Kiyoshi Omine

Microbial fuel cell (MFC) for bioelectricity generation from organic wastes.

Microbial fuel cells (MFCs) have gained a lot of attention recently as a mode of converting organic matter into electricity. In this study, a compost-based microbial fuel cell that generates bioelectricity by biodegradation of organic matter is developed. Grass cuttings, along with leaf mold, rice bran, oil cake (from mustard plants) and chicken droppings (waste from chickens) were used as organic waste. The electric properties of the MFC under anaerobic fermentation condition were investigated along with the influence of different types of membranes, the mixing of fly ash, and different types of electrode materials. It is observed that the maximum voltage was increased by mixing fly ash. Cellophane showed the highest value of voltage (around 350mV). Bamboo charcoal is good for anode material; however carbon fiber is better for the cathode material in terms of optimization of power generated. This developed MFC is a simple cell to generate electricity from organic waste.

Compost in plant microbial fuel cell for bioelectricity generation

Recycling of organic waste is an important topic in developing countries as well as developed countries. Compost from organic waste has been used for soil conditioner. In this study, an experiment has been carried out to produce green energy (bioelectricity) by using paddy plant microbial fuel cells (PMFCs) in soil mixed with compost. A total of six buckets filled with the same soil were used with carbon fiber as the electrodes for the test. Rice plants were planted in five of the buckets, with the sixth bucket containing only soil and an external resistance of 100 ohm was used for all cases. It was observed that the cells with rice plants and compost showed higher values of voltage and power density with time. The highest value of voltage showed around 700 mV when a rice plant with 1% compost mixed soil was used, however it was more than 95% less in the case of no rice plant and without compost. Comparing cases with and without compost but with the same number of rice plants, cases with compost depicted higher voltage to as much as 2 times. The power density was also 3 times higher when the compost was used in the paddy PMFCs which indicated the influence of compost on bio-electricity generation.

Arsenic, boron and salt resistant Bacillus safensis MS11 isolated from Mongolia desert soil

Arsenic (As) is a toxic metalloid, having both properties of a metal and a non-metal. Boron (B) is a nonmetal, essential micronutrient for plants growth and development but its excess can be toxic to plants with various levels. In this study arsenic, boron and salt resistant bacteria were isolated from desert soil, Mongolia. The bacterial screening was carried out by serial dilution method. One hundred colonies were screened initially using of (2 mM) arsenic and (2 mM) boron containing LB agar medium. From this population, 10 bacterial isolates were selected based on arsenic and boron resistance, boron accumulation, salt tolerance and arsenic oxidizing capability. One of the potent strain, MS 11 from Mongolia desert soil, was tentatively identified as Bacillus sp. The phylogenetic and comparative analysis of 16S rRNA gene sequence with closely related validly published species available in the database showed that the isolate MS11 was closely related to Bacillus safensis FO-036b(T) with the highest sequence similarity (99.439%). The 16S rRNA gene sequence of the strain MS11 was submitted in the NCBI database with the accession number JF836885. B. safensis MS11 exhibited high level of resistance to arsenite (40 mM), arsenate (400 mM), boron (200 mM) and 15% salt tolerance in LB agar medium. B. safensis MS11 was also associated with resistance to multiple heavy metals such as Cd, Cr, Cu, Ni, Pb and Zn. Hence, this bacterium could be useful in the remediation of salt affected soils and biogeochemical cycles of arsenic pollution.

