Heavy metal contamination of green leafy vegetable garden in Itam road construction site in Uyo, Nigeria. Research journal of environmental and earth sciences 4(4

Abstract: Human exposure to heavy metals is a subject of public health concern that have attracted the attention of researchers, health and nutrition experts all over the world. Green Leafy Vegetables (GLVs) are important part of diets in the South-South Region of Nigeria. Consumption of vegetables exposed to heavy metals contamination may lead to serious health complications. In this investigation, we estimated the concentrations of some heavy metals (Pb, Hg, Al, Cd, Fe and Zn) in GLVs harvested from vegetable gardens in the residential areas along Itam road construction site, Uyo, Nigeria. The results showed that Pb, Hg, Al and Cd concentrations were significantly high (p<0.05) in all exposed GLV samples than the control but Teliferia occidentalis had higher values of heavy metals than Talinium triangulare. However, zinc and iron levels in the GLV exposed samples were not significantly (p>0.05) higher than the control. Our findings showed that heavy metal contamination of edible vegetable is high at road construction sites and may impact negatively on the health of human and animals living in such environment. We suggest that health impact assessment be carried out at construction sites in order to suggest necessary measure that can alleviate the effects of such environmental contaminants

Techno-economic evaluation of post-combustion carbon capture based on chemical absorption for the thermal cracking furnace in ethylene manufacturing

As the core unit of an ethylene production plant, thermal cracking furnace generates a large amount of CO2 emissions. To reduce the CO2 emissions, post-combustion carbon capture based on chemical absorption using monoethanolamine (MEA) solvent is used to capture CO2 from the thermal cracking furnace. The computational fluid dynamics (CFD) method was used to simulate the operation of a 60kt/a thermal cracking furnace to obtain the flow rate and composition of the flue gas. A carbon capture plant model was developed using Aspen Plus® and validated using the pilot plant test data from Technology Centre Mongstad (TCM) in Norway. Scale-up of the capture plant model was carried out to match the flue gas flow rate of the thermal cracking furnace. Two integration cases of the carbon capture plant and the industrial thermal cracking unit were carried out. The results show that the excess heat of the gasoline fractionator can be used to provide heat for the carbon capture plant without affecting ethylene production. The economic evaluation was conducted based on the two case studies. Results show that the cost of CO2 capture can be reduced from $80.03/tonne (without heat integration) to$70.41/tonne with heat integration. When considering the impact of carbon credits on capture costs, the cost will be further reduced to $50.41/tonne