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The effect of aerated rock filter geometry on the rate of nitrogen removal from facultative pond effluents

Hamdan R, Mara DD

Water Sci Technol, 2011;63(5):841-4.
PMID: 21411931 DOI: 10.2166/wst.2011.102

Rock filters are an established technology for polishing waste stabilization pond effluents. However, they rapidly become anoxic and consequently do not remove ammonium-nitrogen. Horizontal-flow aerated rock filters (HFARF), developed to permit nitrification and hence ammonium-N removal, were compared with a novel vertical-flow aerated rock filter (VFARF). There were no differences in the removals of BOD5, TSS and TKN, but the VFARF consistently produced effluents with lower ammonium-N concentrations (<0.3 mg N/L) than the HFARF (0.8-1.5 mg N/L) and higher nitrate-N concentrations (24-29 mg N/L vs. 17-24 mg N/L).
Efficiencies and mechanisms of steel slag with ferric oxides for removing phosphate from wastewater using a column filter system

Ahmad SZN, Al-Gheethi A, Hamdan R, Othman N

Environ Sci Pollut Res Int, 2020 Oct;27(28):35184-35194.
PMID: 32583114 DOI: 10.1007/s11356-020-09582-7

The current study aimed to investigate the efficiencies and mechanisms of slag filter media for removing phosphorus from synthetic wastewater. The steel slag with high ferric oxides (Fe2O3) was subjected for the electric arc furnace (EAF) and selected as the filter media (HFe). The chemical characteristics of HFe were determined using pH, point of zero charge (PZC) and XRF. The phosphorus removal efficiency was studied in a designed vertical steel slag column rock filters in unaerated HFe (UEF) and aerated HFe (AEF) system. The microstructure of HFe was analyzed by FTIR, XRD and SEM-EDX analysis. The results of XRF revealed that ferric oxide (Fe2O3) ranged from 26.1 to 38.2%. PZC for Filter HFe was recorded at pH 10.55 ± 0.27. The highest efficiencies were recorded by UEF and AEF systems at pH 3 and pH 5 (89.97 ± 4.02% and 79.95 ± 6.25% at pH 3 and 72.97 ± 8.38% and 66.00 ± 12.85% at pH 5 for UEF and AEF, respectively). These findings indicated that AEF exhibiting higher removal than UEF systems might be due to presence high Fe concentration in AEF which play important role in the phosphorus removal. The main elements available on the surface of HFe included carbon, oxygen, iron, calcium, magnesium, silicon, platinum, sulphur, manganese, titanium and aluminium. The XRD analysis indicated that the precipitation of orthophosphate as calcium and iron-phosphates was the removal mechanism as confirmed using FT-IR analysis. These findings demonstrated the efficiency of HFe in removing of phosphorus from wastewater.
Antibacterial and cytotoxic activity assessment of Channa striatus (Haruan) extract

Mat Zawawi NZ, Shaari R, Luqman Nordin M, Hayati Hamdan R, Peng TL, Zalati CWSCW

Vet World, 2020 Mar;13(3):508-514.
PMID: 32367957 DOI: 10.14202/vetworld.2020.508-514

Background and Aim: Channa striatus extract, a freshwater snakehead fish known as Haruan, is popular in Southeast Asia for consumption and as a traditional therapeutic remedy for wound healing. C. striatus is also used in osteoarthritic for its anti-inflammatory. The aim of this study was to determine the presence of antibacterial properties of C. striatus extract against oral bacteria and to investigate the cytotoxic activity against Vero cells.
Materials and Methods: The authors prepared C. striatus extract in chloroform-methanol solvents. Next, the authors took subgingival microbiological samples from 16 cats that had periodontal disease. The authors determined the antibacterial properties of C. striatus extract against the isolated bacteria using the disk diffusion method and a broth microdilution-based resazurin microtiter assay. Finally, the authors used the Vero cell line to evaluate the cytotoxic activity, and they assessed the cell availability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.
Results: The results showed weak antibacterial activity of C. striatus extract against Pseudomonas spp. and Escherichia coli. In addition, the authors found that minimum inhibition concentration values ranged between 400 and 500 mg/mL, and minimum bactericidal concentration values ranged between 650 and 550 mg/mL. However, the cytotoxic results were promising, showing that C. striatus extract increased the cell viability and growth when it was at a higher concentration. The extract also promotes growth and cell proliferation.
Conclusion: These findings suggest that C. striatus extract promoted cell proliferation in vitro and could be a plausible therapeutic wound healing alternative for periodontal disease in cats.
Efficiency of magnetic zeolitic imidazolate framework-8 (ZIF-8) modified graphene oxide for lead adsorption

Zu Nurain Ahmad S, Salleh WNW, Yusof N, Yusop MZM, Hamdan R, Ismail AF

Environ Sci Pollut Res Int, 2024 May 10.
PMID: 38727970 DOI: 10.1007/s11356-024-33322-w

