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Fulltext Waste management developments in the last five decades: Asian perspective

Agamuthu P, Babel S

Waste Manag Res, 2023 Dec;41(12):1699-1716.
PMID: 37823520 DOI: 10.1177/0734242X231199938

Solid waste management was explored in Asia's last five decades, and the issues and challenges were identified. Waste generation has increased in all nations in the previous 50 years, although more recently, a declining trend has been observed in Japan and Korea. The composition has been predominantly organic, with 45-50% being kitchen waste. Material extraction and productivity to sustain the most populous part of the globe are explained. Waste management technologies have evolved, with more nations slowly transitioning from landfills to using waste-to-energy options. However, landfilling and open dumps are still the major disposal choice in most developing countries in Asia. Thus, the issues of concern include dumpsites management, the informal sector, waste collection, open burning and food waste. Changes (increasing trends) in the recycling technologies and quantum are evident, as seen in several country reports from India, Indonesia, Japan, Malaysia, Singapore, South Korea, Thailand and Vietnam. There are several issues and challenges for recycling, which are explored in the text. Lastly, the drivers that propel the whole scenario of waste management in Asia and the evolution of these drivers over time are discussed. Several recommendations are included to achieve sustainable waste management in Asia.

Matched MeSH terms: Refuse Disposal*
The knowledge, attitude, and practice of the public regarding household pharmaceutical waste disposal: a systematic review (2013-2023)

Hiew SY, Low BY

Int J Pharm Pract, 2024 Mar 06;32(2):120-132.
PMID: 38300734 DOI: 10.1093/ijpp/riae001

OBJECTIVE: The improper disposal of household pharmaceutical waste (HPW) is an emerging cause of environmental pollution. Behavioural practices are intricately linked to individuals' knowledge levels and attitudes. Thus, this systematic review aims to assess the knowledge, attitude, and practice (KAP) of HPW disposal among the public and to examine the interconnectedness of these KAP components.
METHODS: A literature review for articles published from 2013 to 2023 was carried out in scientific databases PubMed, Scopus, and Web of Science, identifying quantitative studies involving the assessment of KAP of the public concerning HPW disposal.
RESULTS: This review incorporated 12 studies conducted in Africa, South Asia, and Southeast Asia. Nine studies highlighted a consistent trend of limited to inadequate knowledge regarding safe medication disposal. Notwithstanding, respondents largely exhibited a positive attitude towards proper medication disposal. This encouraging disposition, unfortunately, stands in stark contrast to the reported practices, which appeared to be inadequate. This dissonance might be due to a deficit in accessible disposal facilities and information, compounded with insufficient guidance from healthcare professionals. Interestingly, the majority expressed support for take-back programs aimed at managing unused and expired medications.
CONCLUSION: This review identified a need for a comprehensive understanding of the interconnected dynamics among KAP components regarding safe medication disposal. The exploration of theoretical behavioural frameworks could help predict public intentions to adopt safe medication disposal practices. Ultimately, a multi-faceted approach that addresses knowledge gaps, reinforces positive attitudes, and promotes accessible safe medication disposal services can collectively safeguard the environment and public health.

Matched MeSH terms: Refuse Disposal*
Fulltext Integrated models for solid waste management in tourism regions: Langkawi Island, Malaysia

Shamshiry E, Nadi B, Mokhtar MB, Komoo I, Hashim HS, Yahaya N

J Environ Public Health, 2011;2011:709549.
PMID: 21904559 DOI: 10.1155/2011/709549

The population growth, changing consumption patterns, and rapid urbanization contribute significantly to the growing volumes of solid waste that are generated in urban settings. As the rate of urbanization increases, demand on the services of solid waste management increases. The rapid urban growth in Langkawi Island, Malaysia, combined with the increasing rates of solid waste production has provided evidence that the traditional solid waste management practices, particularly the methods of waste collection and disposal, are inefficient and quite nonsustainable. Accordingly, municipal managers and planners in Langkawi need to look for and adopt a model for solid waste management that emphasizes an efficient and sustainable management of solid wastes in Langkawi Island. This study presents the current practices of solid waste management in Langkawi Island, describes the composition of the solid waste generated in that area, and presents views of local residents and tourist on issues related to solid waste management like the aesthetic value of the island environment. The most important issue of this paper is that it is the first time that integrated solid waste management is investigated in the Langkawi Island.

