Displaying publications 121 - 140 of 301 in total

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  1. Kasan NA, Yusof SZM, Manan H, Khairul WM, Zakeri HA
    J Environ Manage, 2021 Sep 15;294:113008.
    PMID: 34119989 DOI: 10.1016/j.jenvman.2021.113008
    High nutrient loading in aquatic environment has become the main causative of harmful algae blooms (HABs) in water resources particularly pond, lake and river. HABs are mostly dominated by microalgae derived from the group of blue-green algae which are capable of releasing harmful toxins. Therefore, this study aims to investigate the inhibitory effects of thiourea derivatives on the growth of such blue-green algae. Thiourea derivatives have been proven to exhibit antifungal and antibacterial effects. However, there is still limited study had been conducted on the effect of thiourea derivatives toward blue-green algae species in recent years. In this research, a species of blue-green algae from Kenyir Lake, Terengganu, Malaysia was successfully isolated using morphological characters and molecularly identified as Synechoccus elongatus. Four new thiourea derivative compounds were also successfully synthesised. The compounds were designed with variation on different R-substitution group and characterised using Nuclear Magnetic Resonance (NMR) to confirm their molecular structure. Those compounds were characterised as 1-Benzyl-3-(3,5-dimethoxy-benzoyl)-thiourea (C1), 1-(3-Chloro-benzyl)-3-(3,5-dimethoxy-benzoyl)-thiourea (C2), 1-(3,5-Dimethoxy-benzoyl)-3-(3-methyl-benzyl)-thiourea (C3) and 1-(3,5-Dimethoxy-benzoyl)-3-(3-trifluoromethyl-benzyl)-thiourea (C4). For the inhibition assessment,S. elongatus were treated with C1-C4 for 5 day at concentration of 2, 5, 10 and 20 μg/ml, respectively. C3 compound showed the highest inhibition percentage with 98% of inhibition after 5 days treatment. By using Bradford method, protein extraction of S. elongatus was conducted at the highest inhibition percentage. Protein concentration of treated species was observed with 3.28 μg/ml as compared to protein concentration of control with 6.48 μg/ml. This result indicated the reduction of protein content after the treatment. Protein band pattern was identified intensed after the treatment SDS PAGE was carried out. The thiourea derivatives compound proved to have successfully inhibited the growth of blue-green algae. Hence, further study should be carried out to ensure the compound can be practically utilized in the pond and in natural environment.
  2. Valizadeh S, Ko CH, Lee J, Lee SH, Yu YJ, Show PL, et al.
    J Environ Manage, 2021 Sep 15;294:112959.
    PMID: 34116308 DOI: 10.1016/j.jenvman.2021.112959
    This study highlights the potential of pyrolysis of food waste (FW) with Ni-based catalysts under CO2 atmosphere as an environmentally benign disposal technique. FW was pyrolyzed with homo-type Ni/Al2O3 (Ni-HO) or eggshell-type Ni/Al2O3 (Ni-EG) catalysts under flowing CO2 (50 mL/min) at temperatures from 500 to 700 °C for 1 h. A higher gas yield (42.05 wt%) and a lower condensable yield (36.28 wt%) were achieved for catalytic pyrolysis with Ni-EG than with Ni-HO (34.94 wt% and 40.06 wt%, respectively). In particular, the maximum volumetric content of H2 (21.48%) and CO (28.43%) and the lowest content of C2-C4 (19.22%) were obtained using the Ni-EG. The formation of cyclic species (e.g., benzene derivatives) in bio-oil was also effectively suppressed (24.87%) when the Ni-EG catalyst and CO2 medium were concurrently utilized for the FW pyrolysis. Accordingly, the simultaneous use of the Ni-EG catalyst and CO2 contributed to altering the carbon distribution of the pyrolytic products from condensable species to value-added gaseous products by facilitating ring-opening reactions and free radical mechanisms. This study should suggest that CO2-assisted catalytic pyrolysis over the Ni-EG catalyst would be an eco-friendly and sustainable strategy for disposal of FW which also provides a clean and high-quality source of energy.
