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The smaller particles that dominate the particle number concentration (PNC) in the ambient air only contribute to a small percentage of particulate matter (PM) mass concentration although present in high particle number concentration. These small particles may be neglected upon assessing the health impacts of the PM. Hence, the knowledge on the particle number concentration size distribution deserves greater attention than the particulate mass concentration. This study investigates the measurement of the particle mass concentrations (PM2.5) and PNC of 0.27 μm

The present work investigates the feasibility of aerobic granulation for the treatment of low-medium strength domestic wastewater for long-term operation and effects of a static mixer on the properties and removal performances of the aerobic granules formed. The static mixer was installed in a sequential batch reactor to provide higher hydrodynamic shear force in enhancing the formation of the aerobic granules. Aerobic granules were successfully formed in the domestic wastewater, and the granulation treatment system was sustained for a period of 356 days without granules disintegration. Subsequent to the installation, aerobic granules with a low SVI30 of 41.37 mL/gTSS, average diameter 1.11 mm, granular strength with integrity coefficient 10.4% and regular shape with minimum filamentous outgrowth were formed. Mineral concentrations such as Fe, Mg, Ca and Na as well as composition of protein and polysaccharide in tightly bound-extracellular polymeric substance of the aerobic granules were found to be higher under the effect of the static mixer. However, no significant improvement was observed on the TCOD, NH4+-N and TSS removal performance. Good TCOD and TSS removal performance of above 85% and 90%, respectively and moderate NH4+-N removal performance of about 60% were observed throughout the study. Higher simultaneous nitrification and denitrification (SND) efficiency of 56% was observed after the installation of the static mixer, as compared to 21% prior. Therefore, it may be concluded that the installation of the static mixer significantly improved the properties of aerobic granules formation and SND efficiency but not the TCOD, NH4+-N and TSS removal performance.

Extra-cellular polymeric substances are responsible towards bioflocculation and settleability of sludge. This substances act as glue that holds the bioflocs to form larger aggregates by intervening both cells cohesion and adhesion. Different composition of this substances lead to different circumstances of sludge problem including bulking. Numerous studies have been conducted in optimizing the content of extra-cellular polymeric substances using various approaches. However, none of the approaches investigated on the use of magnetic field. Therefore, this study is aimed to investigate the effect of magnetic field on extra-cellular polymeric substances specifically its soluble-bound composition and its chemical constituents. Magnetic field of 88 mT was used in Reactor A, while Reactor B acted as control system. Results showed that Reactor A obtained mostly higher tightly bound extra-cellular polymeric substances compared to Reactor B in order of predominance: protein > polysaccharides > carbohydrates. These observations implied that magnetic field influenced the production of polymeric substances mainly its tightly bound constituent as well as protein and polysaccharides content. These productions were significant in improving bioflocculation and sludge settleability, thus minimizing potential occurrence of bulking.

Over the decades the palm oil industry has managed some challen ging environmental concerns regarding land transformation and degradation, increas e in eutrophication, changing habitats of wildlife, pesticides runoff into inland wa tercourses, and probable climate change. Countries producing palm oil desire to do so in a more sustainable way that will leave the environment evergreen. Therefore this paper aims to encourage sustainable management of agro-industrial waste and its potenti al in making financial returns from the same waste. Hence, the study was conducted with the participation of seven local palm oil mills having different capacities and oper ation age. Attention was given to milling waste as they could cause serious environmenta l menace if unattended to properly. Milling waste includ es lignocellulosic palm biomas s namely the empty fruit bunches (EFB), oil palm shell (OPS), mesocarp fibres, pal m oil mill effluent (POME), and palm oil mill sludge (POMS), as well as solid waste generated from the further processing of these biomass into the palm oil fuel ashe s (POFA) and palm oil clinkers (POC). The opportunities available to the Malaysian pa lm oil industry and the financial benefits which may accr ue from waste generated during palm oil production process cannot be over emphasized.