Matched MeSH terms: Refuse Disposal*
Municipal solid waste management for low-carbon transition: A systematic review of artificial neural network applications for trend prediction

Hoy ZX, Phuang ZX, Farooque AA, Fan YV, Woon KS

Environ Pollut, 2024 Mar 01;344:123386.
PMID: 38242306 DOI: 10.1016/j.envpol.2024.123386

Improper municipal solid waste (MSW) management contributes to greenhouse gas emissions, necessitating emissions reduction strategies such as waste reduction, recycling, and composting to move towards a more sustainable, low-carbon future. Machine learning models are applied for MSW-related trend prediction to provide insights on future waste generation or carbon emissions trends and assist the formulation of effective low-carbon policies. Yet, the existing machine learning models are diverse and scattered. This inconsistency poses challenges for researchers in the MSW domain who seek to identify and optimize the machine learning techniques and configurations for their applications. This systematic review focuses on MSW-related trend prediction using the most frequently applied machine learning model, artificial neural network (ANN), while addressing potential methodological improvements for reducing prediction uncertainty. Thirty-two papers published from 2013 to 2023 are included in this review, all applying ANN for MSW-related trend prediction. Observing a decrease in the size of data samples used in studies from daily to annual timescales, the summarized statistics suggest that well-performing ANN models can still be developed with approximately 33 annual data samples. This indicates promising opportunities for modeling macroscale greenhouse gas emissions in future works. Existing literature commonly used the grid search (manual) technique for hyperparameter (e.g., learning rate, number of neurons) optimization and should explore more time-efficient automated optimization techniques. Since there are no one-size-fits-all performance indicators, it is crucial to report the model's predictive performance based on more than one performance indicator and examine its uncertainty. The predictive performance of newly-developed integrated models should also be benchmarked to show performance improvement clearly and promote similar applications in future works. The review analyzed the shortcomings, best practices, and prospects of ANNs for MSW-related trend predictions, supporting the realization of practical applications of ANNs to enhance waste management practices and reduce carbon emissions.

Matched MeSH terms: Refuse Disposal/methods
Trends in sustainable landfilling in Malaysia, a developing country

Fauziah SH, Agamuthu P

Waste Manag Res, 2012 Jul;30(7):656-63.
PMID: 22455994 DOI: 10.1177/0734242X12437564

In Malaysia, landfills are being filled up rapidly due to the current daily generation of approximately 30,000 tonnes of municipal solid waste. This situation creates the crucial need for improved landfilling practices, as sustainable landfilling technology is yet to be achieved here. The objective of this paper is to identify and evaluate the development and trends in landfilling practices in Malaysia. In 1970, the disposal sites in Malaysia were small and prevailing waste disposal practices was mere open-dumping. This network of relatively small dumps, typically located close to population centres, was considered acceptable for a relatively low population of 10 million in Malaysia. In the 1980s, a national programme was developed to manage municipal and industrial wastes more systematically and to reduce adverse environmental impacts. The early 1990s saw the privatization of waste management in many parts of Malaysia, and the establishment of the first sanitary landfills for MSW and an engineered landfill (called 'secure landfill' in Malaysia) for hazardous waste. A public uproar in 2007 due to contamination of a drinking water source from improper landfilling practices led to some significant changes in the government's policy regarding the country's waste management strategy. Parliament passed the Solid Waste and Public Cleansing Management (SWPCM) Act 2007 in August 2007. Even though the Act is yet to be implemented, the government has taken big steps to improve waste management system further. The future of the waste management in Malaysia seems somewhat brighter with a clear waste management policy in place. There is now a foundation upon which to build a sound and sustainble waste management and disposal system in Malaysia.

