Groundwater Quality Assessment Using Water Quality Index, Principal Component and Cluster Analyses: A Case Study

This study assessed groundwater quality in Can Tho city, Vietnam using groundwater quality index (GWQI), principal component analysis (PCA), and cluster analysis (CA). Groundwater samples were collected in April (dry season) and October (rainy season) in 2019 and then analyzed for thirteen parameters: pH, color, total hardness, chloride, sulfate, chemical oxygen demand, magnesium, total iron, nitrate, arsenic, lead, mercury, and coliforms. The results showed that the values of these parameters were mainly within the Vietnamese regulations on groundwater quality, except for coliform density. Computed GWQI values in all monitoring sites were lower than 50 and suitable for potable purposes. The GWQI values in the dry season were slightly higher than in the rainy season because of higher concentrations of Cl-, SO42-, COD, As, Pb, and coliforms in the southeast of Can Tho. The results of CA revealed that 27 monitoring sites can be divided into nine clusters in the dry season and five clusters in the rainy season, which means that more noticeable spatial variation in groundwater quality occurred in the dry season. The PCA results can explain 63.4% and 73.9% of the total variation in the dry season via 4PCs and in the rainy season via 3PCs, respectively. It also indicated that this water resource could be affected by different sources such as industrial and agricultural activities, domestic wastewaters, and saltwater intrusion. These findings can be useful for policymakers in assessing current groundwater status and recognizing threats to its quality, and then developing long-term management policy.

Biogas Production through Co-Digestion of Olive Mill with Municipal Sewage Sludge and Cow Manure

The treatment of olive mill (OM) residues from agricultural facilities is a daunting challenge since tremendous amounts are disposed per annum that should be treated. One of the promising treatment methods is the anaerobic methanogenic digestion of OM residues. In current investigations, the anaerobic digestion of the OM substrate is enhanced through mixing its slurries with sewage sludge (SS) or with cow manure (C), which consists of the kernels for the digestion process. Besides feedstock, other operational parameters such as hydraulic retention time (HRT), temperature and pH have a great impact on the biogas production rate and quality. Experimental investigations were conducted by means of the anaerobic biodegradation of the substrate for OM-SS and -C using a batch reactor under mesophilic conditions and foreseen HRT for 30 days. Almost neutral pH values of 7.4-7.6 were found for the anaerobic treatment of the substrate for OM-SS, and a slightly acidic pH in the range of 4.8-5.3 was found for the anaerobic treatment of the substrate for OM-C. The results revealed that the biogas production for OM-SS and -C exceeded 0.07 and 0.31 LBiogas/(LFerm·day), respectively. Regarding the COD reduction, its removal efficiency was obtained as 46.1 and 53.8% for OM-SS and -C respectively. For economic concerns, significant methane yields were attained as 56.8 and 115.8 [LCH4/kgCOD] for the OM-SS and -C substrates, respectively. In virtue of these remarkable merits, anaerobic methanogenic digestion should be adapted to a commercial scale for the treatment and biogas production of OM residues.

Glass Production from River Silica of Bangladesh: Converting Waste to Economically Potential Natural Resource

The Ganges-Brahmaputra river system at the Bengal Basin carries large amounts of sediments on the way to finally deposit at the Bay of Bengal. Those river-transported sediments form bar deposits during dry season in many areas of Bangladesh and accumulate economic mineral depositions at suitable geological environments. Dredging is a must for most of those rivers for proper navigation, as well as protecting bank erosion, which generates millions of tons of waste sand. The dredged materials from river beds are mostly composed of silicate minerals, especially quartz and feldspar along with several dark colored heavy minerals. Like the industrial processing of heavy minerals from bulk sands, various physical separation techniques can be utilized for the beneficiation of silica from those river-born silicate minerals in dredged sands. Those silica have been successfully upgraded to near-glass sand grade in the laboratory, however, they have yet to be utilized for any kind of commercial venture. The present study attempts characterization of several river sands through physical separation and laboratory analysis. The upgraded silica was successfully compared with several quality glass sands and laboratory production of glasses. This experimental production of glass from upgraded silica could potentially be economical considering its industrial application with positive environmental consequences through minimizing the dredging cost, increasing the navigability of the river and ecological balance along the flood plain.

