The influenced of PAC, zeolite, and Moringa oleifera as biofouling reducer (BFR) on hybrid membrane bioreactor of palm oil mill effluent (POME)

The main objective of this work was to determine the effectiveness of various biofouling reducers (BFRs) to operational condition in hybrid membrane bioreactor (MBR) of palm oil mill effluent (POME). A series of tests involving three bench scale (100 L) hybrid MBR were operated at sludge retention times (SRTs) of 30 days with biofouling reducer (BFR). Three different biofouling reducers (BFRs) were powdered actived carbon (PAC), zeolite (Ze), and Moringa oleifera (Mo) with doses of 4, 8 and 12 g L⁻¹ respectively were used. Short-term filtration trials and critical flux tests were conducted. Results showed that, all BFRs successfully removed soluble microbial products (SMP), for PAC, Ze, and Mo at 58%, 42%, and 48%, respectively. At their optimum dosages, PAC provided above 70% reductions and 85% in fouling rates during the short-term filtration and critical flux tests.     

Aerobic granular sludge formation for high strength agro-based wastewater treatment

The present study investigates the formation of aerobic granular sludge in sequencing batch reactor (SBR) fed with palm oil mill effluent (POME). Stable granules were observed in the reactor with diameters between 2.0 and 4.0 mm at a chemical oxygen demand (COD) loading rate of 2.5 kg COD m⁻³ d⁻¹. The biomass concentration was 7600 mg L⁻¹ while the sludge volume index (SVI) was 31.3 mL g SS⁻¹ indicating good biomass accumulation in the reactor and good settling properties of granular sludge, respectively. COD and ammonia removals were achieved at a maximum of 91.1% and 97.6%, respectively while color removal averaged at only 38%. This study provides insights on the development and the capabilities of aerobic granular sludge in POME treatment.     

Complex Network Theory Applied to the Growth of Kuala Lumpur’s Public Urban Rail Transit Network

Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL) based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD) of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality’s closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network’s growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks.     

Arsenic Removal Technologies for Drinking Water Treatment

Arsenic contamination as a consequence of human activities such as mining and pesticide use is affecting the water resource quality worldwide. Because of the high risk of arsenic exposure, specific water treatment processes are required to meet the anticipated more severe water quality standards. Better understanding of presently available processes is necessary to develop economic, efficient and effective methods for arsenic removal. Arsenic could either be coagulated, adsorbed using a wide range of materials both mineral and organic or could be directly rejected by membrane processes such as reverse osmosis and nanofiltration. The recent development of submerged hybrid membrane systems, such as membrane bioreactor in wastewater treatment, offers alternative technologies for arsenic treatment. The membrane in hybrid systems allows a better phase separation between the particles binding the arsenic and the treated water. The effect of pH and contact time, and the existence of other ionic compounds must be taken into account when designing the system for optimum arsenic rejection. Further research on both hydraulic and removal performances of hybrid adsorption/membrane technology is still required to assess the full potential of this technology for arsenic removal.     

Carbon balance impacts of land use changes related to the life cycle of Malaysian palm oil-derived biodiesel

Purpose

The area of oil palm plantations in Malaysia is expanding by approximately 0.14 million hectare per year, and with the increasing demand for palm oil worldwide, there is no sign of the expansions slowing down. This study aims to identify the greenhouse gas emissions associated with land conversion to oil palm, in a life cycle perspective.

Methods

LCA methodology is applied to existing land use change data. The assessment includes the issue of temporary carbon storage in the plantations. Through quantification of emissions from state forest reserve and rubber plantation conversions, the average Malaysian palm oil-related land use changes are calculated.

Results and discussion

The results show that there are high emissions associated with the conversion of Malaysian state forest reserve to oil palm, whereas the conversion of rubber leaves a less significant carbon debt when indirect land use change is not included. Looking at the average Malaysian land use changes associated with oil palm shows that land use change emissions are responsible for approximately half of the total conventional biodiesel production emissions. The sensitivity analysis shows that the results could be significantly influenced by data variations in indirect land use changes, peat soils, and state forest reserve carbon stock.