Matched MeSH terms: Refuse Disposal/legislation & jurisprudence; Refuse Disposal/methods*; Refuse Disposal/statistics & numerical data
Challenges and issues in moving towards sustainable landfilling in a transitory country - Malaysia

Agamuthu P, Fauziah SH

Waste Manag Res, 2011 Jan;29(1):13-9.
PMID: 20880936 DOI: 10.1177/0734242X10383080

Malaysia disposes of 28,500 tonnes of municipal solid waste directly into landfills daily. This fact alone necessitates sustainable landfills to avoid adverse impacts on the population and the environment. The aim of the present study was to elucidate the issues and challenges faced by waste managers in moving towards sustainable landfilling in Malaysia. Various factors influence the management of a landfill. Among them is the human factor, which includes attitude and public participation. Although Malaysia's economy is developing rapidly, public concern and awareness are not evolving in parallel and therefore participation towards sustainable waste management through the 'reduce, reuse and recycle' approach (3Rs) is severely lacking. Consequently, landfill space is exhausted earlier than scheduled and this is no longer sustainable in terms of security of disposal. Challenges also arise from the lack of funding and the increase in the price of land. Thus, most waste managers normally aim for 'just enough' to comply with the regulations. Investment for the establishment of landfills generally is minimized since landfilling operations are considered uneconomical after closure. Institutional factors also hamper the practice of sustainable landfilling in the country where 3Rs is not mandatory and waste separation is totally absent. Although there are huge obstacles to be dealt with in moving towards sustainable landfilling in Malaysia, recent developments in waste management policy and regulations have indicated that positive changes are possible in the near future. Consequently, with the issues solved and challenges tackled, landfills in Malaysia can then be managed effectively in a more sustainable manner.

Matched MeSH terms: Refuse Disposal/economics*; Refuse Disposal/legislation & jurisprudence; Refuse Disposal/methods
Fulltext BIOMASS ACTIVATED CARBON PROPERTIES THROUGH ACTIVATION METHOD FOR SUPERCAPACITOR – A MINI-REVIEW

Madhiyah Yahaya Bermakai, Nor Farahin Jafri, Norha Abdul Hadi

Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2021;9(1):8-13.
MyJurnal

Recently, the development of activated carbon electrodes from agricultural waste biomass for application in carbon-based electrode of supercapacitor is increasing. The use of agricultural waste biomass as a precursor for the production of activated carbon become popular because it is economical, easily available and also beneficial in reducing waste disposal problem in agricultural industries. In this review, the biomass material for activated carbon using various activators is presented. The effects of activating methods which is physical and chemical activation on the properties of activated carbons are reviewed. Carbonaceous materials with high surface area, which is above 1000 m2g-1 and good porosity with total pore volume approximately 1.0 cm3g-1 promote fast ion-transport, making them an ideal choice to be used in supercapacitor. Previous study had shown that different types of activation method influence significantly on the properties of activated carbon produced. Producing a high porosity and high surface area of activated carbon are essentials to fabricate a high quality of supercapacitor. With proper treatment, it is found that many agriculture wastes have high potential and carry good properties as an electrode in supercapacitor.

Matched MeSH terms: Refuse Disposal
Fulltext Screening of significant media components for production of bioprotein from coconut dregs using statistical approach

Hafiza, S., Ahmad Anas, N.G., Nor Hidayah, B.

International Food Research Journal, 2012;19(2):499-502.
MyJurnal

The production of bioprotein by coconut dregs is found to be a novel and cheaper carbon source.
Media optimization for bioprotein production from coconut dregs through solid state fermentation has been developed as a one of the approaches to increase the protein production. The utilization of these coconut dregs provides as alternative substrates and also helps in solving waste disposal problems. Among the seven media components, only NH4NO3, MgSO4.7H2O and CuSO4.5H2O were found to be significantly affecting the bioprotein production.