Kinetic and mass transfer aspects of biosorption of oxidisable organic matter (OOM) from wastewater are important for better understanding of the mechanisms of granules initiation and development. The modified mass transfer factor models were used to predict the liquid–solid mass transfer rates of OOM biosorption from palm oil mill effluent (POME) attached to aerobic granular sludge (AGS) in a sequencing batch reactor (SBR). The variations of [kLa]g, [kLa]f and [kLa]d pursuant to time were verified to have a zigzag pattern due to the organic loading rate varies with a change in the quality of POME feeding the SBR. The influence of added Serratia marcescens SA30 on the rates of mass transfer would be very remarkable due to the effects of metabolites and biomass growth this can lead to a rapid utilisation of OOM accumulated into AGS. The maximum efficiencies of SBR reaching 48% for CODt removal at [kLa]g value of 3.054 h−1 and 68% for CODs removal at [kLa]g value of 21.012 h−1 were verified before the addition of S. marcescens SA30 and those reaching 68% for CODt removal at [kLa]g value of 1.229 × 1063 h−1 and 94% for CODs removal at [kLa]g value of 7.152 × 1064 h−1 were verified after the addition of S. marcescens SA30. The resistance of mass transfer could be dependent on external mass transfer, which controls the movement of organic molecules along the experimental period of POME fed the SBR without and with added S. marcescens SA30. The performance of SBR would increase with increase of [kLa]g value, and this provides new insight into dynamic response of the aerobic digestion to AGS development.

Sludge bulking caused by filamentous microorganisms is one of the prevailing operational problems in activated sludge process. Its severity is determined by the relative abundance of filame...

This study investigated the effect of various cations (Ca2+, Mg2+, Al3+, Mn2+, Zn2+) on the autoaggregation (AAg) and surface hydrophobicity (SHb) of three different bacteria (Brevibacillus panacihumi strain (ZB1), Lysinibacillus fusiformis strain (ZB2) and Enterococcus faecalis strain (ZL)) using a 2-level factorial design. The AAg ratio was measured from the changes in the absorbance of the media. Results show that ZB2 had maximum AAg for the three bacteria investigated. A microscopic clustering of cells was observed when Ca2+ was added to ZB2. The AAg was in the range of 62%, 58% and 34% for ZB2, ZB1 and ZL, respectively and correlated to the SHb. The aggregation and SHb of the microbial cells increased with increasing ionic strength due to the repulsive steric or overlap forces between the polymer covered surfaces. Ca2+ demonstrated a more significant effect on aggregation and SHb of microbial cells due to an attractive binding force.

In this study, activated sludge was exposed by magnetic field exhibited from NdFeB – type of permanent magnets. The exposure was aimed to improve the physical properties of the activated sludge used in treating wastewater. Hence, it was hypothesized that the magnetically-exposed activated sludge is potential in enhancing the efficiency of removal performances of the wastewater treatment processes. The influence of magnetic field, exposure time, biomass concentration and mixing intensity on turbidity reduction, aggregation and settling velocity was thoroughly investigated. Response surface methodology (RSM) was applied for experimental design, analysis and optimization. Based on the results, magnetically-exposed activated sludge displayed certain trends showing that its properties were positively affected by magnetic field. At the optimum conditions of magnetic field of 88.0 mT, exposure time of 38.5 hrs, biomass concentration of 3380 mg/L and mixing intensity of 345 rpm achieved 68.3%, 60.1% and 0.0104 cm/s of turbidity reduction, aggregation and settling velocity, respectively.

