Ecorisk evaluation and treatability potential of soils contaminated with petroleum hydrocarbon-based fuels

We used a series of toxicity tests to monitor oil degradation in the Kuwaiti oil lakes. Three soils from different locations with a history of hydrocarbon contamination were treated in bench-scale microcosms with controlled nutrient amendments, moisture content, and temperature that had promoted mineralization of total hydrocarbon and oil and grease in a preliminary study. Two hundred days of bioremediation treatment lowered hydrocarbon concentration to below 2 and 5 mg g(-1) for soils A and B, respectively, while in soil C hydrocarbon concentration remained at 12 mg g(-1). Although 85% of the total petroleum hydrocarbons (TPHs) in soil A were reduced 50d after treatment, results of the seed germination and Microtox tests suggested an initial increase in toxicity, indicating that toxic intermediary metabolites may have formed during biodegradation. Also, the significant decrease of TPHs and corresponding high toxicity levels were noted in soil B 200d after bioremediation. Clearly, toxicity values, and not just hydrocarbon concentration, are a key factor in assessing the effectiveness of bioremediation techniques. Field chemistry data showed a significant reduction in hydrocarbon levels after the biological treatment. We concluded that the toxicity assessment of the contaminated soil with a battery of toxicity bioassays could provide meaningful information regarding a characterization procedure in ecological risk assessment.     

Traffic-generated noise pollution: exposure of road users and populations in Metropolitan Kuwait

This study was carried out in metropolitan Kuwait with a sound level meter to assess peak hour and off-peak hour noise level. In local/collector streets, noise ranged between 56.0 to 79.2 dBA and 55.3 to 76.4 dBA; in arterial streets, 62.3 to 89.2 dBA and 59.6 to 78.9 dBA; and in freeways, 66.7 to 94.8 dBA and 64.9 to 89.1 dBA during peak and off-peak hour respectively. Values were higher than their prescribed standards which may pose a significant impact on quality of life. Findings of this research have shown that the level of traffic-generated noise pollution in Kuwait urban area is high enough to adversely affect the human health and well-being of its residents. Over 1,400 subjects responded to a randomly administered survey that assessed the physical health, personal well-being, and mental health. People residing in neighborhoods exposed to higher noise levels have significantly higher stress and noise annoyance levels and also adversely affected their sense of well-being. In the responder analysis, those people living in quiet neighborhoods had significantly higher mean scores in general health (35 points higher, p < 0.05), sense of vitality (30 points higher, p < 0.05), and mental health (20 points higher, p < 0.05) when compared to the other group. In addition, the component scores of stress and noise sensitivity for the participants living in quiet neighborhoods had significantly lower values (30 points lower and 59 points lower, respectively) than that of the participants living in noisy neighborhood. With the rapid expansion of the infrastructures in metropolitan Kuwait, it is virtually definite that traffic noise will shortly assume a dangerous dimension, and will be a ground of escalating fear for both the public and liable policy-makers. The quality of life in metropolitan Kuwait will certainly be negatively affected.     

Effect of microsilica addition on compressive strength of rubberized concrete at elevated temperatures

An experimental investigation was carried out to study the effects of various percentages of fine/coarse tire waste and microsilica at various temperatures on the compressive strength of concrete. The compressive strength of concrete mixtures made with tire rubber was assessed statistically with those of concrete containing microsilica and conventional concretes in order to evaluate the usefulness of recycling rubber waste as a component of concrete. Results confirmed that the recipe and processing temperature of concrete cubes influence the compressive strength values. Generally, the use of microsilica or fine rubber mixed with microsilica as aggregate replacement of 5% by volume improved the compressive strength of concrete processed at a temperature of 150°C. The addition of coarse rubber did not achieve any increase in strength when used as an aggregate replacement at any percentage. Moreover, the reductions in the compressive strength of concrete mixes at higher temperatures were much smaller for the fine rubber with 5 vol% microsilica than those for control and coarse rubber mixes. The specimens made with fine rubber and 5 vol% microsilica at elevated temperatures above 400°C appeared to show very similar compressive strength values. The use of fine rubber in building construction could help save energy and reduce costs and solve the solid waste disposal problem posed by this type of waste.     

Environmental management of construction and demolition waste in Kuwait

There is an increasing pressure on the construction industry to reduce costs and improve the quality of our environment. The fact is that both of these goals can be achieved at the same time. Although construction and demolition (C&D) constitutes a major source of waste in terms of volume and weight, its management and recycling efforts have not yet seen the light in Kuwait. This study focuses on recycling efforts leading to the minimization of the total C&D waste that is currently landfilled in Kuwait. This paper presents the current status of C&D waste disposal system in Kuwait and identifies the potential problems to the environment, people and economy. Then, it investigates alternative solutions to manage and control this major type of waste in an economically efficient and environmentally safe manner. Next, the paper describes the feasibility of establishing a C&D waste recycling facility in Kuwait. It concludes by highlighting the major benefits and bottleneck problems with such a recycling facility.     

Enhancing the performance of sequencing batch reactors by adding crushed date seeds to remove high concentrations of 2,4-dinitrophenol

Wastewater treatment systems using simultaneous adsorption and biodegradation processes have been successful in treating toxic pollutants present in industrial wastewater. The goal of this investigation was to assess the effectiveness of date seeds in reducing the toxic effects of 2,4-dinitrophenol (DNP) on activated sludge microorganisms. Two identical sequencing batch reactors (SBRs) (4-L glass vessel), each with a 3.5-L working volume, were used. The initial DNP concentrations in the reactor were 50, 75, 100, 250, and 500 mg/L. The reactor amended with date seeds was capable of degrading DNP at significantly greater rates (11 +/- 2.5 mg/L x h) than the control SBR (4 +/- 1.2 mg/L x h) at a 95% confidence level. Date seeds can be added to the mixed liquor of activated sludge treatment plants to remove high concentrations of DNP from wastewater, to protect the treatment plant against toxic components in the influent and enhance the settling characteristics of the mixed liquor.     

Functional biodiversity of microbial communities in aerobic selector slaughterhouse wastewater.

The biodiversity of the microbial communities of an aerobic selector and a conventional system treating slaughterhouse wastewater were evaluated using the Biolog technique (Biolog Inc., Hayward, California). Principal components analysis of patterns and level of microbial activity indicate that microbial communities statistically differentiate between the selector and conventional system. Biolog data indicated that there was seasonal variation in the structure and function of the microbial community in conventional samples, which may be a useful indicator of wastewater community disturbance and unsteadiness, while, for the selector system, there were no recognizable statistical differences between winter and summer data communities, Biodiversity indices indicated that the selector system maintained a high functional diversity (Shannon-Weaver diversity index [H'] from 3.8 to 4.6) than the conventional system (H' from 1.8 to 2.8). The high values in the selector system were a reflection of the fact that most of the carbon sources were used, contributing to the very high Shannon indices. In addition, the high substrate equitability values (J) obtained for the selector samples indicated that the microbial communities between the summer and winter samples used the carbon sources in the same proportion. In contrast, differences in the equitability of the microbial communities within the conventional system were observed. This indicated a pattern representing unevenness.