Influence of aggregated particles on biodegradation activities for dimethylarsinic acid (DMA) in Lake Kahokugata

Aquatic arsenic cycles mainly depend on microbial activities that change the arsenic chemical forms and influence human health and organism activities. The microbial aggregates degrading organic matter are significantly related to the turnover between inorganic arsenic and organoarsenic compounds. We investigated the effects of microbial aggregates on organoarsenic mineralization in Lake Kahokugata using lake water samples spiked with dimethylarsinic acid (DMA). The lake water samples converted 1 μmol L⁻¹ of DMA to inorganic arsenic for 28 d only under anaerobic and dark conditions in the presence of microbial activities. During the DMA mineralization process, organic aggregates >5.0 μm with bacterial colonization increased the densities. When the organic aggregates >5.0 μm were eliminated from the lake water samples using filters, the degradation activities were reduced. DMA in the lake water would be mineralized by the microbial aggregates under anaerobic and dark conditions. Moreover, DMA amendment enhanced the degradation activities in the lake water samples, which mineralized 50 μmol L⁻¹ of DMA. The DMA-amended aggregates >5.0 μm completely degraded 1 μmol L⁻¹ of DMA with a shorter incubation time of 7 d. The supplement of KNO₃ and NaHCO₃ to lake water samples also shortened the DMA-degradation period. Presumably, the bacterial aggregates involved in the chemical heterotrophic process would contribute to the DMA-biodegradation process in Lake Kahokugata, which is induced by the DMA amendment.     

Estimation of contribution from non-point sources to perfluorinated surfactants in a river by using boron as a wastewater tracer

The contribution of non-point sources to perfluorinated surfactants (PFSs) in a river was evaluated by estimating their fluxes and by using boron (B) as a tracer. The utility of PFSs/B as an indicator for evaluating the impact of non-point sources was demonstrated. River water samples were collected from the Iruma River, upstream of the intake of drinking water treatment plants in Tokyo, during dry weather and wet weather, and 13 PFSs, dissolved organic carbon (DOC), total nitrogen (TN), and B were analyzed. Perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUA), and perfluorododecanoate (PFDoDA) were detected on all sampling dates. The concentrations and fluxes of perfluorocarboxylates (PFCAs, e.g. PFOA and PFNA) were higher during wet weather, but those of perfluoroalkyl sulfonates (PFASs, e.g. PFHxS and PFOS) were not. The wet/dry ratios of PFSs/B (ratios of PFSs/B during wet weather to those during dry weather) agreed well with those of PFS fluxes (ratios of PFS fluxes during wet weather to those during dry weather), indicating that PFSs/B is useful for evaluating the contribution from non-point sources to PFSs in rivers. The wet/dry ratios of PFOA and PFNA were higher than those of other PFSs, DOC, and TN, showing that non-point sources contributed greatly to PFOA and PFNA in the water. This is the first study to use B as a wastewater tracer to estimate the contribution of non-point sources to PFSs in a river.     

Decolorization and estrogenic activity of colored livestock wastewater after electrolysis treatment

Livestock wastewater is treated by activated sludge treatment. Untreated livestock wastewater has high estrogen activity because animal excreta contains estrogen. When activated sludge treatment is applied, the estrogen activity declines or is lost. However, the color of treated livestock wastewater is deep brownish-red because of the decomposition of organic compounds or the synthesis of metabolites. Discharging colored wastewater to the environment could cause some problems, so it is necessary to decolorize colored wastewater before it is discharged. It has been suggested that electrolysis decolorization technology is suitable for treating colored wastewater; however, the process produces volatile organic compounds (VOCs). In fact, little research has been conducted with reference to estrogen activity in wastewater that has undergone electrolysis, especially on the contribution of the electrolysis decolorization process to estrogen activity, i.e., the possibility of resynthesis of some substance with estrogen activity due to resolved and metabolized colored components. In this study, the concentration of VOC was measured for various electrolysis conditions, and estrogen activity was examined using a yeast two-hybrid assay. From the results, decolorization of colored livestock wastewater by electrolysis was possible, and the VOC generation during electrolysis could be controlled depending on the electrolysis conditions. Estrogen activity in colored livestock wastewater disappeared on electrolysis decolorization.     

Migration of C in the paddy soil-to-rice plant system after C-acetic acid breakdown by microorganisms below the plow layer

Migration of ¹⁴C derived from ¹⁴C-acetic acid was examined by using soils sampled from paddies in four administrative areas in Japan (Aomori, Yamanashi, Ehime and Okinawa) and rice plant in a tracer experiment to understand the fate of ¹⁴C in the paddy soil-to-rice plant system. The loss of ¹⁴C radioactivity levels derived from ¹⁴C-acetic acid was caused by soil microorganism breakdown. A part of the ¹⁴C fixation to soil was caused by microbial assimilation into the fatty acid fraction. ¹⁴C moved upward via two different types of ¹⁴C dynamics in soil: quick movement upward; and constant but slow movement upward. ¹⁴C was highly assimilated into the plant panicle and that was caused by the root-uptake and the transfer of ¹⁴C. Migration of ¹⁴C derived from ¹⁴C-acetic acid relied heavily upon changes of chemical forms and characteristics of ¹⁴C-compound as caused by microorganisms in soil.     

