Godlisten Namwel Shao

Background: There is a challenge with employing dumpsites as waste disposal methods due to the formation of leachates. These leachates may include dangerous chemicals that may harm human health and the ecosystem. Despite the drawbacks of leachates, it contains precious minerals that can be retrieved and used to restore soil fertility for agricultural activities to contribute to the circular economy. Results: The chemical composition of leachates from the Pugu dumpsite was assessed to explore their potential in agricultural application. Leachates were alkaline with a pH of 8.88 ± 0.98. The concentrations of NH₄-N and PO₄-P were 960.80 ± 610.44 and 431.60 ± 209.65 mg/L, respectively. The concentrations of minerals determined were Mg (33.73 ± 9.73), Na (485.70 ± 51.47), Ca (254.66 ± 6.04), and K (113.67 ± 8.53). The concentrations of heavy metals determined were Cd (0.03 ± 0.01), Cu (0.33 ± 0.09), Zn (0.32 ± 0.04), Cr (0.03 ± 0.01), Fe (2.63 ± 0.64), Ni (0.13 ± 0.03), and Pb (0.94 ± 0.06) mg/L. The concentrations of Cd, Cu, Zn, Cr, Fe, and Ni in the leachates under study, with the exception of Pb, were within the Tanzania Bureau of Standards (TBS)-established allowable limits for wastewater from cities and industries. Conclusions: The study evaluated the chemical composition of leachate from the Pugu dumpsite to explore its potential in agricultural applications. The results showed that the leachates were alkaline with a pH of 8.88 ± 0.88, with concentrations of NH₄-N and PO₄-P exceeding the allowable limit for municipal and industrial wastewater effluents. Concentrations of minerals such as Mg, Na, Ca, and K were within limits set by the Tanzania Bureau of Standards (TBS) for city and industrial wastewater. However, the concentrations of PO₄-P and NH₄-N exceeded the permissible limit of TBS, which could have adverse effects on the ecosystem. The study proposes a subtle method to recover plant nutrients from leachate, thus contributing to the circular economy.

Background: Approximately 69% of population in Tanzania lacks better sanitation, while 45.6% lacks access to clean and safe water. To leverage this shortage, several technologies have been used for purifying water from various sources; however, there is still persistence of waterborne diseases. Main body: This article reviewed the efficiency of common water filters in removing water contaminants such as Escherichia coli, fluoride, TSS, turbidity, nitrate, virus, BOD, COD, fecal coliform and color. Common water filters available in Tanzania markets include slow sand filter, ceramic filter, bone char, membrane purifier and bio sand filter. The effectiveness of each technology was evaluated in terms of its ability to remove water contaminants. Ceramic filter was found to be less expensive technology compared to the rest. Ineffectiveness of common water filters can be linked to persistence of waterborne diseases in Tanzania. Conclusion: Ability of water filters in viral removal is of greater concern. This study suggests a ceramic filter as the best filter among all common filters available in Tanzania. Ceramic filters can be synthesized by locally available materials such as clay, saw dust, rice husk ashes and flour which make it efficient in removing all water contaminants, especially viruses.

The present study introduces a modified approach to synthesize polyaniline (PANI) and polypyrrole (PPy) doped with graphene oxide (GO) or graphene (GN) through an in situ emulsion polymerization (EP) technique. Dodecyl benzene sulfonic acid (DBSA) was used as a surfactant and doping agent as well during the polymerization reaction. The morphology and microstructure of the synthesized polymers and their nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. All of these characterization techniques confirmed the superior morphology and thermal properties of the nanocomposites. The electroconductive properties of the synthesized polymers and their nanocomposite pellets containing 5 wt% of either GN or GO pressed at pressures of 2, 4, and 6 tons were investigated with a four‐probe analyzer. Nanocomposites showed very high electrical conductivity compared to individual PANI and PPy samples pressed at the same pressures. The addition of GO and GN not only improved the thermal stability but also significantly enhanced the electrical conductivity of the nanocomposites. Thus, the present work signifies the importance of the direct loading of GO and GN into conductive polymers during the EP process using DBSA as a surfactant to achieve nanocomposites with promising properties for various semiconductive applications. POLYM. COMPOS., 39:2142–2150, 2018. © 2016 Society of Plastics Engineers