This paper presents the effect of different sizes of palm kernel shell (PKS) activated carbon as the carrier material in a micro-bioreactor system to treat the palm oil mill effluent (POME). Three different sizes of PKS activated carbon were used as the carrier material, i.e. 4.750 – 2.360 mm (large), 1.180 – 0.710 mm (average) and 0.425 – 0.300 mm (small). The systems were run for a total of 29 days under hydraulic retention time (HRT) of 24 hours. The performances of several effluent quality parameters of POME regarding the use of PKS activated carbon of different sizes were studied. PKS activated carbon with size 1.180 – 0.710 mm showed the highest removal performances for chemical oxygen demand (COD), ammoniacal-nitrogen (AN), and solids, with 41 %, 84.6 %, and 88 % of removal respectively. The system with PKS activated carbon of size 4.750 - 2.360 mm showed the highest performance in removing TP (45 %), while 1.180 – 0.710 mm size of PKS activated carbon showed the highest performance in removing TN (53 %). The system was also found to effectively reduce the effluent colour. In overall, the PKS activated carbon of size 1.180 – 0.710 mm showed the best results as a carrier material to be used in the micro-bioreactor system in treating POME compared to the other two sizes.

Factorial design and response surface methodology were employed to investigate the effects of substrate (500–3,000 mg/L) and riboflavin (1–150 μM) concentrations on the chemical oxygen demand (COD) and color removal with biogranules in the treatment of textile effluent using sequential anaerobic–aerobic batch experiment. Both variables, except for the concentration of riboflavin under anaerobic conditions, and the interaction between both variables show significant effects on COD removal. The substrate and riboflavin concentrations also significantly affect on the decolorization of Synozol Red K-4B and Sumifix Navy Blue EXF. In addition, the effect of substrate on color removal was found to be time dependent. The highest COD removal was 85.5%, which corresponds to substrate and riboflavin concentrations of 2,634 mg/L and 23 μM, respectively. The highest color removal for Synozol Red K-4B and Sumifix Navy Blue EXF was achieved after 12 h of treatment, with more than 80% color removal at substrate a...

The developed microbial granules containing photosynthetic pigments had successfully achieved approximately 18–21% of carbon dioxide (CO2) removal in POME for one complete SBR cycle. Also, the granules had reached CO2 removal at 15–29% within 24 h and removal of 25% after 5 days. Both results were inconsistent possibly due to the slow mass transfer rate of CO2 from gas to liquid as well as the simultaneous effect of CO2 production and respiration among the microbes. Furthermore, results showed the removal of CO2 from air increases proportionally with the CO2 removed in liquid. The CO2 biofixation of granules attained was approximately 0.23 g/L/day for a week. Using the regression model, the removal of CO2 between liquid and gas, CO2 biofixation rate were highly correlated with the treatment time. A statistically significant relationship was obtained between CO2 concentration in liquid, biomass productivity and treatment time for the CO2 biofixation rate of the granules.

Granular sludge was successfully cultivated under intermittent anaerobic and aerobic reaction phase strategy using synthetic textile wastewater for 72 days. The granules were developed under superficial air velocity of 2.4 cm/s in the SBR system that operated at hydraulic retention time of 8 hours. The unique feature of the granules is that they were cultivated using anaerobic granules as seeding material. The microscopic examination showed clear, smooth and spherical shape of mature granules with diameters ranging from 0.85 to 1 mm after 60 days of operation. The particle size distribution has shifted from less than 0.3 mm in the beginning to about 1 mm with some reaching 2.5 mm. The granules had good settling properties indicated by their high settling velocity reaching up to about 42 m/h and low sludge volume index (SVI) of 61 mL/g. The MLSS has also increased from 4.8 g/L to 7 g/L while the granular strength has also increased with time. During the development process, the granular sludge system was capable of treating synthetic textile dyeing wastewater containing mixed dyes with 93% of COD and ammonia removal and 56% of color removal. Keyword: color, granular sludge, intermittent, mixed dyes, sequential batch reactor

