Membrane based technologies are highly reliable for water and wastewater treatment, including for removal of total oil and grease from produced water. However, performances of the pressure driven processes are highly restricted by membrane fouling and the application of traditional air bubbling system is limited by their low shear stress due to poor contacts with the membrane surface. This study develops and assesses a novel finned spacer, placed in between vertical panel, for membrane fouling control in submerged plate-and-frame module system for real produced water filtration. Results show that permeability of the panel is enhanced by 87% from 201 to 381 L/(m2 h bar). The spacer system can be operated in switching mode to accommodate two-sided panel aeration. This leads to panel permeability increment by 22% higher than the conventional vertical system. The mechanisms of finned spacer in encouraging the flow trajectory was proven by visual observation and flow simulation. The fins alter the air bubbles flow trajectory toward the membrane surface to effectively scour-off the foulant. Overall results demonstrate the efficacy of the developed spacer in projecting the air bubble trajectory toward the membrane surface and thus significantly enhances membrane panel productivity.
Air pollution is a widely discussed topic amongst the academic and industrial spheres as it can bring adverse effects to human health and economic loss. As humans spend most of their time at the office and at home, good indoor air quality with enriched oxygen concentration is particularly important. In this study, polysulfone (PSF) hollow fiber membranes fabricated by dry-jet wet phase inversion method were coated by a layer of polydimethylsiloxane (PDMS) or poly(ether block amide) (PEBAX) at different concentrations and used to evaluate their performance in gas separation for oxygen enrichment. The surface-coated membranes were characterized using SEM and EDX to determine the coating layer thickness and surface chemical properties, respectively. Results from the gas permeation study revealed that the PSF membrane coated with PDMS offered higher permeance and selectivity compared to the membrane coated with PEBAX. The best performing PDMS-coated membrane demonstrated oxygen and nitrogen gas permeance of 18.31 and 4.01 GPU, respectively with oxygen/nitrogen selectivity of 4.56. Meanwhile, the PEBAX-coated membrane only showed 12.23 and 3.11 GPU for oxygen and nitrogen gas, respectively with a selectivity of 3.94. It can be concluded the PDMS coating is more promising for PSF hollow fiber membrane compared to the PEBAX coating for the oxygen enrichment process.
Analysis of count event data such as mortality cases, were often modelled using Poisson regression model. Maximum likelihood procedures were used by using SAS software to estimate the model parameters of a Poisson regression model. However, the Negative Binomial distribution has been widely suggested as the alternative to the Poisson when there is proof of overdispersion phenomenon. We modelled the mortality cases as the dependent variable using Poisson and Negative Binomial regression and compare both of the models. The procedures were done in SAS by using the function PROC GENMOD. The results showed that the mortality data in Poisson regression exhibit large ratio values between deviance to degree of freedom which indicate model misspecification or overdispersion. This large ratio was found to be reduced in Negative Binomial regression. The Normal probability plot of Pearson residual confirmed that the Negative Binomial regression is a better model than Poisson regression in modelling the mortality data. The objective of this study is to compare the goodness of fit of Poisson regression model and Negative Binomial regression model in the application of air pollution epidemiologic time series study by using SAS software.
This study intended to investigate the level on airborne microbe in indoor air for new constructed building. It was divided by three different phase of building commissioning in Bandar Baru Bangi, Selangor. The first phase of the sampling was carried out after the building fully handed over from the main contractor to the building owner. Second phase of the sampling take place after the building is equipped with furniture. Phase three sampling is conducted after one month of building occupancy. Airborne microbes’ concentrations were determined by using a single stage impactor (Biosampler) as per requirement of National Institute of Occupational Safety and Health (NIOSH) method, NIOSH Manual Analytical Method MAM 0800. The total concentration of airborne bacteria and fungi were average to 641 and 38 CFU/m³ in the first phase, 133 and 117 CFU/m³ in the second phase, and 389 and 52 CFU/m³ in the third phase. These findings indicate that although a new constructed building should be having a significant background level of airborne microbe (total bacteria and total fungi). The building owner should be aware to their indoor air status to protect the occupant from the safety and health problem (risk) especially for ventilated building.