  3. Alsaleh M, Abdul-Rahim AS, Abdulwakil MM
    J Environ Manage, 2021 Sep 15;294:112960.
    PMID: 34116310 DOI: 10.1016/j.jenvman.2021.112960
    This study examined the impact of worldwide governance indicators on the sustainability of the bioenergy industry in selected European countries for the period 1996-2018. Applying the Fixed Effect (FE) Model, the results reveal that the bioenergy industry can significantly grow by improving the quality of worldwide governance indicators in European countries, especially in Western European Countries (WEC). Government effectiveness, rule of law, regulatory quality, and voice and accountability are found to be increasing the growth of the bioenergy industry. Precisely, the results further show that the magnitude of the effect of government effectiveness, voice and accountability, and Gross Domestic Product (GDP) on bioenergy output is higher in Western European Countries (WEC) as compared to the Central and Eastern European Countries (CEEC). Also, the findings further elaborate that the significant positive impact of regulatory quality and rule of law on bioenergy output is higher in CEEC countries compared to the WEC countries. The finding implies that the growth of the bioenergy industry in European countries can be effectively increased by improving the practice and quality of worldwide governance indicators. The study recommends for European countries to increase the efficiency of worldwide governance in their bioenergy industry to increase the sustainability of bioenergy production and reduce Dioxide Carbon (CO2) emissions. Policymakers in these countries should also invest more in worldwide governance to increase its effectiveness and transparency in the bioenergy industry. The authorities should equally emphasize the effectiveness and transparency of worldwide governance indicators to attain bioenergy security and lessen the dependence on fossil fuels.
  4. Abunama T, Ansari M, Awolusi OO, Gani KM, Kumari S, Bux F
    J Environ Manage, 2021 Sep 01;293:112862.
    PMID: 34049159 DOI: 10.1016/j.jenvman.2021.112862
    To ensure the safe discharge of treated wastewater to the environment, continuous efforts are vital to enhance the modelling accuracy of wastewater treatment plants (WWTPs) through utilizing state-of-art techniques and algorithms. The integration of metaheuristic modern optimization algorithms that are natlurally inspired with the Fussy Inference Systems (FIS) to improve the modelling performance is a promising and mathematically suitable approach. This study integrates four population-based algorithms, namely: Particle swarm optimization (PSO), Genetic algorithm (GA), Hybrid GA-PSO, and Mutating invasive weed optimization (M-IWO) with FIS system. A full-scale WWTP in South Africa (SA) was selected to assess the validity of the proposed algorithms, where six wastewater effluent parameters were modeled, i.e., Alkalinity (ALK), Sulphate (SLP), Phosphate (PHS), Total Kjeldahl Nitrogen (TKN), Total Suspended Solids (TSS), and Chemical Oxygen Demand (COD). The results from this study showed that the hybrid PSO-GA algorithm outperforms the PSO and GA algorithms when used individually, in modelling all wastewater effluent parameters. PSO performed better for SLP and TKN compared to GA, while the M-IWO algorithm failed to provide an acceptable modelling convergence for all the studied parameters. However, three out of four algorithms applied in this study proven beneficial to be optimized in enhancing the modelling accuracy of wastewater quality parameters.
  5. Chong JWR, Yew GY, Khoo KS, Ho SH, Show PL
    J Environ Manage, 2021 Sep 01;293:112782.
    PMID: 34052610 DOI: 10.1016/j.jenvman.2021.112782
    Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible polyester which are biosynthesized from the intracellular cells of microalgae through the cultivation of organic food waste medium. Before cultivation process, food waste must undergo several pre-treatment techniques such as chemical, biological, physical or mechanical in order to solubilize complex food waste matter into simpler micro- and macronutrients in which allow bio-valorisation of microalgae and food waste compound during the cultivation process. This work reviews four microalgae genera namely Chlamydomonas, Chlorella, Spirulina, and Botryococcus, are selected as suitable species due to rapid growth rate, minimal nutrient requirement, greater adaptability and flexibility prior to lower the overall production cost and maximized the production of PHAs. This study also focuses on the different mode of cultivation for the accumulation of PHAs followed by cell wall destabilization, extraction, and purification. Nonetheless, this review provides future insights into enhancing the productivity of bioplastic derived from microalgae towards low-cost, large-scale, and higher productivity of PHAs.
