Biological removal of selenate in saline wastewater by activated sludge under alternating anoxic/oxic conditions

Removal of selenate in saline wastewater by activated sludge was examined. Sequencing batch reactor was operated under alternating anoxic/oxic conditions. Above 97% removal of soluble selenium (Se) was achieved continuously. Major Se removal mechanism varied depending on the length of aeration period. Various Se-reducing bacteria likely contributed to coordinately to Se removal. Selenium (Se)-containing industrial wastewater is often coupled with notable salinity. However, limited studies have examined biological treatment of Se-containing wastewater under high salinity conditions. In this study, a sequencing batch reactor (SBR) inoculated with activated sludge was applied to treat selenate in synthetic saline wastewater (3% w/v NaCl) supplemented with lactate as the carbon source. Start-up of the SBR was performed with addition of 1–5 mM of selenate under oxygen-limiting conditions, which succeeded in removing more than 99% of the soluble Se. Then, the treatment of 1 mM Se with cycle duration of 3 days was carried out under alternating anoxic/oxic conditions by adding aeration period after oxygen-limiting period. Although the SBR maintained soluble Se removal of above 97%, considerable amount of solid Se remained in the effluent as suspended solids and total Se removal fluctuated between about 40 and 80%. Surprisingly, the mass balance calculation found a considerable decrease of Se accumulated in the SBR when the aeration period was prolonged to 7 h, indicating very efficient Se biovolatilization. Furthermore, microbial community analysis suggested that various Se-reducing bacteria coordinately contributed to the removal of Se in the SBR and main contributors varied depending on the operational conditions. This study will offer implications for practical biological treatment of selenium in saline wastewater.     

Carbon nanotube-like materials in the exhaust from a diesel engine using gas oil/ethanol mixing fuel with catalysts and sulfur

Particulate matter from a diesel engine, including soot and carbon nanomaterials, was collected on a sampling holder and the structure of the materials was studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). As a result of employing gas oil/ethanol mixing fuel with sulfur and ferrocene/molybdenum as catalyst sources, formation of carbon nanotubes (CNT)-like materials in addition to soot was observed in the exhaust gas from a diesel engine. It was revealed that CNT-like materials were included among soot in our system only when the following three conditions were satisfied simultaneously: high ethanol fraction in fuel, high sulfur loading, and presence of catalyst sources in fuel. This study confirmed that if at least one of these three conditions was not satisfied, CNT-like materials were not observed in the exhaust from a diesel engine. These experimental results shown in this work provide insights into understanding CNT-like material formation mechanism in a diesel engine.

Implications: Recent papers reported that carbon nanotube-like materials were included in the exhaust gas from engines, but conditions for carbon nanotube-like material formation have not been well studied. This work provides the required conditions for carbon nanotube-like material growth in a diesel engine, and this will be helpful for understanding the carbon nanotube-like material formation mechanism and taking countermeasures to preventing carbon nanotube-like material formation in a diesel engine.     

The Fukushima Nuclear Power Plant accident and exposures in the environment

The Great East Japan Earthquake has occurred on March 11, 2011, in the Tohoku District of Japan. Due to the earthquake, big tsunamis were induced, and they rushed to the Fukushima Nuclear Power Stations, causing severe accidents. Radioactive materials including I-131, Cs-137 and so on were emitted from the plant to the environment. The Japanese government, Fukushima prefectural government and other local governments have struggled against the accidents. The restricted area and deliberate evacuation area are set by the government, and the residents are evacuated. The dose rates in and around Fukushima Prefecture have been monitored by the governments and other involved organizations. Fukushima government has started the health management survey for all residents in Fukushima Prefecture including the questions on their activities for the estimations of their external doses.     

Evaluation by year of the valuable/hazardous material content of lithium-ion secondary battery cells and other components of notebook computer battery packs

Journal of Material Cycles and Waste Management - Our objective was to provide the information necessary to efficiently recover metals from end-of-life lithium-ion secondary batteries by assessing...     