Stack ventilation in the hot and humid climate is inherently inefficient due to minimal air temperature differences between indoor and outdoor environment of a naturally ventilated building. Solar induced ventilation is a viable alternative in enhancing this stack ventilation. This paper aims to demonstrate investigations on the effective solar collector orientation and stack height for a solar induced ventilation prototype that utilizes roof solar collector and vertical stack. The orientation of the solar collector is significant as it determines the amount of solar radiation absorbed by the solar collector. Meanwhile, the height of the vertical stack influences the creation of the stack pressure in inducing air movement. Investigations were executed using a simulation modelling software called FloVENT. The validation of the simulation modelling against physical experiment indicated a good agreement between these two results. Analyses were executed on the air temperature increments inside the solar collector. A high increment of the air temperature resulted in the effective orientation. Meanwhile, the air temperature and mass flow rate of the various heights of the vertical stack were also analyzed. The findings concluded that the recommended orientation for the prototype’s solar collector is the west-facing orientation. It was also found that the higher the vertical stack, the lower the air temperature inside the stack would be, but with greater induced mass flow rate.
An accurate forecasting of tropospheric ozone (O3) concentration is benefi-
cial for strategic planning of air quality. In this study, various forecasting techniques are
used to forecast the daily maximum O3 concentration levels at a monitoring station
in the Klang Valley, Malaysia. The Box-Jenkins autoregressive integrated movingaverage
(ARIMA) approach and three types of neural network models, namely, backpropagation
neural network, Elman recurrent neural network and radial basis function
neural network are considered. The daily maximum data, spanning from 1 January
2011 to 7 August 2011, was obtained from the Department of Environment, Malaysia.
The performance of the four methods in forecasting future values of ozone concentrations
is evaluated based on three criteria, which are root mean square error (RMSE),
mean absolute error (MAE) and mean absolute percentage error (MAPE). The findings
show that the Box-Jenkins approach outperformed the artificial neural network
methods.
The cultivation of indoor plants in indoor environment has become a topic of interest among researchers worldwide for its
potential to improve indoor air quality (IAQ). However, the adaptations of environmental factor of each plant need to be investigated
to correspond with the native environment. The study investigate the capability of plants selected to live indoor. Before experiment was
conducted, all plants selected were assimilated with indoor environment for two months. Photosynthesis proses in this experiment will
be a guidance to determine the comparative for every plant. The portable photosynthesis system equipment (LI-COR 6400) was used to
determine the level of photosynthesis rate for each of plants. Accordingly, among of all plants tested, Spider Plant showed less effective
to be grown with indoor environment by the rate of photosynthesis value up to -0.15. Moreover, light compensation point (LCP) of
Spider Plant also indicated the light intensity consumption was 2960 lux which is extremely higher than 300 lux. As a conclusion, only
six plants in this study which are Anthurium, Dumb Cane, Golden Pothos, Kadaka Fern, Prayer Plant, and Syngonium are able to
survive with indoor environment. In the next stage of study, this six plants may give good results to enhance the IAQ.
The indoor and outdoor radon concentrations in Cameron Highlands (Peninsular Malaysia) and Ranau (East Malaysia) were measured. The measurements were carried out using passive method based on CR-39 solid state nuclear track detector (SSNTD) (for indoor measurements in Cameron Highlands) and active method using continuous radon/thoron progeny monitor (for indoor and outdoor measurements in Ranau and outdoor measurements in Cameron Highlands). The mean indoor radon concentrations in Cameron Highlands and Ranau were 50 Bqm-3 and 1.5 Bqm-3, respectively. The mean indoor radon concentration in Cameron Highlands was slightly higher compare to the world average. The maximum value recorded was 97 Bqm-3 which is almost similar to WHO reference level. The mean outdoor radon concentrations in Cameron Highlands and Ranau were 7.4 Bqm-3and 1.7 Bqm-3, respectively. The outdoor concentrations were low and comparable to world outdoor average.
Cerebral air embolism is potentially a catastrophic event that occurs as a consequence of air entry into the vasculature. We report a mechanically ventilated 72-year-old woman who underwent multiple procedures during intensive care stay with few possible sources of emboli postulated. We also discuss regarding the preventive measures to minimise the risk of air embolism.