Matched MeSH terms: Refuse Disposal
Fulltext A review on materials waste quantification and management in construction activities

C.H. Asmawati, M.R. Ahmad Ruslan, Y. Zulkiflee, M.N.N. Husna

ASM Science Journal, 2013;7(2):113-117.
MyJurnal

Nowadays, construction and demolition waste has become a major issue to environmental problems faced by many countries. This concern comes from the inefficiencies of waste management which includes the waste generated from construction and demolition activities. In Malaysia, there is a lack of database records on construction waste and this has affected proper management planning of the waste. As there is a lack of policy on construction waste management, control on construction waste disposal is very hazy and this has aggravated environmental problems and exhausted landfill usage and increased illegal dumping. This paper reviews the critical issues on construction waste management and also discusses several estimation models on construction waste generation from several countries. Based on the review, most of the countries faced problems regarding construction waste management and the models developed were considered as one of the methods which could be adopted for better management of construction wastes.

Matched MeSH terms: Refuse Disposal
Feature extraction using Hough transform for solid waste bin level detection and classification

Hannan MA, Zaila WA, Arebey M, Begum RA, Basri H

Environ Monit Assess, 2014 Sep;186(9):5381-91.
PMID: 24829160 DOI: 10.1007/s10661-014-3786-6

This paper deals with the solid waste image detection and classification to detect and classify the solid waste bin level. To do so, Hough transform techniques is used for feature extraction to identify the line detection based on image's gradient field. The feedforward neural network (FFNN) model is used to classify the level content of solid waste based on learning concept. Numbers of training have been performed using FFNN to learn and match the targets of the testing images to compute the sum squared error with the performance goal met. The images for each class are used as input samples for classification. Result from the neural network and the rules decision are used to build the receiver operating characteristic (ROC) graph. Decision graph shows the performance of the system waste system based on area under curve (AUC), WS-class reached 0.9875 for excellent result and WS-grade reached 0.8293 for good result. The system has been successfully designated with the motivation of solid waste bin monitoring system that can applied to a wide variety of local municipal authorities system.

Matched MeSH terms: Refuse Disposal/methods*
Quantifying (12/13)CH(4) migration and fate following sub-surface release to an agricultural soil

Shaw G, Atkinson B, Meredith W, Snape C, Steven M, Hoch A, et al.

J Environ Radioact, 2014 Jul;133:18-23.
PMID: 23958331 DOI: 10.1016/j.jenvrad.2013.07.006

Following gas generation in a Geological Disposal Facility (GDF), (14)C-containing gases could migrate through the geosphere, eventually diffusing into soils at the Earth's surface. This paper reports summary results from laboratory and field experiments to obtain information on the probable rates of a) diffusive transport and b) oxidation of (12/13)CH(4) (as a surrogate for (14)CH4) in a typical agricultural soil in the UK. Rates of CH(4) oxidation were generally low in the field and undisturbed soil columns, though a re-packed column of homogenised topsoil oxidised ambient atmospheric CH(4) 20× faster than an undisturbed soil column. In contrast to low observed rates of CH(4) oxidation, the effective diffusion of CH(4) through the soil was rapid. Isotopically labelled CH(4) injected at a depth of 45 cm in the field diffused to the surface and exited the soil over a time period ranging from 8 to 24 h. The rate of CH(4) diffusion through the soil was increased by the presence of ryegrass roots which increased soil porosity and decreased water content. δ(13)C values for laboratory column soils after labelled CH(4) injection experiments showed no sign of residual (13)C, despite the extremely high δ(13)C values of the injected (12/13)CH(4). If laboratory observations are confirmed by measurements in field samples it can be concluded that the majority of (14)CH(4) from a GDF which enters a soil with low methanotrophic activity will be lost to the free atmosphere after diffusing rapidly through the soil column.