Bioelectricity from kitchen and bamboo waste in a microbial fuel cell

This study evaluated bioelectricity generation by using kitchen garbage (KG) and bamboo waste (BW) as a solid waste management option by a microbial fuel cell (MFC) method. The nutrient content [nitrogen, phosphorus and potassium (NPK)] of the by-products of bioelectricity were also analyzed and assessed for their potential use as a soil amendment. A one-chamber MFC was used for bioelectricity generation in laboratory experiments using both KG and BW. A data-logger recorded voltage every 20 mins at a constant room temperature of 25°C over 45 days. The trend of voltage generation was different for the two organic wastes. In the case of KG, the voltage at the initial stage (0–5 days) increased rapidly and then gradually to a peak of 620 mV. In contrast, the voltage increased gradually to a peak of 540 mV in the case of BW. The by-products of bioelectricity can be used as soil conditioner as its NPK content was in the range of soil conditioner mentioned in other literature. Thus, the MFC has emerged as an efficient and eco-friendly solution for organic waste management, especially in developing and technologically less sophisticated countries, and can provide green and safe electricity from organic waste.

Characterization of boron resistant and accumulating bacteria Lysinibacillus fusiformis M1, Bacillus cereus M2, Bacillus cereus M3, Bacillus pumilus M4 isolated from former mining site, Hokkaido, Japan.

Boron is known to be widespread environmental contaminant that is relatively mobile in soil when compared to other metal contaminants. The present study made an attempt to isolate and characterize the boron resistant and accumulating bacteria from former mining site at Hokkaido, Japan. Four potential strains M1, M2, M3 and M4 were selected based on high degree of boron and heavy metal resistances. The morphological, biochemical and 16S rDNA sequencing analysis of mining bacteria revealed that the isolates were highly homology to Lysinibacillus fusiformis M1 (99 %), Bacillus cereus M2 (99 %), Bacillus cereus M3 (99 %) and Bacillus pumilus M4 (99 %) respectively. The strains M1, M2, M3 and M4 showed resistance to several heavy metals such as As (III), As (V) and Cr (VI), Cu, Ni, Pb and Zn. The selected strains were found to be arsenic oxidizing bacteria confirmed by Silver nitrate test. The resting and growing cells of mining bacteria were used for boron accumulation analysis. Selected strains were found to be efficiently accumulating boron concentration ranging from 0.1–2.3 mg L −1 and 1.5–4.7 mg L −1 at 24 h and 168 h, respectively. The following results conclude that the mining bacteria act as potent bioaccumulator of boron and its resistant, removal characteristic can be valuable in boron bioremediation.

Fluoride: A World Ubiquitous Compound, Its Chemistry, and Ways of Contamination

Fluoride, an incompatible lithophile and the most electronegative element, forms a number of soluble, pH-dependent formation of complexes with polyvalent metal ions in water. The interaction between water and sedimentary carbonates ultimately causes fluoride concentration gradient as a sequel of hydrogeochemistry. The occurrence of fluoride in groundwater due to fluorapatite solubility and the other governing factors such as rock chemistry, residence time, well depth, preferential pathways for the upward movement of deep groundwater, hydrologic condition of the pathways, and geologic structure have also been discussed. In this chapter, in addition to the geochemistry of fluoride, the chemistry of fluoride in water and its association with the other physicochemical parametric factors such as total dissolved solids and dissolved ions such as sodium, calcium, magnesium, arsenic, boron, and hydrogen carbonate have been elaborated. As fluoride and arsenic ions participate together in their occurrence in soil and hence water, their co-contamination has been exemplified from the research reports. Fluoride solubility as a function of evaporation, evapotranspiration, temperature, and water softening has also been accounted. The leaching aspects of soil-based adsorption–desorption mechanism and its ultimate destiny on fluoride enrichment of groundwater have also been added in the chapter.

Bimodal and multimodal descriptions of soil-water characteristic curves for structural soils

In the last decades several approaches have been developed to describe bimodal or multimodal soil-water characteristic curves (SWCCs). Unfortunately, most of these models were derived empirically. In the presented study, physically based bimodal and multimodal SWCC functions have been developed for structural soils. The model involved two or more continual pore series; the probability density functions for each pore series were assumed to be lognormal distribution and can be superposed to obtain the overall probability density function of the structural soils. The proposed functions were capable of simulating bimodal or multimodal SWCCs using parameters which can be related to physical properties of the structural soils. The experimental SWCC data were used to verify the proposed method. The fitting results showed that the proposed approaches resulted in good agreement between measurement and simulation. These functions can potentially be used as effective tools for indentifying hydraulic porosities in the structural mediums.

