Effects of nano-SiO(2) and different ash particle sizes on sludge ash-cement mortar

The effects of nano-SiO₂ on three ash particle sizes in mortar were studied by replacing a portion of the cement with incinerated sewage sludge ash. Results indicate that the amount of water needed at standard consistency increased as more nano-SiO₂ was added. Moreover, a reduction in setting time became noticeable for smaller ash particle sizes. The compressive strength of the ash–cement mortar increased as more nano-SiO₂ was added. Additionally, with 2% nano-SiO₂ added and a cure length of 7 days, the compressive strength of the ash–cement mortar with 1 μm ash particle size was about 1.5 times better that of 75 μm particle size. Further, nano-SiO₂ functioned to fill pores for ash–cement mortar with different ash particle sizes. However, the effects of this pore-filling varied with ash particle size. Higher amounts of nano-SiO₂ better influenced the ash–cement mortar with larger ash particle sizes.     

Statistical determination of the optimal sample size of secondary effluent BOD5 and SS

A statistical technique is presented for determining the optimal sample size required to estimate the true geometric mean with an allowable error at a desired level of confidence. Attention is focused on its application in the monitoring of secondary effluent BOD₅ and SS. It is concluded that continuous monitoring of effluent BOD₅ or SS throughout the year may generate much more data than are required for practical purposes. This statistical method may be used by operators or regulatory agencies to formulate cost-effective monitoring schemes. Records of the sample size data of secondary effluent BOD₅ and SS across Canada are also discussed.     

Annual ambient atmospheric mercury speciation measurement from Longjing,a rural site in Taiwan

The main purpose of this study was to monitor ambient air particulates and mercury species [RGM, Hg(p), GEM and total mercury] concentrations and dry depositions over rural area at Longjing in central Taiwan during October 2014 to September 2015. In addition, passive air sampler and knife-edge surrogate surface samplers were used to collect the ambient air mercury species concentrations and dry depositions, respectively, in this study. Moreover, direct mercury analyzer was directly used to detect the mercury Hg(p) and RGM concentrations. The result indicated that: (1) The average highest RGM, Hg(p), GEM and total mercury concentrations, and dry depositions were observed in January, prevailing dust storm occurred in winter season was the possible major reason responsible for the above findings. (2) The highest average RGM, Hg(p), GEM and total mercury concentrations, dry depositions and velocities were occurred in winter. This is because that China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. (3) The results indicated that the total mercury ratios of Kaohsiung to that of this study were 5.61. This is because that Kaohsiung has the largest industry density (~60 %) in Taiwan. (4) the USA showed average lower mercury species concentrations when compared to those of the other world countries. The average ratios of China/USA values were 89, 76 and 160 for total mercury, RGM and Hg(p), respectively, during the years of 2000–2012.     

Effect of metal ions on decomposition of chlorinated organic substances by ozonation in acetic acid

The objective of this study is to find metal ions that enhance the ozone decomposition of chlorinated organic substances in acetic acid. Although the pseudo-first order degradation rate constant for 2,4-DCP by ozone in acetic acid in addition of Ca2+, Mg2+, Al3+ and Fe2+ were almost the same as that with no metal ion, the degradation rate in addition of Mn2+ and Fe3+ were 2.4 and 4.5 times as high as that with no metal ion, respectively. The presence of Fe3+ enhanced the degradation of 2,4-DCP by ozone in acetic acid because Fe3+-phenolate complex which have high reactivity with ozone was produced by the reaction between 2,4-DCP and Fe3+ in acetic acid.     

Preliminary investigation of greenhouse gas emissions from the environmental sector in Taiwan

The United Nations Framework Conventions on Climate Change (UNFCCC) asks their Parties to submit a National Inventory Report (NIR) for greenhouse gas (GHG) emissions on an annual basis. However, when many countries are quickly growing their economy, resulting in substantial GHG emissions, their inventory reporting systems either have not been established or been able to be linked to planning of mitigation measures at national administration levels. The present research was aimed to quantify the GHG emissions from an environmental sector in Taiwan and also to establish a linkage between the developed inventories and development of mitigation plans. The "environmental sector" consists of public service under jurisdiction of the Taiwan Environmental Protection Administration: landfilling, composting, waste transportation, wastewater treatment, night soil treatment, and solid waste incineration. The preliminary results were compared with that of the United States, Germany, Japan, United Kingdom, and Korea, considering the gaps in the scopes of the sectors. The GHG emissions from the Taiwanese environmental sector were mostly estimated by following the default methodology in the Intergovernmental Panel on Climate Change guideline, except that of night soil treatment and waste transportation that were modified or newly developed. The GHG emissions from the environmental sectors in 2004 were 10,225 kilotons of CO2 equivalent (kt CO2 Eq.). Landfilling (48.86%), solid waste incineration (27%), and wastewater treatment (21.5%) were the major contributors. Methane was the most significant GHG (70.6%), followed by carbon dioxide (27.8%) and nitrous oxide (1.6%). In summary, the GHG emissions estimated for the environmental sector in Taiwan provided reasonable preliminary results that were consistent and comparable with the existing authorized data. On the basis of the inventory results and the comparisons with the other countries, recommendations of mitigation plans were made, including wastewater and solid waste recycling, methane recovery for energy, and waste reduction/sorting.     

Deodorization of Dimethyl Sulfide Using a Discharge Approach at Room Temperature

Abstract

The traditional technologies for odor removal of thiol usually create either secondary pollution for scrubbing, adsorption, and absorption processes, or sulfur (S) poisoning for catalytic incineration. This study applied a laboratory-scale radio-frequency plasma reactor to destructive percentage-grade concentrations of odorous dimethyl sulfide (CH₃SCH₃, or DMS). Odor was diminished effectively via reforming DMS into mainly carbon disulfide (CS₂) or sulfur dioxide (SO₂). The removal efficiencies of DMS elevated significantly with a lower feeding concentration of DMS or a higher applied rf power. A greater inlet oxygen (O₂)/DMS molar ratio slightly improved the removal efficiency. In an O₂-free environment, DMS was converted primarily to CS₂, methane (CH₄), acetylene (C₂H₂), ethylene (C₂H₄), and hydrogen (H₂), with traces of hydrogen sulfide (H₂S), methyl mercaptan (CH₃SH), and dimethyl disulfide. In an O₂-containing environment, the species detected were SO₂, CS₂, carbonyl sulfide, carbon dioxide (CO₂), CH₄, C₂H₄, C₂H₂, H₂, formal-dehyde, and methanol. Differences in yield of products were functions of the amounts of added O₂ and the applied power. This study provided useful information for gaining insight into the reaction pathways for the DMS dissociation and the formation of products in the plasmolysis and conversion processes.