Journal of Engineering and Technological Sciences
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Anaerobic Treatment for Palm Oil Mill Effluent Using Covered In-the Ground Anaerobic Reactor (CIGAR)
Get PDFWastewater from crude palm oil mills contains high organic matter, which potentially produces biogas through anaerobic digestion processes. The design and operation of an anaerobic bioreactor require a good understanding of the reaction kinetic in the bioreactor. This study aimed to evaluate the biogas production from POME and to determine the kinetic parameters of microbial growth and the substrate utilization rates in a CIGAR. An experiment was conducted using a 5-m3 bioreactor with a working volume of 4.4 m3. Wastewater from the Bekri palm oil mill was stored in a 5-m3 tank. After stabilization, the wastewater was loaded into the reactor at a rate of 100 to 250 L/d, corresponding to a COD loading rate of 1.373-3.097 kg·m-3.d-1, and an HRT of 18-44 days. Monod, Contois, Moser, and Shuler kinetic models were evaluated. The results showed that the Shuler model performed best for microbial activities, while the first order reaction model performed best for the substrate utilization kinetic. The maximum specific growth rate (μmax) for the Shuler model was 0.052 d-1 and the saturation constant (Kso) was 0.119. The maximum substrate utilization rate constant (ks) was 2.183 d-1 and biomass yield (Yx/s) 0.024 kg/kg. The maximum average efficiency of anaerobic degradation (34.4%) occurred at a feeding rate of 100 L/d with methane yield of 0.120 Nm3/kg of removed COD. This value is relatively low compared to the maximum potential of 0.350 Nm3/kg CODr
Redesign of a Biomechanical Energy Regeneration-based Robotic Ankle Prosthesis using Indonesian Gait Data
Get PDFIn this research, the robotic ankle design from Arizona State University (ASU) known as SPARKy was redesigned to accommodate the specific needs of Indonesian people. Most active prosthetic legs are designed based on gait parameters for people from Western countries, which may differ for people from other cultures that have a different anthropometry and economic background. Indonesians have smaller actuating power characteristics compared to people from Western cultures due to their smaller average weight and body height. Thus, the applied design strategy took advantage of a biomechanical energy regeneration scheme to reduce the actuator input power requirement and the relatively smaller mechanical power of the typical Indonesian ankle to create a potentially affordable robotic ankle with a smaller actuator that meets the technical specifications. The specifications of the powered prosthetic ankle were determined through the same methods used by SPARKy. Only one low-level control system, to actuate normal walking, was designed and tested on a fully assembled robotic ankle. The test results indicated a promising low-level control, where the robotic ankle can follow the predetermined trajectory required to actuate normal walking based on Indonesian gait data
Comparison of Liquid Product Characteristics of PFAD Metal Soap Decarboxylation by Batch and Continuous Process
Get PDFWell-run continuous processes will benefit the industrial world in the future. This paper investigated the effect of batch and continuous processes on metal basic soap decarboxylation in terms of the liquid product characteristics. The metal soap used in the process was made from palm fatty acid distillate (PFAD) reacted with mixed metal oxides of Zn, Mg, and Ca. While the batch decarboxylation was carried out in a batch reactor at 400 °C for 5 hours, the continuous decarboxylation was conducted at 400 °C with a feed flow rate of 3.75 gr/minutes. Theoretically, the yield of batch decarboxylation is 76.6 wt% while the yield of continuous decarboxylation is 73.37 wt%. The liquid product was fractionated to separate short-chain hydrocarbon of C7-C10 (gasoline fractions) from medium- to long-chain hydrocarbons, or greater than C11 (green diesel fraction). The result showed that the alkane content from the batch process was higher than from the continuous process, whereas the continuous process produced more ketone products compared to the batch process. Furthermore, the GC-FID analysis showed a similar amount of total hydrocarbon (alkane, iso-alkane, and alkene) in both the batch and the continuous process
Analysis of Faecal Sludge Treatment Alternatives to Enhance the Treatment Performance of Wastewater Treatment Plant (WWTP) Denpasar Sewerage Development Project (DSDP) Suwung Denpasar City
Get PDFMost of the wastewater generated from domestic activities in Denpasar city is treated in an off-site treatment plant located in WWTP DSDP Suwung. This includes faecal sludge that originates from on-site treatment plants. The existing treatment facilities can only treat wastewater that has a maximum biochemical oxygen demand (BOD) concentration of around 225 mg/l while the disposed faecal sludge’s BOD concentration reaches 3,394 mg/l. Therefore, an additional faecal sludge treatment plant needs to be established in order to separate the solid phase from the liquid phase. According to the treatment performance calculation, some alternative treatments can achieve BOD5 and TSS removal of up to 97% and 98% respectively. The selection of the alternative treatment was decided from weighting results of several aspects, such as economic, land use, technological and environmental aspects. The weighting method that was used in this research was Simple Additive Weighting (SAW). The advantage of SAW is its ability to do the assessment highly precisely because it is based on predetermined criteria and preference weights. Based on the weighting result, the treatment technology selected was a Solid Separation Chamber as primary treatment, combined with an Anaerobic Baffled Reactor as a secondary treatment. A Belt Filter-Press was applied to reshape the sludge into a recyclable cake. The required cost is approximately 16 billion rupiahs
Corrosion Assessment of Pre-corrosion Concrete Specimens using Acoustic Emission Technique
Get PDFThe acoustic emission (AE) technique is known as a non-destructive testing (NDT) method, which is effective for assessing corrosion in concrete structures. This study aims to utilize the AE technique, for the assessment of pre-corroded concrete specimens, which are under load testing. Experiments were carried out on small-scale pre-corroded specimens, which were subjected to monotonic loading. The results showed that the majority of the beam specimens failed with shear cracks. Three AE parameters, namely acoustic emission hits, as well as the RA and AF values, were also used, in order to assess the flexure behaviour of the pre-corroded beam specimens. These experiments helped to understand the flexural behaviour of pre-corroded specimens, which were under a loading test, via the use of the AE technique
Tension Stiffening Behavior of Polypropylene Fiber- Reinforced Concrete Tension Members
Get PDFThis paper focuses on comparing the behavior of RC tension members with and without the addition of polypropylene fibers at various corrosion levels. Eight cylindrical tensile specimens were tested to evaluate their tension-stiffening and cracking behavior. The content of polypropylene fiber added into the concrete mix was the main variable (0.25%, 0.50%, 0.75%, and 1.0% of total volume). The corrosion level was varied from slight (5%), medium (10%) to severe (30%) and, like the other variables, applied only to 1.0% polypropylene fiber-reinforced concrete (PFRC) specimens. The test results showed that the fiber addition significantly increased the tension-stiffening effect but was largely unable to reduce the effect of bond degradation caused by corrosion. Moreover, the addition of polypropylene fibers was able to improve the cracking behavior in terms of crack propagation, as shown by smaller crack spacing compared to the specimen without fiber addition at the same corrosion level