Preliminary estimations of energy and cost for CO2 recovery by a membrane flash process utilizing waste thermal energy

The membrane flash process utilizing waste thermal energy was developed to achieve an energy-saving technology and to substitute it for a conventional regenerator. The operating conditions of the membrane flash at high temperature were studied. The petroleum refining process and iron manufacturing process were proposed for candidate processes that actually had waste energy sources. The DEA concentration and the flashing pressure had optimum values to improve the performance and reduce the energy consumption for CO₂ recovery. Energy consumptions and costs for CO₂ recovery in the membrane flash and chemical absorption were estimated by a process simulator and discussed under the same conditions. The membrane flash can achieve lower energy capture than the chemical absorption for the above industrial processes. The membrane flash is suitable for the CO₂ emission sources that had high CO₂ concentration independently of the plant scale. The chemical absorption can be applied if the plant scale is large and also the CO₂ concentration is low.     

Evaluation of operational parameters in thermophilic acid fermentation of kitchen waste

In this study, the effect of operational parameters, such as solids retention time (SRT), pH, and substrate total solids (TS) concentration, on acid fermentation efficiency was investigated. From batch tests, it was shown that the appropriate pH range for thermophilic acidogens was around 6–7 and that the optimum pH condition was 6. From the continuous experiment, pH and SRT were shown to be the most important operational parameters for solubilization and organic acid production. In contrast, TS concentration did not show any obvious effect on chromium chemical oxygen demand (CODcr) solubilization when TS was in the range 3.5%–10%. The optimum operational conditions for thermophilic acid fermentation were an SRT of 2 days and a pH of 6. This research was carried as a part of the CREST project of Japan Science and Technology Agency.     

PCDDs/PCDFs and dioxin-like PCBs: recent body burden levels and their determinants among general inhabitants in Japan

OBJECTIVE: The objective was to grasp the recent body burden levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) and to investigate their determinants among general inhabitants in Japan. METHODS: This study was performed on 1374 participants aged 15-73 years, who were not occupational exposure to PCDDs/PCDFs and DL-PCBs, living widely in 75 different residential areas of 25 prefectures in Japan. Seven PCDDs, ten PCDFs, twelve DL-PCBs, which are assigned a toxicity equivalent factor, and biochemical factors were determined in fasting blood. A questionnaire survey on life-style was also performed. RESULTS: The median of total toxicity equivalent (TEQ) was 20pgTEQ/g lipid. The TEQs of PCDDs/PCDFs, DL-PCBs and total TEQ increased with age. The intake frequency of fish-and-shellfish was positively associated with the TEQ of DL-PCBs in both sexes. Current smoking was negatively related to the TEQ of DL-PCBs in male subjects but not in female subjects. Feeding status was significantly related to the TEQs of PCDDs/PCDFs, DL-PCBs and total TEQ, being lowest in breast feeding and highest in never and bottle feeding. According to the results of subgroup analysis, parity was not associated with the TEQs. CONCLUSIONS: The fish-and-shellfish consumption may contribute to the accumulation of DL-PCBs, and smoking may induce some biological action for the elimination of DL-PCBs from the human body. Breast feeding is considered to be one of the major excretory pathways of PCDDs/PCDFs and DL-PCBs in women, while parity may not largely contribute to the elimination of these pollutants.     

The treatment of infectious waste arising from home health and medical care services: present situation in Japan

The management of waste materials arising from home health and medical care services (HHMC wastes) in Japan is now receiving greater attention from governmental workers dealing with general household waste materials. In general, HHMC waste materials are collected in a mixed form, transported and disposed of along with municipal solid wastes. As a result, municipal workers are suffering needle stick accidents so that infections associated with HHMC waste materials may occur. The collection and transportation by patients and their families of HHMC waste materials with sharp-edges, such as injection needles, to medical-related facilities can prevent municipal workers from experiencing needle-prick accidents. One of the most important strategies for medical-related facilities is hence the education of patients and their families. Improved rules for handling HHMC waste materials are essential for the safe and effective management.     

Evaluating the strength development of mortar using clinker fine aggregate with a combination of fly ash and its inhibitory effects on alkali–silica reaction and delayed ettringite formation

The aggregate composed of cement clinker, an intermediate cement product, improves strength development and mass transfer resistance of concrete. Fly ash (FA) is a supplementary cementitious material that can be substituted by cement. This study investigated the strength development of highly FA-substituted mortar mixed with cement clinker fine aggregate (CL) and tested its inhibitory effect against the alkali–silica reaction (ASR). In addition to these, this study provides the testing results of evaluating the effects of using cement clinker fine aggregate on delayed ettringite formation (DEF), which can be problematic for precast concrete products. The study results revealed that at 91 days of age, in the case of 80% replacement ratio of fly ash to cement, using CL exhibited similar strength development as mortar with limestone fine aggregate and no FA substitution. Furthermore, mortars with 70% and 80% FA substitution did not exhibit clear ASR-induced expansion even at 182 days of age. Lastly, mortar using clinker fine aggregate could suppress DEF-induced expansion at 182 days of age, which was similar to the effect obtained using FA. These results can promote the utilization of CL resources for concrete and using clinker as fine aggregate in precast concrete products.

     

Verification of the mutually complementary effect of fly ash and clinker aggregate on the strength,heat of hydration,and alkali-silica reaction

Journal of Material Cycles and Waste Management - Although fly ash, as used for supplementary cementitious material in Portland cement concrete, can reduce the heat of hydration and suppress the...