  6. Uke A, Nakazono-Nagaoka E, Chuah JA, Zain NA, Amir HG, Sudesh K, et al.
    J Environ Manage, 2021 Oct 01;295:113050.
    PMID: 34198177 DOI: 10.1016/j.jenvman.2021.113050
    Oil palm trunks (OPT) are logged for replantation and the fiber residues are disposed of into the palm plantation area. The fiber residues are expected to increase soil fertility through recycling of carbon and minerals via fiber decomposition. This study investigated the effects of OPT fiber disposal and other lignocellulosic biomass on plant growth and microbial diversity in the soil environment. Four treatment plots were tested: (A) soil+OPT fiber (1:20), (B) soil+sugarcane bagasse (1:20), (C) soil+cellulose powder (1:20), and (D) unamended soil as a negative control. Low plant height, decreased chlorophyll content, and low biomass was observed in corn grown on soil mixed with OPT fiber, cellulose, and sugarcane bagasse, when compared with those of the control. The plants grown with OPT fiber were deficient in total nitrogen and magnesium when compared with those without fiber amendment, which suggested that nitrogen and minerals in soil might be taken up by changing microflora because of the OPT fibers presence. To confirm differences in the soil microflora, metagenomics analysis was performed on untreated soil and soil from each lignocellulose treatment. The microflora of soils mixed with OPT fiber, cellulose and sugarcane bagasse revealed substantial increases in bacteria such as families Cytophagaceae and Oscillospiraceae, and two major fungal genera, Trichoderma and Trichocladium, that are involved in lignocellulose degradation. OPT fiber resulted in a drastic increase in the ratios and amounts of Trichocladium in the soil when compared with those of cellulose and sugarcane bagasse. These results indicate that unregulated disposal of OPT fiber into plantation areas could result in nutrient loss from soil by increasing the abundance of microorganisms involved in lignocellulose decomposition.
  7. Ahamad Sanadi NFB, Ibrahim N, Ong PY, Klemeš JJ, Li C, Lee CT
    J Environ Manage, 2021 Oct 01;295:113010.
    PMID: 34348429 DOI: 10.1016/j.jenvman.2021.113010
    Compost leachate (CL) is often treated as sewage. Limited studies have characterised the use of CL for agriculture application due to the variation of nutrient range, potential pollutants and need for pretreatment before use. This paper reviewed the characteristics of CL in terms of its nutrients and physical characteristics from three types of biowastes, i.e. the organic portion of municipal solid waste (OP-MSW), animal manure and green waste. The nutrient range characterised are used to develop the dilution rate of the CL as fertigation water for three types of vegetables. The dilution rate of CL developed is based on the fertigation standards set by the Food and Agriculture Organization of the United Nations and Malaysia Standards. The results show that all CL contain high organic content and micronutrients, which exceeded the upper limits. For the fertigation of vegetables using the CL, based on the requirement of COD and micronutrients (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Cr) of the vegetables, the CL from green waste required the lowest dilution rate (8-45 fold), followed by animal waste (33-65 fold) and the OP-MSW (193-1770 fold). The novel dilution range developed is vital to balance the essential nutrients in the CL while avoiding phototoxicity on plant and soil pollution. The dilution strategy developed is essential to support the conversion of CL as an organic liquid fertiliser for agricultural application.
  8. Hermawan AA, Teh KL, Talei A, Chua LHC
    J Environ Manage, 2021 Nov 01;297:113298.
