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This study is aimed at improving the recovery of Natural Gas Condensate from a Niger-Delta Reservoir in Nigeria, with 35.1 million stock tank barrel (MMSTB) and a 6879 pounds per square inch (psi) reservoir pressure. ECLIPSE 300, a compositional reservoir simulator, was employed to simulate (mimic) the candidate reservoir conditions so as to understand the performance of Carbon-dioxide (CO2) as the injecting fluid, while enhancing the recovery of the natural gas condensate from the reservoir. Nine case studies with different CO2 injection rates were considered to determine the optimum CO2 injection rate. These were compared with the recovery from the natural energy drive of the reservoir. Using the natural energy (drive) of the reservoir, only 11.04MMSTB of natural gas condensates was recovered, which indicated a 32% recovery factor for the natural drive system. Case 6 with CO2 injection rate of 4000 stock tank barrel per day (STB/D) recorded the optimum recovery factor for this natural gas condensate reservoir. This case 6 yielded an ultimate recovery of 21.65MMSTB with a recovery factor of 62%. This simulation results, precisely considering the reservoir conditions, indicated that CO2 can be used to enhance natural gas condensate recovery from NigerDelta reservoirs as demonstrated in this study. Another significance of this study is that CO2 with its adverse effects to the atmosphere and environment can be gainfully used for enhanced natural gas recovery as well as stored in hydrocarbon reservoirs so as to reduce its volume in the atmosphere. [ABSTRACT FROM AUTHOR]

In Sub-Saharan Africa, effluents from abattoirs that contain dissolved suspended particles which could be either organic or inorganic are discharged untreated into rivers and lakes. Activated carbon filters can be employed in the process of removing these organic compounds from effluent, thereby making the water suitable for discharge or use in other processes. 5 liters of abattoir wastewater was used for this study, during which two different synthesized activated carbon from sawdust ACC and ACH were employed as filters for the treatment of abattoir wastewater, and thus physico-chemical, heavy metal and microbial analysis were conducted. Activated carbon used was synthesized by means of physicochemical activation of waste sawdust and later heated at 250oC, the material was chemically activated using a base calcium chloride, ACC and an acid phosphoric acid, ACH, respectively. It was found that the maximum percent removal of turbidity, pH, Alkalinity, BOD5, COD, TSS and Chloride ions were 88%, 16.4%, 0%, 89.5%, 95.2%, 96.9% and 81.9% for ACC and 99.8%, 20%, 22.9%, 92.2%, 96.2%, 97.9% and 80.8% for ACH. An increase in DO was observed at 51.1% and 53.3% for ACC and ACH respectively. It was concluded that the constructed ACC has better performance than that of ACH for most However, ACH presented better performance especially for the removal of dissolved solids. There is a need to dope activated carbon with nanoparticles for the treatment of abattoir wastewater. [ABSTRACT FROM AUTHOR]

Amid surging population and industrial growth, there is a need to assess the vulnerability of groundwater to pollution. In this study, the case of Xingshan County in South China where karst groundwater is a major water source is presented. Field survey revealed hazardous landuse practices in highly karstified areas. To delineate areas of high vulnerability, an intrinsic vulnerability map (IVM) was created based on the EPIK (Epikarst, Protective cover, Infiltration condition, Karst network) method. Results show that 10.1, 25.8, 58.7 and 5.3% of the area are of low, medium, high and very high vulnerability. Although IVMs are powerful tools since they highlight areas of high "intrinsic" susceptibility to pollution, they do not answer the important question, "what sources are at immediate risk." With this limitation, tracer technique was coupled with IVM to establish a link to resources/sources. Rhodamine and uranine were injected into two sinkholes in high vulnerability zones near hazardous activities. Both were detected 57.3 and 5.65 h after injection at a major spring (Bailongquan). This established link validates the IVM and highlights specific sources at risk. This study demonstrates the need to couple IVMs with tracer test in order to prioritize areas to probe in order to determine the extent of their impact by establishing active karstic groundwater flow paths. The case here is an example of source/resource vulnerability assessment, hazard/risk assessment and validation of an IVM. Our findings present a cost-effective approach to vulnerability assessment by emphasizing the reliability of EPIK method as it requires less data. [ABSTRACT FROM AUTHOR]