PENGARUH KOMPOSISI DAN WAKTU FERMENTASI CAMPURAN LIMBAH INDUSTRI TAHU DAN KOTORAN SAPI TERHADAP KANDUNGAN GAS METHANE PADA PEMBANGKIT BIOGAS

Biogas is alternative energy produced from the anaerobic activity process of methane bacteria obtained by fermentation. Anaerobic activation is a sequence of microorganism processes breaking down biodegradable materials without oxygen. Biogas is mostly produced from cow dung and tofu industry waste that has the potential to contain methane (CH4), carbon dioxide (CO2) and hydrogen sulfide (H2S). To reduce the content of (CO2) and (H2S) and to increase the element of methane gas, the purification process is needed to do. Purification can be carried out by absorption techniques using water, NaOH solution, and zeolite/silica gel. The purpose of this study is to examine the methane gas content of variations in the composition of cow dung and tofu liquid waste and the fermentation time. The method used was an experiment by varying the composition of cow dung and tofu liquid waste by 40%: 60%; 50%: 50%; and 60%: 40%, as well as variations in the fermentation time of120, 168 and 216 hours of fermentation. The results showed that the highest methane gas content in the composition of a mixture of cow dung and tofu liquid waste was 50:50 in 168 hours of fermentation which was equal to 2.806%. The content of methane gas was influenced by the fermentation time, the pH conditions in the digester, and the intensity of stirring the biogas material in the digester.

Response Surface Methodology to Optimize Methane Production from Mesophilic Anaerobic Co-Digestion of Oily-Biological Sludge and Sugarcane Bagasse

Oily-biological sludge (OBS) generated from petroleum refineries has high toxicity. Therefore, it needs an appropriate disposal method to reduce the negative impacts on the environment. The anaerobic co-digestion process is an effective method that manages and converts organic waste to energy. For effective anaerobic digestion, a co-substrate would be required to provide a suitable environment for anaerobic bacteria. In oily-biological sludge, the carbon/nitrogen (C/N) ratio and volatile solids (VS) content are very low. Therefore, it needs to be digested with organic waste that has a high C/N ratio and high VS content. This study investigates the use of sugarcane bagasse (SB) as an effective co-substrate due to its high C/N ratio and high VS content to improve the anaerobic co-digestion process with oily-biological sludge. The sugarcane bagasse also helps to delay the toxicity effect of the methane bacteria. Batch anaerobic co-digestion of oily-biological sludge was conducted with sugarcane bagasse as a co-substrate in twelve reactors with two-liter capacity, each under mesophilic conditions. The interaction effect of a C/N ratio of 20-30 and a VS co-substrate/VS inoculum ratio of 0.06-0.18 on the methane yield (mL CH4/g VSremoved) was investigated. Before the anaerobic digestion, thermochemical pre-treatment of the inoculum and co-substrate was conducted using sodium hydroxide to balance their acidic nature and provide a suitable pH environment for methane bacteria. Design and optimization for the mixing ratios were carried out by central composite design-response surface methodology (CCD-RSM). The highest predicted methane yield was found to be 63.52 mL CH4/g VSremoved, under optimum conditions (C/N ratio of 30 and co-substrate/inoculum ratio of 0.18).

GAS BIOGENIK DAN UNSUR MINERAL PADA SEDIMEN DELTA KAPUASKALIMANTAN BARAT

Gas metan biogenik merupakan gas metan yang terbentuk akibat aktivitas anaerobik. Gas biogenik yang terdapat di daerah penelitian merupakan gas biogenik yang terdapat pada sedimen Kuarter. Sedimen Kuarter yang mengalasi daerah telitian terdiri atas perselingan pasir dan lempung yang mengandung unsur pembentuk mineral dan material organik. Pada sumur bor BH-3 yang mengandung gas biogenik, kandungan bakteri metanogenik sebesar 1,5% dari total bakteri umum, kandungan karbon total sekitar 4%, unsur utama, unsur logam berat, dan unsur tanah jarang (REE) mengalami perubahan yang signifikan. Pada sumur BH-1, BH-2, dan BH-4 kandungan unsur-unsur tersebut tidak menunjukkan perubahan yang mencolok. Penelitian ini adalah untuk memahami keberadaan gas biogenik di daerah Delta Kapuas dengan melihat keragaman sedimen dan unsur pembentuk mineral Kata kunci: gas metan biogenik, bakteri metanogenik, karbon total, unsur utama, unsur logam berat, unsur tanah jarang, Delta Kapuas, Kalimantan Barat Biogenic methane was formed by anaerobic activity. The biogenic gas was found in the Quaternary sediments in the study area. This sediments consist of alternating sand and clay that contain the element-forming minerals and organic material. Analysis metanogenik bacteria(1,5%), total carbon content(4%), major elements, heavy metals, and rare earth elements (REE) in borehole BH-3 containing biogenic gas is significantly changing. In the borehole of BH-1, BH-2, and BH-4 content elements do not show significant changes. This research is to understand the existence of biogenic gas in the Kapuas Delta region by looking at the diversity of sediment and mineral-forming elements. Keywords: biogenic methane, bacteria metanogenik, total carbon, major elements, heavy metal elements, rare earths, Delta Kapuas, West Kalimantan

