Denitrification with acrylonitrile as a substrate using pure bacteria cultures isolated from acrylonitrile-butadiene-styrene wastewater

This study attempted to isolate and identify the denitrifying bacteria that utilize acrylonitrile as a substrate from acrylonitrile-butadiene-styrene (ABS) resin wastewater. The performance of the denitrifying bacteria for treating different initial acrylonitrile concentrations was also investigated under anoxic conditions. The results showed that seven strains of denitrifying bacteria that can use acrylonitrile or acrylic acid as a substrate were isolated from the denitrification tank of a wastewater treatment plant in a ABS resin manufacturing plant and a lab-scale anoxic granular activated carbon-fluidized bed. The bacteria strains Acidovorax facilis B and Pseudomonas nautica could utilize acrylonitrile up to 279 mg/l as a substrate for denitrification. For complete nitrate removal, an adequate supply of acrylonitrile was necessary. Under the assumption that the acrylic acid would be completely removed, the removal of 1 mg/l nitrate by A. facilis B or P. nautica, about 0.64-0.74 mg/l acrylonitrile or 0.87-1 mg/l acrylic acid was needed. Because strains A. facilis B and P. nautica could utilize acrylonitrile for denitrification, they are expected to play an important role in the treatment of acrylonitrile in the wastewater treatment plant (denitrification and nitrification processes) and lab-scale granular activated carbon-fluidized bed.     

Seedling insensitivity to ozone for three conifer species native to Great Smoky Mountains National Park

Field symptoms typical of ozone injury have been observed on several conifer species in Great Smoky Mountains National Park, and tropospheric ozone levels in the Park can be high, suggesting that ozone may be causing growth impairment of these plants. The objective of this research was to test the ozone sensitivity of selected conifer species under controlled exposure conditions. Seedlings of three species of conifers, Table Mountain pine (Pinus pungens), Virginia pine (Pinus virginiana), and eastern hemlock (Tsuga canadensis), were exposed to various levels of ozone in open-top chambers for one to three seasons in Great Smoky Mountains National Park in Tennessee, USA. A combination of episodic profiles (1988) and modified ambient exposure regimes (1989-92) were used. Episodic profiles simulated an average 7-day period from a monitoring station in the Park. Treatments used in 1988 were: charcoal-filtered (CF), 1.0x ambient, 2.0x ambient, and ambient air-no chamber (AA). In 1989 a 1.5x ambient treatment was added, and in 1990, additional chambers were made available, allowing a 0.5x ambient treatment to be added. Height, diameter, and foliar injury were measured most years. Exposures were 3 years for Table Mountain pine (1988-90), 3 years for hemlock (1989-91), and 1 and 2 years for three different sets of Virginia pine (1990, 1990-91, and 1992). There were no significant (p<0.05) effects of ozone on any biomass fraction for any of the species, except for older needles in Table Mountain and Virginia pine, which decreased with ozone exposure. There were also no changes in biomass allocation patterns among species due to ozone exposure, except for Virginia pine in 1990, which showed an increase in the root:shoot ratio. There was foliar injury (chlorotic mottling) in the higher two treatments (1.0x and 2.0x for Table Mountain and 2.0x for Virginia pine), but high plant-to-plant variability obscured formal statistical significance in many cases. We conclude, at least for growth in the short-term, that seedlings of these three conifer species are insensitive to ambient and elevated levels of ozone, and that current levels of ozone in the Park are probably having minimal impacts on these particular species.     

