The influence of physical and chemical parameters on the abundance and diversity of chironomids was studied in six rivers with moderate to highly polluted water in the Juru River Basin. The rivers: Ceruk Tok Kun (CTKR) as reference site, and polluted rivers of Pasir (PR), Juru (JR), Permatang Rawa (PRR), Ara (AR) and Kilang Ubi (KUR) were sampled over a period of five months (November 2007-March 2008). Nine chirnomid species: Chironimus kiiensis, C. javanus, Polypedilum trigonus, Microchironomus sp., Dicrotendipes sp., Tanytarsus formosanus, Clinotanypus sp., Tanypus punctipennis and Fittkauimyia sp. were identified. Assessment of their relationships with several environmental parameters was performed using the canonical correspondence analysis (CCA). Tanytarsus formosanus was the most dominant in the relatively clean CTKR and moderately polluted JR with mean densities of 19.66 and 25.32 m(-2), respectively while C. kiiensis was abundant in more polluted rivers. Tanytarsus formosanus, Dicrotendipes sp. and Microchironomus sp. were grouped under moderate to high water temperature, total organic matter (TOM), total suspended solids (TSS), velocity, pH, phosphates and sulphates. However, Tanypus punctipennis, Fittkauimyia sp., and Clinotanypus sp. were associated with high contents of river sediment such as TOM, Zn and Mn and water ammonium-N and nitrate-N and they were associated with higher dissolved oxygen (DO) content in the water. Chironomus kiiensis, C. javanus and P. trigonus showed positive relationships with TOM, ammonium-N and nitrate-N as well as trace metals of Zn, Cu and Mn. These three species could be considered as tolerant species since they have the ability to survive in extreme environmental conditions with low DO and high concentrations of pollutants. Based on the water parameter scores in all rivers, the highest diversity of chironomid larvae was reported in CTKR. With higher concentrations of organic and/or inorganic pollutants as reported in PPR, KUR and AR, the chironomid larval diversity decreased, and the abundance of tolerant species, mainly Chironomus spp., increased.
Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range for lead adsorption was 4-5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed. The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60-90 min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo second-order fitted well with correlation coefficients greater than 0.99.
Available composting models do not describe accurately the dynamics of composting processes. Difficulty in modeling composting processes is attributed mainly to the unpredicted change in process rate caused by change in activation energy value (E). This article presented the results of an attempt made to utilize patterns of change in carbon, nitrogen and temperature profiles to model sewage sludge composting process as a multi-stage process. Results of controlled sewage sludge composting experiments were used in the study. All the experiments were carried out as batch experiments in a 300-liter Horizontal Drum Bioreactor (HDB). Analysis of the profiles of carbon, nitrogen and temperature has indicated that there were clear patterns that could be used to develop simple models of the process, the initial C/N ratio was between 7-8 and the final C/N ratio of the compost in most experiments were found to be around 15.0, indicating the compost was fully matured and could be used safely for agricultural purpose. Electrical conductivity of composting material decreased from 1.83 to 1.67 dS/m, after a period, it increased gradually from 2.01 to 2.23 dS/m and remained at around 2.33 dS/m till the end of composting. It is found that change in the concentration of total carbon can reasonably be described by three constant process rate coefficients (k1, k2, k3). It is found that the process starts with a certain process rate coefficient (k1) and continues until peak temperature is reached, then it reaches lower process (k2) in the declining phase of the thermophilic stage, and finally it proceeds with a faster process rate (k3) when maturation is reached. Change in the concentration of total nitrogen has shown to have the same patterns of change as carbon.
The capabilities of chitosan and chitosan-EGDE (ethylene glycol diglycidyl ether) beads for removing Acid Red 37 (AR 37) and Acid Blue 25 (AB 25) from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function of pH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan for both acid dyes were comparatively higher than those of chitosan-EGDE. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3+ on chitosan. Langmuir isotherm model showed the best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.