Characterization and Effective Utilization of Volcanic Ash for Soil Improvement

Volcanic ash becomes environmental important issues as waste material if it is not effectively reduced or reused. In engineering practice, utilization of volcanic ash as substitution material is limited. Indonesia has a large road on soft soil and volcanic ash. The objectives of this paper are focused to study the characterization, classification and utilization of volcanic ash as soil stabilization material which give benefit in engineering practice and also be environmental friendly material. Engineering properties, mineral composition and soil mixture characteristics involve physical and mechanical properties are discussed. Result shows that the effect of addition of volcanic ash after curing time 14 days can improve the engineering properties of soft soil, decrease liquid limit, change curve of grain size distribution, increase bearing capacity, and decrease swelling potential. The soil-volcanic ash mixture with 35% of volcanic ash and 5% of lime is obtained as optimum mixture design. This result is still early stage and need further study.

Slope stability and bearing capacity of landfills and simple on-site test methods:

This study discusses strength characteristics (slope stability, bearing capacity, etc.) of waste landfills through on-site tests that were carried out at 29 locations in 19 sites in Japan and three other countries, and proposes simple methods to test and assess the mechanical strength of landfills on site. Also, the possibility of using a landfill site was investigated by a full-scale eccentric loading test. As a result of this, landfills containing more than about 10 cm long plastics or other fibrous materials were found to be resilient and hard to yield. An on-site full scale test proved that no differential settlement occurs. The repose angle test proposed as a simple on-site test method has been confirmed to be a good indicator for slope stability assessment. The repose angle test suggested that landfills which have high, near-saturation water content have considerably poorer slope stability. The results of our repose angle test and the impact acceleration test were related to the internal friction angle and the cohesion, respectively. In addition to this, it was found that the air pore volume ratio measured by an on-site air pore volume ratio test is likely to be related to various strength parameters.

Eco-Friendly Post-Consumer Waste Management Utilizing Vermitechnology

Solid waste could be defined as the unwanted solid fractions which are generated from domestic and commercial sectors, trade centres, industrial activities, agricultural practices, various institutions and mining activities. Out of the various categories of municipal solid waste, post-consumer waste was of our concern as these wastes are no longer recycled and have the possibility of creating aesthetic pollution in particular. One of the post-consumer wastes is the paper cups which are found in large quantum occupying the MSW. Though there exists many numbers of techniques to manage these wastes, vermitechnology was found to be the simplest, cost-effective methodology for its management. Equal ratio of paper cup waste and cow dung was formed to get decomposed into manure with a C/N ratio<20 within a period of 19 weeks due to the activity of Eudrilus eugeniae. The bacterial strains such as Bacillus anthracis (KM289159), Bacillus endophyticus (KM289167), Bacillus funiculus (KM289165), Virigibacillius chiquenigi (KM289163), Bacillus thuringiensis (KM289164), Bacillus cereus (KM289160), Bacillus toyonensis (KM289161), Acinetobacter baumannii (KM289162) and Lactobacillus pantheries (KM289166) were identified and are confirmed by 16srRNA sequencing. The enzymes such as amylase, cellulose and protease were assayed both qualitatively and quantitatively. Further the cellulose degradation was confirmed with the bacterial consortia using high performance liquid chromatography(HPLC) analysis. The arearetention (380,620–245,696) and height reduction (6061–3303) confirmed the same. The change in the catalase, glutathione-S-transferase, and glutathione peroxidase and superoxide dismutase was recorded. On comparison, the SOD is found to vary during the paper cup decomposition and thus the parameter acts as a biomarker. During the plastic separation from the paper cup by the earthworm in the 8th week, the morphological and histological changes were also recorded. But it was clear that the earthworms required their lost weight when introduced into fresh waste again. Hence, vermicomposting is one of the eco-friendly methods for the post-consumer waste degradation.