Lead Accumulation of Siam Weed (Chromolaena odorata) Grown in Hydroponics Under Drought-stressed Conditions

The phytoremediation potential of Siam weed (Chromolaena odorata) was tested in lead (Pb) contaminated nutrient media with 5% (w/v) of polyethylene glycol (PEG) 6000 induced drought stress conditions. The plant was treated with 0, 5, 10, 20, and 50 mg/L Pb for 15 days. Different concentrations of Pb or in combination with PEG had no effect on plant growth parameters. Drought reduced water content (WC) (p<0.05), but did not affect the reduction of chlorophyll content and photochemical efficiency in plant tissues after 15 days of treatment. Under drought conditions, plants showed the largest Pb accumulation in roots (5,503.7 mg/kg) and exhibited the highest uptake at 50 mg/L solution (18.24 g/plant), but the translocation factor values (TFs) of Pb from root to shoot were all less than 1. Under both drought and non-drought conditions, the bioconcentration factor values (BCFs) decreased with increasing Pb concentrations. According to BCFs and TFs, C. odorata may be promising for phytostabilization of Pb. Based on high biomass, tolerance, and Pb uptake, the result of this hydroponic study test reveals that C. odorata has a good potential for developing Pb phytoremediation strategies in drought-stressed conditions.

Assessing and Simulating Impacts of Land Use Land Cover Changes on Land Surface Temperature in Mymensingh City, Bangladesh

Urban developments in the cities of Bangladesh are causing the depletion of natural land covers over the past several decades. One of the significant implications of the developments is a change in Land Surface Temperature (LST). Through LST distribution in different Land Use Land Cover (LULC) and a statistical association among LST and biophysical indices, i.e., Urban Index (UI), Bare Soil Index (BI), Normalized Difference Builtup Index (NDBI), Normalized Difference Bareness Index (NDBaI), Normalized Difference Vegetation Index (NDVI), and Modified Normalized Difference Water Index (MNDWI), this paper studied the implications of LULC change on the LST in Mymensingh city. Landsat TM and OLI/TIRS satellite images were used to study LULC through the maximum likelihood classification method and LSTs for 1989, 2004, and 2019. The accuracy of LULC classifications was 84.50, 89.50, and 91.00 for three sampling years, respectively. From 1989 to 2019, the area and average LST of the built-up category has been increased by 24.99% and 7.6ºC, respectively. Compared to vegetation and water bodies, built-up and barren soil regions have a greater LST each year. A different machine learning method was applied to simulate LULC and LST in 2034. A remarkable change in both LULC and LST was found through this simulation. If the current changing rate of LULC continues, the built-up area will be 59.42% of the total area, and LST will be 30.05ºC on average in 2034. The LST in 2034 will be more than 29ºC and 31ºC in 59.64% and 23.55% areas of the city, respectively.

Maceral Association in Coal-bearing Formation of Mae Than Coal Mine in Lampang, Thailand - Implication for Depositional Environment

The Mae Than Basin in Lampang Province contains low-ranked coal reserves of northern Thailand. Coal seams and ball clays were mined in the southern part of the basin. This study focuses on the coal petrography of coal samples collected from the upper coal seam in the Mae Than Coal Mine. Both the organic and inorganic constituents provide information on the nature and characteristics of the coal, reflecting the physical and chemical behaviors of coal. Petrological analysis reveals that the Mae Than coals contain more huminite than liptinite macerals, while inertinite is negligible. Huminite occurs mainly in the form of texto-ulminite, textinite, densinite, and gelinite. Liptinite consists of sporinite, cutinite, resinite, suberinite, liptodetrinite, and terpenite. The morphology of cutinite, sporinite, and the presence of terpenite indicate that the peat-forming vegetation may consist of conifers. In addition to the macerals, the coal samples contain a small to moderate amount of mineral matter. Silica and clay minerals are the main minerals found in the cavities and between the cracks of the coals. The assemblage of macerals and mineral matter indicates that the Mae Than coals were formed mainly from common peat-forming vegetation, possibly conifers, in a freshwater forest swamp or mire in a warm temperate climate. In addition, the high degree of preservation of the macerals indicates a high water table and suggests rheotrophic, anoxic, limnotelmatic to telmatic conditions during deposition.

Alteration of Fractionation and Bioavailability of Arsenic (As) in Paddy Soil under Transition from Aerobic to Anaerobic Conditions

The impact of the change from aerobic to anaerobic immersed soil conditions on arsenic (As) fractionation (Tessier’s method) and its bioavailability (ethylene diamine tetraacetic acid extractable) were assessed. As-contaminated paddy soils were tested by laboratory simulation experiments. The samples were aerobic, with 35-49 mg/kg of As at low bioavailability (<2%). Most As was distributed in the stable fraction (77%), followed by As bound to ferric and manganese oxide (17%) and organic compounds (5%), while the mobile fraction (exchangeable and mildly acid-soluble) was limited (1%). After one month under anaerobic simulation, redox potential reduced to less than zero (-32 to -124 mV). The stable fraction of As decreased (-17%), while the mobile fraction increased (+16%) and As bioavailability also increased (+26% total As). Increase in the As mobile fraction was associated with freshly precipitated compounds. The As content in the soil altered from a stable fraction to an available fraction when confined in an anaerobic environment for a long period. Results indicated that agricultural methods which promoted anaerobic conditions in As-contaminated soil should be avoided.

