research variables are the ratio of corn and zeolite (1:0, 1:3, 1:1, 3:1) and intake air temperature (room temperature, 30oC, 40oC, 50oC). Sampling for moisture testing performed every 15 minutes. For energy purposes also calculated the energy efficiency (h) based on the amount of heat used to evaporate water from the corn (Qevap) divided by the total heat requirement to regenerate the zeolite and raising the air temperature (Qintr). Profiles of temperature and water in the mixed adsorption dryer are also studied. The results showed that the greater number of zeolite used, the water content of the final outcome a little more drying, protein and fat content of the final result of drying is relatively constant. The larger intake air temperature, the water content of the less drying results, protein content decreases, and the fat content does not change/relatively constant. The best variable was a ratio of corn: zeolite is 1:3 and air temperature was 50oC. While the variables that are suitable and in accordance with ISO standards for dry foods (14%) are air temperature of between 40oC and 50oC with a ratio of corn:zeolite is 1:3. The energy efficiency of 81.23% is obtained. Modeling done with FEMLAB (COMSOL) can describe the moisture content and temperature profiles in the corn and zeolite

204-210

Authors: Darmawan Darmawan, Dyah Tjahyandari Suryaningtyas, Juniska Muria Sariningpuri

Wastewater treatment produces semi-solid residue (sludge) that must be handled carefully during dumping and discharge to avoid polluting the environment. A low cost and easy treatment of dewatering is needed. This research aimed to apply electroosmosis technique for dewatering sludge in order to seek for parameters that can efficiently reduce water content of sludge, including range of voltage, type of electrodes, and distance between electrodes; and to determine the effect of electroosmosis processes on changes of chemical characteristics of sludge. The results showed that: (1) electroosmosis dewatering occurred on the sludge taken from waste water treatment of landfill but not on sludge from water purification plant (PDAM), (2) direct current voltage of 30 volts was the optimum voltage, (3) copper rod cathode provided electroosmosis process as good as stainless steel cathode and both were better than the woven stainless steel cathode, (4) the dewatering time to reduce 1200% (w/w) water content to about 400% was about 40 hours for sludge of 2500 cm3 in volume (laboratory bench scale), (5) the anode need to reinserted gradually approaching the cathode due to current lost when the water content at the anode point reached 400% and sludge at the point shrink, and (6) some chemical elements in the sludge decreased significantly after treatment.

218-224

Authors: Mariana Mariana, Farid Muluna, Purwana Satriyo

Gases produced by garbage burning consist of dangerous gases such as CO, SO2 and other gases. Technology for reducing dangerous gases from incinerator outlet can be done by using a dry or wet process. The dry process is more economical process because of simple process, easy maintenance and no liquid waste as product. However, the weakness of the dry process is low absorption conversion and low gas removal efficiency. One way to overcome these problems is to use sorbent which has high reactivity. An inexpensive sorbent that commonly used is Ca(OH)2. The aim of this research was to increase the reactivity of Ca(OH)2 sorbent by using diatomaceous earth and compost as a source of silica and biosorbent, respectively. Diatomaceous earth contains CaO, SiO2 and Al2O3 and compost contains bacteria as a biosorbent that can convert CO to CO2 and CH4. The reaction between SiO2 and Ca(OH)2 would form calcium silicate hydrate (CaO.SiO2.2H2O) that has a high porosity and reactivity. The results showed that the reactivity of Ca(OH)2 sorbent increased by addition of diatomaceous earth and compost. The results also showed that the sorption of CO gas increases with increasing of height of sorbent bed and temperature. The highest CO gas sorption was obtained at temperature of 150oC and sorbent bed height of 6 cm using the modified sorbent with Ca(OH)2/DE/compost ratio of 3:1:1.

234-241

Authors: Tutuk Djoko Kusworo, Desmile Yusufina, Atyaforsa Atyaforsa

Carbon Nanotubes (CNTs) is one of the most well known nano-technology applications which the most of attracting the attention of researchers, because it has more advantages than other materials. The application of the CNT has extended into various aspects, such as electronics, materials, biology and chemistry. This research uses a system of Catalytic Chemical Vapour Deposition (CCVD), which aims to determine the influence of Co and Fe as a catalyst and zeolite 4A as a support catalyst with acetylene gas (C2H2) as carbon source in the synthesis of Carbon Nanotubes (CNTs). In this experiment, used the ratio of acetylene gas and flow rate of N2 gas is 1:1 by weight of the catalyst Co/Zeolite and Fe/Zeolite amounted to 0.5 grams at the operating temperature of 700oC for 20 minutes. N2 gas serves to minimize the occurrence of oxidation reaction (explosion) when operating. From analysis result by Scanning Electron Microscopy (SEM) shows the CNTs formed a type of MWNT with different of diameter size and product weight, depending on the size of the active component concentration on the catalyst. The larger of active components produced CNTs with larger diameter, whereas product weight syntheses result smaller. Use of the catalyst Fe/Zeolite produce CNTs with a diameter larger than the catalyst Co/Zeolite.

247-254

Authors: Nyoman Jaya Wistara, Gokma Silaban, Gustan Pari

The main goal of the present works was to determine chemical changes, thermal decomposition, and the content of moisture, ash, volatile, fixed carbon and calorific value of soda pulping black liquor of the rice straw. Neutralized black liquor was dried to a moisture content of 10% and then pyrolized at 106oC-750oC. It was found that calorific value, fixed carbon, volatile mater, and moisture content were in the range of 2782-4716 cal/g, 49.2-81.6%, 15.5-47.5%, and 0.2-3.5%, respectively. Ash content was not influenced by the temperature of pyrolysis and was thought to depend on its initial silicate content. The weight loss of pulp was higher than that of black liquor. Extreme weight loss has been found in the temperature of 200-400oC. Noticeable functional groups changes were found with the increasing temperature of pyrolysis. Hydroxyl group completely disappeared at 300oC and above. Carbonyl related groups were also disappeared at 300-500oC, but it was reformed at 650 and 750oC. It might be brought about by the deformation of chemical bonding of oxygen ring in lignin structures.