Urbanization and its impact on groundwater: a remote sensing and GIS-based assessment approach

The perils of unplanned urbanization and increasing pressure of human activities on hydro-geomorphologic system often result in modification of the existing recharge mechanism, which leads to many environmental consequences. In the present research, an attempt has been made to investigate the applicability of remote sensing and geographical information system (GIS) in dealing with spatial and temporal variability of dynamic phenomena, like urbanization and its impact on groundwater. This paper covers primarily, quantitative and qualitative impacts of urban growth on the behavior of aquifer in Ajmer city (India). Urban growth of the Ajmer city in last 17 years has been estimated from the satellite images. Database related to urbanization and groundwater has been created in GIS. Groundwater recharge has been computed using a water balance approach known as Water Level Fluctuation Methodology. Recharge estimation methodology has been implemented in GIS to introduce the spatial variability of hydro-geological characteristics. Further, temporal and spatial variations in groundwater quality and quantity have been correlated with urban growth using overlay analysis in GIS. The study reveals a general decline in water table and quality with urbanization. Further, remote sensing and GIS technologies have been found useful in assessment of spatial and temporal phenomena of urbanization and its impact on groundwater system.     

Assessment of Reclaimed Municipal Wastewater Application on Rice Cultivation

Field research was carried out to assess the effects of the application of reclaimed municipal wastewater on rice cultivation in Thessaloniki, Greece during a 2-year period (1999–2000). Effects on production cost, soil composition, and health risk were examined. A randomized complete block design was used for the paddy field with three treatments and four replicates. The treatments were (1) river irrigation water with N–P fertilization, (2) reclaimed wastewater irrigation with surface N fertilization, and (3) reclaimed wastewater irrigation without fertilization. The results showed that the total production cost decreased 8.8% and 11.9% by applying the second and third treatments, respectively, compared to the first treatment, without significant differences in the agronomic and rice quality traits. Soil composition showed discrepancies between the 2 years and the three treatments, whereas the pathogens of the reclaimed wastewater and rice tissues posed a low human risk when taking the needed precautions.     

Path analysis of factors influencing household solid waste generation: a case study of Xiamen Island,China

Comprehensive study of the factors influencing household solid waste (HSW) generation is crucial and fundamental for exploring the generation mechanism and forecasting future dynamics of HSW. A case study of Xiamen Island, China was employed to reveal the direct and indirect effects of demographic/socioeconomic factors on solid waste generation at the urban household scale. Based on a face-to-face questionnaire and two-stage survey of solid waste generation, a path analysis model was built. Results showed that the proposed path model exhibited good fit indices. Family size and dinning-at-home rate (DR), whose coefficients were ?0.40 and 0.43, respectively, were the two major factors influencing HSW directly. Moreover, family size, education level, employment rate and age structure played different degrees of indirect effects on HSW generation through respective paths, which should not be ignored. In terms of total effects, coefficients of family size, DR and employment rate were ?0.46, 0.43 and ?0.37, respectively, which were three most dominant factors influencing HSW generation. As for waste composition, organic waste was the most representative of HSW dynamics, and was the most sensitive to impact by the factors studied. Quantitative results of this study have important policy implications for sustainable municipal solid waste management.     

The application and evaluation research of coffee residue ash into mortar

Coffee residue is usually regarded as a kind of agriculture waste; as its quantity increases the treatment of coffee residue will become an environmental problem. This research is innovative in that it derives the possibility of recycle application using coffee residue ash for cement replacement. In this research, coffee residue is burned in an electronic oven to three kinds of coffee residue ash at 500, 600 and 700 °C, and then appropriate apparatus is used to check the chemical and physical properties of these three types of coffee residue ash. After a general comparison, this study selected 500 and 600 °C coffee residue ashes with 2, 3, 5, 10 and 15 % cement replacements to make 5 cm³ cube mortar specimen to test different curing ages’ compressive strength. Through measurement and experiment, this research found that the compressive strength decreased by adding 500 or 600 °C coffee residue ash into the mortar. By considering waste reduction and practice application, this research derives that using the 600 °C coffee residue ash with 10 % replacement is better than others application, such using result also can get valuable efficiencies of financial and CO₂ reduction.     

Rare earth element recovery potentials from end-of-life hybrid electric vehicle components in 2010–2030

Increasing attention is currently given to the management of end-of-life (EoL) hybrid electric vehicles (HEVs), because approximately two decades have passed since they were first introduced to the market. A HEV would be one of the largest consumers of rare earth elements (REEs), and hence represents the greatest potential for REE recovery in the future. The purpose of this study is to clarify the present and future recovery potential of REEs that are disposed of as EoL HEVs. This study first estimated the numbers of EoL HEVs during fiscal years (FYs) 2010–2030, and then clarified the potential for recovery of REEs from two HEV-specific components—the hybrid transmission and NiMH battery unit. The results suggest that 0.51–0.65 million HEVs will reach the EoL stage in FY2030, compared with only 11,000 HEVs in FY2010. As of FY2030, REE recovery potentials will increase to 220 tons and 2900 tons for EoL hybrid transmission and NiMH battery units, respectively. A total of 49,000 tons of REEs will be contained within HEV-specific components of HEVs still in use. Moreover, the potential for recovery of REEs from EoL hybrid transmissions and NiMH battery units is estimated to equal 35.4 and 92.1 % of respective demand.     

A dynamic simulation of methane fermentation process receiving heterogeneous food wastes and modelling acidic failure

Microbial response on volatile fatty acids (VFAs) is a key for methane fermentation processes since accumulation of VFAs often causes an acidic failure, especially treating such organics as food wastes composed of mostly readily biodegradable materials. To evaluate the impact of VFA accumulation, a lab-scale continuous experiment was performed for 110 days with sequential feeding of heterogeneous food wastes. When the volumetric loading rate was increased from 6 to 8 kg-COD/m³/day, a sudden decrease of methane production was observed with an accumulation of acetate and propionate in the fermenter. After discontinuation of feeding for 10 days, the digestate in the fermenter was centrifuged and washed with tap water to reduce the VFAs to be acceptable concentration below 1000 mg-COD/L. Nevertheless, no recovery of methane production was observed and VFA concentrations consistently increased. To model the event, a modification of ADM1 was made assuming the methanogens in the fermenter were irreversibly inactivated under very high VFA. Also considering the different nature of the fed food wastes over 11 samples, decomposition kinetics of individual food wastes were manipulated. The modified ADM1 with methanogenic activity decay reasonably reproduced the responses for soluble material concentrations and methane gas production rate over the experimental period.