Conclusions

The relatively extensive conversions of the state forest reserve must be reversed and preferably with a shift toward conversion of degraded land in order for the average Malaysian land use changes to have less impact on the production life cycle of palm oil and biodiesel.     

Selenium status of the Australian population: effect of age, gender and cardiovascular disease

Selenium (Se) is an essential trace element and the clinical consequences of Se deficiency have been well-documented. Se is primarily obtained through the diet and recent studies have suggested that the level of Se in Australian foods is declining. Currently there is limited data on the Se status of the Australian population so the aim of this study was to determine the plasma concentration of Se and glutathione peroxidase (GSH-Px), a well-established biomarker of Se status. Furthermore, the effect of gender, age and presence of cardiovascular disease (CVD) was also examined. Blood plasma samples from healthy subjects (140 samples, mean age = 54 years; range, 20-86 years) and CVD patients (112 samples, mean age = 67 years; range, 40-87 years) were analysed for Se concentration and GSH-Px activity. The results revealed that the healthy Australian cohort had a mean plasma Se level of 100.2 +/- 1.3 microg Se/L and a mean GSH-Px activity of 108.8 +/- 1.7 U/L. Although the mean value for plasma Se reached the level required for optimal GSH-Px activity (i.e. 100 microg Se/L), 47% of the healthy individuals tested fell below this level. Further evaluation revealed that certain age groups were more at risk of a lowered Se status, in particular, the oldest age group of over 81 years (females = 97.6 +/- 6.1 microg Se/L; males = 89.4 +/- 3.8 microg Se/L). The difference in Se status between males and females was not found to be significant. The presence of CVD did not appear to influence Se status, with the exception of the over 81 age group, which showed a trend for a further decline in Se status with disease (plasma Se, 93.5 +/- 3.6 microg Se/L for healthy versus 88.2 +/- 5.3 microg Se/L for CVD; plasma GSH-Px, 98.3 +/- 3.9 U/L for healthy versus 87.0 +/- 6.5 U/L for CVD). These findings emphasise the importance of an adequate dietary intake of Se for the maintenance of a healthy ageing population, especially in terms of cardiovascular health.     

Stepped water activity control for efficient enzymatic interesterification

The benefits of controlling water activity, a _w, during enzymatically catalysed synthesis reactions, such as reverse-hydrolytic reactions promoted by lipases, are now well recognized. Numerous techniques for controlling a _w in the laboratory and their implementation in continuous reactors have been discussed in the published literature. However, in enzymatic interesterification reactions, such as acidolysis and transesterification, it is not appropriate merely to maintain the a _w of the reaction system at one value since the two stages of the reaction, namely the cleavage of the original acyl bond and the formation of a new one, are best carried out at different levels of water activity – the former at a high a _w and the latter at a lower one. The use of a continuous packed-bed hollow-fibre reactor has been described in this article for carrying out solvent-free acidolysis of ethyl laurate with octanoic acid with in situ a _w control, using air that has been pre-equilibrated with saturated salt solutions to the desired a _w. At a single optimum (a _w = 0.54), the highest steady-state conversion to ethyl octanoate was 32%. However, it is possible to obtain a steady-state conversion of 46% by operating the reactor with a step change in the water activity, from an initial value of unity to 0.23. Received: 10 February 1998 / Received revision: 2 June 1998 / Accepted: 7 June 1998     

Nutrient improvement using statistical optimization for growth of Schizophyllum commune, and its antifungal activity against wood degrading fungi of rubberwood

Two statistical tools, Plackett-Burman design (PBD) and Box-Behnken design (BBD) were used to optimize the mycelia growth of Schizophyllum commune with different nutrient components. Results showed that 32.92 g/L of biomass were produced using a medium consisting of 18.74 g/L yeast extract, 38.65 g/L glucose, and 0.59 g/L MgSO(4).7H(2)O. The experimental data fitted well with the model predicted values within 0.09 to 0.77% error. The biomass was also tested for antifungal activity against wood degrading fungi of rubberwood. Results showed that the minimum inhibitory concentration (MIC) values for antifungal activity range from 0.16 to 5.00 μg/μL. The GC-MS analysis indicated that this fungus produced several compounds, such as glycerin, 2(3H)-furanone, 5-heptyldihydro-, 4H-pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl-, and triacetin.