This study aimed to measure the equilibrium equivalent radon (EECRn) concentration in an old building (Building-1) and a new building (Building-2) with mechanical ventilation and a natural ventilation system, respectively. Both buildings were located at the campus of University Kebangsaan Malaysia. The concentration of indoor radon was measured at 25 sampling stations using a radon detector model DOSEman PRO. The sampling was conducted for 8 h to represent daily working hours. A correlation of the radon concentration was made with the annual inhalation dose of the occupants at the indoor stations. The equilibrium factor and the annual effective dose on the lung cancer risks of each occupant were calculated at each sampling station. The average equilibrium equivalent radon measured in Building-1 and Building-2 was 2.33 ± 0.99 and 3.17 ± 1.74 Bqm-3, respectively. The equilibrium factor for Building 1 ranged from 0.1053 to 0.2273, and it ranged from 0.1031 to 0.16 for Building 2. The average annual inhalation doses recorded at Building-1 and Building-2 were 0.014 ± 0.005 mSv y-1and 0.020 ± 0.013 mSv y-1, respectively. The annual effective dose for Building-1 was 0.034 ± 0.012 mSv y-1, and it was 0.048 ± 0.031 mSv y-1for Building-2. The values of equilibrium equivalent radon concentration for both buildings were below the standard recommended by the International Commission on Radiological Protection (ICRP). However, people may have different radon tolerance levels. Therefore, the inhalation of the radon concentration can pose a deleterious health effect for people in an indoor environment.
To identify the isopod parasite, which has been recorded from Miri, East Malaysian marine fishes. During the present study, four cymothoid isopods are reported three genera, including Cymothoa eremita, Lobothorax typus, Nerocila longispina and Nerocila loveni. Nerocila longispina and N. loveni are also previously reported from Malaysia and two additional cymothoids C. eremita and L. typus are reported for the first record of Miri coast, East Malaysia. New hosts were identified for N. loveni on Chirocentrus dorab for the first time in the world fauna. The Parasitological indexes were calculated. The site of attachment of the parasites on their hosts was also observed. These parasites can cause the damage in gill, eye and internal organ including swim bladder. Marine fish parasitology is a rapidly developing field of aquatic science.
This review discusses how climate undergo changes and the effect of climate change on air quality as well as public health. It also covers the inter relationship between climate and air quality. The air quality discussed here are in relation to the 5 criteria pollutants; ozone (O3), carbon dioxide (CO2), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter (PM). Urban air pollution is the main concern due to higher anthropogenic activities in urban areas. The implications on health are also discussed. Mitigating measures are presented with the final conclusion.
Matched MeSH terms: Air Pollutants/analysis*; Air Pollution/adverse effects*
Exposure to secondhand smoke (SHS) is a major threat to public health. Asian countries having the highest smoking prevalence are seriously affected by SHS. The objective of the study was to measure SHS levels in hospitality venues in seven Asian countries and to compare the SHS exposure to the levels in Western countries. The study was carried out in four types of related hospitality venues (restaurant, café, bar/club and entertainment) in China, India, Japan, Korea, Malaysia, Pakistan and Sri Lanka. Real-time measurement of particulate matter of <2.5microm aerodynamic diameter (PM(2.5)) was made during business hour using a handheld laser operated monitor. A total of 168 venues were measured in seven countries. The average indoor PM(2.5) level was 137microg/m(3), ranging from 46microg/m(3) in Malaysia to 207microg/m(3) in India. Bar/club had the highest PM(2.5) level of 191microg/m(3) and restaurants had the lowest PM(2.5) level of 92microg/m(3). The average indoor PM(2.5) level in smoking venues was 156micro/m(3), which was 3.6 times higher than non-smoking venues (43microg/m(3)). Indoor PM(2.5) levels were significantly associated with country, type of venue, smoking density and air exchange rate (p<0.05). In the seven Asian countries, PM(2.5) levels were high due to SHS in public places. The current levels are comparable to the levels in Western countries before the adoption of smoke-free policy. Since Asian country has high prevalence of SHS in public places, there is an urgent need for comprehensive smoke-free regulation in Asian countries.
