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Enhanced biogas production from rice straw with various pretreatment : a review Fahriya Puspita Sari; Budiyono Budiyono
Waste Technology Vol 2, No 1 (2014)
Publisher : Diponegoro University

Rice straw is one of organic material that can be used for sustainable production of bioenergy and biofuels such as biogas (about 50-75% CH4 and 25-50% CO2). Out of all bioconversion technologies for biogas production, anaerobic digestion (AD) is a most cost-effective bioconversion technology that has been implemented worldwide for commercial production of electricity, heat, and compressed natural gas (CNG) from organic materials. However, the utilization of rice straw for biogas production via anaerobic digestion has not been widely adopted because the complicated structure of the plant cell wall makes it resistant to microbial attack. Pretreatment of recalcitrant rice straw is essential to achieve high biogas yield in the AD process. A number of different pretreatment techniques involving using physical pretreatment (hydrothermal and freeze), chemical pretreatment (sodium carbonate – sodium sulfite, hydrogen peroxide, NMMO, alkaline, and dilute acid) and biological pretreatment (fungal pretreatment) also combined pretretment (microwave irradiation and chemical) approaches have been investigated, but there is no report that systematically compares the performance of these pretreatment methods for application on rice straw for biogas production. This paper reviews the methods that have been studied for pretreatment of rice straw for delignification, reducing sugar, and conversion to biogas. It describes the AD process, structural and compositional properties of rice straw, and various pretreatment techniques, including the pretreatment process, parameters, performance, and advantages vs. drawbacks.

Study of Biogas Production Rate from Water Hyacinth by Hydrothermal Pretreatment with Buffalo Dung as a Starter Teguh Kurniawan; Yuhelsa Putra; Dewi Murni
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

In this paper we report the effects of hydrothermal pretreatment on biogas enhancement production rates from water hyacinth mixed with buffalo dung. The focus of the experiment was on the time of hydrothermal pretreatment and the ratio of water hyacinth with buffalo dung. The hydrothermal pretreated substrates were characterized by TDS, BOD and pH. The hydrothermal pretreatment of 60 minutes with the ratio of water hyacinth to buffalo dung 1:2 showed the highest biogas production rate at 7889 ml/day. However, the highest methane composition was 52.82% which resulted on the hydrothermal treatment of 30 minutes with equal ratio of water hyacinth and buffalo dung. Thus, the optimum of methane yield obtained at hydrothermal pretreatment for 30 minutes with equal ratio of water hyacinth to buffalo dung is 2856 ml/day. The hydrothermal pretreatment increases the rate production of biogas 102% and the methane yield 51% relative to untreated water hyacinth. The ratio of water hyacinth and buffalo dung has a great impact on biogas production rate and compositions for hydrothermal pretreated substrates.

Life Cycle Assessment on Cement Treated Recycling Base (CTRB) Construction Sudarno Sudarno; Purwanto Purwanto; Pratikso Pratikso
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

LCA is one of the few environmental management techniques that are used to perform a risk assessment, environmental performance evaluation, environmental auditing, and environmental impact assessment and must be applied to the construction CTRB. The purpose of this study was to determine the amount of energy consumption is used and determine the amount of emissions (CO2) in the implementation of the Foundation Layer Top (base course) with the former asphalt pavement aggregate blended cement / Recycling Cement Treated Base (CTRB). This study uses: (i) Compilation and data inventory of relevant inputs and outputs of a product system; (ii) Evaluating the potential environmental impacts associated with the data input and output; (iii) Interpret the results of the inventory analysis and impact assessment in relation to the research objectives. The results showed that Energy consumption in the implementation of recycling pavement (CTRB) is 225.46 MJ / km of roads and the resulting GHG emissions 17,43Ton CO2 / km of roads. Previous researchers to calculate the energy consumption of road works on the implementation of conventional (hotmix) is 383.46 MJ / km of roads and the resulting GHG emissions 28.24 Ton CO2 / km of roads. If the calculated difference between a job and Hotmix CTRB and then a comparison is made CTRB energy consumption is 158 MJ / km of road, this happens 70.07% savings and GHG emissions resulting difference is 10.81 tons of CO2 / km of road, resulting in a decrease in 62,02%.

