The efficiency of biogas production in semi-continuous anaerobic digester is influenced by several factors, among other is loading rate. This research aimed at determining the effect of hydraulic retention time (HRT) on the biogas yield. Experiment was conducted using lab scale self-designed anaerobic digester of 36-L capacity with substrate of a mixture of fresh cow dung and water at a ratio of 1:1. Experiment was run with substrate initial amount of 25 L and five treatment variations of HRT, namely 1.31 gVS/L/d (P1), 2.47 gVS/L/d (P2), 3.82 gVS/L/d (P3), 5.35 gVS/L/d (P4) and 6.67 gVS/L/d (P5). Digester performance including pH, temperature, and biogas yield was measured every day. After stable condition was achieved, biogas composition was analyzed using a gas chromatograph. A 10-day moving average analysis of biogas production was performed to compare biogas yield of each treatment. Results showed that digesters run quite well with average pH of 6.8-7.0 and average daily temperature 28.7-29.1. The best biogas productivity (77.32 L/kg VSremoval) was found in P1 treatment (organic loading rate of 1.31 g/L/d) with biogas yield of 7.23 L/d. With methane content of 57.23% treatment P1 also produce the highest methane yield. Biogas production showed a stable rate after the day of 44. Modified Gompertz kinetic equation is suitable to model daily biogas yield as a function of digestion time.Article History: Received March 24th 2018; Received in revised form June 2nd 2018; Accepted June 16th 2018; Available onlineHow to Cite This Article: Haryanto, A., Triyono, S., and Wicaksono, N.H. (2018) Effect of Loading Rate on Biogas Production from Cow Dung in A Semi Continuous Anaerobic Digester. Int. Journal of Renewable Energy Development, 7(2), 93-100.https://doi.org/10.14710/ijred.7.2.93-100

The objective of this research was to evaluate economic benefit and greenhouse gas (GHG) emission reduction potential of a family-scale anaerobic cowdung biogas digester. Research was conducted at two villages in Lampung Province, namely Marga Lestari, District of South Lampung and Pesawaran Indah, District of Pesawaran. Economic benefit and GHG emission reduction potential were evaluated from LPG saving due to biogas utilisation for cooking and fertilizer substitution by slurry digestate. Results showed that a family-scale anaerobic cowdung biogas digester demonstrated a good potential to reduce GHG emission, but not in economic. A digester with 4 heads of cow produced biogas at a rate of 1582 L/day. With average methane content of 53.6%, energy value of the biogas was equivalent to 167 kg LPG and able to substitute 52 bottles LPG annually. A family-scale biogas contributed 108.1 USD/year and potentially reduced GHG emission by 5292.5 kg CO2e/year resulted from biomethane potential, LPG, and fertilizer savings.Article History: Received November 15th 2016; Received in revised form January 16th 2017; Accepted February 2nd 2017; Available onlineHow to Cite This Article: Haryanto, A., Cahyani, D., Triyono, S., Murdapa, F., and Haryono, D. (2017) Economic Benefit and Greenhouse Gas Emission Reduction Potential of A Family-Scale Cowdung Anaerobic Biogas Digester. International Journal of Renewable Energy Development 6(1), 29-36.http://dx.doi.org/10.14710/ijred.6.1.29-36

The objective of multi years study was to formulate an alternative organic based fertilizer by mixing a fresh manureand phosphate rock with several different grain sizes conducted in the Field Experimental Station of the Universityof Lampung. Both materials of the fresh manure and phosphate rock were obtained from local sources. Five levelsof mixture of fresh manure and phosphate rock, three levels of grain size of phosphate rock, and two kinds ofcomposting technique were factorial set up. The mixture materials were aerobically composted for 12 weeks. Theresults of the first year study show that (a) the optimum ratio of the mixture of fresh manure and phosphate rock was80% to 20% with the optimum of grain size of phosphate rock < 3 mm; (b) 6-8 weeks of incubation of the mixturematerials has been optimally composted under aerobic conditions of the complete mixture of batch compostedtechnique; (c) the quality of the final produced compost was considered to fulfill the requirement of standard criteriaof organic fertilizer; while (d) the quantity of compost recovered up to 75.07% which was a reliable quantity of massproduction of organic fertilizer.[How to Cite: Nugroho SG, Dermiyati, J Lumbanraja, S Triyono, H Ismono, YT Sari and E Ayuandari. 2012. Optimum Ratio of Fresh Manure and Grain Size of Phosphate Rock Mixture in a Formulated Compost for Organomineral NP Fertilizer. J Trop Soils 17 (2) : 121-128. Doi: 10.5400/jts.2012.17.2.121][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.2.121]