The capability of carbon nanotubes (CNTs) to adsorb lead (Pb) in aqueous solution was investigated. Batch mode adsorption experiment was conducted to determine the effects of pH, agitation speed, CNTs dosage and contact time. The removal of Pb(II) reached maximum value 85% or 83% at pH 5 or 40 mg/L of CNTs, respectively. Higher correlation coefficients from Langmuir isotherm model indicates the strong adsorptions of Pb(II) on the surface of CNTs (adsorption capacity Xm = 102.04 mg/g). The results indicates that the highest percentage removal of Pb (96.03%) can be achieved at pH 5, 40 mg/L of CNTs, contact time 80 min, and agitation speed 50 r/min.
Oxidation of sulfide in aqueous solution by hydrogen peroxide was investigated in the presence of hydrated ferric oxide catalyst. The ferric oxide catalyst was synthesized by sol gel technique from ferric chloride and ammonia. The synthesized catalyst was characterized by Fourier transform infrared spectroscopy, X-Ray diffraction analysis, scanning electrom microscope and energy dispersive X-ray analysis. The catalyst was quite effective in oxidizing the sulfide by hydrogen peroxide. The effects of sulfide concentration, catalyst loading, H2O2 dosing and temperature on the kinetics of sulfide oxidation were investigated. Kinetic equations and activation energies for the catalytic oxidation reaction were calculated based on the experimental results.
Palm oil industry is the most important agro-industry in Malaysia, but its by-product-palm oil mill effluent (POME), posed a great threat to water environment. In the past decades, several treatment and disposal methods have been proposed and investigated to solve this problem. A two-stage pilot-scale plant was designed and constructed for POME treatment. Anaerobic digestion and aerobic biodegradation constituted the first biological stage, while ultrafiltration (UF) and reverse osmosis (RO) membrane units were combined as the second membrane separation stage. In the anaerobic expanded granular sludge bed (EGSB) reactor, about 43% organic matter in POME was converted into biogas, and COD reduction efficiency reached 93% and 22% in EGSB and the following aerobic reactor, respectively. With the treatment in the first biological stage, suspended solids and oil also decreased to a low degree. All these alleviated the membrane fouling and prolonged the membrane life. In the membrane process unit, almost all the suspended solids were captured by UF membranes, while RO membrane excluded most of the dissolved solids or inorganic salts from RO permeate. After the whole treatment processes, organic matter in POME expressed by BOD and COD was removed almost thoroughly. Suspended solids and color were not detectable in RO permeate any more, and mineral elements only existed in trace amount (except for K and Na). The high-quality effluent was crystal clear and could be used as the boiler feed water.
The potential of kenaf (Hibiscus cannabinus L.) for phytoremediation of lead (Pb) on sand tailings was investigated. A pot experiment employing factorial design with two main effects of fertilizer and lead was conducted in a nursery using sand tailings from an ex-tin mine as the growing medium. Results showed that Pb was found in the root, stem, and seed capsule of kenaf but not in the leaf. Application of organic fertilizer promoted greater biomass yield as well as higher accumulation capacity of Pb. In Pb-spiked treatments, roots accumulated more than 85% of total plant Pb which implies that kenaf root can be an important sink for bioavailable Pb. Scanning transmission electron microscope (STEM) X-ray microanalysis confirmed that electron-dense deposits located along cell walls of kenaf roots were Pb precipitates. The ability of kenaf to tolerate Pb and avoid phytotoxicity could be attributed to the immobilization of Pb in the roots and hence the restriction of upward movement (translocation factor < 1). With the application of fertilizer, kenaf was also found to have higher biomass and subsequently higher bioaccumulation capacity, indicating its suitability for phytoremediation of Pb-contaminated site.