Liquid and Gaseous Fuel from Waste Plastics by Sequential Pyrolysis and Catalytic Reforming Processes over Indonesian Natural Zeolite Catalysts Mochamad Syamsiro; Shuo Cheng; Wu Hu; Harwin Saptoadi; Nosal Nugroho Pratama; Wega Trisunaryanti; Kunio Yoshikawa
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

In this study, the performance of several differently treated natural zeolites in a sequential pyrolysis and catalytic reforming of plastic materials i.e. polypropylene (PP) and polystyrene (PS) were investigated. The experiments were carried out on two stage reactor using semi-batch system. The samples were degraded at 500°C in the pyrolysis reactor and then reformed at 450°C in the catalytic reformer. The results show that the mordenite-type natural zeolites could be used as efficient catalysts for the conversion of PP and PS into liquid and gaseous fuel. The treatment of natural zeolites in HCl solution showed an increase of the surface area and the Si/Al ratio while nickel impregnation increased the activity of catalyst. As a result, liquid product was reduced while gaseous product was increased. For PP, the fraction of gasoline (C5-C12) increased in the presence of catalysts. Natural zeolite catalysts could also be used to decrease the heavy oil fraction (>C20). The gaseous products were found that propene was dominated in all conditions. For PS, propane and propene were the main components of gases in the presence of nickel impregnated natural zeolite catalyst. Propene was dominated in pyrolysis over natural zeolite catalyst. The high quality of gaseous product can be used as a fuel either for driving gas engines or for dual-fuel diesel engine.

Study of Chlorination Application in Tapioca Wastewater Cyanide Removal Happy Mulyani; Maria Endah Prasadja
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

Tapioca wastewater contains a high concentration of organic matter and cyanide. Chlorination has known as one of alternative cyanide removal methods. The fact that must be an attention is carcinogenic compound such as Tri Halo Methane could be produced as byproduct chlorination of organic waste. This research aimed to determine condition of chlorination application in tapioca wastewater cyanide removal especially calcium hypochlorite dosage and pH thus meeting the criteria of the quality standard of waste and Tri Halo Methane identification. Efluent of chlorination using calcium hypochlorite dosage based on stoichiometry reaction between chlor and cyanide (mole ratio chlor:cyanide = 1:1) which carried out at pH operation 8 for 60 minutes has observed for cyanide content and Tri Halo Methane identification. Other variation of calcium hypochlorite dosage applied until meet the standart quality or lower cyanide content of effluent with no Tri Halo Methane detected. pH optimum determined from comparation of quality effluent of chlorination using calcium hypochlorite optimum dosage with variation pH operation 6, 7, 8. The results showed that the optimum condition for chlorination application in tapioca wastewater removal was 5,986 mg/L for calcium hypochlorite dosage (1,75 stoichiometry reaction) and 8 for pH operation. This chlorination condition able to reduce cyanide of 192 mg/L to 0,272 mg/L wuth no Tri Halo Methane detected in the effluent.

ACCUMULATION LEVEL AND POLLUTION STATE OF ZINC (Zn) WITHIN MANGROVE FOREST SEDIMENT AND WATER OF DEMAK COASTAL REGION Endah Dwi Hastuti
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

Zinc (Zn) is essential heavy metal for plant growth, but could be lethal for some aquatic organisms. While its accumulation in mangrove ecosystem increased along with the increasing input to the river runoff. This research aimed to observe the concentration of Zn in mangrove sediment and water within mangrove ecosystem in Demak coastal area and its pollution state. This research was conducted through observation involving 4 sampling stations and 3 sampling transects at each station. Data collection including mangrove structure and concentration of Zn in mangrove sediment and water. The result showed that mangrove distribution along Demak coastal area varied among stations. Station 1 and station 2 consist of Avicennia marina only, while station 3 consist of Avicennia marina and Rhizophora mucronata and station 4 consist of Avicennia marina, Rhizophora mucronata and Rhizophora stylosa. Average sediment heavy metal concentration at each station was: 415.81 mg/kg; 561.15 mg/kg; 486.23 mg/kg and 11,507.18 mg/kg respectively. While average heavy metal concentration in mangrove water was 0.12 mg/l; 0.12 mg/l; 0.09 mg/l and 0.17 mg/l respectively. The concentration of heavy metal in mangrove water of Demak region had exceed the maximum limit allowed by the government; while the sediment concentration of heavy metal had exceed tha suitable concentration for organisms.