Simple and efficient removal of Pb(II) ion from aqueous solution through adsorption has accelerated the development of many new composites to improve this popular method. In this study, the composites of graphene oxide (GO), zeolitic imidazolate framework-8 (ZIF-8), and magnetic materials were synthesized via coprecipitation method utilizing a different molar ratio between FeCl2 and FeCl3 of 1:0.5, 2:1, 3:1.5, and 4:2. The ZIF-8/GO was prepared via room temperature synthesis method prior to its further modification with magnetic materials for ease of separation. It was observed that the MZIF-8/GO2 of molar ratio 2:1 showed the best performance in adsorbing Pb(II) ion. As confirmed by FESEM image, it appeared to be ZIF-8 particles that have grown all over the GO platform and overlayed with Fe3O4 granular-shaped particles. The MZIF-8/GO2 successfully achieved 99% removal of Pb(II) within 10 min. The optimum values obtained for the initial concentration of Pb (II) were 100 mg/L, pH of 4 to 6, and adsorbent dosage used was 10 mg. The Langmuir isotherm and the pseudo-second-order kinetic model were deemed suitable to evaluate the adsorption of Pb(II) using MZIF-8/GO2. Results showed that MZIF-8GO2 achieved a maximum adsorption capacity of 625 mg/g of Pb(II) adsorption. All parent materials demonstrated a good synergistic effects, while exhibiting a significant contribution in providing active sites for Pb(II) adsorption. Therefore, this ternary composite of MZIF-8/GO2 is expected to be a promising adsorbent for Pb(II) adsorption from aqueous solution with an added value of ease of post phase separation using external magnetic field.
Fulltext A clustering approach to identify multidimensional poverty indicators for the bottom 40 percent group

Abdul Rahman M, Sani NS, Hamdan R, Ali Othman Z, Abu Bakar A

PLoS One, 2021;16(8):e0255312.
PMID: 34339480 DOI: 10.1371/journal.pone.0255312

The Multidimensional Poverty Index (MPI) is an income-based poverty index which measures multiple deprivations alongside other relevant factors to determine and classify poverty. The implementation of a reliable MPI is one of the significant efforts by the Malaysian government to improve measures in alleviating poverty, in line with the recent policy for Bottom 40 Percent (B40) group. However, using this measurement, only 0.86% of Malaysians are regarded as multidimensionally poor, and this measurement was claimed to be irrelevant for Malaysia as a country that has rapid economic development. Therefore, this study proposes a B40 clustering-based K-Means with cosine similarity architecture to identify the right indicators and dimensions that will provide data driven MPI measurement. In order to evaluate the approach, this study conducted extensive experiments on the Malaysian Census dataset. A series of data preprocessing steps were implemented, including data integration, attribute generation, data filtering, data cleaning, data transformation and attribute selection. The clustering model produced eight clusters of B40 group. The study included a comprehensive clustering analysis to meaningfully understand each of the clusters. The analysis discovered seven indicators of multidimensional poverty from three dimensions encompassing education, living standard and employment. Out of the seven indicators, this study proposed six indicators to be added to the current MPI to establish a more meaningful scenario of the current poverty trend in Malaysia. The outcomes from this study may help the government in properly identifying the B40 group who suffers from financial burden, which could have been currently misclassified.
Detection of pathogenic Vibrio species and antibiogram activity in Asian Seabass (Lates calcarifer) in Tumpat, Kelantan

Auzureen AMZ, Michael MS, Mohamed M, Peng TL, Fauzi F, Mohamad NFA, et al.

Trop Biomed, 2022 Dec 01;39(4):569-574.
PMID: 36602217 DOI: 10.47665/tb.39.4.013

Some of Vibrio species is well known as pathogenic bacteria in aquaculture and the marine industry. Its infection is able to generate a massive outbreak and affect the fish population, especially for net caged fish such as seabass. This study was conducted to investigate the prevalence of Vibrio spp. isolated from seabass (Lates calcarifer) in Sri Tujuh Lagoon, Tumpat, Kelantan. Then, to determine the antibiotic resistance in Vibrio isolates. Polymerase chain reaction (PCR) was used to detect Vibrio species using specific primer VR169 and VR744 with estimation base pair size band, 597 bp and further identified by sequencing. On the other hand, antibiotic susceptibility tests were continued by using 13 types of antibiotics; kanamycin (K30), chloramphenicol (C30), neomycin (N10), ampicillin (AMP10), nitrofurantoin (F300), tetracycline (TE30), streptomycin (S10), norfloxacin (NOR10), ciprofloxacin (CIP5), nalidixic acid (NA30), gentamicin (CN10), doxycycline (DO30) and sulfamethoxazole (SXT100). As a result, 14 Vibrio isolates were identified, including Vibrio fluvialis (n=6), Vibrio parahaemolyticus (n=3), Vibrio harveyi (n=2) and each isolate for Vibrio vulnificus, Vibrio alginolyticus and Vibrio spp. The results showed that all isolates were sensitive to most antibiotics except ampicillin, neomycin and streptomycin. The MAR index value was ranging from 0 to 0.31. This study demonstrates the prevalence of Vibrio spp. in seabass and the report on multidrug resistance strains that could be of concern to the fish farmers. In addition, data from this study can be further used in fish disease management plans.