This study involves the production of a value-added product of polyhydroxyalkanoates (PHAs) from pineapple cannery wastes by isolated bacterial strain of Bacillus sp. SV13 via batch fermentation process. Two carbon sources, glucose and sucrose, were used to investigate the potential of PHAs production compared to when the agro-industrial waste was used. Batch fermentation was performed in a flask scale under controlled conditions: 37°C, and 200 rpm of agitation rate. The PHAs concentration [g/L], biomass in the forms of dried cell weight (DCW) [g/L] and specific product yield (Yp/x) were determined by two-way analysis of variance (two-way ANOVA). The results revealed that PHAs concentration, biomass, and Yp/x obtained from pineapple waste were significantly greater than the results obtained from glucose and sucrose. The Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) techniques were used to examine the chemical structure of PHAs. It was found that the extracted PHAs remarkably showed in the form of polyhydroxybutyrate (PHB).
In local cities with decentralized small wastewater treatment plants (WWTPs), centralized anaerobic digestion at a WWTP that accepts more sludge from others can serve as the energy hub of the region. In this system, transportation of sewage sludge with a high solid content by vehicles and the use of digested sludge as fertilizer are promising. The present study evaluated the effect of high solid content on anaerobic digestion and on the quality of the digested sludge as a fertilizer in a 1,100-day continuous laboratory experiment. Mixed sewage sludge with 10% total solids was subjected to mesophilic anaerobic digestion with a volatile solids (VS) removal ratio of approximately 0.6. The acceptable organic loading rate was lower than 3.2 kgVS/(m3•d). The viscosity increased to 8.5 dPa•s, but computational fluid dynamics analysis confirmed that mixing need not be upgraded under conditions of high solid content. Component and eluted material analyses of the digested sludge as a fertilizer confirmed that the high solid content in the sewage sludge does not limit the use of digested sludge as a fertilizer according to the Japanese Fertilizer Control Act. The results showed that this centralized anaerobic digestion system is useful for sludge management in small facilities.
The adsorption of tungsten(VI) from a single solution onto zeolite fly ash (FA60) produced by hydrothermally treating fly ash (FA) in alkaline solution had been reported. However, taking into account practical considerations, the tungsten(VI) adsorption from a complex solution system containing cobalt, nickel, and tungsten should be investigated. In this study, the amounts of cobalt(II), nickel(II), and tungsten(VI) adsorbed onto the FA and FA60 surfaces were evaluated for a complex solution system. It was observed that a higher amount of tungsten(VI) was adsorbed onto the FA60 surface than onto the FA surface. The adsorption isotherms for tungsten(VI) were fitted using both the Freundlich and Langmuir equations. The result suggest that tungsten(VI) was adsorbed onto the FA and FA60 surfaces through electrostatic interactions between the positively charged FA or FA60 surfaces and the tungsten(VI) anions in complex solution. The pseudo-second-order model described the data more accurately than the pseudo-first-order model. The data obtained for various contact times indicated that the adsorption of tungsten(VI) proceeded through a multistep process involving the adsorption of tungsten(VI) onto the external surface and its subsequent diffusion into the interior of the absorbent. These results suggest that FA60 has a promising potential for the adsorption of tungsten(VI) in complex solution.
The increasing demand of rice crops leads to elevated levels of nitrogen in water bodies in Asia. The concentrations of organic and inorganic nitrogen and the nitrogen isotope ratio in nitrate (NO3-) were analysed to identify the sources of nitrogen in the outflow waters from a paddy field in Japan in 2013. Nitrogen concentrations in the drainage and percolation waters were the highest during the paddling period, NO3- was the dominant form of dissolved total nitrogen and the δ15N-NO3- values in both types of water were close to that of the chemical fertilizer. During the irrigation and non-irrigation periods, NO3- and dissolved organic nitrogen (DON) were the dominant in percolation water, whereas DON was dominant in drainage water. The strong correlation between the δ1515N-NO3- values in the irrigation and drainage water suggested that the irrigation water is one of the N sources in the drainage water during the irrigation period. Nitrate in percolation water during irrigation and non-irrigation periods might have been affected by the nitrified ammonium in the chemical fertilizer, or mineralized nitrogen in the soil or organic fertilizer.
Radioactive contamination resulting from the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station disaster following the Great East Japan earthquake and tsunami on March 11, 2011, has affected large areas of land in Fukushima, Japan. At present, agriculture has been limited to some areas, and there are concerns that radioactive substances carried by rainwater might contaminate water bodies such as ponds and rivers. In order to resume safe agricultural activities, evaluating the dynamics of radioactive substances in agricultural water is essential. In this study, we measured the concentration and analyzed the impact of radioactive cesium in irrigation water on rice in five districts having limited residential population. Further, we analyzed the radioactive cesium balance and soil samples from decontaminated paddy fields. The main findings of the study are (1) radioactive cesium in agricultural water was mainly in suspended form at the experimental locations within the 40 km zone; (2) most of the radioactive cesium in the irrigation water was accumulated in the paddy field, but radioactive cesium in irrigation water had limited impact on brown rice cultivation; and (3) continual monitoring of areas with radiation levels higher than those recorded in this study is recommended.