Minato Wakisaka

Production of mono sugar from acid hydrolysis of seaweed

The purpose of this work was to optimize the process conditions for the saccharification of macroalgae (seaweed) into mono sugar using the following parameters such as: Amount of biomass, catalyst concentration, temperature and reaction time. The major component of Ulva pertusa (green seaweed), Laminaria japonica (brown seaweed) and Gelidium amansii (red seaweed) is carbohydrate which can be converted into variety of sugars using sulfuric acid with hot-compress treatment. Rhamnose (37.89 wt %) and glucose (16.14 wt %) were extracted from dried U. pertusa , while galactose (49.32 wt %) and glucose (12.62 wt %) were extracted from dried G. amansii . Mannitol (31.53 wt %) was produced from dried L. japonica . Key words: Marine biomass, seaweed, saccharification, sulfuric acid hydrolysis, mono sugars.

Ice crystallization in a pilot-scale freeze wastewater treatment system

Abstract A pilot plant for freeze wastewater treatment producing an annular ice layer in a square pillar shape was constructed. Experiments were carried out to examine ice productivity and the effect of operating conditions such as ice seeding, solution concentration and flow rate on ice crystallization using glucose solution as a substitute for the actual wastewater. The productivity of ice per unit floor area of the ice maker was 578.6 kg/m2 h in one batch operation of 70 min. A 1.4 fold concentrated solution was obtained after this freeze wastewater treatment. Ice seeding was important for removal of solute during ice crystal growth. Although inclusion of solute in the ice occurred at high concentrations of solution, the effect was reduced with increasing flow rate.

Effect of seed ice on formation of tube ice with high purity for a freeze wastewater treatment system with a bubble-flow circulator

A freeze wastewater treatment system with a bubble-flow circulator is advantageous from an industrial point of view because a bubble-flow circulation requires much less energy for the mixing of the wastewater to facilitate heat, mass and momentum transfers in the system than that using agitators or pumping circulation. In this work an ice tube was produced in a bubble-flow circulator and the effect of seed ice crystals on tube ice formation with a high purity was investigated. Without seed ice crystals a large supercooling appears before ice crystal formation and dendritic ice crystals are suddenly formed. Components in wastewater are contaminated and trapped between dendritic ice crystals, resulting in poor quality in the wastewater treatment. To avoid abrupt ice crystallization it is necessary to keep supercooling small. A seed ice crystal is effective for this purpose because a seed ice crystal generates other ice crystals, resulting in no supercooling. Model wastewater including polypeptone with concentrations of 5000 and 10000 ppm, corresponding to 1290 to 3800 ppm in COD (chemical oxygen demand) was used. Two kinds of experiments with different types of seed ice addition were examined. In each concentration examined more than 30% COD normalized by initial COD was confirmed in the melted ice tube with no seed ice. On the other hand, only a few % of COD of the initial values were detected when seed ice crystals were used to initiate the ice tube formation.

Measuring organic carbon, nutrients and heavy metals in rivers receiving leachate from controlled and uncontrolled municipal solid waste (MSW) landfills.

Since landfilling is the common method of waste disposal in Malaysia, river water is greatly exposed to the risk of contamination from leachate unless proper leachate management is carried out. In this study, leachates from three different types of landfills, namely active uncontrolled, active controlled and closed controlled, were characterized, and their relationships with river water chemistry were examined monthly for a year. The influence of leachate on river water chemistry from each type of landfill depended on many factors, including the presence of a leachate control mechanism, leachate characteristics, precipitation, surface runoff and the applied treatment. The impact of leachate from an active uncontrolled landfill was the highest, as the organic content, NH(4)(+)-N, Cd and Mn levels appeared high in the river. At the same time, influences of leachate were also observed from both types of controlled landfills in the form of inorganic nitrogen (NH(4)(+)-N, NO(3)(-)-N and NO(2)(-)-N) and heavy metals (Fe, Cr, Ni and Mn). Improper treatment practice led to high levels of some contaminants in the stream near the closed controlled landfill. Meanwhile, the active controlled landfill, which was located near the coastline, was exposed to the risk of contamination resulting from the pyrite oxidation of the surrounding area.

Nitrification of ammonium-rich sanitary landfill leachate

The nitrification of ammonium-rich wastewater is considered challenging due to the substrate inhibition particularly in the form of free ammonia (FA) and free nitrous acid (FNA) in ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). The feasibility of the nitrifying activated sludge system to completely nitrify synthetic stabilized landfill leachate with N-NH(4)(+) concentration of 1452mg/L was tested in this study. The process started with 0.4kg N-NH(4)(+)/m(3)/day of nitrogen loading rate (NLR) in a fed-batch mode to avoid any accumulation of the FA and FNA in the system followed by increasing the nitrogen loading rate (NLR) gradually. Complete nitrification was achieved with a very high ammonium removal percentage (approximately 100%). The maximum specific and volumetric nitrification rate obtained were 0.49g N-NH(4)(+)/g VSS/day and 3.0kg N-NH(4)(+)/m(3)/day, respectively which were higher than those reported previously for ammonium-rich removal using activated sludge system. The nitrifying sludge exhibited good settling characteristics of up to 36mL/g VSS and a long SRT of more than 53 days which contributed to the success of the nitrification process. The coexistence and syntrophic association of the AOB and NOB was observed by using Fluorescence in situ hybridization (FISH) technique which supported the results on complete nitrification obtained in the system. These findings would be of prominent importance for further treatment of actual sanitary landfill leachate.

