Journal of Pollution

The municipality of Buea currently lacks a conventional wastewater treatment system for domestic wastewater. The management of wastewater in the area under study is inadequate, making use of septic tanks, most of which are not constructed following standard norms, and are rarely emptied. The purpose of this work was to evaluate the current system for wastewater treatment and to propose a better conventional system capable of meeting environmental standards. The wastewater treatment system was designed using standard procedures and made use of the trickling filter technology for biological treatment. A gravity sewer was designed for the conveyance of wastewater, followed by primary and secondary settling tanks, and a biological treatment unit which is the trickling filter. The method used for this study involved carrying out a quantitative survey to gather relevant data needed to design the system, followed by the application of standard design procedures. The dimensions of the gravity sewer network made of polyvinyl chloride pipes ranged between diameters of 110 mm and 160 mm. The treatment system includes two primary settling tanks of diameters of 8 m and heights of 2.5 m, two trickling filters of diameter 26.4 m and height of 3.6 m, and two secondary settling tanks with a diameter 8m and height of 4.5 m. The theoretical performance of the system showed a Biochemical Oxygen demand reduction from 222 mg/L to 16.3 mg/L, Total Kjeldahl Nitrogen reduction from 55 mg/L to 22.5 mg/L and total Phosphorus reduction from 15 mg/L to 9.5 mg/L. The pollution reduction exhibited by the system enables the treated wastewater to meet the country’s environmental discharge standards. The design proposed with a cost estimate of about 1,528,023 USD (United States Dollar) is relatively low compared to constructing a septic tank for the households in the study area which costs about 4,183,041 USD. The system proposed is less costly at a city scale and more environmentally friendly compared to a standard septic tank. Hence such a system is recommended for developing cities especially Buea.

Water as an inevitable human need has encountered many problems during the last decades. One of these problems is water pollution. In recent years, water quality has been reduced in Karaj watershed as the most important source of drinking water in Tehran and surrounding areas. In the present study, three sub-watersheds were selected at the upper, middle and lower section of the main river of Karaj watershed called Varangeh Rud, Doab and Varian. In order to estimate and compare their pollution potential, two different methods including risk assessment (as a scientific method) and organizing (as an experimental-practical method) methods were applied. Out of the several risk assessment methods, only the WRASTIC Index method was used to estimate the risk of surface water sources pollution, particularly dams, and to weight the 7 main parameters of water pollution. Organizing method, in turn, involves several methods including ecological capacity assessment using GIS to determine the proportion between existing uses, analyzing the 10-year average of water pollution parameters for identifying the river water quality and SWOT analysis to determine threats and opportunities in the watershed water quality. Results showed little pollutant potential in all the three sub-watersheds, but based on the organizing method, there is little, average and very little pollution in Varangeh Rud, Doab and Varian sub-watersheds, respectively. Similar results were obtained using both methods. Hence, the organizing method, as an experimental method, can also be used for zoning the potential of water pollution in Karaj Dam watershed.

Objective: The purpose of the synthesis was the preparation of porous materials with capacity for adsorption of gases, such as CO2 and CH4, in order to contribute to the search for temporary solutions to the energy needs and pollution problems in nowadays.
Methodology: We used an experimental modification of the previously reported ionothermal methodology for the polymerization of the monomers, which were 2,3-dicyanohydroquinone, 2,3-dicyanopyrazine, and 4,5 dicyanoimidazole. We used data from Scanning Electron Microscopy (SEM), Fourier Transformed Infrared Spectroscopy (FT-IR), Raman spectroscopy; X-Ray Diffraction (XRD), Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (CP-MAS-NMR), and gas adsorption experiments for characterization of the materials.
Results: Three Covalent Triazine-Based Polymers (CTFs) were synthesized and characterized, the adsorption experiments of the polymers showed a very small pore size (230 pm), compared to the kinetic diameter of the gases: CO2 (330 pm), N2 (370 pm), and CH4 (380 pm).
Conclusion: The pore sizes of the synthesized polymers were too small in order to adsorb the intended gases; nevertheless, we have improved the methodology for the ionothermal synthesis of CTFs; these materials, by modeling and selection of appropriate monomers could be prepared with improved adsorption capacity.