Considerations for the design of organic mulch permeable reactive barriers

Organic mulch consists of insoluble carbon biopolymers that are enzymatically hydrolyzed during decomposition to release aqueous total organic carbon (TOC). The released TOC is utilized by microorganisms as an electron donor to transform electrophilic contaminants via reductive pathways. Over the last decade, organic mulch permeable reactive barriers (PRBs), or biowalls, have received increased interest as a relatively inexpensive slow‐release electron donor technology for addressing contaminated groundwater. To date, biowalls have been installed to enhance the passive bioremediation of groundwater contaminated with a variety of electrophilic compounds, including chlorinated solvents, explosives, and perchlorate. In addition, several mulch biowall projects are currently under way at several U.S. Department of Defense facilities. However, at the present time, the guidelines available for the design of mulch PRBs are limited to a few case studies published in the technical literature. A biowall design, construction, and operation protocol document is expected to be issued by the Air Force Center for Environmental Excellence in 2007. In this publication, three technical considerations that can have a significant impact on the design and performance of mulch PRBs are presented and discussed. These technical considerations are: (1) hydraulic characteristics of the mulch bed; (2) biochemical characteristics of different types of organic amendments used as mulch PRB fill materials; and (3) a transport model that can be used to estimate the required PRB thickness to attain cleanup standards. © 2007 Wiley Periodicals, Inc.     

Present status of the recycling of waste electrical and electronic equipment in Korea

In Korea due to rapid economical growth followed by urbanisation, breakage of large traditional families into small nuclear families, continuous changes in equipment features and capabilities causes tremendous increase in sale of new electrical and electronic equipment (EEE) and decrease in sale of used EEE. Subsequently, the ever-increasing quantity of waste electrical and electronic equipment (WEEE) has become a serious social problem and threat to the environment. Therefore, the gradual increase in the generation of WEEE intensifies the interest for recycling to conserve the resources and protect the environment. In view of the above, a review has been made related to the present status of the recycling of waste electrical and electronic equipment in Korea. This paper describes the present status of generation and recycling of waste electrical and electronic equipment, namely TVs, refrigerators, washing machines, air conditioners, personal computers and mobile phones in Korea. The commercial processes and the status of developing new technologies for the recycling of metallic values from waste printed circuit boards (PCBs) is also described briefly. Since 1998, three recycling centers are in full operation to recycle WEEE such as refrigerators, washing machines and air conditioners, having the total capacity of 880,000 units/year. All waste TVs are recently recycled on commission basis by several private recycling plants. The recycling of waste personal computers and mobile phones is insignificant in comparison with the amount of estimated obsolete those. Korea has adopted and enforced the extended producer responsibility (EPR) system. Korea is making consistent efforts to improve the recycling rate to the standards indicated in the EU directives for WEEE. Especially environmentally friendly and energy-saving technologies are being developed to recycle metal values from PCBs of WEEE.     

USE OF A PREDICTIVE MODEL IN EVALUATING WATER CONSUMPTION CONSERVATION1

ABSTRACT: The effectiveness of water conservation policies on reduction of water consumption was evaluated by use of a multiple regression predictive model. Data were obtained from eight Iowa communities, with regard to water consumption and water conservation policies adopted during the drought of 1977. The proposed model, which takes precipitation, temperature, month effects, and uniqueness of communities into account, is considered superior to the use of simple percent changes in evaluating the significance of reduction in water consumption due to conservation efforts. Among the variety of policies reviewed, mandatory policies with per capita restrictions were found to be most effective. However, voluntary conservation policies also resulted in significant reduction in some communities located in close proximity to other communities with severer water shortages. High credibility of local governments as to water shortage information was singled out as the most important factor in successful conservation by water resource policymakers of these communities. Use of the proposed predictive model for water consumption was demonstrated. Recommendations regarding future water conservation were made.     

Review of ozone and temperature lidar validations performed within the framework of the Network for the Detection of Stratospheric Change