    PMID: 34280854 DOI: 10.1016/j.jenvman.2021.113298
    The discharge of high levels of heavy metals into the environment is of concern due to its toxicity to aquatic life and potential human health impacts. Biofiltration systems have been used in urban environments to address nutrient contamination, but there is also evidence that such systems can be effective in reducing heavy metals concentration in stormwater. However, the accumulation pattern of heavy metals and lifespan of such systems, which are important in engineering design, have not been thoroughly explored. This study investigated the accumulation patterns of lead (Pb), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe), which are common in urban runoff, in non-vegetated filtration columns using three different types of filter media, namely sand (S), and mixtures of sand with fly ash (sand-fly ash mix, SF), and with zeolite (sand-zeolite mix, SZ). The columns were assessed in terms of infiltration rate, the mass of heavy metals accumulation at different depths, and formation of crust layer (schmutzdecke) at the surface. The results show that most of the heavy metals accumulated at the top 5-10 cm of the filter media. However, Zn was found adsorbed to a depth of 15 cm in S and SZ columns, while Mn and Fe were present in column S throughout the entire 30 cm depth of the filter media. The presence especially of Zn, Mn, and Fe in the deeper portions of the filter media before the top 5 cm layer reached its maximum adsorption capacity, hints that transport to the deeper layers is not necessarily dependent on saturation of the upper layers for these heavy metals. SF accumulated heavy metals most at the top 5 cm of the filter media layer, and retained twice the mass of heavy metals in the crust layer, compared to S and SZ columns. SF also yielded the lowest value of infiltration rate of 31 mm/h. Considering both metals accumulation and clogging potential of the filter media, the periodic maintenance of these systems is suggested to be approximately between 1.5 and 3 years.
  9. Pandey AK, Reji Kumar R, B K, Laghari IA, Samykano M, Kothari R, et al.
    J Environ Manage, 2021 Nov 01;297:113300.
    PMID: 34293672 DOI: 10.1016/j.jenvman.2021.113300
    This article offers a trend of inventions and implementations of photocatalysis process, desalination technologies and solar disinfection techniques adapted particularly for treatment of industrial and domestic wastewater. Photocatalysis treatment of wastewater using solar energy is a promising renewable solution to reduce stresses on global water crisis. Rendering to the United Nation Environment Programme, 1/3 of world population live in water-stressed countries, while by 2025 about 2/3 of world population will face water scarcity. Major pollutants exhibited from numerous sources are critically discussed with focus on potential environmental impacts & hazards. Treatment of wastewater by photocatalysis technique, solar thermal electrochemical process, solar desalination of brackish water and solar advanced oxidation process have been presented and systematically analysed with challenges. Both heterogenous and homogenous photocatalysis techniques employed for wastewater treatment are critically reviewed. For treating domestic wastewater, solar desalination technologies adopted for purifying brackish water into potable water is presented along with key challenges and remedies. Advanced oxidation process using solar energy for degradation of organic pollutant is an important technique to be reviewed due to their effectiveness in wastewater treatment process. Present article focused on three key issues i.e. major pollutants, wastewater treatment techniques and environmental benefits of using solar power for removal of pollutants. The review also provides close ideas on further research needs and major concerns. Drawbacks associated with conventional wastewater treatment options and direct solar energy-based wastewater treatment with energy storage systems to make it convenient during day and night both listed. Although, energy storage systems increase the overall cost of the wastewater treatment plant it also increases the overall efficiency of the system on environmental cost. Cost-efficient wastewater treatment methods using solar power would significantly ensure effective water source utilization, thereby contributing towards sustainable development goals.
  10. Chien F, Sadiq M, Nawaz MA, Hussain MS, Tran TD, Le Thanh T
    J Environ Manage, 2021 Nov 01;297:113420.