ABSTRAKBiogas merupakan energi alternatif yang dapat dikembangkan untuk menjadi salah satu solusi krisis energi.  Biogas merupakan hasil fermentasi anaerob bahan organik menjadi gas metana (CH4).  Gas metana (CH4) hasil produksi biogas dapat dijadikan menjadi bahan bakar gas.  Penelitian biogas ini memproduksi biogas dari campuran kotoran ayam, kotoran sapi dan rumput gajah mini (pennisetum purpureum cv. Mott) dalam digester volume 2 L dengan sistem batch.  Penelitian biogas ini menggunakan empat perlakuan campuran kotoran ayam, kotoran sapi dan rumput gajah yaitu A 0:100:0, B 0:80:20, C 20:60:20, dan D 30:20:50.  Penelitian ini bertujuan untuk mengetahui campuran optimum untuk produksi biogas.  Hasil penelitian diperoleh nilai optimum rasio C/N untuk produksi biogas yaitu perlakuan A 27,52, B 25,47, dan C 22,23 sedangkan D dibawah optimum yaitu 19,18.  Hasil produksi biogas perlakuan A 4916 mL, B 4610 mL, C 3909 mL dan D 2640 mL.  Produktivitas biogas perlakuan A 60,71 mL/g VS, B 109,58 mL/g VS, C 134,29 mL/g VS dan D 53,88 mL/g VS.  Uji nyala masing-masing perlakuan A dan B menghasilkan api berwarna biru, C api berwarna biru kekuningan dan D tidak dapat menyala.  Perlakuan A dan B paling optimum untuk produksi biogas berdasarkan total produksi biogas, rasio C/N dan hasil uji nyala. Kata Kunci:   Rumput gajah mini; produksi biogas; rasio C/N; uji nyala

Purpose The research aimed to study the effects of size reduction and composting duration of empty fruit bunches (EFB) on straw mushroom production, and to examine the doses of fertilizers commonly used among farmers. Methods The experiment was done in two stages. The first stage was for identifying the optimum physical parameters of EFB, and the second stage focused on enhancing the performance of EFB chosen based on the findings of the first experiment. A randomized complete block design with 3 × 3 factorial arrangement in both stages of the study used the same approach. The first stage had three levels of aggregate sizes factor (S) and three levels of composting duration factor (C) of EFB. The second stage had three levels of NPK factor (N) and three levels of organic fertilizer factor (O). Results Whole stalk EFB had the highest productivity of 2458.47 ± 1015.23 g m −2. The supplementation of fertilizers increased the EFB decomposition rate and productivity to 2950.24 ± 208.50 g m −2 , and nutritive values (particularly for protein content of 41.00 ± 3.79%). Averaged biological conversion efficiency (BCE) was also improved from 3.61 ± 1.22 to 6.56 ± 0.46%. Conclusions EFB did not need to be cut into smaller pieces, and should not be composted for more than 8 days, because there was a tendency to decrease yield. Supplemental fertilizers increased the decomposition rates of EFB as well as the yield and nutritive values of straw mushroom. BCE can potentially be improved by increasing the dosages of fertilizers.

ABSTRAKTujuan penelitian ini adalah mempelajari pengaruh intensitas daya dan waktu reaksi terhadap rendemen dan karakteristik gelombang mikro ( ). Minyak jelantah diperoleh dari pabrik kerupuk yang berlokasi di Sukarame, Bandar Lampung. Reaksi pembuatan biodiesel dilakukan menggunakan gelas erlenmeyer yang dipanaskan di dalam oven berdaya 399 watt dan frekuensi 2.450 MHz yang telah dilengkapi dengan pengaduk listrik berkecepatan 1446 RPM. Penelitian menggunakan rancangan acak faktorial dengan dua faktor. Kedua faktor adalah intensitas daya gelombang mikro dengan tiga taraf [(30, 50, dan 70%) dan waktu reaksi, juga dengan tiga taraf (30, 60, dan 120 detik). minyak jelantah pada perbandingan molar minyak jelantah terhadap metanol 1:6. Parameter yang dianalisis meliputi rendemen, bilangan asam, massa jenis, dan viskositas biodiesel. Data dianalisis menggunakan ANOVA diikuti uji beda = 5% dan = 1%. Hasil penelitian menunjukkan bahwa intensitas daya gelombang mikro dan waktu reaksi tidak berpengaruh terhadap bilangan asam, viskositas, dan massa jenis biodiesel. Biodiesel yang dihasilkan memiliki bilangan asam 2,98-4,20 mgKOH/g, massa jenis 0,87-0,88 g/mL, dan viskositas 1,9-2,0 cSt. Intensitas daya gelombang mikro dan waktu reaksi serta interaksinya berpengaruh nyata pada rendemen biodiesel. Dalam penelitian ini, tanpa memperhatikan intensitas daya gelombang mikro, waktu reaksi terbaik adalah 30 detik saat rendemen biodiesel rata-rata mencapai 91,1%. Kata kunci ABSTRACTThe purpose of this research was to study the effect of power intensity and reaction time on the yield and the characteristic using an erlenmeyer glass heated in a microwave oven with power capacity of 399 watt and frequency of 2,450 arrangements was used in this experiment. Treatment consisted of two factors, namely power intensity and reaction time. The power intensity included three levels (30, 50, and 70%). Similarly did for the reaction time (30, 60, and 120 cooking oil to methanol). Parameters to be analyzed included biodiesel yield, acid number, density, and viscosity of = 1%. The results showed that both microwave power intensity and reaction time and their interaction had no effect on the viscosity, acid number and density of produced biodiesel. Biodiesel produced has acid number of 2.98 to 4.20 mgKOH/g, density of 0.87 to 0.88 g/mL, and viscosity of 1.9 to 2 cSt. Microwave power intensity and reaction time and time of 30 seconds was adequate for microwave-assisted biodiesel synthesis with an average yield reaching 91.1%.