Matched MeSH terms: Air Pollution, Indoor/analysis; Air Pollution, Indoor/statistics & numerical data*
Results from the present study in Kuala Terengganu, Malaysia indicated a significant spatial variation but generally the total suspended particulate concentrations (mean = 17.2-148 microg/m(3)) recorded were below the recommended Malaysia guideline for total suspended particulate (mean of 24-h measurement = 260 microg/m(3)). Some of the elemental composition of particulate aerosol is clearly affected by non crustal sources, e.g. vehicular emission sources. Based on correlation and enrichment analyses, the elements could be grouped into two i.e. Pb, Cd and Zn group with sources from vehicular emission (r > 0.6; enrichment factor > 10) and Al, Fe, Mn and Cr group that appears to be of crustal origin (r > 0.6; enrichment factor < 10). It can also be concluded that the mean levels of Pb (1 ng/m(3)), Cd (0.02 ng/m(3)) and Zn (2 ng/m(3)) in the study area are generally lower than other urban areas in Malaysia (Pb < 181 ng/m(3); Cd < 6 ng/m(3); Zn < 192 ng/m(3)).
Matched MeSH terms: Air Pollutants/analysis; Air Pollutants/chemistry*
During 2006 the CDM market in Malaysia became established and by December 2007 a total of 20 Malaysian projects had registered with the CDM Executive Board. The Kyoto Protocol defines the Annex 1 countries, as countries that are obliged to reduce their greenhouse gas (GHG) emissions and the clean development mechanism (CDM) allows Annex 1 countries to develop projects, which contribute to emission reduction, in non-Annex 1 (developing) countries. Currently, two projects have been corrected due to request for review and there is one project for which review is requested. Two projects have been rejected by the Executive Board. The broad knowledge of CDM in Malaysia and the number of successful projects are partly due to the well-functioning CDM institutional framework in Malaysia. As an illustration this article focuses on a Malaysian-Danish project and describes the implementation of CDM in Malaysia and refers to this specific project. The project was registered with the CDM Executive Board in May 2007 and is a methane avoidance project in which methane is captured from a landfill and used to generate electricity.
Matched MeSH terms: Air Pollution/analysis; Air Pollution/prevention & control*
The 'seasonal haze' problem is one which afflicts large parts of Southeast Asia in years of drought. The major cause is forest, bush and field fires in the states of Kalimantan and Sumatra in Indonesia, and to a lesser extent in Sabah, Sarawak, and other parts of Malaysia. Almost all of these fires now seem preventable, since they are intentionally set to clear land for cultivation. Theoretically, the government authorities at central, provincial and local levels in these countries should be responsible for controlling activities in their territory. In practice, however, air pollution control through regulatory policies and practices is extraordinarily difficult to implement and maintain in a situation of this kind in developing countries, especially at a time of crippling economic setbacks. Moreover, the establishment of legal liability, through an international tribunal or otherwise, hardly seems a politically feasible course of action for the government of an affluent 'victim state' such as Singapore. Faith in the usual solutions--science, regulation, law and diplomacy--is weakened by one's sense of current realities. The purpose of this paper is to review the issues and suggested responses, the cost implications of each, the responsibilities as well as entitlements that might apply to the various stakeholders, and the special role of Singapore as an affluent 'victim state'. We also discuss the incentive mechanisms that would be needed to manage forest fires.