Reduction of Methane Released from Palm Oil Mill Lagoon in Malaysia and Its Countermeasures

Palm oil industry in Malaysia is one of the potential candidates for the CDM project because large amount of methane is emitted from the lagoons and open digesting tank of the wastewater treatment system. Therefore the first objective of the project is to investigate the actual GHG emission from the lagoons and open digesting tank in palm oil mills in order to establish the baseline for CDM project. Results indicated that methane contribution to biogas released from the open digesting tank and lagoon systems were 35% and 45%, respectively. These values are much lower than the reported value of 65% obtained by complete anaerobic condition of lab-scale experiments. Based on actual methane release measurement and information gathered from palm oil mill about wastewater treatment, significant amount of methane emission to the atmosphere can be reduced with the installation of new closed digesting tank system converted from the open digesting tank such as just by covering it with applying CDM. It is estimated that a total of RM2.6 million could be obtained from the selling of electricity generated from biogas generation and Certified Emission Reduction(CER).

Conditions of producing an ice layer with high purity for freeze wastewater treatment

Abstract A freeze wastewater treatment has several advantages: (1) wastewater, including toxic compounds which is difficult to be treated biologically can be treated; (2) the ice crystals produced can be used for cold heat storage; and (3) a smaller facility is required than that for biological wastewater treatment. However, freeze wastewater treatment does not currently prevail in the world. This is because low-purity ice crystals are produced, resulting in poor wastewater treatment. In this paper, conditions of producing an ice layer with high purity were investigated. An ice layer was formed on an aluminum plate heat exchanger. Model wastewater including polypepton with concentrations from 2000 ppm, to 10000 ppm corresponding to 670 ppm to 3800 ppm in chemical oxygen demand (COD) was used. A seed ice layer was effective for producing an ice layer of higher purity. The greater the flow rate on the plate heat exchanger, the higher the purity of the ice layer involved, resulting in 10–30 ppm in COD at the superficial flow rate of 0.3 m/s regardless of the initial COD levels. The coolant temperature also affected little to produce an ice layer with high purity, whether the coolant temperature was 268 K or 263 K.

Characteristics and Microbial Succession in Co-Composting of Oil Palm Empty Fruit Bunch and Partially Treated Palm Oil Mill Effluent

Microbial communities and cellulolytic enzymes activities were analyzed during the co-composting of empty fruit bunch (EFB) and partially treated palm oil mill effluent (POME) in pilot scale. The physicochemical parameters were also measured during the composting. The diversity of the bacterial community was investigated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results indicated that the composting process of EFB with partially treated POME was dominated by uncultured bacteria species. The dominant bacterial group changed from the phylum proteobacteria in the thermophilic stage to the phylum chloroflexi in the maturing stage. Scanning elec- tron microscope (SEM) analysis exhibited the significant degradation of EFB structure during the composting process. The maximum cellulase activity for carboxymethylcellulase (CMCase), filter paperase (FPase) and � -glucosidase were 13.6, 4.1 and 20.3 U/g of dry substrate, respectively at day 30 of composting. The results of this study significantly con- tributed to a better understanding of mechanisms involved in co-composting process in pilot scale.

Flocculation characteristics of an isolated mutant flocculent Saccharomyces cerevisiae strain and its application for fuel ethanol production from kitchen refuse.

A stable mutant flocculent yeast strain of Saccharomyces cerevisiae KRM-1 was isolated during repeated-batch ethanol fermentation using kitchen refuse as the medium. The mechanism of flocculation and interaction with the medium was investigated. According to sugar inhibition assay, it was found that the mutant flocculent strain was a NewFlo phenotype. Flocculation was completely inhibited by protease, proteinase K and partially reduced by treatments with carbohydrate-hydrolyzing enzymes. Flocculation ability showed no difference for pH 3.0-6.0. Furthermore, the mutant flocculent yeast provided repeated-batch cultivations employing cell recycles by flocculation over 10 rounds of cultivation for the production of ethanol from kitchen refuse medium, resulting in relatively high productivity averaging 8.25 g/L/h over 10 batches and with a maximal of 10.08 g/L/h in the final batch. Cell recycle by flocculation was fast and convenient, and could therefore be applicable for industrial-scale ethanol production.

Bioconversion of glycerol for bioethanol production using isolated Escherichia coli SS1

Bioconverting glycerol into various valuable products is one of glycerols promising applications due to its high availability at low cost and the existence of many glycerol-utilizing microorganisms. Bioethanol and biohydrogen, which are types of renewable fuels, are two examples of bioconverted products. The objectives of this study were to evaluate ethanol production from different media by local microorganism isolates and compare the ethanol fermentation profile of the selected strains to use of glucose or glycerol as sole carbon sources. The ethanol fermentations by six isolates were evaluated after a preliminary screening process. Strain named SS1 produced the highest ethanol yield of 1.0 mol: 1.0 mol glycerol and was identified as Escherichia coli SS1 Also, this isolated strain showed a higher affinity to glycerol than glucose for bioethanol production.