Testing the international linkage in the platinum-group metal futures markets

This study tests whether an international market exists in the platinum-group metal (PGM) futures markets. For this purpose, we tested the law of one price (LOP) and the causality between the U.S. and Japanese platinum and palladium futures markets. We also performed the test when structural breaks are considered. Long-run price relationships were found in both platinum and palladium markets but the LOP only sustained in the palladium market. The causality test revealed that it is the U.S. market that leads the price to transmit information between the U.S. and Japanese markets. Structural breaks had large impacts on the test results, suggesting that incorporating breaks is important when investigating the international price linkage in the PGM futures markets.     

Does the housing market respond to information disclosure?: Effects of toxicity indices in Japan

The policy instruments that provide information on a firm’s or facility’s environmental performance, such as the U.S. Toxic Release Inventory (TRI) and the Pollutant Release and Transfer Register system (PRTRs) used in some European countries and Japan, play an important role in encouraging firms or facilities to improve their environmental performance, if investors, consumers and residents recognize their environmental performance. This study uses a hedonic approach to explore how the Japanese rental housing market responds to carcinogenic risk arising from releases and transfers of chemical substances produced and used at close facilities. We found that residents do not perceive carcinogenic risk generated more than 1.0 km away from their residence and that they seem to recognize the increased carcinogenic risk at distances from 0.5 km to 1.0 km away; a 1% increase in carcinogenic risk reduces the average rent by 0.0007%. The distance at which residents perceive the risk arising from such facilities is less than in previous studies. This suggests that the risk perception recognized in previous studies may capture the other externalities in addition to the chemical risk because the risk is measured by the distance.     

Does trade openness improve environmental quality?

The literature on trade openness, economic development, and the environment is largely inconclusive about the environmental consequences of trade. This study treats trade and income as endogenous and estimates the overall impact of trade openness on environmental quality using the instrumental variables technique. We find that whether or not trade has a beneficial effect on the environment varies depending on the pollutant and the country. Trade is found to benefit the environment in OECD countries. It has detrimental effects, however, on sulfur dioxide (SO₂) and carbon dioxide (CO₂) emissions in non-OECD countries, although it does lower biochemical oxygen demand (BOD) emissions in these countries. We also find the impact is large in the long term, after the dynamic adjustment process, although it is small in the short term.     

Resource recovery treatment of waste sludge using a solubilizing reagent

The dewatering of waste sludge continues to be a major problem in wastewater treatment. In this study, the solubilization treatment of waste sludge and extracellular polymeric substances using a solubilizing reagent was examined experimentally. For this purpose, a compression test of thickened waste sludge obtained after solubilization treatment was carried out. The total solid content of the dewatered cake was over 30% when using hydrochloric acid or acetic acid as the solubilizing reagent; however, it was about 20% when using sodium hydroxide. The thickened waste sludge was effectively solubilized when the concentration of acetic acid in the sludge, assuming that it was diluted by free water and not bound water in the sludge, was greater than 0.3 kmol/m³. A flocculated sedimentation test using the supernatant water after solubilization treatment was also carried out, revealing that it functions in a similar manner to commercial flocculant in aggregating solid particles under gravity. This result indicates that the supernatant water can act as a bioflocculant. Methane fermentation of the supernatant water was subsequently carried out. The findings showed that by using acetic acid as a solubilizing reagent, solubilized organic substances in the supernatant water could be recovered as a bioenergy resource.     

Can secondary organic aerosol formed in an atmospheric simulation chamber continuously age?

This work investigates the oxidative aging process of SOA derived from select aromatic (m-xylene) and biogenic (α-pinene) precursors within an environmental chamber. Simultaneous measurements of SOA hygroscopicity, volatility, particle density, and elemental chemical composition (C:O:H) reveal only slight particle aging for up to the first 16 h of formation. The chemical aging observed is consistent with SOA that is decreasing in volatility and increasing in O/C and hydrophilicity. Even after aging, the O/C (0.25 and 0.40 for α-pinene and m-xylene oxidation, respectively) was below the OOAI and OOAII ambient fractions measured by high-resolution aerosol mass spectra coupled with Positive Matrix Factorization (PMF). The rate of increase in O/C does not appear to be sufficient to achieve OOAI or OOAII levels of oxygenation within regular chamber experiment duration. No chemical aging was observed for SOA during dark α-pinene ozonolysis with a hydroxyl radical scavenger present. This finding is consistent with observations by other groups that SOA from this system is comprised of first generation products.