Takashi Kameya

A preliminary categorization of end-of-life electrical and electronic equipment as secondary metal resources

End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection methods were suggested for equipment types that currently have no specific collection systems in Japan, particularly for video games, notebook computers, and mid-size ICT and audio/video equipment.

Occurrence of estrogenic endocrine disrupting chemicals concern in sewage plant effluent

The purpose of this study was to give a worldwide overview of the concentrations of typical estrogenic endocrine disrupting chemicals (EDCs) in the effluent of sewage plants and then compare the concentration distribution of the estrogenic EDCs in ten countries based on the survey data of the estrogenic EDCs research. The concentrations of three main categories (totally eight kinds) of estrogenic EDCs including steroidal estrogens (estrone (E1), estradiol (E2), estriol (E3) and 17α-ethynylestradiol (EE2)), phenolic compounds (nonylphenol (NP) and bisphenol A (BPA)) and phthalate esters (dibutyl phthalate (DBP) and dibutyl phthalate (2-ethylhexyl) phthalate (DEHP)) in the effluents of sewage plants reported in major international journals over the past decade were collected. The statistics showed that the concentration distributions of eight kinds of EDCs were in the range of ng·L−1 to μg·L−1. The concentrations of steroidal estrogens mainly ranged within 50.00 ng·L−1, and the median concentrations of E1, E2, E3 and EE2 were 11.00, 3.68, 4.90 and 1.00 ng·L−1, respectively. Phenolic compounds and phthalate esters were found at μg·L−1 level (some individual values were at the high level of 40.00 μg·L−1). The median concentrations of BPA, NP, DBP and DEHP were 0.06, 0.55, 0.07 and 0.88 μg·L−1, respectively. The concentrations of phenolic compounds and phthalate esters in the effluents were higher than that of steroids estrogens. The analysis of the concentration in various ten countries showed that steroids estrogens, phenolic compounds and phthalate esters in sewage plant effluents were detected with high concentration in Canada, Spain and China, respectively.

Adsorption equilibriums of principal herbicides on paddy soils in Japan.

Herbicides used in paddy fields during the flooding season can easily cause pollution by run-off into rivers or by other routes. It is very important to know the adsorption characteristics that influence their fate in the soil. The adsorption equilibriums have often been expressed by Henry equations, and the values of equilibrium constant, Kd, are estimated from the adsorption constants, K(OC), based on organic carbon contents of soils. There is little information concerning the equilibrium values expressed by the Freundlich equations, and insufficient information on the actual concentration levels in the paddy field. Therefore, adsorption equilibriums of the five principal herbicides: esprocarb, mefenacet, pretilachlor, simetryn and thiobencarb, on five kinds of paddy soil in Japan were investigated. It was found that their equilibrium values were better expressed by the Freundlich equation for concentration levels for the paddy fields, and that the values for the adsorption coefficient, n, varied from 1.0 to 1.6. Values for the coefficient, k, were in the range of 29-420 mg(1 - 1/n) l(1/n)/kg-dry, and the values were poorly related to solubilities in water or to the octanol-water partition coefficients of the herbicides. For each herbicide, except for simetryn, the values of k among the soils differed by 2-3 times, and no correlation could be found with the organic carbon contents, specific surface areas, pH, cation exchange capacity or major minerals of the soils. The adsorption equilibriums calculated from the values of adsorption constant Kd by the values of K(OC) in the literature were found to be very different from the experimental equilibriums. From the experimental values of coefficient k and n of the Freundlich equation, the maximum runoff concentrations of the herbicides were preliminarily estimated by a simple equilibrium model.

Biodegradation ranks of priority organic compounds under anaerobic conditions

The biodegradations of 52 priority organic compounds were evaluated under anaerobic conditions by two tests developed in a preceding paper (Urano et al., 1995). Namely, the biodegradabilities of the compounds were classified into 13 ranks by the method proposed by Urano et al. (1995). Most of the aliphatic alcohols and carboxylic acids were not inhibitory and were biodegraded, but the compounds having ether bonds or branched hydrocarbon groups were biodegraded slowly. Aliphatic aldehyde and amines were not so much inhibitory but were hardly biodegraded. The benzene substitutes having groups of -CH2OH, -CHO, -CH2CH(NH2)COOH, -COOH and -OH were easily biodegraded, but the compounds having groups of -NO2, -NH2 and -SO3H were hardly biodegraded. Most of the nitro compounds were inhibitory in the higher concentration test though they were reduced into amino compounds. Since the biodegradation characteristics of many organic compounds could be classified and discussed appropriately, the suitability of the proposed method is substantiated.

Chlorination by-products of fenitrothion

The mutagens produced through chemical reaction between chlorine and the insecticide fenitrothion were studied by using a quadrupole GC-MS. The mutagenicity and the mutagen formation potential (MFP) of the identified by-products were evaluated by the Ames assay (preincubation method) using Salmonella typhimurium TA100 without exogenous activation by S9 mix (TA100-S9). Before conducting GC/MS analyses, six compounds were presumed to be produced in chlorinated fenitrothion. These compounds were confirmed to be produced by the GC/MS analyses, but none of them were mutagenic. One of the chlorination by-products, 3-methyl-4-nitrophenol, has 19 times greater MFP than that of fenitrothion. This result suggests that a major mutagen in chlorinated fenitrothion will be produced via a chemical reaction between chlorine and 3-methyl-4-nitrophenol.