Analysis of Crout, Lu, Cholesky Decomposition, and QR Factorization: A Case Study On The Relationship Between Abiotic (Carbon and Nitrogen) and Biotic (Macrobenthos Diversity) Factors Widowati Widowati
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

Many real world problems can be represented by a system of linear equations, such as in the field of ecology, i.e, the relationship of carbon and nitrogen with macrobenthos diversity. There are many methods to solve linear equations system, then it is necessary to do an analysis of which method is the best so that the user can choose the most efficient method. The methods that will be analyzed are LU, Crout, Cholesky decomposition, and QR factorization. From the calculation of arithmetic operations obtained Cholesky decomposition method is the most efficient method because it has the fewest arithmetic operations. Further, to verify the proposed method we demonstrated simulation with a case study of the relationship between carbon and nitrogen with the macrobenthos diversity based on data from the area of polyculture system and PT. Kayu Lapis Indonesia coastal, Mororejo village subdistrict Kaliwungu district Kendal. From the simulation resultsis obtained that computing time the smallest is the Cholesky decomposition is equal to 1.4664 seconds, which means that the Cholesky decomposition is the most efficient method than the method of LU, Crout decomposition and QR factorization. Keywords— LU Decomposition, Crout decomposition, QR factorization, Cholesky decomposition, Carbon, Nitrogen, Macrobenthos

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Quantitative Study of Biogas Generation Potential from Different Landfill Sites of Nepal Bikash Adhikari; Sanjay Nath Khanal; Raju Miyan; Bijay Thapa
Waste Technology Vol 3, No 1 (2015)
Publisher : Diponegoro University

This research paper was study of waste composition and quantitative analysis of biogas generation potential with its recovery at Sisdole, Pokhara and Karaute Dada landfill sites (LFS) of Nepal. The waste management practice in LFS are significant deciding factors for the assessment of environmental impacts caused including the release of green house gases like methane, carbondioxide etc to the atmosphere, that could contribute significantly to global warming and climate change. The total waste disposed to Sisdole LFS, Pokhara LFS and Karaute Dada LFS are 410, 80 and 7.8 tons respectively. The waste composition was studied onsite with waste reduction method and analyzed for their composition. The organic component of wastes was found high as 61.6%, 52.5% and 65% at Sisdole, Pokhara and Karaute Dada LFS respectively. The biogas potential at these landfill sites were 12157.78 cum, 851.99 cum and 169 cum of biogas per day in Sisdole, Pokhara and Karaute Dada LFS respectively. 4.68, 0.33 and 0.07 MW energy per day can be generated from these amounts of biogas produced in Sisdole, Pokhara and Karaute Dada LFS respectively. Proper gas collection system can be the source of income from these landfill sites and help to mitigate the adverse impact of methane that is being released from these landfill sites

Studies of thermal annealing and dope composition on the enhancement of separation performance cellulose acetate membrane for brackish water treatment from Jepara Tutuk Djoko Kusworo; Budiyono Budiyono; U. N. A. Rochyani; E. Sofiana
Waste Technology Vol 2, No 2 (2014)
Publisher : Diponegoro University

Membrane is an alternative technology of water treatment with filtration principle that is being widely developed and used for water treatment. The main objective of this study was to make an asymmetric membrane using cellulose acetate polymer and study the effect of additive and annealing treatment on the morphology structure and performance of cellulose acetate membranes in brackish water treatment. Asymmetric membranes for brackish water treatment were casted using a casting machine process from dope solutions containing cellulose acetates and acetone as a solvent. Membranes was prepared by phase inversion method with variation of polyethylene glycol (PEG) concentration of 1 and 5 wt% and with thermal annealing at 60 oC in 10 seconds and without thermal annealing behavior. Membrane characterization consists of calculation of membrane flux and rejection with brackish water as a feed from Jepara. The research concluded that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion method. The more added concentration of PEG will be resulted the larger pore of membrane. Meanwhile the higher temperature and the longer time of annealing treatment, the skin layer of membrane become denser. Membrane with the composition of 18 wt% cellulose acetate, 5 wt% PEG, 1 wt% distilled water, with heat treatment at temperature of 60 oC for 10 seconds is obtained optimal performance.

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