Tokyo Environmental Public Service Corporation

Resource and environmental safety protocols of incineration residues were evaluated by analyzing the metal concentration, heavy metal elution, desalination behavior, and chlorine removal ratio owing to particle size differences between bottom ash (BA) and grate sifting deposition ash (GA). In the total content test, Cl, Zn, and Cr in the incinerator BA exceeded the cement acceptance standard (Cl: 1000 mg/kg; Zn: 1700 mg/kg, and Cr: 170 mg/kg) at almost all of the particle sizes, while Au, Ag, Pd, and Zn had high contents in the GA. When using BA as a construction material, heavy metal elution values and contents are restricted as per the product quality standards based on the Japanese soil pollution control law. Lead within the BA and GA exceeded the standard values for most particle sizes. We predicted that there would be a limit on the elution of K by only washing with water. The removal ratio of total chlorine by particle size was approximately 20–70%, where the effect of the particle size on the removal ratio was small, suggesting that the elution of chlorine was complete in approximately 6 hours. These results contribute to information on the recycling of BA and GA.

東京の地先海域では, 夏季に発生する赤潮等の富栄養化に起因する水質悪化が課題となっている。その対策として, かつて東京の海岸線を形成し水質浄化機能があるとされている浅場・干潟の再生が有効と考えられる。本稿では, その水質浄化能力が明らかになっていない多摩川の河口域を対象区域として, 浅場・干潟等の浅い水域に多く分布する底生動物の浄化能力を定量的に評価することを目的として調査を行った。調査の結果, 多数のヤマトシジミが東京・羽田地区と川崎・大師地区を結ぶ大師橋付近の干潟に生息し, 多摩川河口域における底生動物相の大部分を占めていることが確認された。ヤマトシジミを主とする多摩川河口干潟の底生動物による粒子状有機窒素 (PON) 除去能力は, 調査期間 (2015年8～11月) において1日当たり58.6 kgNと算出され, 同期間の多摩川における窒素負荷量の0.5%に相当するPONが除去されていると推計された。

最終処分量に対する都市ごみ焼却残渣の割合は，2016 (平成 28) 年度時点で 77 % にまで上昇していることから，資源化を加速する必要がある。セメント原料化において，特に都市部では，焼却残渣を多量に活用する際には脱塩が必要な普通ポルトランドセメント原料だけでなく，焼却残渣の原料化率 50 % 以上のエコセメント原料化の広域処理も検討すべきである。一方で，地域特性により，既存セメント工場の利用，溶融スラグ化，抽出や物理選別による金属回収についても検討するとともに，2018 (平成 30) 年 4 月に閣議決定された第五次環境基本計画で示されたとおり，環境，経済，社会の統合的取組に資する最適な焼却残渣の資源化システムを提示していくことが求められている。

Up-flow column percolation tests are used at laboratory scale to assess the leaching behavior of hazardous substance from contaminated soils in a specific condition as a function of time. Monitoring the quality of these test results inter or within laboratory is crucial, especially if used for Environment-related legal policy or for routine testing purposes. We tested three different sandy loam type soils (Soils I, II and III) to determine the reproducibility (variability inter laboratory) of test results and to evaluate the difference in the test results within laboratory. Up-flow column percolation tests were performed following the procedure described in the ISO/TS 21268–3. This procedure consists of percolating solution (calcium chloride 1 mM) from bottom to top at a flow rate of 12 mL/h through softly compacted soil contained in a column of 5 cm diameter and 30 ± 5 cm height. Eluate samples were collected at liquid-to-solid ratio of 0.1, 0.2, 0.5, 1, 2, 5 and 10 L/kg and analyzed for quantification of the target elements (Cu, As, Se, Cl, Ca, F, Mg, DOC and B in this research). For Soil I, 17 institutions in Japan joined this validation test. The up-flow column experiments were conducted in duplicate, after 48 h of equilibration time and at a flow rate of 12 mL/h. Column percolation test results from Soils II and III were used to evaluate the difference in test results from the experiments conducted in duplicate in a single laboratory, after 16 h of equilibration time and at a flow rate of 36 mL/h. Overall results showed good reproducibility (expressed in terms of the coefficient of variation, CV, calculated by dividing the standard deviation by the mean), as the CV was lower than 30% in more than 90% of the test results associated with Soil I. Moreover, low variability (expressed in terms of difference between the two test results divided by the mean) was observed in the test results related to Soils II and III, with a variability lower than 30% in more than 88% of the cases for Soil II and in more than 96% of the cases for Soil III. We also discussed the possible factors that affect the reproducibility and variability in the test results from the up-flow column percolation tests. The low variability inter and within laboratory obtained in this research indicates that the ISO/TS 21268–3 can be successfully upgraded to a fully validated ISO standard.