The reaction characteristics of wastewater containing nitrophenol, treated using an anaerobic biological fluidized bed

An anaerobic biological fluidized bed was used to treat a synthetic wastewater containing three types of nitrophenols. The results proved that para-nitrophenol (p-NP) was the most toxic nitrophenol to methane producing bacteria while meta-nitrophenol (m-NP) was found to be less toxic, with ortho-nitrophenol (o-NP) being the least toxic to the methane bacteria. The results also showed that o-NP was much more easily decomposed by the microbes on the activated carbon biofilm. During the anaerobic digestion it was found that wastewater containing o-NP had the largest specific methane production rate, specific growth rate, and specific substrate utilization rate, while wastewater containing p-NP had the smallest rate figures. In addition, analyzing metabolites of the effluent indicated the anaerobic metabolism of m-NP started with a hydrogenation reduction, resulting in the production of m-aminophenol follwed by phenol after deamination.

The Anaerobic Biodegradability and Methanogenic Toxicity of Pulping Wastewaters

The objective of this study was to evaluate the effect of various pulping conditions and different lignocellulosic feedstocks on the anaerobic treatability of pulping wastewaters. Wastewaters were prepared from lignocellulosic feedstocks commonly used in the forest industry, namely, pine, spruce and birch wood, and wheat straw. The pulping conditions used were representative of those applied in TMP and soda pulping processes. The anaerobic biodegradability and the methanogenic toxicity of the various wastewaters were evaluated in standardized batch bioassays using anaerobic granular sludge. The acidification of the TMP wastewaters (conversion to CH4 and VFA) ranged from 68 to 87% of the total COD, indicating their high anaerobic biodegradability. TMP wastewaters were non-toxic to methane bacteria at concentrations expected in paper mill wastewaters. No inhibition was observed at 10 g COD/l. In contrast, wastewaters prepared in alkaline conditions were poorly biodegradable (approx. 50% acidification) and they caused severe inhibition of the methanogenic activity. The 50% inhibitory concentrations ranged from 2.1 to 5.4 g COD/l. Additional experiments showed that wood resin components, poorly solubilized at acidic to neutral pH, but easily extractable in alkali, are responsible for most of the methanogenic toxicity observed in alkaline pulping wastewaters. These results indicated that contact of wood with alkali contributes significantly to increase the methanogenic toxicity of the pulping wastewater.

Disposal and Treatment of Concentrated Human Wastes

Many communities in Canada's northern areas rely on trucked supply of water and pickup of human waste from bucket toilets or holding tanks. The high capital cost of conventional piped water and gravity sewer systems and the lack of funds necessitate the continued used of trucked systems for many years, particularly in the smaller settlements in permafrost regions. Promising methods of cheaper piped collection of wastes,such as vacuum and pressure sewers may be used in the near future. Both require only small quantities of water for transport of solids. Human wastes in plastic bags (“honey-bags”) are now disposed of at a dump, in waste pits or lagoons. Satisfactory treatment methods for these strong wastes and for wastes from holding tanks, vacuum and pressure sewers are needed. Results of a five year study simulating a waste pit in permafrost show that it merely serves as a holding tank and does not provide satisfactory treatment. Pathogens are likely to remain viable in such a pit for many years. Anaerobic digestion of undiluted human waste has been found feasible at 20° C, but is not likely to be a practical and economical solution for communities using trucked systems. Properly located, constructed and operated waste pits are recommended for these situations. Conventional anaerobic digestion of vacuum sewer wastes or holding tanks wastes which are much less dilute than sewage, is feasible at a temperature of 20° C and with a minimum detention time of 30 days. The process may be applicable at lower temperatures, provided a high proportion of methane bacteria is maintained in the reactor. This may be accomplished either by longer detention time or through the anaerobic contact process. However, anaerobic filter treatment of these wastes appears to be most practical, economical and effective, providing about 85% and 80% COD reduction for detention times of 3 and 8 days at 25° C and 10° C respectively. It is recommended that a pilot installation can be constructed in a northern community using anaerobic filter as the method of treatment of vacuum or pressure sewer wastes or holding tank wastes.