The use of assimilation tools for satellite validation requires true estimates of the accuracy of the reference data. Since its inception, the Network for Detection of Stratospheric Change (NDSC) has provided systematic lidar measurements of ozone and temperature at several places around the world that are well adapted for satellite validations. Regular exercises have been organised to ensure the data quality at each individual site. These exercises can be separated into three categories: large scale intercomparisons using multiple instruments, including a mobile lidar; using satellite observations as a geographic transfer standards to compare measurements at different sites; and comparative investigations of the analysis software. NDSC is a research network, so each system has its own history, design, and analysis, and has participated differently in validation campaigns. There are still some technological differences that may explain different accuracies. However, the comparison campaigns performed over the last decade have always proved to be very helpful in improving the measurements. To date, more efforts have been devoted to characterising ozone measurements than to temperature observations. The synthesis of the published works shows that the network can potentially be considered as homogeneous within +/-2% between 20-35 km for ozone and +/-1 K between 35-60 km for temperature. Outside this altitude range, larger biases are reported and more efforts are required. In the lower stratosphere, Raman channels seem to improve comparisons but such capabilities were not systematically compared. At the top of the profiles, more investigations on analysis methodologies are still probably needed. SAGE II and GOMOS appear to be excellent tools for future ozone lidar validations but need to be better coordinated and take more advantage of assimilation tools. Also, temperature validations face major difficulties caused by atmospheric tides and therefore require intercomparisons with the mobile systems, at all sites.     

Linkages in Ghana's gold mining industry: Challenging the enclave thesis

By 2009, Ghana was the second-ranked African producer after South Africa, and had become the world's ninth largest producer of gold, at some 3.8% of global production, up from 2.6% five years earlier. Gold production volumes and revenues rose significantly over the decade from 2000. Yet gold mining tends to be perceived negatively in Ghana, and is seen as providing far less than it should in terms of public revenue, employment, skills development and spillovers, and localised economic development. Gold mining is often depicted as having an enclave status, disconnected and isolated from the rest of the economy. In contrast, the research findings here demonstrate that after a period of strong investment and growth, gold mining can no longer be viewed as an enclave activity: it is in fact more deeply linked into the Ghanaian economy than hitherto understood, through a set of as yet under-researched but promising economic linkages, notably backward linkages, which can potentially be strengthened by policy and support measures.     

Recycling municipal incinerator fly- and scrubber-ash into fused slag for the substantial replacement of cement in cement-mortars

Fly- and scrubber-ash (weight ratio of approximately 1:3) from municipal solid waste incinerators (MSWI) are a major land-fill disposal problem due to their leaching of heavy metals. We uniformly mixed both types of ash with optimal amounts of waste glass frit, which was then melted into a glassy slag. The glassy slag was then pulverized to a particle size smaller than 38 μm for use as a cement substitute (20–40% of total cement) and blended with sand and cement to produce slag-blended cement-mortar (SCM) specimens. The toxicity characteristics of the leaching procedure tests on the pulverized slag samples revealed that the amount of leached heavy metals was far below regulatory thresholds. The compressive strength of the 28-day cured SCM specimens was comparable to that of ordinary Portland cement mortars, while the compressive strength of specimens cured for 60 or 90 days were 3–11% greater. The observed enhanced strength is achieved by Pozzolanic reaction. Preliminary evaluation shows that the combination of MSWI fly- and scrubber-ash with waste glass yields a cost effective and environmentally friendly cement replacement in cement-mortars.     

Seasonal characteristics of chemically apportioned aerosol optical properties at Seoul and Gosan,Korea

Seasonal variations of aerosol optical properties in Seoul (polluted urban site) and Gosan (coastal background site), Korea, with an emphasis on the relative humidity were investigated using ground-based aerosol measurements and optical model calculations. The mass fraction of elemental carbon was 9–20%, but the optical contribution of these particles to light extinction was higher, up to 33–55% in Seoul. In Gosan, the contribution of non-sea-salt water-soluble aerosols on extinction was 81–93% due to the high mass fraction of these particles. Based on daily MODIS datasets, our analysis showed that the aerosol optical depths at Seoul and Gosan were highest in spring due to the influence of dust particles. The aerosol water content at Gosan, calculated using a thermodynamic equilibrium model, was higher than that at Seoul; this was attributed to the high relative humidity and high fraction of water-soluble aerosols at Gosan. At Seoul, despite abundant water vapors in summer, the possibility of hygroscopic growth of water-soluble aerosols was not more significant than that at Gosan.