Evaluation of Ecosystem Service Changes due to Land Use and Land Cover Dynamics in Cham Chu Nature Reserve

Assessment of ecosystem services is vital for successful natural resource allocation; however, these have been less studied within Vietnam. This study estimated the ecosystem services value (ESV) and its change in Cham Chu nature reserve, Vietnam using a benefit transfer method. Ecosystem service values estimation and trend analyses were carried out based on land use and land cover datasets from 1986, 1998, 2007, and 2017, with their corresponding global value coefficients. The results revealed that the total value of ecosystem services in Cham Chu was approximately 64.4, 63.9, 60.7, and 63.4 million USD in 1986, 1998, 2007, and 2017, respectively. Changes have also occurred in the values of individual ecosystem service functions. From 1986 to 2017, ecosystem service functions showed significant decreases in gas regulation, pollination, biological control, water regulation, water supply, and food production of 62.9%, 51.2%, 44.4%, 24.7%, 23.1%, and 13.0%, respectively. We conclude that the loss of ESV is a result of ecological deterioration in the studied landscape, and we propose further research to examine future solutions and establish action strategies. In summary, the research approach methodology developed can be used by land managers and planners in Vietnam as a guideline to estimate the importance of ecosystem services in Vietnam.

Emissions of CH4 and CO2 from Wastewater of Palm Oil Mills: A Real Contribution to Increase the Greenhouse Gas and Its Potential as Renewable Energy Sources

Palm oil mill effluent (POME) treatment in Indonesia is still predominant using an open pond system. This system has the weakness of the unknown and uncontrollable value of greenhouse gas (GHG) emissions into the atmosphere. This study estimated GHG emissions (CH4 and CO2) from anaerobic ponds and their potential as a renewable energy source and obtain GHG emission conversion coefficients for each kg of COD POME and ton of crude palm oil (CPO). Gas samples were collected using a closed static chamber. GHG sample concentration testing was done using Gas Chromatography with a flame ionization detector (FID) and thermal conductivity detector (TCD). The results showed that the emission rate of CH4 and CO2 in the anaerobic pond POME treatment was relatively high, 261.93 and 595.99 g/m2/day, respectively, equivalent to 48.572 t CO2-eq/day or 14,571.5 t CO2-eq/year. CO2 emissions were greater than two times CH4 emissions, both spatially and temporally. There was a process of facultative biodegradation, aerobic and or anaerobic process according to the biotic-abiotic environment and the levels of organic components in the substrate. In anaerobic ponds, the optimal requirements for the biodegradation process tended to be unfulfilled, so the emission rate of CH4 was less than CO2. The GHG conversion coefficient was obtained, namely each kg of COD from POME emitted 6.266 kg CO2-eq of GHG; for each m3 of POME emitted by 0.163 t CO2-eq of GHG; and 0.556 t CO2-eq/t CPO. The maximum potential for POME to energy conversion was 1.045 MWe with a power capacity of 8,603 MWh/year.

The Alternating Growth of Bacteria within a Consortium During Desulfurization of Coal

Efforts to reduce organic sulfur in coal are taken through biodesulfurization by using desulfurization bacteria to release covalently-bound sulfur from the coal matrix. Coal is a complex hydrocarbon material that requires collaboration from more than one type of bacteria in a consortium for desulfurization. The current study shows how the individual members of a bacterial consortium obtained directly from coal samples grew on the coal. Mineral medium containing sub-bituminous coal with a concentration of 10%, 15%, and 20% served as a carbon source and the only sulfur to support the consortium's growth. The examination included growth patterns, concentrations of dibenzothiophene as an organic sulfur representative, pH, and sulfate concentration as the sulfur product released into the medium. The growth of individual members of the consortium was observed for 336 h. The consortium grew in all three coal concentrations with slightly different cell growth patterns and the release of dibenzothiophene. Members of the consortium grew alternately and overlapped, which showed possible linkages or dependence on products and existence from the growth of other members. The existence of the primary strain Moraxella osloensis COK1 indicated that they played a role in the activities and growth of other members. The alternating growth is discussed to produce a hypothetical illustration of how several other members play in using sulfur in a well-known desulfurization pathway. In conclusion, this study provides a deeper insight into the value of consortium members individually but growing together while swarming coal as a complex resource to become low-sulfur coal.