Silver Nanoparticles in the Water Environment in Malaysia: Inspection, characterization, removal, modeling, and future perspective.

The current status of silver nanoparticles (AgNPs) in the water environment in Malaysia was examined and reported. For inspection, two rivers and two sewage treatment plants (STPs) were selected. Two activated carbons derived from oil palm (ACfOPS) and coconut (ACfCS) shells were proposed as the adsorbent to remove AgNPs. It was found that the concentrations of AgNPs in the rivers and STPs are in the ranges of 0.13 to 10.16 mg L-1 and 0.13 to 20.02 mg L-1, respectively, with the highest concentration measured in July. ACfOPS and ACfCS removed up to 99.6 and 99.9% of AgNPs, respectively, from the water. The interaction mechanism between AgNPs and the activated carbon surface employed in this work was mainly the electrostatic force interaction via binding Ag+ with O- presented in the activated carbon to form AgO. Fifteen kinetic models were compared statistically to describe the removal of AgNPs. It was found that the experimental adsorption data can be best described using the mixed 1,2-order model. Therefore, this model has the potential to be a candidate for a general model to describe AgNPs adsorption using numerous materials, its validation of which has been confirmed with other material data from previous works.

A purely green synthesis of silver nanoparticles using Carica papaya, Manihot esculenta, and Morinda citrifolia: synthesis and antibacterial evaluations.

Green procedure for synthesizing silver nanoparticles (AgNPs) is currently considered due to its economy and toxic-free effects. Several existing works on synthesizing AgNPs using leaves extract still involve the use of physical or mechanical treatment such as heating or stirring, which consume a lot of energy. To extend and explore the green extraction philosophy, we report here the synthesis and antibacterial evaluations of a purely green procedure to synthesize AgNPs using Carica papaya, Manihot esculenta, and Morinda citrifolia leaves extract without the aforementioned additional treatment. The produced AgNPs were characterized using the ultraviolet-visible spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and antibacterial investigations. For antibacterial tests, two bacteria namely Escherichia coli and Bacillus cereus were selected. The presently employed method has successfully produced spherical AgNPs having sizes ranging from 9 to 69 nm, with plasmonic characteristics ranging from 356 to 485 nm, and energy-dispersive X-ray peak at approximately 3 keV. In addition, the smallest particles can be produced when Manihot esculenta leaves extract was applied. Moreover, this study also confirmed that both the leaves and synthesized AgNPs exhibit the antibacterial capability, depending on their concentration and the bacteria type.

Supporting data for identification of biosurfactant-producing bacteria isolated from agro-food industrial effluent.

The goal of this study was to identify the biosurfactant-producing bacteria isolated from agro-food industrial effluet. The identification of the potential bacterial strain using a polymerase chain reaction of the 16S rRNA gene analysis was closely related to Serratia marcescens with its recorded strain of SA30 "Fundamentals of mass transfer and kinetics for biosorption of oil and grease from agro-food industrial effluent by Serratia marcescens SA30" (Fulazzaky et al., 2015) [1]; however, many biochemical tests have not been published yet. The biochemical tests of biosurfactant production, haemolytic assay and cell surface hydrophobicity were performed to investigate the beneficial strain of biosurfactant-producing bacteria. Here we do share data collected from the biochemical tests to get a better understanding of the use of Serratia marcescens SA30 to degrade oil, which contributes the technical features of strengthening the biological treatment of oil-contaminated wastewater in tropical environments.

A review on bisphenol A occurrences, health effects and treatment process via membrane technology for drinking water.