The efficiency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The effects of physicochemical parameters on biosorption capacities such as stirring speed, pH, biosorbent dose, initial concentrations of copper, and ionic strength were studied. The biosorption capacities of NHBL increased with increase in pH, stirring speed and copper concentration but decreased with increase in biosorbent dose and ionic strength. The isotherm study indicated that NHBL fitted well with Langmuir model compared to Freundlich and Dubinin-Radushkevich models. The maximum biosorption capacity determined from Langmuir isotherm was 14.97 mg/g at 27 degrees C. The kinetic study revealed that pseudosecond order model fitted well the kinetic data, while Boyd kinetic model indicated that film diffusion was the main rate determining step in biosorption process. Based on surface area analysis, NHBL has low surface area and categorized as macroporous. Fourier transform infrared (FT-IR) analyses revealed that hydroxyl, carboxyl, and amino are the main functional groups involved in the binding of copper ions. Complexation was one of the main mechanisms for the removal of copper ions as indicated by FT-IR spectra. Ion exchange was another possible mechanism since the ratio of adsorbed cations (Cu2+ and H+) to the released cations (Na+, Ca2+, and Mg2+) from NHBL was almost unity. Copper ions bound on NHBL were able to be desorbed at > 99% using 0.05 mol/L HCl, 0.01 mol/L HNO3, and 0.01 mol/L EDTA solutions.
The adsorption capacity of activated carbon produced from oil palm empty fruit bunches through removal of 2,4-dichlorophenol from aqueous solution was carried out in the laboratory. The activated carbon was produced by thermal activation of activation time with 30 min at 800 degrees C. The adsorption process conditions were determined with the statistical optimization followed by central composite design. A developed polynomial model for operating conditions of adsorption process indicated that the optimum conditions for maximum adsorption of phenolic compound were: agitation rate of 100 r/min, contact time of 8 h, initial adsorbate concentration of 250 mg/L and pH 4. Adsorption isotherms were conducted to evaluate biosorption process. Langmuir isotherm was more favorable (R2 = 0.93) for removal of 2,4-dichlorophenol by the activated carbon rather than Freundlich isotherm (R2 = 0.88).
Activated carbons derived from oil palm empty fruit bunches (EFB) were investigated to find the suitability of its application for removal of phenol in aqueous solution through adsorption process. Two types of activation namely; thermal activation at 300, 500 and 800 degrees C and physical activation at 150 degrees C (boiling treatment) were used for the production of the activated carbons. A control (untreated EFB) was used to compare the adsorption capacity of the activated carbons produced from these processes. The results indicated that the activated carbon derived at the temperature of 800 degrees C showed maximum absorption capacity in the aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon at 800 degrees C. It was observed that the adsorption capacity was higher at lower values of pH (2-3) and higher value of initial concentration of phenol (200-300 mg/L). The equilibrium data fitted better with the Freundlich adsorption isotherm compared to the Langmuir. Kinetic studies of phenol adsorption onto activated carbons were also studied to evaluate the adsorption rate. The estimated cost for production of activated carbon from EFB was shown in lower price (USD 0.50/kg of activated carbon) compared the activated carbon from other sources and processes.
The optimization of process parameters for the bioconversion of activated sludge by Penicillium corylophilum was investigated using response surface methodology (RSM). The three parameters namely temperature of 33 degrees C, agitation of 150 r/min, and pH of 5 were chosen as center point from the previous study of fungal treatment. The experimental data on chemical oxygen demand (COD) removal (%) were fitted into a quadratic polynomial model using multiple regression analysis. The optimum process conditions were determined by analyzing response surface three-dimensional surface plot and contour plot and by solving the regression model equation with Design Expert software. Box-Behnken design technique under RSM was used to optimize their interactions, which showed that an incubation temperature of 32.5 degrees C, agitation of 105 r/min, and pH of 5.5 were the best conditions. Under these conditions, the maximum predicted yield of COD removal was 98.43%. These optimum conditions were used to evaluate the trail experiment, and the maximum yield of COD removal was recorded as 98.5%.