The physical characteristics, microbial activities and kinetic properties of the granular sludge biomass were investigated under the influence of different hydraulic retention times (HRT) along with the performance of the system in removal of color and COD of synthetic textile wastewater. The study was conducted in a column reactor operated according to a sequential batch reactor with a sequence of anaerobic and aerobic reaction phases. Six stages of different HRTs and different anaerobic and aerobic reaction time were evaluated. It was observed that the increase in HRT resulted in the reduction of organic loading rate (OLR). This has caused a decrease in biomass concentration (MLSS), reduction in mean size of the granules, lowered the settling ability of the granules and reduction of oxygen uptake rate (OUR), overall specific biomass growth rate (ìoverall), endogeneous decay rate (kd) and biomass yield (Yobs, Y). When the OLR was increased by adding carbon sources (glucose, sodium acetate and ethanol), there was a slight increase in the MLSS, the granules mean size, ìoverall, and biomass yield. Under high HRT, increasing the anaerobic to aerobic reaction time ratio caused an increase in the concentration of MLSS, mean size of granules and lowered the SVI value and biomass yield. The ìoverall and biomass yield increased with the reduction in anaerobic/aerobic time ratio. The HRT of 24 h with anaerobic and aerobic reaction time of 17.8 and 5.8 h respectively appear to be the best cycle operation of SBR. Under these conditions, not only the physical properties of the biogranules have improved, the highest removal of color (i.e. 94.1±0.6%) and organics (i.e. 86.5±0.5%) of the synthetic textile dyeing wastewater have been achieved.

In this study, the particulate matter with diameter less than 10 micrometers (PM10) is being observed. Other factors that influenced the pollutant dispersion are also being studied prior to identification of their relationship. The aim of this study is to identify the trend of PM10 concentrations in the Southern Peninsular of Malaysia during the period 2005 to 2015 by using spatio-temporal analysis in regards to air pollution. The inverse distance weighted (IDW) is used for the spatio interpolation data and mapping. The trends of the PM10 concentration are illustrated via map which indicates the affected and vulnerable area of Southern Peninsular Malaysia especially during Haze episode.

In activated sludge system, the performance of the process largely depends on the balance between filamentous and floc-forming microorganisms. When the normal balance of these biological communities is disturbed, filamentous microorganisms tend to proliferate, causing various problems to the treatment performances such as sludge bulking. Various approaches have been used to control the proliferation of filamentous microorganisms. However, the approaches led to various drawbacks that eventually worsen the performances of treatment systems. Therefore, this study is aimed to investigate the potential approach using static magnetic field in inhibiting filamentous microorganisms that presence in the sludge bulking. Magnetic field of intensity 88 mT was used. Its exposure on the filamentous microorganisms was investigated in terms of filaments' characteristics such as branching, shape and filaments' location. The analysis indicated that the magnetically exposed activated sludge showed less possibility presence of the filamentous microorganisms compared to unexposed activated sludge.

Natural coagulants have been increasingly popular in the past few years due to its benefits and the fact that it resolves most of the associated problems when using chemical coagulants. Plant-based natural coagulants perform coagulation either by polymer bridging or charge neutralization, it can be extracted from various plant components. Concerted research and development efforts have been conducted in discovering new plant species and constituents that can be used as natural coagulants, which further boosting the effectiveness of existing plant-based natural coagulants. The objective of this paper is to provide a mini review on studies done over the span of ten years regarding plant-based natural coagulants. This paper also includes advantages and disadvantages of natural coagulants prior to identify several potential research gaps to provide platform towards the need of further study.

The Malaysian palm oil industry is a major revenue earner and the country is ranked as one of the largest producers in the world. However, growth of the industry is synonymous with a massive production of agro-industrial wastewater. As an environmental protection and public health concern, the highly polluting palm oil mill effluent (POME) has become a major attention-grabber. Hence, the industry is targeting for POME pollution abatement in order to promote a greener image of palm oil and to achieve sustainability. At present, most palm oil mills have adopted the ponding system for treatment. Due to the successful POME pollution abatement experiences, Malaysia is currently planning to revise the effluent quality standards towards a more stringent discharge limits. Hence, the current trend of POME research focuses on developing tertiary treatment or polishing systems for better effluent management. Biotechnologically-advanced POME tertiary (polishing) technologies as well as other physicochemical methods are gaining much attention as these processes are the key players to push the industry towards the goal of environmental sustainability. There are still ongoing treatment technologies being researched and the outcomes maybe available in a while. However, the research completed so far are compiled herein and reported for the first time to acquire a better perspective and insight on the subject with a view of meeting the new standards. To this end, the most feasible technology could be the combination of advanced biological processes (bioreactor systems) with extended aeration, followed by solids separation prior to discharge. Chemical dosing is favoured only if effluent of higher quality is anticipated.

