In this study, vesicular basalt volcanic rock was taken and its application for adsorption of chromium (VI) from aqueous solution was investigated. Different physical and chemical properties of the powdered rock was studied using Fourier transform infrared spectroscopy (FT-IR), Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). A series of batch experiments were carried out to study the effect of various experimental parameters (pH, ionic strength and contact time) on chromium (VI) adsorption. It was found that the removal efficiency of chromium (VI) decreased with increasing pH and ionic strength. The adsorption process was optimal at pH 2. The maximum adsorption capacity was 79.20 mg kg−1 at an initial concentration of 5.0 mg L−1 and adsorbent dosage of 50 g L−1. In individual adsorption tests, Pseudo-second-order kinetic and Freundlich isotherm models could better describe chromium (VI) adsorption on the vesicular basalt. This study indicated that vesicular basalt, which is inexpensive, has the potential to remove chromium (VI) from polluted water.

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Textile dyes are causing serious environmental problems in the world. The treatment of dyes from textile wastewater is necessary to protect the environment. Adsorbents with high adsorption potential from local materials are required to solve these problems. In this study, the treatment of acid yellow 17 dye from aqueous solutions was carried out using an activated bone char, collected from slaughterhouses. The dye removal performance was measured using a UV-Vis spectrometer. Adsorption experiments were carried out in a batch process under different operating conditions including initial dye concentration, adsorbent dose, contact time, and solution pH. From the experimental data, the maximum dye removal efficiency of 91.43% was achieved at an optimum pH of 2, contact time of 120 min, initial dye concentration of 50 mg/L, and adsorbent dose of 20 g/L. The adsorption models: adsorption isotherm and adsorption kinetics of acid yellow 17 dye onto the activated animal bone char, data fitted well with the Langmuir isotherm model (R2 = 0.9245) and pseudo-second-order model (R2 = 0.9967), respectively. This study indicated that the activated bone char, which is obtained from animal slaughterhouses and discharged as waste into the environment has a high potential to remove acid yellow 17 dye from polluted water.

Dye-containing wastewater has been known as a serious environmental treat. There are many treatment methods, but they are not practical in many developing countries. In this study, batch adsorption of acid yellow 17 dye from aqueous solution has been carried out on a lab scale using activated water hyacinth root powder. The dye removal efficiency was measured using UV-Vis spectrometer. Adsorption experiments were carried out in a batch process at different operating parameters including initial dye concentration, adsorbent dose, contact time, and solution pH. From the experimental data, the maximum dye removal efficiency achieved was 92.26% at pH 2, initial dye concentration 50 mg/L, contact time 120 min, and adsorbent dose 20 g/L. Experimental studies indicated Pseudo-second-order kinetic (R2 = 1) and Langmuir isotherm (R2 = 0.953) models could better describe acid yellow 17 dye adsorption on the activated water hyacinth. Adsorption experiments revealed that activated water hyacinth prepared from locally available infesting water bodies had a high potential for removing acid yellow 17 dye from aqueous solution.

Background: Substance use and problems arising from it are increasing all over the world, and currently together with HIV/AIDS epidemic, become one of the most threatening and challenging social and public health problems. College students are more vulnerable to wider sexual and reproductive health and HIV/AIDS problems due to new environment with poor protection, age and the need to explore life, peer pressure and absence of proactive programs. Objective: The main objective of this study was to assess the magnitude of risky sexual behavior and its association with substance use among Bonga town public college students. Methods: A cross-sectional study was conducted among 396 Bonga town public college students from March 2014 to April 2014 using stratified sampling technique and a self-administered questionnaire was used. Descriptive statistics was used to describe the study population, prevalence, and to check the missing values, outliers, and inconsistencies. Logistic regressions to determine independent predictors of risky sexual behaviors and the p-value of 0.05 was used as cut off point for the presence of statistical significance. Results: Among 396 participants 72.7% reported having used at least one substance in their life time. Commonly used substances were: alcohol (51.3%) followed by khat (15.4%), cigarette (3.6%) and other illicit substances (2.5%). From total respondents 38.1% admitted having sexual experience. Among sexually experienced males 4.6% have had sexual intercourse with commercial sex workers and 4.6% had sexual intercourse with more than one person. Condom use rate was 64.9% but, its consistency was 58.3%. Sex, educational status, income and ever use of khat were statistically associated with risky sexual behavior with AOR (95%CI) of 4.5 (1.7, 12), 4.7 (1.6, 12.9), 3.7 (1.4, 10), 2.5 (1.1, 6.5) respectively. Conclusion: The prevalence of substance use among Bonga college students was high. The study also showed that many of the students who were sexually active engaged in unsafe and risky sexual practices. Awareness rising about safer sex and consequences of substance use for college students is necessary measure that should be taken.

Phytoremediation, which is an emerging technology for cleaning up contaminated sites, is cost effective and has aesthetic advantages and long term applicability. The technology involves efficient use of plant species to remove, detoxify or immobilize contaminants in a growth matrix (soil, water or sediments) through natural processes. For this study, swamp smartweed (Polygonum coccineum), para grass (Brachiara mutica) and papyrus (Cyprus papyrus) were grown on 20 mm crushed rock filled plastic vessel watered with synthetic chromium containing solution in a greenhouse under ambient conditions. For comparison, the plants were also grown on both synthetic solution and tannery effluent with known concentration of 0.1, 0.5 and 1 mg/L Cr3+ at Bahir Dar tannery. Plants were harvested after 72 days of planting period and their roots and above ground parts were cleaned and digested through microwave digester for further analysis. Chromium in roots and shoots was determined by ICP-OES. It was observed that all plant species have the ability to remove both Cr3+ and Cr6+ from the aqueous solution for the specified initial concentration. Interestingly, using single factor analysis of variance, significant differences were also observed in their partitioning. All the three plants exhibited a significant transfer of Cr from wastewater to roots and shoots, but removal efficiency of Cr for swamp Smartweed was relatively low as compared to para grass and papyrus. On average translocation factor and removal efficiency of para grass for synthetic solution at 0.5 mg/L level and papyrus for tannery effluent at 1 mg/L level of chromium were relatively high (1.260, 83.08% and 1.715, 73.77% respectively). This finding indicated that all the tested plants (swamp smartweed, para grass and papyrus) can be used for phytoremediation of Cr3+ and Cr6+ containing wastewater discharged from industries.

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