Adsorption of petroleum products by modified and activated adsorbents

This research is aimed at investigating the adsorption of petroleum products from aqueous solutions by adsorbents modified with HCl and those activated by microwave radiation. The research objects were carbon adsorbents: activated coals, such as AD-05-2, IPI-T, KAD-iodine and zeolites of the TransBaikal deposit. The quantitative analysis of waters (standardised test solutions with an initial concentration of petroleum products not exceeding 10 mg/l) was carried out by the fluorimetric method using a Fluorat-02 liquid analyser. The adsorbents were activated in a microwave oven at a wave power of 800 W for 1 min. The modification was carried out according to the following procedure: 10 g of the adsorbents dried to a constant weight at a temperature of 120-150 °C were stirred for 24 h with 200 ml of a 12% HCl solution in water.Next, the suspension was filtered and washed with distilled water until neutral. It was found that the value of adsorption of petroleum products by adsorbents modified with HCl increases by 3.8 times for activated carbon KAD-iodine, 0.5 times for IPI-T, and equals 0.71 mg/g and 0.80 mg/g respectively. Among the studied sorbents, these sorbents have the largest grain size (3-5 mm) and micropore volume (0.28-0.29 cm3/g). It was established that the method of short-term (within 1 min) microwave activation makes it possible to increase the adsorption of petroleum products by: 4.2 times for activated carbon KAD-iodine and 0.6 times for IPI-T in comparison with the original adsorbents. The highest adsorption value of petroleum products corresponds to zeolites and equals 0.99 mg/g. The action of microwave radiation is associated with the dissociation and evaporation of the water bound in the adsorbents and flammable organic substances, which leads to an increase in the porosity of the adsorbent. The application of the microwave activation method is highly promising in comparison with the classic methods of chemical and steam-gas activation. This method simplifies the technological design and reduces the consumption of reagents for the production of effective adsorbents used to extract petroleum products from aqueous solutions, which acquires particular importance in the context of maintaining the environmental safety of water use.

Seasonal variation of bacterial load in river and lake waters of Dhaka city, Bangladesh

Surface water is often contaminated due to human excreta and urban and industrial pollution. The increased population growth and industrialization are likely to exacerbate the situation. Microbiological analysis of waters from rivers (Turag and Buriganga) and lakes (Banani and Dhanmondi) around Dhaka city were conducted for Spring, Monsoon and Fall seasons of the year, 2016 and 2017. Total Viable Count (TVC), Total Coliform Count (TCC), Total Fecal Coliform Count (TFCC) and Total Salmonella Shigella Count (TSSC) were conducted to obtain bacterial load in both enriched and without enrichment water samples. All the Isolates were identified by microscopy, cultural characteristics and biochemical methods. Most of the water reservoirs have a decline in the bacterial load in monsoon where the microbial load of pathogens is highest during spring. Without enrichment, E. coli, Enterobacter sp., Klebsiella sp. and S. aureus were abundant, where others like Shigella sp., Proteus sp., Serratia sp., Pseudomonas sp., Acinetobacter sp., and Alcaligenes faecalis mostly exhibited growth following enrichment. Results indicate that pathogenic environmental isolates can cause serious health issue if water is left untreated or poorly treated from reservoirs within and around Dhaka city. Bangladesh J Microbiol, Volume 35 Number 2 December 2018, pp 116-121

Geochemistry exploration environment analysis of waters: the case of the basin of the Great Sebkha of Oran

Water resources are economically and environmentally the most valuable for countries affected by aridity. This study is to identify the factors influencing the quality of the waters of the aquifer system of the Great Sebkha of Oran, one area that is already in a stress situation. The determination of the origin of the salinity of the waters was approached from an analysis of the chemical type. Water mineralization is mainly governed by the phenomena of dissolution and precipitation of minerals (calcite, dolomite, anhydrite, gypsum and halite).

APLICACION DE LA ESPECTROFOTOMETRIA ULTRAVIOLETA PARA DETERMINAR EL OXIGENO DISUELTO EN AGUA POR EL METODO WINKLER

Ultraviolet spectrophotometry as an alternative technique to the thiosulphate titration for the dissolved oxygen evaluation of natural waters byWinkler method was used. Analysis of waters with different salinities (Río Manzanares, Ciénaga Grande, Bahía de Santa Marta) did not show statistically significant differences (p<0.05) between titration and photometry measurements, which suggest this technical modification can be applied in freshwater and marine aquatic systems.