    PMID: 34333309 DOI: 10.1016/j.jenvman.2021.113420
    Environmental degradation is significantly studied both in the past and the current literature; however, steps towards reducing the environmental pollution in carbon emission and haze pollution like PM2.5 are not under rational attention. This study tries to cover this gap while considering the carbon emission and PM2.5 through observing the role of renewable energy, non-renewable energy, environmental taxes, and ecological innovation for the top Asian economies from 1990 to 2017. For analysis purposes, this research considers cross-sectional dependence analysis, unit root test with and without structural break (Pesaran, 2007), slope heterogeneity analysis, Westerlund and Edgerton (2008) panel cointegration analysis, Banerjee and Carrion-i-Silvestre (2017) cointegration analysis, long-short run CS-ARDL results, as well as AMG and CCEMG for robustness check. The empirical evidence in both the short- and long-run has confirmed the negative and significant effect of renewable energy sources, ecological innovation, and environmental taxes on carbon emissions and PM2.5. Whereas, non-renewable energy sources are causing environmental degradation in the targeted economies. Finally, various policy implications related to carbon emission and haze pollution like PM2.5 are also provided to control their harmful effect on the natural environment.
  11. Zhang D, Hussain HI
    J Environ Manage, 2021 Nov 01;297:113360.
    PMID: 34346402 DOI: 10.1016/j.jenvman.2021.113360
    The triple components of energy consumption, carbon dioxide emissions, and economic expansion are important to achieving sustained economic activity and sound ecological advancement. This study aims to estimate the impact of wide-ranging parameters on environmental circumstances in South Asian countries. This analysis required two approaches: 1)quantile autoregressive distributed lag (QARDL) as an econometric model, and 2) data envelopment analysis (DEA) non-parametric comparable composite index to examine concurrently South Asian nations' data for the 2000-2018 period. The underscored category of the parameters were grouped into four key indices, namely financial, fiscal, human, and energy. The DEA's mathematical composite findings reveal varied circumstances regarding environmental self-maintenance in South Asian nations. India and Pakistan are doing quite well; Afghanistan is abysmal. In addition, the QARDL approach findings reveal that energy use and fiscal indicators abate pollution. Furthermore, the correlation between fiscal decentralization and ecological attributes is strengthened by the excellent level of institutions and human capital progress. There is a unidirectional impact emanating from fiscal devolution, gross domestic product, human capital, eco-innovation, and institutional excellence on carbon dioxide pollution, although different from the other correlations obtained.
  12. Chien Bong CP, Alam MNHZ, Samsudin SA, Jamaluddin J, Adrus N, Mohd Yusof AH, et al.
    J Environ Manage, 2021 Nov 15;298:113461.
    PMID: 34435568 DOI: 10.1016/j.jenvman.2021.113461
    Polyhydroxyalkanoate (PHA) is a type of polyesters produced in the form of accumulated intracellular granules by many microorganisms. It is viewed as an environmentally friendly bioproduct due to its biodegradability and biocompatibility. The production of the PHA using oil substrates such as waste oil and plant oil, has gained considerable attention due to the high product yield and lower substrate cost. Nevertheless, the PHA fermentation using oil substrate is complicated due to the heterogenous fatty acid composition, varied bio-accessibility and possible inhibitory effect on the bacterial culture. This review presents the current state-of-the-art of PHA production from oil-based substrates. This paper firstly discusses the technical details, such as the choice of bacteria strain and fermentation conditions, characteristic of the oil substrate as well as the PHA composition and application. Finally, the paper discusses the challenges and prospects for up-scaling towards a cleaner and effective bioprocess. From the literature review, depending on the cell culture and the type of PHA produced, the oil platform can have a PHA yield of 0.2-0.8 g PHA/g oil substrate, with PHA content mostly from 40 to 90% of the cell dry weight. There is an on-going search for more effective oil-utilising PHA producers and lower cost substrate for effective PHA production. The final application of the PHA polymer influences the treatment needed during downstream processing and its economic performance. PHA with different compositions exhibits varied decomposition behaviour under different conditions, requiring further insight towards its management towards a sustainable circular economy.
  13. Sreenath S, Sudhakar K, Yusop AF
    J Environ Manage, 2021 Dec 01;299:113639.