Massive utilization of bisphenol A (BPA) in the industrial production of polycarbonate plastics has led to the occurrence of this compound (at µg/L to ng/L level) in the water treatment plant. Nowadays, the presence of BPA in drinking water sources is a major concern among society because BPA is one of the endocrine disruption compounds (EDCs) that can cause hazard to human health even at extremely low concentration level. Parallel to these issues, membrane technology has emerged as the most feasible treatment process to eliminate this recalcitrant contaminant via physical separation mechanism. This paper reviews the occurrences and effects of BPA toward living organisms as well as the application of membrane technology for their removal in water treatment plant. The potential applications of using polymeric membranes for BPA removal are also discussed. Literature revealed that modifying membrane surface using blending approach is the simple yet effective method to improve membrane properties with respect to BPA removal without compromising water permeability. The regeneration process helps in maintaining the performances of membrane at desired level. The application of large-scale membrane process in treatment plant shows the feasibility of the technology for removing BPA and possible future prospect in water treatment process.

Removal of bisphenol A by adsorption mechanism using PES-SiO2 composite membranes.

Polyethersulphone (PES) membranes blended with silicon dioxide (SiO2) nanoparticles were prepared via a dry-jet wet spinning technique for the removal of bisphenol A (BPA) by adsorption mechanism. The morphology of SiO2 nanoparticles was analysed using a transmission electron microscopy and particle size distribution was also analysed. The prepared membranes were characterized by several techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy and water contact angle. The adsorption mechanism of membrane towards BPA was evaluated by batch experiments and kinetic model. The influence of natural organic matter (NOM) in feed water on membrane BPA removal was also studied by filtration experiments. Results showed that BPA adsorption capacity as high as 53 µg/g could be achieved by the PES membrane incorporated with 2 wt% SiO2 in which the adsorption mechanism was in accordance with the pseudo-second-order kinetic model. The intraparticles diffusion model suggested that the rate limiting factor of membrane adsorption mechanism is governed by the diffusion of BPA into the membrane pores. The presence of 10 ppm NOM has reported to negatively reduce BPA removal by 24%, as it tended to compete with BPA for membrane adsorption. This work has demonstrated that PES-SiO2 membrane has the potential to eliminate trace amount of BPA from water source containing NOM.

Influence of palm oil mill effluent as inoculum on anaerobic digestion of cattle manure for biogas production.

Anaerobic digestion for palm oil mill effluent (POME) is widely known for its potential in biogass production. In this study, the potential of using cattle manure for biogas production in complete mix anaerobic bioreactor was investigated using POME at unregulated pH and temperature. Two identical bioreactors were used in this study; namely R1 and R2 fed with cattle manure without and with POME as inoculum, respectively. Both bioreactors were allowed for five days to run in batch mode followed by semi continuous operations at HRT of 20 days. R2 produced 41% methane content compared to 18% produced in R1. A better COD percentage reduction of 45% was found in R2 which was operated with POME as inoculum compared to R1 with 35%. These results indicated that POME as inoculum has an influence on the start-up time and the rate of biogas produced.This findings will help in waste reduction.

Degradation and transformation of anthracene by white-rot fungus Armillaria sp. F022.

Characterization of anthracene metabolites produced by Armillaria sp. F022 was performed in the enzymatic system. The fungal culture was conducted in 100-mL Erlenmeyer flask containing mineral salt broth medium (20 mL) and incubated at 120 rpm for 5-30 days. The culture broth was then centrifuged at 10,000 rpm for 45 min to obtain the extract. Additionally, the effect of glucose consumption, laccase activity, and biomass production in degradation of anthracene were also investigated. Approximately, 92 % of the initial concentration of anthracene was degraded within 30 days of incubation. Dynamic pattern of the biomass production was affected the laccase activity during the experiment. The biomass of the fungus increased with the increasing of laccase activity. The isolation and characterization of four metabolites indicated that the structure of anthracene was transformed by Armillaria sp. F022 in two routes. First, anthracene was oxidized to form anthraquinone, benzoic acid, and second, converted into other products, 2-hydroxy-3-naphthoic acid and coumarin. Gas chromatography-mass spectrometry analysis also revealed that the molecular structure of anthracene was transformed by the action of the enzyme, generating a series of intermediate compounds such as anthraquinone by ring-cleavage reactions. The ligninolytic enzymes expecially free extracellular laccase played an important role in the transformation of anthracene during degradation period.

