No abstract

Methanogenesis is the conversion of carbon dioxide (CO2) to methane (CH4) using microbes. In the context CO2 utilization, methanogenesis process in the utilizing native microbes from a particular reservoir can be a very slow process without any external intervention. To accelerate the conversion rate and methane yield, this study investigates the use of agriculture by-product such as palm oil mill effluent (POME) as substrates as well as potential microbial isolates that can produce biohydrogen at high temperatures. This paper covers the three laboratory assessments of microbes from anaerobic sludge from a local palm oil mill, use of POME to augment the microbial growth, and physicochemical manipulation to identify key parameters that increases CH4 yield and rate: i) biohydrogen production ii) biomethane production, and iii) syntrophic reactions. All experiments are conducted at 70°C which is considered a hyperthermophilic condition for many microbes. Biohydrogen production achieved with highest H2 production of 66.00 (mL/Lmedium). For biomethane production, the highest production rate achieved was 0.0768 CH4 µmol/mL/day which 10,000X higher than 19.6 pmol/mL/day used as a benchmark. Syntrophic reaction with both types of hydrogen-producing and methanogen in the same reactor, and pure H2 and CO2 supplemented externally was able to achieve the highest methane production of 10.095 µmol/mL and 2.524 µmol/ml/day. Methane production rate is 2.5 times faster than without external gasses being introduced. Introduction of external CO2 to the syntrophic reaction is to mimic actual carbon injection and storage in the reservoir. Our paper shows that stimulation of microbes using POME as substrates and H2/CO2 supplementation are important in accelerating the rate of methane production and yield. Future work will focus on optimizing the gas ratio, pH of growth media, and performing syntrophic reaction in porous media to emulate conditions of a reservoir.

Precipitated calcium carbonate (PCC) is synthetic calcium carbonate that has high purity of more than 98 wt% of CaCO3 content.  Owing to its unique characteristic whereby its shape and size can be controlled to tailor to various applications, PCC has seen great demands in many industries such as paper, paint, plastic, food, ceramics, cosmetics, pharmaceutical, and many others.  PCC can be synthesized via various methods and the most often used method in industry is via carbonation process.  This process has caught interest of the oil and gas industry for utilizing existing carbon dioxide waste from plant processes.  Precipitation of PCC is carried out using hydrated lime under various conditions at different gas purity (1 mol% CH4 + 99 mol% CO2 , 40 mol% CH4  + 60 mol% CO2 ), different gas flowrate, and different stirring rate.  All experiments are carried out using 1 litre of ionic solution at ambient conditions.  All samples are characterized using Field Emission Scanning Electron Microscopy (FESEM), Particle Size Distribution, X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF).  FESEM analysis shows different surface morphology for different methane content with calcite formation.  The particle size for all PCC produced at different parameters are comparable at the range 5-9 microns depending on the mixing rate used whereas XRF results indicate very high purity of CaCO3 of more than 99 wt%.

CO2 utilization into minerals is one of the most efficient methodologies although much research concerns the utilization of CO2 to produce chemicals. The production of precipitated calcium carbonate (PCC) from three different starting materials has been reported. The gas-liquid reaction is carried out by bubbling carbon dioxide into a solution of lime products with fixed parameters of 99% CO2 purity, 4.0 L/min of flow rate and 1500 rpm stirring rate at atmospheric pressure. The PCC was then characterized for X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-Ray fluorescence (XRF) and particle size. Experimental results indicate that the PCC produced from quick lime showed the highest yield of 17.27 g, however there is no significant difference for both carbide lime and hydrated lime at 12.04 g and 11.57 g respectively. Morphology, phase structure and particle size of PCC produced reveals insignificant influence with different starting materials. Producing PCC from CO2 and natural minerals can be a potential method of reducing CO2 emissions by locking-up CO2 in a stable mineral form, whilst at the same time turning low quality natural minerals into high valuable products.

Permanent abatement of CO2 has become a major challenge in many gas field developments especially within this South –East Asia region. Among the challenges are on how to dispose or utilize this huge amount anthropogenic CO2 safely and economically. Therefore, the objective of this study is to identify the best technology for non-catalytic CO2 Direct utilization to manage and support economic development of high CO2 gas field in Malaysia. A Market survey was conducted to a few shortlisted technologies to assess on the technology landscape and the market potential. The feedback was analyzed based on the criteria established on the basis of company requirement. From the study, ‘Mineral Carbonation’ has been identified as one of the potential technology solution for permanent sequestration of CO2 in Malaysia. The future of this technology application is very promising due to the availability of the local feedstock, mineral waste and the potential market of this product especially for carbonate product such as precipitated calcium carbonate (PCC). However, this technology still possesses some technical challenges due to slow kinetic reaction. For a large scale application, this will become more demanding especially in terms of footprint as the current technology is mainly on batch process. Therefore, the current R&D should look into area where this process kinetic can be improved and to look into continuous or semi-continuous process for smaller footprint.