    PMID: 34479146 DOI: 10.1016/j.jenvman.2021.113639
    Sustainability has become a focus area for practitioners and scholars due to the growing socio-economic issues. The sustainability of airport operations is being raised in various international platforms. This paper aims to identify the dimensions of sustainability and evaluate sustainable practices in airports of selected ASEAN countries. The various dimensions associated with the environmental aspect are energy management, emissions management, water and effluents management, solid waste management. It was understood that noise management, employee development, and community investment belong to the social dimension. Similarly, the factors such as economic contribution, passenger experience, airport safety, and security are inclined to economic dimensions of sustainability. It was found that environmentally sustainable practices have greater importance than social and economic initiatives in the airport context which provide quantifiable benefits for airports in the long term. Airport operators in South East Asia strived to mitigate carbon emissions, reduce waste and effluents, enhance the economic contribution, satisfy passengers, and meet employee needs. Compared to the total economic and social benefits obtained from these airports, the negative impacts of airport operation (such as noise emission from aircraft) are minimal but significant. The most common sustainable initiatives in airports, such as employee development, energy management, and passenger safety, supported sustainable development goals (SDG) 8, SDG 9, and SDG 11. A weak connection is observed between SDG 14 & SDG 15 and the airport's sustainable practices. The new technological innovations are concentrated in busy and profitable airports. A slow trend towards the adoption of new technologies for sustainable practices is observed in airports. The paper concludes that major airport operators in South-East Asia have effectively responded to the growing sustainability challenges in aviation markets. The sustainable dimensions and practices discussed will be valuable resource for airports striving to achieve sustainability goals.
  14. Kalu JU, Buang A, Aliagha GU
    J Environ Manage, 2016 Nov 01;182:519-524.
    PMID: 27529312 DOI: 10.1016/j.jenvman.2016.08.011
    Corporate real estate management holds the tent that risk which is not understood cannot be measured or managed. The effect of global warming on real estate investment and need for climate change mitigation through disclosures by companies of carbon emission information has becomes a sine-qua-non for the management of companies' carbon footprint and reducing its overall effect on global warming. This study applied the structural equation modeling technique to determine the determinants influencing Carbon Disclosure in Real Estate Companies in a developing economy. The analysis was based on 2013 annual reports of 126 property sector companies listed in Malaysia stock exchange market. The model was validated through convergent validity, discriminant validity, composite reliability and goodness of fit. The result reveals that social and financial market were critical determinant factors for carbon disclosure while the economic and institutional factors did not achieve significant effect on voluntary carbon disclosure. The result is consistent with legitimacy theory and agency theories. The implication of this finding is that increase in public education and awareness will enhance community demand for disclosure from companies and they will increase level of disclosure; also as financial institutions consider sustainability practice as a viable investment and term for credit financing, companies will be motivated to increase disclosure.
  15. Yusuf I, Ahmad SA, Phang LY, Syed MA, Shamaan NA, Abdul Khalil K, et al.
    J Environ Manage, 2016 Dec 01;183:182-95.
    PMID: 27591845 DOI: 10.1016/j.jenvman.2016.08.059
    Biodegradation of agricultural wastes, generated annually from poultry farms and slaughterhouses, can solve the pollution problem and at the same time yield valuable degradation products. But these wastes also constitute environmental nuisance, especially in Malaysia where their illegal disposal on heavy metal contaminated soils poses a serious biodegradation issue as feather tends to accumulate heavy metals from the surrounding environment. Further, continuous use of feather wastes as cheap biosorbent material for the removal of heavy metals from effluents has contributed to the rising amount of polluted feathers, which has necessitated the search for heavy metal-tolerant feather degrading strains. Isolation, characterization and application of a novel heavy metal-tolerant feather-degrading bacterium, identified by 16S RNA sequencing as Alcaligenes sp. AQ05-001 in degradation of heavy metal polluted recalcitrant agricultural wastes, have been reported. Physico-cultural conditions influencing its activities were studied using one-factor-at-a-time and a statistical optimisation approach. Complete degradation of 5 g/L feather was achieved with pH 8, 2% inoculum at 27 °C and incubation period of 36 h. The medium optimisation after the response surface methodology (RSM) resulted in a 10-fold increase in keratinase production (88.4 U/mL) over the initial 8.85 U/mL when supplemented with 0.5% (w/v) sucrose, 0.15% (w/v) ammonium bicarbonate, 0.3% (w/v) skim milk, and 0.01% (w/v) urea. Under optimum conditions, the bacterium was able to degrade heavy metal polluted feathers completely and produced valuable keratinase and protein-rich hydrolysates. About 83% of the feathers polluted with a mixture of highly toxic metals were degraded with high keratinase activities. The heavy metal tolerance ability of this bacterium can be harnessed not only in keratinase production but also in the bioremediation of heavy metal-polluted feather wastes.