Matched MeSH terms: Refuse Disposal*
VFA and ammonia from residential food waste as indicators of odor potential

Qamaruz-Zaman N, Milke MW

Waste Manag, 2012 Dec;32(12):2426-30.
PMID: 22819598 DOI: 10.1016/j.wasman.2012.06.023

Research was conducted to determine suitable chemical parameters as indicators of odor from decomposing food wastes. Prepared food scraps were stored in 18 l plastic buckets (2 kg wet weight each) at 20 °C and 8 °C to reproduce high and low temperature conditions. After 1, 3, 7, 10 and 14 days of storage, the odor from the buckets were marked to an intensity scale of 0 (no odor) to 5 (intense) and the corresponding leachate analyzed for volatile fatty acids, ammonia and total organic carbon. A linear relationship between odor intensity and the measured parameter indicates a suitable odor indicator. Odor intensified with longer storage period and warmer surroundings. The study found ammonia and isovaleric acid to be promising odor indicators. For this food waste mixture, offensive odors were emitted if the ammonia and isovaleric acid contents exceeded 360 mg/l and 940 mg/l, respectively.

Matched MeSH terms: Refuse Disposal*
Measurement of biochemical oxygen demand of the leachates

Fulazzaky MA

Environ Monit Assess, 2013 Jun;185(6):4721-34.
PMID: 23001555 DOI: 10.1007/s10661-012-2899-z

Biochemical oxygen demand (BOD) of the leachates originally from the different types of landfill sites was studied based on the data measured using the two manometric methods. The measurements of BOD using the dilution method were carried out to assess the typical physicochemical and biological characteristics of the leachates together with some other parameters. The linear regression analysis was used to predict rate constants for biochemical reactions and ultimate BOD values of the different leachates. The rate of a biochemical reaction implicated in microbial biodegradation of pollutants depends on the leachate characteristics, mass of contaminant in the leachate, and nature of the leachate. Character of leachate samples for BOD analysis of using the different methods may differ significantly during the experimental period, resulting in different BOD values. This work intends to verify effect of the different dilutions for the manometric method tests on the BOD concentrations of the leachate samples to contribute to the assessment of reaction rate and microbial consumption of oxygen.

Matched MeSH terms: Refuse Disposal*
Treatment of landfill leachate by using lateritic soil as a natural coagulant

Syafalni, Lim HK, Ismail N, Abustan I, Murshed MF, Ahmad A

J Environ Manage, 2012 Dec 15;112:353-9.
PMID: 22964042 DOI: 10.1016/j.jenvman.2012.08.001

In this research, the capability of lateritic soil used as coagulant for the treatment of stabilized leachate from the Penang-Malaysia Landfill Site was investigated. The evaluation of lateritic soil coagulant in comparison with commercialized chemical coagulants, such as alum, was performed using conventional jar test experiments. The optimum pH and coagulant dosage were identified for the lateritic soil coagulant and the comparative alum coagulant. It was found that the application of lateritic soil coagulant was quite efficient in the removal of COD, color and ammoniacal-nitrogen content from the landfill leachate. The optimal pH value was 2.0, while 14 g/L of lateritic soil coagulant was sufficient in removing 65.7% COD, 81.8% color and 41.2% ammoniacal-nitrogen. Conversely, the optimal pH and coagulant dosage for the alum were pH 4.8 and 10 g/L respectively, where 85.4% COD, 96.4% color and 47.6% ammoniacal-nitrogen were removed from the same leachate sample. Additionally, the Sludge Volume Index (SVI) ratio of alum and lateritic soil coagulant was 53:1, which indicated that less sludge was produced and was an environmentally friendly product. Therefore, lateritic soil coagulant can be considered a viable alternative in the treatment of landfill leachate.

