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Measuring organic carbon, nutrients and heavy metals in rivers receiving leachate from controlled and uncontrolled municipal solid waste (MSW) landfills

Yusof N, Haraguchi A, Hassan MA, Othman MR, Wakisaka M, Shirai Y

Waste Manag, 2009 Oct;29(10):2666-80.
PMID: 19564103 DOI: 10.1016/j.wasman.2009.05.022

Since landfilling is the common method of waste disposal in Malaysia, river water is greatly exposed to the risk of contamination from leachate unless proper leachate management is carried out. In this study, leachates from three different types of landfills, namely active uncontrolled, active controlled and closed controlled, were characterized, and their relationships with river water chemistry were examined monthly for a year. The influence of leachate on river water chemistry from each type of landfill depended on many factors, including the presence of a leachate control mechanism, leachate characteristics, precipitation, surface runoff and the applied treatment. The impact of leachate from an active uncontrolled landfill was the highest, as the organic content, NH(4)(+)-N, Cd and Mn levels appeared high in the river. At the same time, influences of leachate were also observed from both types of controlled landfills in the form of inorganic nitrogen (NH(4)(+)-N, NO(3)(-)-N and NO(2)(-)-N) and heavy metals (Fe, Cr, Ni and Mn). Improper treatment practice led to high levels of some contaminants in the stream near the closed controlled landfill. Meanwhile, the active controlled landfill, which was located near the coastline, was exposed to the risk of contamination resulting from the pyrite oxidation of the surrounding area.
Baseline study of methane emission from open digesting tanks of palm oil mill effluent treatment

Yacob S, Hassan MA, Shirai Y, Wakisaka M, Subash S

Chemosphere, 2005 Jun;59(11):1575-81.
PMID: 15894045

Anthropogenic release of greenhouse gases, especially CO2 and CH4 has been recognized as one of the main causes of global warming. Several measures under the Kyoto Protocol 1997 have been drawn up to reduce the greenhouse gases emission. One of the measures is Clean Development Mechanisms (CDM) that was created to enable developed countries to cooperate with developing countries in emission reduction activities. In Malaysia, palm oil industry particularly from palm oil mill effluent (POME) anaerobic treatment has been identified as an important source of CH4. However, there is no study to quantify the actual CH4 emission from the commercial scale wastewater treatment facility. Hence, this paper shall address the CH4 emission from the open digesting tanks in Felda Serting Hilir Palm Oil Mill. CH4 emission pattern was recorded for 52 weeks from 3600 m3 open digesting tanks. The findings indicated that the CH4 content was between 13.5% and 49.0% which was lower than the value of 65% reported earlier. The biogas flow rate ranged between 0.8l min(-1)m(-2) and 9.8l min(-1)m(-2). Total CH4 emission per open digesting tank was 518.9 kgday(-1). Relationships between CH4 emission and total carbon removal and POME discharged were also discussed. Fluctuation of biogas production was observed throughout the studies as a result of seasonal oil palm cropping, mill activities, variation of POME quality and quantity discharged from the mill. Thus only through long-term field measurement CH4 emission can be accurately estimated.
Baseline study of methane emission from anaerobic ponds of palm oil mill effluent treatment

Yacob S, Ali Hassan M, Shirai Y, Wakisaka M, Subash S

Sci Total Environ, 2006 Jul 31;366(1):187-96.
PMID: 16125215

The world currently obtains its energy from the fossil fuels such as oil, natural gas and coal. However, the international crisis in the Middle East, rapid depletion of fossil fuel reserves as well as climate change have driven the world towards renewable energy sources which are abundant, untapped and environmentally friendly. Malaysia has abundant biomass resources generated from the agricultural industry particularly the large commodity, palm oil. This paper will focus on palm oil mill effluent (POME) as the source of renewable energy from the generation of methane and establish the current methane emission from the anaerobic treatment facility. The emission was measured from two anaerobic ponds in Felda Serting Palm Oil Mill for 52 weeks. The results showed that the methane content was between 35.0% and 70.0% and biogas flow rate ranged between 0.5 and 2.4 L/min/m(2). Total methane emission per anaerobic pond was 1043.1 kg/day. The total methane emission calculated from the two equations derived from relationships between methane emission and total carbon removal and POME discharged were comparable with field measurement. This study also revealed that anaerobic pond system is more efficient than open digesting tank system for POME treatment. Two main factors affecting the methane emission were mill activities and oil palm seasonal cropping.
Enhanced crystallinity and thermal properties of cellulose from rice husk using acid hydrolysis treatment

