Feasibility Assessment of Basin Solar Stills

The present study assesses the feasibility of exploiting single- and double-basin solar stills in our daily lives. An investigation is carried out to determine the thermal performance and economic viability of making use of solar stills in water desalination. The climatic conditions of Tehran (35°44?N, 51°30?E) are considered to assess the feasibility of the basins. Transient energy and mass balance equations are utilized for modeling the thermal performance. The equations are solved by using fourth-order Runge–Kutta method in FORTRAN. The daily productivities of single- and double-basin solar stills are found to be 5.22 kg/m² and 7.73 kg/m², respectively, while the effect of different water masses (20–100 kg) on the productivity of each system was found to be optimum at 20 kg/m². The results are compared with experimental work performed under different climatic conditions to examine the validity of the feasibility of basins in general. A life cycle cost analysis performed for Tehran, yields that single- and double-basin solar stills have savings-to-investment ratios of 4.2 and 4.8, respectively, indicating that they are economically feasible.     

Technological Innovation and Developmental Strategies for Sustainable Management of Aquatic Resources in Developing Countries

Sustainable use and allocation of aquatic resources including water resources require implementation of ecologically appropriate technologies, efficient and relevant to local needs. Despite the numerous international agreements and provisions on transfer of technology, this has not been successfully achieved in developing countries. While reviewing some challenges to technological innovations and developments (TID), this paper analyzes five TID strategic approaches centered on grassroots technology development and provision of localized capacity for sustainable aquatic resources management. Three case studies provide examples of successful implementation of these strategies. Success requires the provision of localized capacity to manage technology through knowledge empowerment in rural communities situated within a framework of clear national priorities for technology development.     

Purification,characterization and toxicity of a mannose-binding lectin from the seeds of Treculia africana plant

In this study, a mannose-specific, homodimeric lectin from the seeds of Treculia africana was purified, characterized and its adverse effects were investigated in mice. The purification protocol involved anionic exchange chromatography on DEAE-Cellulose followed by gel filtration on Sephadex G-100. The hemagglutinating activity of lectin towards human erythrocytes was sensitive to inhibition by D-mannose. Treatment of the protein with EDTA exerted no inhibitory effect; however, analysis of metal content by atomic absorption spectroscopy revealed the presence of Cu²⁺, Fe³⁺, and Mg²⁺. The results obtained showed that the lectin possesses maximum hemagglutinating activity towards human erythrocytes activity over the pH range 3–7.2 and is relatively thermostable up to 50°C. Periodic acid Schiff's (PAS) reagent staining showed that the protein was non-glycosylated while its amino acid composition analysis revealed that the protein contained 155 residues per subunit. The subunit had a minimal molecular weight of 22,139 Daltons, while the native molecular weight was estimated to be 41,000 Daltons. The lectin was found to be moderately toxic to mice with an LD₅₀ of 47.21 µg g^?1 body weight while, histopathological analysis showed no treatment related effects in any of the organs examined.     

Characterization and performance of nanofiltration membranes

The availability of clean water has become a critical problems facing the society due to pollution by human activities. Most regions in the world have high demands for clean water. Supplies for freshwater are under pressure. Water reuse is a potential solution for clean water scarcity. A pressure-driven membrane process such as nanofiltration has become the main component of advanced water reuse and desalination systems. High rejection and water permeability of solutes are the major characteristics that make nanofiltration membranes economically feasible for water purification. Recent advances include the prediction of membrane performances under different operating conditions. Here, we review the characterization of nanofiltration membranes by methods such as scanning electron microscopy, thermal gravimetric analysis, attenuated total reflection Fourier transform infrared spectroscopy, and atomic force microscopy. Advances show that the solute rejection and permeation performance of nanofiltration membranes are controlled by the composition of the casting solution of the active layer, cross-linking agent concentration, preparation method, and operating conditions. The solute rejection depends strongly on the solute type, which includes charge valency, diffusion coefficient, and hydration energy. We also review the analysis of the surface roughness, the nodule size, and the pore size of nanofiltration membranes. We also present a new concept for membrane characterization by quantitative analysis of phase images to elucidate the macro-molecular packing at the membrane surface.     

Trends in the management of waste tyres and recent experimental approaches in the analysis of polycyclic aromatic hydrocarbons (PAHs) from rubber crumbs

The health and environmental consciousness of waste tires has increased tremendously over the years. This has motivated efforts to develop secondary applications that will utilize tire when they reach the end of their life cycle and limit their disposal in landfills. Among the applications of waste tires which are discussed in this review, the use of rubber crumbs in artificial turf fields has gained worldwide attention and is increasing annually. However, there are serious concerns regarding chemicals that are used in the manufacturing process of tires, which ultimately end up in rubber crumbs. Chemicals such as polycyclic aromatic hydrocarbons (PAH) and heavy metals which are found in rubber crumbs have been identified as harmful to human health and the environment. This review paper is intended to highlight some of the methods which have been used to manage waste tire; it also looks at chemicals/materials used in tire compounding which are identified as possible carcinogenic.

     

Impact of land clearing methods and cropping systems on labile soil C and N pools in the humid zone Forest of Nigeria

Labile soil C and N play vital roles in soil–plant nutrient dynamics, especially in the low input cropping system and are vulnerable to perturbation. Surface (0–0.15 m) soils from three land clearing methods (slash and burn, bulldozed non-windrowed and bulldozed windrowed) and each with two cropping systems (5-and 4-year cropping/2-year cassava fallow) were collected in the humid forest ecosystem of Nigeria.The soils were analysed for total C and N, microbial biomass C and N (SMB C and N), particulate organic matter C and N (POM C and N), water-soluble C, potentially mineralizable N (PMN) and mineral N. The size of the labile C and N and their relative contributions to the organic C and total N differed significantly among land clearing methods, irrespective of the cropping system. Soils under slash and burn had a significantly (p > 0.05) higher particulate organic matter C, N (10.80 and 0.16 g kg⁻¹, respectively) and microbial biomass C and N (1.07 and 0.12 g kg⁻¹) compared to the bulldozed windrow, regardless of the cropping system. Four years cropping/2-year cassava fallow resulted in a significant higher labile C and N, relative to 5-year cropped plots across the land clearing methods. Effect of the treatments on the concentration of PMN and mineral N mirrored the SMB N and POM N. However, the quantity of most of the labile C and N pool and crop yield obtained from the slash and burn and bulldozed non-windrowed treatment did not differ significantly. Hence, bulldozed non-windrowed clearing could be a viable alternative to slash and burn in the case of large-scale farming in ensuring reduced losses of soil organic matter and nutrient during land clearing in the humid tropics.