Wiratni Budhijanto

Application of micro bubble generator as low cost and high efficient aerator for sustainable fresh water fish farming

This study aimed to apply a novel type of aerator called Micro Bubble Generator (MBG) for fresh water fish farming. The MBG was run based on the principle of venturi tube in which water was circulated through a narrowed channel so that air was sucked into the device and pushed by the flowing water to create micro-sized bubble. The MBG aerator was tested on the aquaculture of tilapia fish to be compared to conventional aerator (the bubbler currently used in aquaculture experiments) and control (container with no aeration). The population of 150 tilapia fish of the average initial length of 6.44 cm was tested in each container. The water quality parameters (COD, pH, and TAN) and fish growth parameters (length and weight) were observed for 68 days. The results highlighted the promising potential of MBG as affordable aerator to be applied in intensive aquaculture. Although the dissolved oxygen level did not differ significantly with the conventional aerator, MBG aerator indicated faster degradation of organic...

The effect of natural zeolite as microbial immobilization media in anaerobic digestion at various concentrations of palm oil mill effluent (POME)

Anaerobic digestion is one of the solutions in POME treatment because it generates energy in the form of biogas. Nevertheless, high concentration of POME fed into the digester will cause high acidification level and eventually cause process failure. The failure can also be affected by high inhibitor concentration contained in POME, one of which is long chain fatty acid. The addition of immobilization media is commonly used to increase the bacteria resistance to inhibitor. Natural zeolite is considered as appropriate immobilization media for waste treatment purpose since it is cheap, has high mechanical strength, high immobilization capacity, and its ability as cation exchanger. The digested biodiesel waste was used as starter inoculum for its good capability in digesting oil-containing feed such as POME. This research was conducted to evaluate critical concentration of POME fed to digester where the natural zeolite could not reduce the inhibitory effect. The concentrations of POME evaluated were 10,000 mg...

Assessment of start-up mechanisms for anaerobic fluidized bed reactor in series based on mathematical simulation

Anaerobic digestion is associated with long hydraulic residence time and hence leads to huge reactor volume, especially for high rate input to the reactor. To overcome this major drawback, one of the possibilities is optimizing the schemes of reactor configuration and start-up mechanisms. This study aimed to determine the most promising start-up mechanism for anaerobic digestion reactors in series, with respect to the shortest hydraulic residence time to reach the highest biogas production rate. The reactor to be studied is anaerobic fluidized bed reactor (AFBR) which is known as the most efficient reactor for high organic loading rate. Case to be studied is landfill leachate digestion. Although reactor optimization can be conducted experimentally, it could be expensive and time consuming. This study proposed the utilization of mathematical modeling to screen the possibilities towards the best options to be verified experimentally. Kinetic study of landfill leachate anaerobic digestion was first conducted...

On the performance of venturi-porous pipe microbubble generator with inlet angle of 20° and outlet angle of 12°

A unique device, namely as the microbubble generator is a device which is able to maintain more dissolved oxygen inside the water for various purposes including waste water treatment and aquaculture with less energy consumption. One of that types is a venturi-porous pipe microbubble generator. It has the advantages of simple construction and easy to maintain. The purpose of the present study was to investigate the performance of venturi-porous pipe microbubble generator. The developed microbubble generator was a venturi-porous pipe type with inlet angle of 20°, outlet angle of 12°, and inlet-throat diameter ratio (Din/Dt) of 2.5. The experiments were conducted under an adiabatic condition in various air flow rates (QG) of 0.2 lpm to 1.0 lpm and water flow rates (QL) of 30 lpm to 80 lpm. The device was located in the depth of 20 cm from water surface in a glass aquarium with the dimension of 280 cm × 60 cm × 40 cm. To investigate the microbubble behaviors, a high speed video camera was used. A watershed algorithm of a digital image processing technique was implemented to proceed the captured images of microbubbles. Moreover, a pressure transducer recorded the inner pressure of inside the microbubble generator in order to calculate hydraulic power (LW) and bubble generating efficiency (ηB). Disolved Oxygen (DO) was also measured in the point of 60 cm and 180 cm from microbubble generator nozzle tip to determine volumetric oxygen mass transfer coefficient (KLa). As the result, performance of the microbubble was influenced by air and water flow rates. Under a constant QG, the mean bubble diameter reduced as the QL increased. Results from image processing showed that size of the microbubbles was distributed in uni-modal peaked PDF curve. Hydraulic power was significantly influenced by QL whereas bubble generating efficiency decreased as the QL increased. The KLa value decreased as the increase of distance from microbubble nozzle. Results from the present work can be used to validate the available CFD simulation models.