Hafid HS, Omar FN, Zhu J, Wakisaka M

Carbohydr Polym, 2021 May 15;260:117789.
PMID: 33712137 DOI: 10.1016/j.carbpol.2021.117789

Cellulose was extracted from rice husk (RH) using an integrated delignification process using alkaline treatment and acid hydrolysis (concentrated HNO3) for lignocellulosic biomass dissolution. Cellulose yield and quality were assessed through analysis of lignocellulosic content, thermogravimetric, functional group, X-ray diffraction, and surface morphology. HNO3 treatment showed an increment (2.01-fold) in the cellulose content and some enhancement in the crystallinity of cellulose (up to 40.8%). A slight increase was observed in thermal properties from 334.6 °C to 339.3 °C. Economic analysis showed chlorine extraction produce higher cellulose recovery (58%) as compared to HNO3 (26.7%) with the total cost of operation using HNO3 was double compared to chlorine extraction. The economic feasibility of HNO3 can be improved using various progress in the pre-treatment process, chemical recycling and cellulose recovery process since adopting it is crucial for environmental sustainability.
Extraction and surface modification of cellulose fibers and its reinforcement in starch-based film for packaging composites

Hafid HS, Omar FN, Bahrin EK, Wakisaka M

Bioresour Bioprocess, 2023 Jan 25;10(1):7.
PMID: 38647891 DOI: 10.1186/s40643-023-00631-w

BACKGROUND: Cellulose extraction from gloss art paper (GAP) waste is a recycling strategy for the abundance of gloss art paper waste. Here, a study was conducted on the impact of ultrasonic homogenization for cellulose extraction from GAP waste to improve the particle size, crystallinity, and thermal stability.
RESULTS: At treatment temperature of 75.8 °C, ultrasonic power level of 70.3% and 1.4 h duration, cellulose with properties of 516.4 nm particle size, 71.5% crystallinity, and thermal stability of 355.2 °C were extracted. Surface modification of cellulose GAP waste with H3PO4 hydrolysis and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation was done followed by starch reinforcement. Surface hydrophobicity and mechanical strength were increased for H3PO4 hydrolysis and TEMPO oxidation starch-cellulose. No reduction of thermal properties observed during the treatment, while increment of crystallinity index up to 47.65-59.6% was shown. Neat starch film was more transparent, followed by starch-TEMPO film and starch-H3PO4 film, due to better homogeneity.
CONCLUSIONS: The cellulose GAP reinforced starch film shows potential in developing packaging materials and simultaneously provide an alternative solution of GAP waste recycling.
Fulltext Bioconversion of glycerol for bioethanol production using isolated Escherichia coli ss1

Suhaimi SN, Phang LY, Maeda T, Abd-Aziz S, Wakisaka M, Shirai Y, et al.

Braz J Microbiol, 2012 Apr;43(2):506-16.
PMID: 24031858 DOI: 10.1590/S1517-83822012000200011

Bioconverting glycerol into various valuable products is one of glycerol's promising applications due to its high availability at low cost and the existence of many glycerol-utilizing microorganisms. Bioethanol and biohydrogen, which are types of renewable fuels, are two examples of bioconverted products. The objectives of this study were to evaluate ethanol production from different media by local microorganism isolates and compare the ethanol fermentation profile of the selected strains to use of glucose or glycerol as sole carbon sources. The ethanol fermentations by six isolates were evaluated after a preliminary screening process. Strain named SS1 produced the highest ethanol yield of 1.0 mol: 1.0 mol glycerol and was identified as Escherichia coli SS1 Also, this isolated strain showed a higher affinity to glycerol than glucose for bioethanol production.
Mechanical characterisation of lignocellulosic fibres using toy bricks tensile tester

Talib AT, P Mohammed MA, Baharuddin AS, Mokhtar MN, Wakisaka M

J Mech Behav Biomed Mater, 2019 09;97:58-64.
PMID: 31100486 DOI: 10.1016/j.jmbbm.2019.05.010

This paper demonstrates the potential use of toy-bricks as the building block of a mechanical tensile testing instrument for the mechanical characterisation of natural fibres. A table-top tensile testing instrument was developed using LEGO parts (Mindstorms EV3 and Technics) and a 2 kg capacity load cell, whereas deformation modes were programmed in an open source programming language. Experimental work was conducted on oil palm fibres under different tensile modes (i.e. constant deformation, triple-twisted-tension and deformation-relaxation modes), which showed anisotropic-viscoelastic behaviour, and microstructural damages due to deformation.
Fulltext Fabrication of flexible chitosan film reinforced with pulping by-product lignosulfonates for cherry-tomato preservation

Zhu J, Fang Y, Wakisaka M, Saadiah Hafid H, Yang Z, Yin Y, et al.