Matched MeSH terms: Air Pollution/legislation & jurisprudence*; Air Pollution/prevention & control
Tanjung Karang, Selangor, is widely known for its paddy cultivation activity and hosts the third largest paddy field in Malaysia. Pesticides contamination in agriculture fields has become an unavoidable problem, as pesticides are used to increase paddy productivity and reduce plant disease. Human exposure to agrichemicals is common and could results in both acute and chronic health effects, such as acute and chronic neurotoxicity. This study aims to determine the concentrations of commonly used pesticides (azoxystrobin, buprofezin, chlorantraniliprole, difenoconazole, fipronil, imidacloprid, isoprothiolane, pretilachlor, propiconazole, pymetrozine, tebuconazole, tricyclazole, and trifloxystrobin) in personal air samples and their associated health risks among paddy farmers. Eighty-three farmers from Tangjung Karang, Selangor were involved in this study. A solid sorbent tube was attached to the farmer's breathing zone with a clip, and an air pump was fastened to the belt to collect personal air samples. Pesticides collected in the XAD-2 resin were extracted with acetone, centrifuged, concentrated via nitrogen blowdown and reconstituted with 1mL of 3:1 ultrapure water/HPLC-grade methanol solution. The extract was analyzed using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The target compounds were detected with a maximum concentration reaching up to 462.5ngm-3 (fipronil). The hazard quotient (HQ) was less than 1 and the hazard index (HI) value was 3.86×10-3, indicating that the risk of pesticides related diseases was not significant. The lifetime cancer risk (LCR) for pymetrozine was at an acceptable level (LCR<10-6) with 4.10×10-8. The results reported in this study can be beneficial in terms of risk management within the agricultural community.
Matched MeSH terms: Air Pollutants/adverse effects; Air Pollutants/analysis*
Double perovskite-type catalysts including La2CoMnO6 and La2CuMnO6 are first evaluated for the effectiveness in removing volatile organic compounds (VOCs), and single perovskites (LaCoO3, LaMnO3, and LaCuO3) are also tested for comparison. All perovskites are tested with the gas hourly space velocity (GHSV) of 30,000hr-1, and the temperature range of 100-600°C for C7H8 removal. Experimental results indicate that double perovskites have better activity if compared with single perovskites. Especially, toluene (C7H8) can be completely oxidized to CO2 at 300°C as La2CoMnO6 is applied. Characterization of catalysts indicates that double perovskites own unique surface properties and are of higher amounts of lattice oxygen, leading to higher activity. Additionally, apparent activation energy of 68kJ/mol is calculated using Mars-van Krevelen model for C7H8 oxidation with La2CoMnO6 as catalyst. For durability test, both La2CoMnO6 and La2CuMnO6 maintain high C7H8 removal efficiencies of 100% and 98%, respectively, at 300°C and 30,000hr-1, and they also show good resistance to CO2 (5%) and H2O(g) (5%) of the gas streams tested. For various VOCs including isopropyl alcohol (C3H8O), ethanal (C2H4O), and ethylene (C2H4) tested, as high as 100% efficiency could be achieved with double perovskite-type catalysts operated at 300-350°C, indicating that double perovskites are promising catalysts for VOCs removal.
Matched MeSH terms: Air Pollutants/analysis; Air Pollutants/chemistry*
Indoor air quality assessment in residential areas of Al-Hofuf city/Eastern region of Saudi Arabia is investigated through a multi-week multiple sites sampling survey. Critical air pollution indicators, including nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), carbon dioxide (CO2) and total volatile organic compounds (TVOC) as well as temperatures were measured and analyzed during the study period from January to May 2014. Three site-types - roadside, urban and rural - were selected and within each site type, six locations were selected to study the varying indoor/outdoor air quality. The results indicated that NO2 and CO concentrations increased at the starting hours of the day. SO2 concentrations were relatively low and constant. In addition, a strong association between outdoor and indoor air quality was found. Measurements showed that indoor/outdoor ratio for TVOC ranged from 0.8 to 0.99. For CO2, NO2 and SO2, this was 0.92-1.15, 0.5-0.7 and 0.52-0.9, respectively. Finally, the effects of activated carbon (AC) were investigated to assess the extent of the improvement in the indoor air quality. The analysis of data obtained indicated that using locally prepared AC from date stones was an effective way to reduce the indoor air pollution with an overall efficiency of 85.5, while the use of industrial granular AC reduced the air pollutants with an efficiency of less than 0.6. In addition, AC was exposed to an exhaust gas flow to evaluate its elimination potential for high concentrated pollutants. The obtained results demonstrated that AC was also functioning as an efficient absorbent with an overall removal efficiency of 77.8%, even when it was exposed to high concentrations.
Matched MeSH terms: Air Pollutants; Air Pollution; Air Pollution, Indoor