Identification of naphthalene metabolism by white rot fungus Pleurotus eryngii.

The use of biomaterials or microorganisms in PAHs degradation had presented an eye-catching performance. Pleurotus eryngii is a white rot fungus, which is easily isolated from the decayed woods in the tropical rain forest, used to determine the capability to utilize naphthalene, a two-ring polycyclic aromatic hydrocarbon as source of carbon and energy. In the meantime, biotransformation of naphthalene to intermediates and other by-products during degradation was investigated in this study. Pleurotus eryngii had been incubated in liquid medium formulated with naphthalene for 14 days. The presence of metabolites of naphthalene suggests that Pleurotus eryngii begin the ring cleavage by dioxygenation on C1 and C4 position to give 1,4-naphthaquinone. 1,4-Naphthaquinone was further degraded to benzoic acid, where the proposed terepthalic acid is absent in the cultured extract. Further degradation of benzoic acid by Pleurotus eryngii shows the existence of catechol as a result of the combination of decarboxylation and hydroxylation process. Unfortunately, phthalic acid was not detected in this study. Several enzymes, including manganese peroxidase, lignin peroxidase, laccase, 1,2-dioxygenase and 2,3-dioxygenase are enzymes responsible for naphthalene degradation. Reduction of naphthalene and the presence of metabolites in liquid medium showed the ability of Pleurotus eryngii to utilize naphthalene as carbon source instead of a limited glucose amount.

The effect of drastic temperature changes on the performance of MBR treating municipal wastewater.

A study has been carried out to define the effect of drastic temperature changes on the performance of lab-scale hollow-fibre MBR in treating municipal wastewater at a flux of 10 L m(-2) h(-1) (LMH). The objectives of the study were to estimate the activated sludge properties, the removal efficiencies of COD and NH(3)-N and the membrane fouling tendency under critical conditions of drastic temperature changes (23, 33, 42 & 33 °C) and MLSS concentration ranged between 6,382 and 8,680 mg/L. The study exhibited that the biomass reduction, the low sludge settleability and the supernatant turbidity were results of temperature increase. The temperature increase led to increase in SMP carbohydrate and protein, and to decrease in EPS carbohydrate and protein. The BRE of COD dropped from 80% at 23 °C to 47% at 42 °C, while the FRE was relatively constant at about 90%. Both removal efficiencies of NH(3)-N trended from about 100% at 33 °C to less than 50% at 42 °C. TMP and BWP ascended critically with temperature increase up to 336 and 304 mbar respectively by the end of the experiment. The values of suspended solids (SS) and the turbidity in the final effluent were negligible. The DO in the mixed liquor was varying with temperature change, while the pH was within the range of 6.7-8.3.

The effect of hydraulic retention time on granular sludge biomass in treating textile wastewater.

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.

Development of granular sludge for textile wastewater treatment.

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.

Pilot scale microfiltration-coagulation for treatment of retention pond water.

An evaluation of two commonly used coagulants, alum and ferric chloride was conducted to treat retention pond water using microfiltration. To determine the effectiveness of these coagulants in removing turbidity, color, and total suspended solids two different sets of the experiments were performed. Preliminary test was carried out to evaluate the optimum dosages of coagulants. Optimum turbidity removal was achieved with a 4 and 20 mg/L dosage for ferric chloride and alum, respectively. Generally, coupling microfiltration with coagulation using both alum and ferric chloride exhibited excellent effectiveness for turbidity, color, and total suspended solids removal. The efficiency for alum and ferric chloride for turbidity removal were 96 and 98%, respectively, which was greater than 89% removal using microfiltration alone. Furthermore, microfiltration only demonstrated 81 and 83% removal efficiency for color and total suspended solids removal, respectively. However, microfiltration-coagulation using alum and ferric chloride resulted about 83 and 93% color removal, and 92 and 94% total suspended solids removal, respectively.