Matched MeSH terms: Refuse Disposal/methods*
Regional landfills methane emission inventory in Malaysia

Abushammala MF, Noor Ezlin Ahmad Basri, Basri H, Ahmed Hussein El-Shafie, Kadhum AA

Waste Manag Res, 2011 Aug;29(8):863-73.
PMID: 20858637 DOI: 10.1177/0734242X10382064

The decomposition of municipal solid waste (MSW) in landfills under anaerobic conditions produces landfill gas (LFG) containing approximately 50-60% methane (CH(4)) and 30-40% carbon dioxide (CO(2)) by volume. CH(4) has a global warming potential 21 times greater than CO(2); thus, it poses a serious environmental problem. As landfills are the main method for waste disposal in Malaysia, the major aim of this study was to estimate the total CH(4) emissions from landfills in all Malaysian regions and states for the year 2009 using the IPCC, 1996 first-order decay (FOD) model focusing on clean development mechanism (CDM) project applications to initiate emission reductions. Furthermore, the authors attempted to assess, in quantitative terms, the amount of CH(4) that would be emitted from landfills in the period from 1981-2024 using the IPCC 2006 FOD model. The total CH(4) emission using the IPCC 1996 model was estimated to be 318.8 Gg in 2009. The Northern region had the highest CH(4) emission inventory, with 128.8 Gg, whereas the Borneo region had the lowest, with 24.2 Gg. It was estimated that Pulau Penang state produced the highest CH(4) emission, 77.6 Gg, followed by the remaining states with emission values ranging from 38.5 to 1.5 Gg. Based on the IPCC 1996 FOD model, the total Malaysian CH( 4) emission was forecast to be 397.7 Gg by 2020. The IPCC 2006 FOD model estimated a 201 Gg CH(4) emission in 2009, and estimates ranged from 98 Gg in 1981 to 263 Gg in 2024.

Matched MeSH terms: Refuse Disposal*
Effect of adding palm oil mill decanter cake slurry with regular turning operation on the composting process and quality of compost from oil palm empty fruit bunches

Yahya A, Sye CP, Ishola TA, Suryanto H

Bioresour Technol, 2010 Nov;101(22):8736-41.
PMID: 20609579 DOI: 10.1016/j.biortech.2010.05.073

Formation of compost from oil palm empty fruit bunches (EFB) and decanter cake slurry by adding palm oil mill effluent (POME) with regular turning operation was investigated. The experiment was conducted in a commercial composting plant under the normal production process. The addition of decanter cake slurry has hastened the composting process of the EFB. The C/N ratio after 51 days for the mature compost with the decanter cake slurry was 18.65 while that of the matured compost without the decanter cake slurry remained high at 28.96. The compost formed from the addition of decanter cake to EFB and POME had 46.4% nitrogen, 17.9% phosphorus, 17.7% potassium and 23.1% calcium more than that without decanter cake. The use of compost produced from EFB, POME and decanter cake slurry could solve more environmental problems and enhance economic benefits in the oil palm industry.

Matched MeSH terms: Refuse Disposal/methods*
Appraisal of domestic solid waste generation, components, and the feasibility of recycling in Erbil, Iraq

Shuokr Qarani Aziz, Hamidi Abdul Aziz, Mohammed Jk Bashir, Mohd Suffian Yusoff

Waste Manag Res, 2011 Aug;29(8):880-7.
PMID: 21242179 DOI: 10.1177/0734242X10387462

Solid waste collection and disposal are among the most vital services provided to about 700 770 residents of the city of Erbil in northern Iraq. As such, proper waste management systems that consider both the quantity and composition of domestic solid waste are strongly required to address the increasing amount of solid waste. Unfortunately, these essential data are not easily available. The present study sought to gather data on the quantity and composition of domestic solid waste collected from different quarters in Erbil, and the feasibility of recycling these wastes. The solid waste generation rate (GR), uncompacted density, and weight percentages of combustible and incombustible materials were determined based on the collected materials (i.e., food, plastic, paper, metal, glass and cloth). The results show that the average GR and uncompacted density were 0.654 kg capita(-1) day(-1) and 175.72 kg m(-3), respectively. The weight percentages of food, plastic, paper, metal, glass, and cloth as components of domestic solid waste were 79.34, 6.28, 5.9, 3.6, 3.42 and 1.45%, respectively.

