Impact Modeling of Sewage Discharge From Georgetown of Penang, Malaysia on Coastal Water Quality

Currently about 200,000 persons of the Penang Georgetown population is served by a sewerage system which conveys the raw sewage to an open channel flume in Jelutong for discharge into the Western Channel. This has resulted in the degradation of coastal water quality in the affected areas. Therefore, there exists an urgent need to look for other alternatives for sewage treatment and disposal. This paper presents the results of computer simulations on the impacts of sewage discharge on Penang coastal waters under two treatment and disposal options. The preferred option is a conventional activated sludge treatment system capable of treating the sewage to secondary level with a submerged outfall to the Western Channel for the disposal of the treated effluent. The results of computer simulations show that the quality of coastal waters, other than in the immediate vicinity of the discharge point, would be able to achieve the Malaysian proposed criterion for recreational waters up to year 2020.     

Factors affecting the leaching of lead from UPVC pipes

This paper summarizes the results of a series of studies on the various factors that affect the leaching of lead from unplasticized poly(vinyl chloride) (UPVC) pipes. Factors that were studied include temperature, pH and extractants. Results showed that, for a given UPVC pipe, the rate of leaching of lead depended primarily on temperature and the nature of extractants. While the rate of leaching of lead was quite low with distilled water, it was very much enhanced by the presence of low concentration of anions such as Cl^-, HPO _inf4 ^sup2- HCO _inf3 ^sup- , NO _inf3 ^sup- , SO _inf4 ^sup2- and EDTA. EDTA, being a strong complexing agent, was most effective. Rates of leaching were found to be higher at elevated temperature except in the cases of HPO _inf4 ^sup2- and EDTA. Effect of pH was not pronounced. The temperature at which the UPVC pipes were extruded was found to affect the rate of leaching of lead. Pipes extruded at 190°C were found to have lower rate of leaching than those extruded at 180°C and 170°C. Analysis of the pipes by Scanning Electron Microscopy showed that the distribution of lead in the pipes extruded at 190°C was more uniform than those extruded at 170°C.     

Poly(sodium acrylamidoalkanoates) in water treatment

Poly(sodium 6-acrylamidocaproate), poly(sodium 11-acrylamidoundecanoate), poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate) have been synthesized. The performance of these anionic polyelectrolytes as coagulant aids in water treatment was assessed by the jar test. The effects of polymer dosage and pH on their performances were investigated in order to establish the optimum flocculation conditions. The effectiveness of these polyelectrolytes as well as a commercially available cationic polyamine organic coagulant aid was compared in terms of floc size, settling rate and the quality of treated water. Poly(sodium 6-acrylamidocaproate) and poly(sodium 11-acrylamidoundecanoate) were superior to poly(sodium 11-N-methylacrylamidoundecanoate) and poly(sodium 11-N-ethylacrylamidoundecanoate), and they are as effective as the commercial cationic coagulant aid.     

Tsunami run-up and inundation along the coast of Sabah and Sarawak,Malaysia due to a potential Brunei submarine mass failure

Submarine landslides, also known as submarine mass failures (SMFs), are major natural marine disasters that could critically damage coastal facilities such as nuclear power plants and oil and gas platforms. It is therefore essential to investigate submarine landslides for potential tsunami hazard assessment. Three-dimensional seismic data from offshore Brunei have revealed a giant seabed mass deposited by a previous SMF. The submarine mass extends over 120 km from the continental slope of the Baram Canyon at 200 m water depth to the deep basin floor of the Northwest Borneo Trough. A suite of in-house two-dimensional depth-averaged tsunami simulation model TUNA (Tsunami-tracking Utilities and Application) is developed to assess the vulnerability of coastal communities in Sabah and Sarawak subject to potential SMF tsunami. The submarine slide is modeled as a rigid body moving along a planar slope with the center of mass motion parallel to the planar slope and subject to external forces due to added mass, gravity, and dissipation. The nonlinear shallow water equations are utilized to simulate tsunami propagation from deepwater up to the shallow offshore areas. A wetting-drying algorithm is used when a tsunami wave reaches the shoreline to compute run up of tsunami along the shoreline. Run-up wave height and inundation maps are provided for seven densely populated locations in Sabah and Sarawak to highlight potential risks at each location, subject to two scenarios of slide slopes: 2° and 4°. The first wave may arrive at Kudat as early as 0.4 h after the SMF, giving local communities little time to evacuate. Over a small area, maximum inundated depths reaching 20.3 m at Kudat, 26.1 m at Kota Kinabalu, and 15.5 m at Miri are projected, while the maximum inundation distance of 4.86 km is expected at Miri due to its low-lying coast. In view of the vulnerability of some locations to the SMF tsunami, it is important to develop and implement community resilience program to reduce the potential damage that could be inflicted by SMF tsunamis.     

An appraisal perspective of justice,structure, and job control as antecedents of psychological distress

Through the application of cognitive appraisal theory, this study unifies the emergent themes of studying justice in relation to organizational context, as well as justice in relation to employee feelings of psychological distress. A sample of 677 employees from 72 organizations was used to test hypotheses related to justice, job control, mechanistic structure, and employee feelings of anxiety and depression. We found procedural justice, within a primary appraisal role, to be a highly effective tool for minimizing psychological distress. In combination with both distributive justice as well as a mechanistic structure, procedural justice can help to minimize feelings of anxiety and depression, but in different manners for each variable. Further, a strong influence of job control upon both procedural justice and, ultimately, depression and anxiety highlighted its role as a perceived means for avoiding or minimizing the harm of a potential stressor. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of clean technology in alcohol fermentation industry

A zero-discharge system for the alcohol fermentation industry was developed by recycling distillery waste (stillage). Stillage was able to be recycled as cooking water for the next fermentation after treating it with appropriate separation processes. Ultrafiltration with a ceramic membrane played a key role in the separation processes. When the permeate from the ultrafiltration of stillage was recycled to the cooking step, the total fermentation time was prolonged from 60 to 70–80 h, but the average ethanol production yield (8.8%) was similar to that in the conventional process (9.0%). In contrast, direct recycle of stillage without membrane filtration showed negative effects on both fermentation time and alcohol yield as recycling was repeated. This new process was confirmed to have stable operation over eight recycles. This new clean technology for the ethanol production industry makes it possible to eliminate the stillage treatment steps using the conventional biological treatment processes such as anaerobic digestion and activated sludge steps currently being operated in industry.     

ON THE MISMATCH BETWEEN DATA AND MODELS OF HYDROLOGIC AND WATER RESOURCE SYSTEMS1

ABSTRACT: Many difficulties exist in the matching of models with data. This paper identifies elements of this problem and discusses considerations involved in model evaluation. The well known multivariate linear regression model is used to illustrate the distinctions between accuracy and precision and between estimation and prediction (because the model is commonly misused.) No amount of additional data will improve the accuracy of a poor model. A high R², while indicative of a good matching between the observed data and model estimates, is a poor criterion for judging adequacy of the model to make good predictions of future events. Model evaluation also includes the problem of introducing secondary data and proxy variables into a model. Secondary data frequently enter, for example, the mass, energy and water budget equations because of difficulties in measuring the primary variables. Proxy variables arise because of a desire to collapse a vector of incomparable values, say, of water quality into a single number. Review of the above issues indicates that model evaluation is a multi-criterion problem, often imbedded in a larger framework where models are intended to meet multiple objectives. The mismatch of models and data has increasing legal and social consequences.