  16. Emang D, Lundhede TH, Thorsen BJ
    J Environ Manage, 2016 Nov 01;182:436-445.
    PMID: 27521689 DOI: 10.1016/j.jenvman.2016.07.033
    The protected coral reefs off the coast of Malaysia receive numerous tourists, while also being as fishing grounds. These joint environmental pressures raise the need for additional costly conservation measures. It is natural to consider the potential for expanding the 'user pays' principle, already implemented in the form of various user fees. This study explores the potential for price discrimination among scuba divers at Sipadan in Malaysia. The study applies a choice experiment to estimate scuba divers willingness to pay higher user fees for avoiding decreases of or getting improvements in environmental and recreational aspects of the diving experience. We investigate how sensitivity to fee size and hence willingness to pay vary with suitable selected characteristics of divers. We find potentials for a third degree price discrimination strategy exploiting higher willingness to pay among foreign divers (45%), male divers (16%) and people who has visited Sipadan several times (25%). Thus, revised pricing structures could significantly increase funds for the preservation of Sipadan.
  17. Zhang LY, Chung SS, Qiu JW
    J Environ Manage, 2016 Dec 01;183:253-9.
    PMID: 27596939 DOI: 10.1016/j.jenvman.2016.08.075
    Despite considered a non-consumptive use of the marine environment, diving-related activities can cause damages to coral reefs. It is imminent to assess the maximum numbers of divers that can be accommodated by a diving site before it is subject to irreversible deterioration. This study aimed to assess the ecological carrying capacity of a diving site in Mabul Island, Malaysia. Photo-quadrat line transect method was used in the benthic survey. The ecological carrying capacity was assessed based on the relationship between the number of divers and the proportion of diver damaged hard corals in Mabul Island. The results indicated that the proportion of diver damaged hard corals occurred exponentially with increasing use. The ecological carrying capacity of Mabul Island is 15,600-16,800 divers per diving site per year at current levels of diver education and training with a quarterly threshold of 3900-4200 per site. Our calculation shows that management intervention (e.g. limiting diving) is justified at 8-14% of hard coral damage. In addition, the use of coral reef dominated diving sites should be managed according to their sensitivity to diver damage and the depth of the reefs.
  18. Goli A, Shamiri A, Talaiekhozani A, Eshtiaghi N, Aghamohammadi N, Aroua MK
    J Environ Manage, 2016 Dec 01;183:41-58.
    PMID: 27576148 DOI: 10.1016/j.jenvman.2016.08.054
    The extensive amount of available information on global warming suggests that this issue has become prevalent worldwide. Majority of countries have issued laws and policies in response to this concern by requiring their industrial sectors to reduce greenhouse gas emissions, such as CO2. Thus, introducing new and more effective treatment methods, such as biological techniques, is crucial to control the emission of greenhouse gases. Many studies have demonstrated CO2 fixation using photo-bioreactors and raceway ponds, but a comprehensive review is yet to be published on biological CO2 fixation. A comprehensive review of CO2 fixation through biological process is presented in this paper as biological processes are ideal to control both organic and inorganic pollutants. This process can also cover the classification of methods, functional mechanisms, designs, and their operational parameters, which are crucial for efficient CO2 fixation. This review also suggests the bio-trickling filter process as an appropriate approach in CO2 fixation to assist in creating a pollution-free environment. Finally, this paper introduces optimum designs, growth rate models, and CO2 fixation of microalgae, functions, and operations in biological CO2 fixation.