Microbial N2-fixer and P-solubilizer were innoculated in a mixture of fresh manure and phosphate rock formulated as an Organonitrophos fertilizer. The population dynamics of bacteria and fungi growing during the composting process were observed. The inoculation treatments consisted of: K = mixture of 20% phosphate rock and 80% of fresh manure + decomposers (control), N = mixture of 20% phosphate rock and 80% of fresh manure + decomposers + N2-fixer (Azotobacter and Azospirillum sp.) , P = mixture of 20% phosphate rock and 80% of fresh manure + decomposers + P-solubilizer (A. niger and P. fluorescens), and NP = mixture of 20% phosphate rock and 80% of fresh manure + decomposers + N2-fixer + P-solubilizer. The results showed that inoculation of microbial N2-fixer and combination inoculation of N2-fixer and P-solubilizer increased the total bacterial population compared to that of the control as well as the only inoculation of microbial P-solubilizer on the 14th day of observation in which the bacteria reached the highest population. On all the observation days, the population of fungi in the inoculation of microbial P-solubilizer treatment increased significantly compared to that of the control. However, there was no difference between the populations of fungi in the inoculation of N2-fixer and combination inoculation of N2-fixer and Psolubilizer. The genus of fungy identified in the compost of the mixture of fresh manure and phosphate rock were Chytridium sp., Aspergillus sp., Rhizopus sp., and Fusarium sp.[How to Cite : Nugroho SG, Dermiyati, J Lumbanraja, S Triyono, H Ismono. 2013. Inoculation Effect of N2-Fixer and P-Solubilizer into a Mixture of Fresh Manure and Phosphate Rock Formulated as Organonitrofos Fertilizer on Bacterial and Fungal Populations. J Trop Soils, 18 (1): 75-80. doi: 10.5400/jts.2013.18.1.75][Permalink/DOI: www.dx.doi.org/10.5400/jts.2013.18.1.75]

The purpose of this study is to develop a family-size biogas-fueled electricity generating system consisting of anaerobic digester, bio-filter scrubber, and power generating engine. Biogas was produced from a pilot scale wet anaerobic digester (5-m3 capacity). The biogas was filtered using bio-scrubber column filled with locally made compost to reduce hydrogen sulfide (H2S) content. Biogas composition was analysed using a gas chromatograph and its H2S level was measured using a H2S detector. A 750-W four stroke power generating engine was used with 100% biogas. Biogas consumed by the generator engine was measured at different load from 100 to 700 W (13.3 to 93.3% of the rated power). Three replications for each load experiment were taken. Results showed that the total biogas yield was 1.91 m3/day with methane content of 56.48% by volume. Bio-filter successfully reduced H2S content in the biogas by 98% (from 400 ppm to 9 ppm). Generator engine showed good performance during the test with average biogas consumption of 415.3 L/h. Specific biogas consumption decreased from 5.05 L/Wh to 1.15 L/Wh at loads of 100 W to 700 W, respectively. Thermal efficiency increased with loads from 6.4% at 100 W to 28.1 at 700 W. The highest thermal efficiency of 30% was achieved at a load of 600 W (80% of the rated power) with specific biogas consumption of 1.07 L/Wh. Keywords: biogas; family size; generator; electricity; bio-filter. Article History: Received Janury 16th 2017; Received in revised form 2nd June 2017; Accepted 18th June 2017; Available onlineHow to Cite This Article: Haryanto, A., Marotin, F., Triyono, S., Hasanudin, U. (2017), Developing A Family-Size Biogas-Fueled Electricity Generating System. International Journal of Renewable Energy Develeopment, 6(2), 111-118.https://doi.org/10.14710/ijred.6.2.111-118