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Abstract: Efforts have been made to reduce municipal wastewater pollutant discharge and improve river water quality in the Yamato-gawa River basin since 2005, as part of a Social Experiment Programme. The Programme was the first one in Japan to disseminate soft interventions in households, measurements to reduce pollutant discharge, in a large river basin with more than two million population. The soft interventions in households are similar to cleaner production in industrial sector because they are not the wastewater treatment and changing of lifestyles. This paper presents several methods for quantification of the pollutant discharge reduction. Two hypothetical soft intervention combinations were defined, the effects of 16 soft interventions were estimated using their proliferation rates, and estimated pollutant discharge reduction was compared with changes in river water quality during the Programme events. For the first method, environmental accounting housekeeping (EAH) books were applied to estimate a 38–53% reduction in biological oxygen demand (BOD), 26–40% reduction in total nitrogen (TN), and 21–32% reduction in total phosphorus (TP). These estimation results were comparable with the field survey results of approximately 100 person population, which were conducted in the late 1980s. Soft interventions were found to be several times more cost effective than hard interventions, such as development of municipal wastewater treatment and river water purification systems. The BOD discharge reduction effects of soft interventions initiated during Programme events increased from 0.3–2.3% in 2005–2007 to 2.4–4.7% in 2007–2009. The questionnaire surveys found that participants in the Programme events in average newly implemented three or four soft interventions in addition to those already implemented at normal times. [Copyright &y& Elsevier]

Abstract: Ferrous metal production is thought to be a major mercury emission source because it uses large amounts of coal and iron ore, which contain trace amounts of mercury impurities. However, there is limited information about mercury emissions during the production process. In this study, we focused on the coke-oven process, sintering furnace process, and blast furnace process. We measured the mercury concentration in the raw materials, products, and byproducts to estimate the amount of mercury emitted and to investigate the behavior of mercury during the processes. Average mercury concentrations were 30.8 μg kg−1 in 54 samples of iron ore and 59.9 μg kg−1 in 33 samples of coal. The total mercury used for ferrous metal production in Japan was estimated to be 8.45 tons in 2005, with 4.07 tons from iron ore, 3.76 tons from coal, and 0.478 tons from limestone. Emissions from the sintering process accounted for more than 90% of the total emissions, and mercury in the exhaust gas was reduced using an activated coke tower and desulfurization equipment installed downstream of an electrostatic precipitator. When byproduct gas generated from coke-oven and blast furnace processes were included, mercury emissions estimates based on actual measurements were 4.08 tons y−1 (in 2005). Thus, about 50% of the mercury input in ferrous metal production was emitted to the atmosphere. The emission factor was calculated as 0.0488 g Hg ton−1 for crude steel production. The introduction of activated coke tower or desulfurization equipment in sintering furnace facilities would reduce mercury emissions. [Copyright &y& Elsevier]

Abstract: We investigated whether polychlorinated biphenyls (PCBs) and water could be simultaneously removed from river sediment by solvent extraction using liquefied dimethyl ether (DME) as the extractant. DME exists in a gaseous state at normal temperature and pressure and can dissolve organic substances and some amount of water; therefore, liquefied DME under moderate pressure (0.6–0.8MPa) at room temperature can be effectively used to extract PCBs and water from contaminated sediment, and it can be recovered from the extract and reused easily. First, we evaluated the PCB and water extraction characteristics of DME from contaminated sediment. We found that 99% of PCBs and 97% of water were simultaneously extracted from the sediment using liquefied DME at an extraction time of 4320s and a liquefied DME/sediment ratio of 60mLg−1. The extraction rate of PCBs and water was expressed in terms of a pseudo-first-order reaction rate. Second, we estimated the amount of DME that was recovered after extraction. We found that 91–92% of DME could be recovered. In other words, approximately 5–10% of DME was lost during extraction and recovery. It is necessary to optimize this process in order to recover DME efficiently. The extraction efficiency of the recovered DME is similar to that of the pure DME. From the results, we conclude that solvent extraction using liquefied DME is suitable for extracting PCBs and water from contaminated sediment. [Copyright &y& Elsevier]