  19. Kawai M, Nagao N, Kawasaki N, Imai A, Toda T
    J Environ Manage, 2016 Oct 01;181:838-846.
    PMID: 27449962 DOI: 10.1016/j.jenvman.2016.06.057
    The recalcitrant landfill leachate was anaerobically digested at various mixing ratios with labile synthetic wastewater to evaluate the degradation properties of recalcitrant wastewater. The proportion of leachate to the digestion system was increased in three equal steps, starting from 0% to 100%, and later decreased back to 0% with the same steps. The chemical oxygen demand (COD) for organic carbon and other components were calculated by analyzing the COD and dissolved organic carbon (DOC), and the removal efficiencies of COD carbon and COD others were evaluated separately. The degradation properties of COD carbon and COD others shifted owing to changing of substrate degradability, and the removal efficiencies of COD carbon and COD others were improved after supplying 100% recalcitrant wastewater. The UV absorptive property and total organic carbon (TOC) of each molecular size using high performance liquid chromatography (HPLC)-size exclusion chromatography (SEC) with UVA and TOC detectors were also investigated, and the degradability of different molecular sizes was determined. Although the SEC system detected extracellular polymeric substances (EPS), which are produced by microbes in stressful environments, during early stages of the experiment, EPS were not detected after feeding 100% recalcitrant wastewater. These results suggest that the microbes had acclimatized to the recalcitrant wastewater degradation. The high removal rates of both COD carbon and COD others were sustained when the proportion of labile wastewater in the substrate was 33%, indicating that the effective removal of recalcitrant COD might be controlled by changing the substrate's degradability.
  20. Subramonian W, Wu TY, Chai SP
    J Environ Manage, 2017 Feb 01;187:298-310.
    PMID: 27914351 DOI: 10.1016/j.jenvman.2016.10.024
    In this work, heterogeneous photocatalysis was used to treat pulp and paper mill effluent (PPME). Magnetically retrievable Fe2O3-TiO2 was fabricated by employing a solvent-free mechanochemical process under ambient conditions. Findings elucidated the successful incorporation of Fe2O3 into the TiO2 lattice. Fe2O3-TiO2 was found to be an irregular and slightly agglomerated surface morphology. In comparison to commercial P25, Fe2O3-TiO2 exhibited higher ferromagnetism and better catalyst properties with improvements in surface area (58.40 m2/g), pore volume (0.29 cm3/g), pore size (18.52 nm), and band gap (2.95 eV). Besides, reusability study revealed that Fe2O3-TiO2 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. Additionally, this study demonstrated the potential recovery of Fe2O3-TiO2 from an aqueous suspension by using an applied magnetic field or sedimentation. Interactive effects of photocatalytic conditions (initial effluent pH, Fe2O3-TiO2 dosage, and air flow-rate), reaction mechanism, and the presence of chemical oxidants (H2O2, BrO3-, and HOCl) during the treatment process of PPME were also investigated. Under optimal conditions (initial effluent pH = 3.88, [Fe2O3-TiO2] = 1.3 g/L, and air flow-rate = 2.28 L/min), the treatment efficiency of Fe2O3-TiO2 was 98.5% higher than the P25. Based on Langmuir-Hinshelwood kinetic model, apparent rate constants of Fe2O3-TiO2 and P25 were 9.2 × 10-3 and 2.7 × 10-3 min-1, respectively. The present study revealed not only the potential of using magnetic Fe2O3-TiO2 in PPME treatment but also demonstrated high reusability and easy separation of Fe2O3-TiO2 from the wastewater.
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