The study was attempted to produce activated carbons from palm oil mill effluent (POME) sludge. The adsorption capacity of the activated carbons produced was evaluated in aqueous solution of phenol. Two types of activation were followed, namely, thermal activation at 300, 500 and 800 degrees C, and physical activation at 15 degrees C (boiling treatment). A control (raw POME sludge) was used to compare the adsorption capacity of the activated carbons produced. The results indicated that the activation temperature of 800 degrees C showed maximum absorption capacity by the activated carbon (POME 800) in aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon of POME 800. It was observed that the adsorption capacity was higher at lower values of pH (2-3) and higher value of initial concentration of phenol (200-300 mg/L). The equilibrium data were fitted by the Langmuir and Freundlich adsorption isotherms. The adsorption of phenol onto the activated carbon POME 800 was studied in terms of pseudo- first and second order kinetics to predict the rate constant and equilibrium capacity with the effect of initial phenol concentrations. The rate of adsorption was found to be better correlation for the pseudo-second order kinetics compared to the first order kinetics.
PM10 airborne particles and soot deposit collected after a fire incident at a chemical store were analyzed in order to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs). The samples were extracted with 1:1 hexane-dichloromethane by ultrasonic agitation. The extracts were then subjected to gas chromatography-mass spectrometric (GC-MS) analysis. The total PAHs concentrations in airborne particles and soot deposit were found to be 3.27 +/- 1.55 ng/m3 and 12.81 +/- 24.37 microg/g, respectively. Based on the molecular distributions of PAHs and the interpretation of their diagnostic ratios such as PHEN/(PHEN + ANTH), FLT/(FLT + PYR) and BeP/(BeP + BaP), PAHs in both airborne particles and soot deposit may be inferred to be from the same source. The difference in the value of IP/(IP + BgP) for these samples indicated that benzo[g, h, i] perylene and coronene tend to be attached to finer particles and reside in the air for longer periods. Comparison between the molecular distributions of PAHs and their diagnostic ratios observed in the current study with those reported for urban atmospheric and roadside soil particles revealed that they are of different sources.
Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study, contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions (CO2, CO, and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)) from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX, which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency (MCE) changed in response to changes in the sample moisture content. Therefore, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass.
The aim of this study was to determine the source apportionment of dust fall around Lake Chini, Malaysia. Samples were collected monthly between December 2012 and March 2013 at seven sampling stations located around Lake Chini. The samples were filtered to separate the dissolved and undissolved solids. The ionic compositions (NO3-, SO4(2-), Cl- and NH4+) were determined using ion chromatography (IC) while major elements (K, Na, Ca and Mg) and trace metals (Zn, Fe, Al, Ni, Mn, Cr, Pb and Cd) were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the average concentration of total solids around Lake Chini was 93.49±16.16 mg/(m2·day). SO4(2-), Na and Zn dominated the dissolved portion of the dust fall. The enrichment factors (EF) revealed that the source of the trace metals and major elements in the rain water was anthropogenic, except for Fe. Hierarchical agglomerative cluster analysis (HACA) classified the seven monitoring stations and 16 variables into five groups and three groups respectively. A coupled receptor model, principal component analysis multiple linear regression (PCA-MLR), revealed that the sources of dust fall in Lake Chini were dominated by agricultural and biomass burning (42%), followed by the earth's crust (28%), sea spray (16%) and a mixture of soil dust and vehicle emissions (14%).
The direct determination of toxic metal ions, in environmental samples, is difficult because of the latter's presence in trace concentration in association with complex matrices, thereby leading to insufficient sensitivity and selectivity of the methods used. The simultaneous removal of the matrix and preconcentration of the metal ions, through solid phase extraction, serves as the promising solution. The mechanism involved in solid phase extraction (SPE) depends on the nature of the sorbent and analyte. Thus, SPE is carried out by means of adsorption, ion exchange, chelation, ion pair formation, and so forth. As polymeric supports, the commercially available Amberlite resins have been found very promising for designing chelating matrices due to its good physical and chemical properties such as porosity, high surface area, durability and purity. This review presents an overview of the various works done on the modification of Amberlite XAD resins with the objective of making it an efficient sorbent. The methods of modifications which are generally based on simple impregnation, sorption as chelates and chemical bonding have been discussed. The reported results, including the preconcentration limit, the detection limit, sorption capacity, preconcentration factors etc., have been reproduced.
