EVALUATION OF BIOHYDROGEN PRODUCTION FROM SUGARCANE VINASSE IN AN ANAEROBIC FLUIDIZED BED REACTOR WITHOUT PH CONTROL

This study aimed to produce biohydrogen from sugarcane vinasse in an anaerobic fluidized bed reactor operated at ambient temperature (26-35 °C) with a progressive increase of the organic load rate (OLR) (17-155 kg-COD m-3 d-1) and without influent pH control. Hydraulic retention times (HRT) of 12, 6 and 4 h were applied to increase the OLR. The highest hydrogen yield, hydrogen production rate and percentage of hydrogen in the biogas were obtained in the HRT of 4 h, corresponding to the values of 2.40 mol-H2 mol-1-carbohydrate, 0.33 L-H2 h-1 L-1-reactor, and 33%, respectively. The butyric acid fermentative route was favored in the process. The PCR/DGGE analysis showed that the microbial community structure was modified along operational stages and increasing OLR caused an increase in microbial diversity. The results indicate that biohydrogen production from anaerobic digestion of sugarcane vinasse can be achieved with no alkalization pretreatment.

Evaluasi Rangkaian Anaerobic Fluidized Bed Reactor (AFBR) dan Micro Bubble Generator (MBG) untuk Pengolahan Air Lindi Sampah

Abstrak. Timbulan air lindi adalah masalah serius pada tempat pengolahan sampah akhir (TPA) di Indonesia. Kandungan komponen organik pada sampah Indonesia yang mencapai 70-75% dari total timbulan sampah menyebabkan tingginya produksi lindi sebagai cairan hasil pembusukan. Studi ini bertujuan mengoptimalkan proses pembersihan air lindi dengan rangkaian proses anaerob yang diikuti dengan proses aerob pada skala mini pilot plant. Peruraian anaerobik dijalankan dalam anaerobic fluidized bed reactor (AFBR) dengan media imobilisasi mikroorganisme yang difluidisasi. Tahap selanjutnya adalah proses peruraian secara aerob dengan aerasi menggunakan micro bubble generator (MBG). Pilot plant yang didirikan di tempat pengolahan akhir (TPA) Piyungan di Yogyakarta ini terdiri atas AFBR dengan volume 500 L dan bak aerasi dengan MBG berukuran 500 L. Pengamatan data kualitas air (soluble chemical oxygen demand (sCOD) dan volatile fatty acid (VFA)) pada input/output AFBR dan input/output MBG serta volume biogas yang dihasilkan di AFBR dilakukan secara berkala selama 70 hari start-up di mana reaktor mulai dioperasikan secara kontinu setelah inokulasi secara batch dan 50 hari operasional pada kondisi steady state. Walaupun telah dioperasikan selama lebih dari sebulan, performa AFBR setelah tercapai kondisi steady state belum optimal karena baru mencapai kurang lebih 30% pengurangan kandungan senyawa organik. Performa yang lebih baik teramati pada proses aerob dengan aerasi menggunakan MBG. Proses tersebut berhasil menurunkan sCOD sampai 60%. Studi awal ini menunjukkan bahwa rangkaian AFBR dan MBG berpotensi untuk mengatasi masalah pencemaran air lindi di TPA. Optimalisasi kinerja unit ini terutama ditentukan oleh proses start-up yang dipengaruhi oleh teknik inokulasi. Kata Kunci: fluidisasi, imobilisasi mikrobia, lindi, peruraian aerob, peruraian anaerob, sampah. Abstract. Evaluation of Anaerobic Fluidized Bed Reactor (AFBR) and Micro Bubble Generator (MBG) for Landfill Leachate Treatment. Landfill leachate emission is a very serious problem in Indonesian landfill sites. High organic fraction in Indonesian garbage, which accounts for 70-75% of total municipal solid waste amount, emits high flow rate of leachate as the result of decay process. This study aims to optimize landfill leachate treatment by means of anaerobic process followed by aerobic process. The anaerobic digestion was carried out in AFBR in which microbial immobilization media was fluidized. The next stage was aerobic digestion by applying novel aeration technology using MBG. The pilot plant was installed in Piyungan Landfill Site in Yogyakarta, which consisted of 500 L AFBR and 500 L MBG units. Observation was conducted periodically for 70 days of start-up when the unit was operated continuously after batch inoculation followed by 50 days of steady-state operation. The measurement was taken as soluble chemical oxygen demand (sCOD) and volatile fatty acids (VFA) on the input/output of AFBR and input/output of MBG. The biogas volume production in the AFBR was also measured. AFBR performance was not optimal since even after achieving a steady state condition (for one-month operation), it could only reduce less than 30% organic content. A better performance was observed in the aerobic process where MBG was used for the aeration. It could reduce 60% of sCOD. This preliminary study showed that the coupling of AFBR and MBG units is potential for landfill leachate treatment. Optimization of this unit depended on the inoculation technique during the start-up period. Keywords: aerobic digestion, anaerobic digestion, fluidization, landfill leachate, microbial immobilization, municipal solid waste. Graphical Abstract

Biohydrogen production from soft drink industry wastewater in an anaerobic fluidized bed reactor

The wastewater from carbonated soft drinks production was used as substrate in an anaerobic fluidized bed reactor (AFBR) to evaluate the production of biohydrogen as a renewable energy. The hydraulic retention time (HRT) ranged from 8 to 0.5 hours (7.92 to 137.09 kg COD m−3 day−1) throughout the experiment and expanded clay was used as support material for biomass adhesion. The average composition of hydrogen in the biogas under the conditions of this experiment was 34%. The maximum hydrogen yield (HY) and the maximum hydrogen production rate (HPR) was 5.87 mol H2/mol substrate and 2.74 L H2 h−1 L−1, respectively, obtained in the HRT of 0.5 hour. Acetic acid was the predominant soluble metabolite detected (88%). Propionic, butyric and caproic acids were quantified with low production (7%, 4% and 1% of soluble metabolites production (SMP)). The anaerobic fluidized bed reactor optimized the average of hydrogen yield by 17% in relation to packed-bed reactors, in a HRT of 0.5 h. The natural fermentation process and operating conditions were favorable to the inhibition of hydrogen-consuming organisms, such as methanogenic archaeas.