Application of biological safety index in two Japanese watersheds using a bioassay battery

In order to integratedly evaluate the biological safety as a water quality index, an assessment method based on three toxicity tests (algae growth inhibition, daphnia immobilization and larval fish toxicity) was developed. In this study, the developed method was used to screen, evaluate and rank the biological safety of small rivers near agricultural, industrial and residential areas. Twenty-seven representative water samples were collected from the Kaname River watershed and the Hinata River watershed in Kanagawa Prefecture, Japan. The results indicated that (1) the biological safety of water from the Hinata River ranked much higher than those from the Suzu River and the Shibuta River due to less human activities, (2) the biological safety from outlets of paddy fields ranked much worse than those from point source discharges of toxic pollutants, (3) the use of pesticides significantly affected the water quality of nearby small rivers and ditches during the pesticide application season, (4) the effects of different kinds of pesticides could successfully be classified using one toxicity test component of the bioassay battery, and (5) there was no significant quantitative relationship between the toxicity and dissolved organic carbon (DOC) for the studied water samples. The toxicities of water samples in this study were in agreement with the concentrations of pesticides determined with chemical methods by other researchers, which demonstrated that the developed assessment method was reliable to screen site contaminated with organic chemicals for priority management.

Testing and classification methods for the biodegradabilities of organic compounds under anaerobic conditions

Biodegradability is one of the most important characteristics of an organic compound for predicting its fate and life in the environment and its application in biological wastewater treatment. But there is no general testing method for biodegradability under anaerobic conditions. The biodegradabilities of thirteen principal organic compounds was investigated in a batch test using vials under various conditions, such as the concentration of an organic compound, the cultivation method and the concentration of anaerobic bacteria for seeding. Two test methods in the standard concentration and the low concentration were developed. A new method to classify the biodegradabilities of organic compounds into thirteen ranks was proposed by considering inhibition, complete biodegradation and first step biodegradation.

Comparison study on observed and estimated concentrations of perfluorooctane sulfonate using a fate model in Tokyo Bay of Japan

Perfluorooctane sulfonate (PFOS) was quantified in seawater and sediment samples collected from Tokyo Bay, Japan, ranging from 2.0 to 7.3 ng/L for surface seawater, 2.2 to 5.7 ng/L for intermediate seawater, 1.5 to 5.7 ng/L for bottom seawater, and 0.3 to 0.9 ng/g dry wt. for sediment. In addition, a 3-D chemical fate prediction model (National Institute of Advanced Industrial Science and Technology - Risk Assessment Model: AIST-RAM) has been applied to determine the accuracy of estimating PFOS in Tokyo Bay. A decreasing trend of PFOS from the northwestern part (i.e., the closed-off section of Tokyo Bay) to the mouth of the bay was observed, and the trend obtained from the actual surveys in this study was accurately represented by simulation with appropriate input parameters for AIST-RAM. From the comparison of observed concentrations with estimated concentrations, AIST-RAM showed a high degree of accuracy in estimating the concentrations of PFOS in seawater, whereas the estimations of PFOS concentrations in sediment had a relatively larger margin of error than those in seawater. However, our results indicate that AIST-RAM allows estimation of PFOS concentrations in seawater and sediment in Tokyo Bay with satisfactory accuracy.

A simple simulation of adsorption equilibrium of Pb(II) on Andosols in the presence of dissolved humic substances for monitoring soil contamination

The adsorption equilibrium of Pb(II) on Andosols was investigated and described quantitatively in order to develop a simple method for the rapid monitoring of heavy metals in soils. The effect of solution pH on adsorption isotherms was investigated experimentally and in simulations. At pH 7, the considerable desorption of Pb(II) due to the extensive dissolution of humic substances (HS) from soils into aqueous phases is known to be an obstacle to carrying out simulations. In batch experiments, the total organic carbon (TOC) of the aqueous phases was shown to be enhanced by the addition of pre-extracted HS to soil suspensions. By combining the ion-exchange and Freundlich models, the adsorption equilibriums of free Pb2+ ions and Pb2+-HS were simulated and were shown to be in good agreement with the experimental results. By estimating the concentrations and adsorption amounts of Pb2+ and Pb2+-HS from measured CPb and TOC, it is possible to accurately simulate the soil contamination status even in in the presence of dissolved HS in the water in the solid-liquid extraction samples.

Simulation of Adsorption Equilibrium of Heavy Metal Cations on Soils in Circumneutral Aqueous Solution: Influences of Solution PH and Dissolved Humus Substances

Adsorption isotherms are often required for understanding mobility, fate and bioavailability of contaminants in soils. Those about Pb (II) and Cd (II) on Andosols and Kanto loam were investigated in this work. Results show that adsorption increased with cation equilibrium concentration (10-4 - 1 meq L-1) and solution pH (5 - 7), and also that most adsorption isotherms can be simulated precisely with the ion-exchange-based Urano model. The applicability of model in predicting adsorption equilibriums of cations on soils in circumneutral aqueous solution (pH 5 - 7) were experimentally confirmed. There is an exception as to the Pb (II) adsorption on Andosols with the solid-to-liquid phase ratio higher than 1:100, there adsorption isotherms at pH 5 and pH 7 crossed, and the measurement precision decreased. The Urano model equation becomes inapplicable. Further experiment where humus substances (HS) were added indicated that the abnormal phenomenon can be attributed to dissolved HS and their complexation with Pb (II). The dissolution of HS with solution pH has enhanced Pb (II) concentration in solution but hardly reduced the total amount of adsorption on soil.