In this present study, we reported broccoli (Brassica oleracea L.) as a potential candidate for the synthesis of gold and silver nanoparticles (NPs) in green chemistry method. The synthesized metal nanoparticles are evaluated their antimicrobial efficacy against different human pathogenic organisms. The physico-chemical properties of gold nanoparticles were analyzed using different analytical techniques such as a UV-Vis spectrophotometer, Field Emission Scanning Electron Microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and a Fourier Transform Infrared spectrophotometer. In addition, gold and silver NP antimicrobial efficacy was checked by disc diffusion assay. UV-Vis color intensity of the nanoparticles was shown at 540 and 450 nm for gold and silver nanoparticles respectively. Higher magnification of the Field Emission Scanning Electron Microscopy image shows the variable morphology of the gold nanoparticles such as spherical, rod and triangular shapes and silver nanoparticles were seen in spherical shapes. The average spherical size of the particles was observed in 24-38 nm for gold and 30-45 nm for silver NPs. X-ray diffraction pattern confirmed the presence of gold nanoparticles and silver nanoparticles which were crystalline in nature. Additionally, the functional metabolites were identified by the Fourier Transform Infrared spectroscopy. IR spectra revealed phenols, alcohols, aldehydes (sugar moieties), vitamins and proteins are present in the broccoli extract which are accountable to synthesize the nanoparticles. The synthesized gold and silver NPs inhibited the growth of the tested bacterial and fungal pathogens at the concentration of 50 μg/mL respectively. In addition, broccoli mediated gold and silver nanoparticles have shown potent antimicrobial activity against human pathogens.
This paper presents the pattern and changes of fragmented forest in relation with changes of total forest cover in the state of Selangor in three decades. In this study, inventoried forest cover maps of Selangor in 1971/1972, 1981/1982 and 1991/1992 produced by the Forestry Department of Peninsular Malaysia were digitized to examine the changes in area and number of fragmented forest. Results showed that in 1971/1972, 16 fragmented forests were identified in Selangor. All fragmented forests were identified as dipterocarp forest. A decade later the number of fragmented forests increased by approximately 44% (23). Of the 23 fragmented forests, two were peat swamp forests whereas the remaining were dipterocarp forests. In 1991/1992 the number of fragmented forests (12) was reduced by 47.8%. Two of the fragmented forests were identified as peat swamp forest, seven dipterocarp forest and the other three was mixed of dipterocarp forests and plantation forests. Fragmentation of both dipterocarp and peat swamp forests occurred profoundly during the period between 1971/1972 and 1981/1982, which consequently increased the number of fragmented forests compared with before the period of 1971/1972 where fragmentation happened only at dipterocarp forests. However, many fragmented forests vanished between the 1981/1982 and 1991/1992 periods.
This study investigate the relationships between geomorphometric properties and the minimum low flow discharge of undisturbed drainage basins in the Taman Bukit Cahaya Seri Alam Forest Reserve, Peninsular Malaysia. The drainage basins selected were third-order basins so as to facilitate a common base for sampling and performing an unbiased statistical analyses. Three levels of relationships were observed in the study. Significant relationships existed between the geomorphometric properties as shown by the correlation network analysis; secondly, individual geomorphometric properties were observed to influence minimum flow discharge; and finally, the multiple regression model set up showed that minimum flow discharge (Q min) was dependent of basin area (AU), stream length (LS), maximum relief (Hmax), average relief (HAV) and stream frequency (SF). These findings further enforced other studies of this nature that drainage basins were dynamic and functional entities whose operations were governed by complex interrelationships occurring within the basins. Changes to any of the geomorphometric properties would influence their role as basin regulators thus influencing a change in basin response. In the case of the basin's minimum low flow, a change in any of the properties considered in the regression model influenced the "time to peak" of flow. A shorter time period would mean higher discharge, which is generally considered the prerequisite to flooding. This research also conclude that the role of geomorphometric properties to control the water supply within the stream through out the year even though during the drought and less precipitations months. Drainage basins are sensitive entities and any deteriorations involve will generate reciprocals and response to the water supply as well as the habitat within the areas.