Food Chem X, 2024 Mar 30;21:101181.
PMID: 38357373 DOI: 10.1016/j.fochx.2024.101181

The massive production of food waste and plastic pollution necessitates innovative solutions. This study reports the first fabrication of a flexible chitosan (CH) film reinforced with lignosulfonate (LS) derived from pulping byproduct as a sustainable alternative to synthetic food packaging. The CH/LS composite film was prepared by a simple casting method with varying LS contents of 1 % and 2 %. Compared to CH film, the addition of 2 % LS increased the tensile strength by over 4 times and decreased water vapor permeability by 11 %. Moreover, the CH/LS film exhibited excellent UV-shielding properties. This novel use of LS to reinforce CH film presents an eco-friendly active packaging material. When used to package cherry tomatoes for 2 weeks, the CH/LS film effectively maintained fruit freshness and hardness while minimizing weight loss. This work provides new scientific evidence on the optimized preparation and application of CH/LS composite films from renewable resources for food preservation.
Nitrification of high-strength ammonium landfill leachate with microbial community analysis using fluorescence in situ hybridization (FISH)

Yusof N, Hassan MA, Yee PL, Tabatabaei M, Othman MR, Mori M, et al.

Waste Manag Res, 2011 Jun;29(6):602-11.
PMID: 21447612 DOI: 10.1177/0734242X10397581

Nitrification of mature sanitary landfill leachate with high-strength of N-NH(4) + (1080-2350 mg L(-1)) was performed in a 10 L continuous nitrification activated sludge reactor. The nitrification system was acclimatized with synthetic leachate during feed batch operation to avoid substrate inhibition before being fed with actual mature leachate. Successful nitrification was achieved with an approximately complete ammonium removal (99%) and 96% of N-NH(4) + conversion to N-NO(-) (3) . The maximum volumetric and specific nitrification rates obtained were 2.56 kg N-NH(4) (+) m(-3) day(-1) and 0.23 g N-NH(4) ( +) g(-1) volatile suspended solid (VSS) day(-1), respectively, at hydraulic retention time (HRT) of 12.7 h and solid retention time of 50 days. Incomplete nitrification was encountered when operating at a higher nitrogen loading rate of 3.14 kg N-NH(4) (+) m(-3) day(-1). The substrate overloading and nitrifiers competition with heterotrophs were believed to trigger the incomplete nitrification. Fluorescence in situ hybridization (FISH) results supported the syntrophic association between the ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria. FISH results also revealed the heterotrophs as the dominant and disintegration of some AOB cell aggregates into single cells which further supported the incomplete nitrification phenomenon.
Mitigation of oxidative stress damage caused by abiotic stress to improve biomass yield of microalgae: A review

Zhu J, Cai Y, Wakisaka M, Yang Z, Yin Y, Fang W, et al.

Sci Total Environ, 2023 Oct 20;896:165200.
PMID: 37400020 DOI: 10.1016/j.scitotenv.2023.165200

Microalgae have been recognized as emerging cell factories due to the high value-added bio-products. However, the balance between algal growth and the accumulation of metabolites is always the main contradiction in algal biomass production. Hence, the security and effectiveness of regulating microalgal growth and metabolism simultaneously have drawn substantial attention. Since the correspondence between microalgal growth and reactive oxygen species (ROS) level has been confirmed, improving its growth under oxidative stress and promoting biomass accumulation under non-oxidative stress by exogenous mitigators is feasible. This paper first introduced ROS generation in microalgae and described the effects of different abiotic stresses on the physiological and biochemical status of microalgae from these aspects associated with growth, cell morphology and structure, and antioxidant system. Secondly, the role of exogenous mitigators with different mechanisms in alleviating abiotic stress was concluded. Finally, the possibility of exogenous antioxidants regulating microalgal growth and improving the accumulation of specific products under non-stress conditions was discussed.