Matched MeSH terms: Refuse Disposal/methods*
Simplex-centroid mixture formulation for optimised composting of kitchen waste

Abdullah N, Chin NL

Bioresour Technol, 2010 Nov;101(21):8205-10.
PMID: 20624604 DOI: 10.1016/j.biortech.2010.05.068

Composting is a good recycling method to fully utilise all the organic wastes present in kitchen waste due to its high nutritious matter within the waste. In this present study, the optimised mixture proportions of kitchen waste containing vegetable scraps (V), fish processing waste (F) and newspaper (N) or onion peels (O) were determined by applying the simplex-centroid mixture design method to achieve the desired initial moisture content and carbon-to-nitrogen (CN) ratio for effective composting process. The best mixture was at 48.5% V, 17.7% F and 33.7% N for blends with newspaper while for blends with onion peels, the mixture proportion was 44.0% V, 19.7% F and 36.2% O. The predicted responses from these mixture proportions fall in the acceptable limits of moisture content of 50% to 65% and CN ratio of 20-40 and were also validated experimentally.

Matched MeSH terms: Refuse Disposal/methods*
Influence of Fenton reagent oxidation on mineralization and decolorization of municipal landfill leachate

Mohajeri S, Aziz HA, Isa MH, Bashir MJ, Mohajeri L, Adlan MN

J Environ Sci Health A Tox Hazard Subst Environ Eng, 2010;45(6):692-8.
PMID: 20390917 DOI: 10.1080/10934521003648883

This study evaluated the effectiveness of Fenton's technique for the treatment of semi-aerobic landfill leachate collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. The Fe2+ or Fe3+ as catalyst and H2O2 as oxidizing agent are commonly used for the classical Fenton's reaction. In present study, the effect of operating conditions such as pH, reaction time, molar ratio, agitation rate, feeding mode and Fenton reagent concentrations which are important parameters that affect the removal efficiencies of Fenton method were investigated. Under the most favorable conditions, the highest removals of 58.1 and 78.3% were observed for COD and color, respectively. In general, the best operating conditions were pH = 3, Fe = 560 mg L(-1), H2O2 = 1020 mg L(-1), H2O2/Fe2+ molar ratio = 3, agitation rate = 400 rpm and reaction time = 120 minutes. The results highlighted that stepwise addition of Fenton's reagent was more effective than adding the entire volume in a single step. Excessive hydrogen peroxide and iron have shown scavenging effects on hydroxyl radicals and reduced degradation of refractory organics in the landfill leachate.

Matched MeSH terms: Refuse Disposal*
Optimization studies on acid hydrolysis of oil palm empty fruit bunch fiber for production of xylose

Rahman SH, Choudhury JP, Ahmad AL, Kamaruddin AH

Bioresour Technol, 2007 Feb;98(3):554-9.
PMID: 16647852

Oil palm empty fruit bunch fiber is a lignocellulosic waste from palm oil mills. It is a potential source of xylose which can be used as a raw material for production of xylitol, a high value product. The increasing interest on use of lignocellulosic waste for bioconversion to fuels and chemicals is justifiable as these materials are low cost, renewable and widespread sources of sugars. The objective of the present study was to determine the effect of H(2)SO(4) concentration, reaction temperature and reaction time for production of xylose. Batch reactions were carried out under various reaction temperature, reaction time and acid concentrations and Response Surface Methodology (RSM) was followed to optimize the hydrolysis process in order to obtain high xylose yield. The optimum reaction temperature, reaction time and acid concentration found were 119 degrees C, 60 min and 2%, respectively. Under these conditions xylose yield and selectivity were found to be 91.27% and 17.97 g/g, respectively.

Matched MeSH terms: Refuse Disposal/methods

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