Bio-Synthesis of Eicosapentaenoic Acid (EPA) from Palm Oil Mill Effluent Using Anaerobic Process

The supply of omega-3 fatty acids, which are EPA and DHA, was only 14.7% of the prospective demand calculated by using 500 mg/day/person as threshold limit for EPA and DHA consumption for a world population of 7.515 billion people. Alternative sources other than fish oil or seed-based-α linolenic acid (ALA) were necessary. Anaerobic digestion of palm oil mill effluent (POME) offered a new way for one of omega-3 fatty acids production, EPA. The digestion was conducted in anaerobic fluidized bed reactor supported by natural zeolite as the immobilization media. Process condition tried to be optimized was the pH level and the pre-treatment method (TSS filtration) before the digestion. Without any pre-treatment, the fatty acid profile produced after digestion contained considerable amount of polyunsaturated fatty acid with acidic condition provided higher EPA purity. On the other hand, pre-treatment led the digestion to produce saturated fatty acids with acidic condition provided very high purity of butyric acid as the product.

Preparation and characterization modified chitosan by polyelectrolyte complexation

The polyelectrolyte complexes (PECs) of chitosan with various polysaccharides such as alginate, carrageenan, Arabic gum, carboxymethylcellulose (CMC), pectin, and glucomannan were prepared and characterized. The complexation was performed by addition of polysaccharide solution as crosslinking agent into chitosan solution (0.01% and 2 %) under magnetic stirring. The size of the obtained modified chitosan was analyzed by Particle Size Analyzer (PSA). The turbidity and pH were measured to observe the stability of the modified chitosan during the storage. The stability of the complexes was investigated at room temperature (37°C) for 3 weeks. The existence of glucomannan and arabic gum resulted PECs when it reacted with the chitosan solution using ratio 1:1. The changed crosslinker resulted a hydrogel after it blended. The obtained PECs could be affected by the ratio between chitosan and polysaccharide and the molecular weight of both polymers. The crosslinker concentration gave a significantly influenced the ...

The effects of surfactant and electrolyte concentrations on the size of nanochitosan during storage

The nano-sized particle of chitosan (nanochitosan) is a potential natural preservative agent for fresh fish and fish product preservation. Theoretically, nano-sized particles exert strong van der Waals force to each other so that the problem associated with nanochitosan is agglomeration that leads to size instability during storage. Size stability is of importance in the application of nanochitosan as an antimicrobial agent because it considerably affects the antimicrobial activity of chitosan. In this study, the formulation of nanochitosan was optimized with respect to the two major factors in colloid dispersion theory, which were the presence of surfactant and electrolyte. Polysorbate-80 was chosen as the representative of food grade surfactant while NaCl was used as the electrolyte. The purposes of this study were to evaluate the effect of polysorbate-80 concentration and to determine the effect of NaCl ions on the particle size of nanochitosan for at least one month storage period. Data were analyzed ...

Anaerobic treatment of palm oil mill effluent in batch reactor with digested biodiesel waste as starter and natural zeolite for microbial immobilization

Palm oil mill effluent (POME) is the wastewater discharged from sludge separation, sterilization, and clarification process of palm oil industries. Each ton of palm oil produces about half ton of high organic load wastewater. Up to now, POME treatment is done in lagoon, leaving major problems in land requirement and greenhouse gasses release. The increasing of palm oil production provokes the urgency of appropriate technology application in treating POME to prevent the greenhouse gasses emission while exploit POME as renewable energy source. The purposes of this study were firstly to test the effectiveness of using the digested biodiesel waste as the inoculum and secondly to evaluate the effectiveness of natural zeolite addition in minimizing the inhibitory effect in digesting POME. It was expected that the oil-degrading bacteria in the inoculum would shorten the adaptation period in digesting POME. Furthermore, the consortium formation of anaerobic bacteria accelerated by natural zeolite powder addition ...

Anaerobic digestion of palm oil mill effluent with lampung natural zeolite as microbe immobilization medium and digested cow manure as starter

Indonesia is well-known as the world’s biggest palm oil producer with 32.5 million tons of annual production. Palm oil processing contributes to 60% wastewater, leading to environmental problem caused by excessive production of wastewater. This wastewater, i.e. Palm Oil Mill Effluent (POME), has high organic content (40,000-60,000 mg COD/L) which is potential for biogas production. However, its low pH value and long chain fatty acid content likely inhibit the anaerobic digestion. Porous media might reduce the inhibitory effect during POME digestion since the media act as both immobilization media for bacteria and as inhibitor adsorbent. Excessive amount of porous media might interfere with the nutrient consumption by microbes. There will be an optimum amount of porous media added, which depends on the wastewater characteristics. This research studied Lampung natural zeolite as immobilization media in digesting POME. The batch experiment was conducted for 40 days with different amount of natural zeolite, i...