Benzene is one of the biggest challenges of groundwater pollution due to of its toxicity, motility in the environment, and solubility in groundwater. Granular dead activated sludge (GDAS) was investigated as low-cost, and locally available as a sorbent material for removing benzene from aqueous solution. The experimental results show that the removal efficiency has improved, with increasing both of GDAS amount and the time of contact and decreasing the initial concentration of the contaminant. Batch investigations demonstrated that the GDAS efficiency removal for benzene is ranged from 55%-76% while, the maximum uptake (qm) is 14.835 mg/g, at sorbent dose 5 g/100 mL and contact time 5 hours. Langmuir and Freundlich isotherm model gives a proper fitting for the sorption process with high determination coefficient greater than 0.998. The parameter of this model shows favorable sorption for removing benzene by GDAS. Intra-particle diffusion model data fitting shows two separate regions; the first severe portion attributed to the immediate sorption step and another portion is the intraparticle diffusion rate is dominated. The parameters of the model illustrate the external mass transport mechanisms must be considered with intra-particle diffusion. Keyword: Benzene, GDAS, isotherm model, kinetics model, mechanism of removal, sorption. ةسارد ةلازلإ ةيكرحو هينزاوت ولحملا نم نيزنبلا ل يئاملا حلا ةطساوب م أ ة ةطشنملا ةبيبحلا ةتيملا دمحم هللاادبع ةلاسر ,ميهد نسح يلع ,يريهزلا قداص رفظم
A lichen is an intimate association between an alga and a fungus and is regarded as one of the best examples of ‘mutualism’ or ‘symbiosis’ involving microorganisms. In lichens which have Trebouxia as the algal partner, photosynthesis by the algae results in the production of the soluble polyol ribitol which is then transported to the fungus where it is converted to arabitol and mannitol. Within the fungus, arabitol may act as a short-term carbohydrate reserve while mannitol may be involved in stress resistance. The crustose lichen Rhizocarpon geographicum (L.) DC., has an unusual thallus structure consisting of discrete granules (areolae) containing the algal component growing in association with a non-lichenised fungal hypothallus that extends beyond the areolae to form a marginal ring. The concentrations of ribitol, arabitol, and mannitol were measured, using gas chromatography, in the central areolae and marginal hypothallus of the crustose lichen Rhizocarpon geographicum (L.) DC. growing on slate rocks in north Wales, UK. The concentrations of all three polyols were greater in the central areolae than in the marginal hypothallus. In addition, the ratios of polyols in the marginal hypothallus to that in the central areolae varied through the year. The concentration of an individual poyol in the hypothallus was correlated primarily with the concentrations of the other polyols in the hypothallus and not to their concentrations in the areolae. Low concentration of ribitol, arabitol, and mannitol in the marginal hypothallus compared with the central areolae suggests either a lower demand for carbohydrate by the hypothallus or limited transport of polyols from areolae to hypothallus, and may explain the low growth rates of this species. In addition, polyols appear to be partitioned differently through the year with an increase in mannitol compared with arabitol in more stressful periods.
Many landfill sites around the world have been poorly engineered and operated and hence face vociferous public opposition and criticism for their adverse environmental impacts. Because of the concerns arising from poor operation and management, siting and operation of landfill sites are very sensitive public issues in Nepal. The aim of this study was to assess the environmental impacts due to the foul odour during the operation of the the Sisdol landfill in Okharpauwa VDC, Nuwakot, Nepal. The study focused on identifying the composition of gases from the Kathmandu Valley's solid waste and impacts on local areas air flow moments from the land fill site. LandGEM Ver.3.02 Model was used for the emission calculation of the landfill gases. Furthermore, the gastec and specified ditector tubes were used for the measurement of H2S gas at the study area. Among nine sites, the H2S gas concentration at site (Vent pipe of landfill site) was 1.4 ppm (recorded maximum). The gas was found to be diluted at 208m downwind location and reached the value near to clean air, i.e., 0.2 ppb. The observed gas concentration was lower than the toxic range though the concentration level was found to have characteristic odour. The significant level of adverse impact was found nearby the landfill site. People working surrounding area of the landfill site were more vulnerable to different impacts.
The multivariate (R-mode factor analysis) technique was utilized to determine the main adaptive response problems of subsistence farmers to the changing annual rainfall pattern in South-eastern Nigeria. A total of one thousand two hundred and seventy nine (1279) respondent farmers were randomly drawn from sixty (60) farming communities in Cross River, Abia and Akwa Ibom states, Nigeria, a six (6) dimensional solution from an initial fifteen (15) was arrived at accounting for almost 70% of the variations in the original problem matrix. These major problems include the lack of climate information, illiteracy, awareness problem, fertilizers and funding problems, poor agricultural and weather extension services, and difficulties in accessing official information. Non-governmental organisations and governments should be much more interested in climate change issues and act proactively to ameliorate the problem. Key words: Rainfall change, R-mode factor analysis, subsistence farmers, adaptive response.
This study which aim at review of noise pollution levels and its sources in Nigerian urban areas, reveals that noise pollution in Nigeria cities is found to be relatively high when compared to recommended levels by World Health Organization (WHO), Housing and Urban Development (HUD), Committee on Environmental and Occupational Health (CEOH) or Federal Highway Administration (FHWA). In Nigeria, there is no legal frame research upon which noise pollution can be abated. The study observes that Nigerian cities are environmentally noise polluted and the road traffic, industrial machineries and generators are the major sources of it. Noting that the noise levels lie much above the prescribed limits there is an imminent health risk to the exposed population. The complexity and magnitude of the problem of noise pollution call for effective and well-planned measures in the country, Nigeria. Government, industries and research institutions have so far given low priority to evolve strategies to prevent the epidemic of this invisible disease from spreading further. Some measures to combat the problem of noise pollution are outlines in this study so as to have sustainable urban development in Nigeria.