Textile wastewater, one of the most polluted industrial effluents, generally contains substantial amount of dyes and chemicals that will cause increase in the COD, colour and toxicity of receiving water bodies if not properly treated. Current treatment methods include chemical and biological processes; the efficiency of the biological treatment method however, remains uncertain since the discharged effluent is still highly coloured. In this study, granules consisting mixed culture of decolourising bacteria were developed and the physical and morphological characteristics were determined. After the sixth week of development, the granules were 3–10 mm in diameter, having good settling property with settling velocity of 70 m/h, sludge volume index (SVI) of 90 to 130 mL/g, integrity coefficient of 3.7, and density of 66 g/l. Their abilities to treat sterilised raw textile wastewater were evaluated based on the removal efficiencies of COD (initial ranging from 200 to 3,000 mg/L), colour (initial ranging from 450 to 2000 ADMI) of sterilised raw textile wastewater with pH from 6.8 to 9.4. Using a sequential anaerobic-aerobic treatment cycle with hydraulic retention time (HRT) of 24 h, maximum removal of colour and COD achieved was 90% and 80%, respectively.

Microbial granular sludge that is capable to treat textile wastewater in a single reactor under intermittent anaerobic and aerobic conditions was developed in this study. The granules were cultivated using mixed sewage and textile mill sludge in combination with anaerobic granules collected from an anaerobic sludge blanket reactor as seed. The granules were developed in a single sequential batch reactor (SBR) system under alternating anaerobic and aerobic condition fed with synthetic textile wastewater. The characteristics of the microbial granular sludge were monitored throughout the study period. During this period, the average size of the granules increased from 0.02 +/- 0.01 mm to 2.3 +/- 1.0 mm and the average settling velocity increased from 9.9 +/- 0.7 m h(-1) to 80 +/- 8 m h(-1). This resulted in an increased biomass concentration (from 2.9 +/- 0.8 g L(-1) to 7.3 +/- 0.9 g L(-1)) and mean cell residence time (from 1.4 days to 8.3 days). The strength of the granules, expressed as the integrity coefficient also improved. The sequential batch reactor system demonstrated good removal of COD and ammonia of 94% and 95%, respectively, at the end of the study. However, only 62% of color removal was observed. The findings of this study show that granular sludge could be developed in a single reactor with an intermittent anaerobic-aerobic reaction phase and is capable in treating the textile wastewater.

Microbial flocs formed from raw textile wastewater in a prototype Aerobic Biofilm Reactor (ABR) system were characterised and studied for their potential use in the treatment of textile wastewater. After 90–100 days of operation, microbial flocs of loose irregular structures were obtained from the reactor with good settling velocity of 33 m/h and sludge volume index (SVI) of 48.2 mL/g. Molecular analysis of the flocs using PCR-amplified 16S rDNA sequence showed 98% homology to those of Bacillus sp, Paenibacillus sp and Acromobacter sp. Detection of Ca2 + (131 mg/g) and Fe2 + (131 mg/g) using atomic absorption spectrometer might be implicated with the flocs formation. In addition, presence of Co2 + and Ni2 + were indicative of the flocs ability to accumulate at least a fraction of the metals' present in the wastewater. When the flocs were used for the treatment of raw textile wastewater, they showed good removal of COD and colour about 55% and 70% respectively, indicating their potential application.