Modeling of adsorption process establishes mathematical relationship between the interacting process variables and process optimization is important in determining the values of factors for which the response is at maximum. In this paper, response surface methodology was employed for the modeling and optimization of adsorption of phenol onto rice husk activated carbon. Among the action variables considered are activated carbon pretreatment temperature, adsorbent dosage, and initial concentration of phenol, while the response variables are removal efficiency and adsorption capacity. Regression analysis was used to analyze the models developed. The outcome of this research showed that 99.79% and 99.81% of the variations in removal efficiency and adsorption capacity, respectively, are attributed to the three process variables considered, that is, pretreatment temperature, adsorbent dosage, and initial phenol concentration. Therefore, the models can be used to predict the interaction of the process variables. Optimization tests showed that the optimum operating conditions for the adsorption process occurred at initial solute concentration of 40.61 mg/L, pretreatment temperature of 441.46 ∘ C, adsorbent dosage 4 g, adsorption capacity of 0.9595 mg/g, and removal efficiency of 97.16%. These optimum operating conditions were experimentally validated.

<p>In this study, low-cost adsorbent was produced and applied in the treatment of Samaru stream water. Treatment of Samaru stream water was carried out in column mode to determine the efficiency of the low-cost adsorbent for improving the quality of Samaru stream water. To achieve this, the stream water samples were collected from three different points (point 1, 2 and 3) and the values of the following parameters were analyzed before and after treatment: pH, Electrical Conductivity (EC), Total Dissolved Solid (TDS), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Ammonium, Nitrate, Chloride, Iron (III), Copper (II), Lead (II) and Zinc (II). Results obtained from the study show that highest removal efficiency of 96.18 % was attained for chloride and this was followed by 91.76 %, 90.91 % and 90 % for iron (III), copper (II) and ammonium respectively while the least was 6.33 % (pH). Therefore, the high removal efficiency achieved for some sample parameters in the treatment of Samaru stream water implied that the low-cost adsorbent could be employed in the simultaneous removal of contaminants from a multicomponent system.</p>

Unplanned discharges of atmospheric pollutants influenced by intense industrialisation, the population explosion and urbanisation result in injury and damage. The intensity and nature of the damage is a function of the concentration of the pollutant and the duration of exposure (dose). This has immediate (acute) and long (chronic) effects on the quantity and quality of agricultural products.Based on the properties of these pollutants, the resulting effects on the receptor may cause biochemical and physiological modifications at the cellular level as well as whole plant, animal and ecosystem alterations. These may cause significant changes in agricultural output.

Fungi dwelling in soils contaminated by petroleum products can survive on these hydrocarbons due to the highly effective extracellular enzymes. Species belonging to the genus, Aspergillus are known to be efficient degraders of various classes of hydrocarbons as well as other organic contaminants. In this study, the biodegradation of crude oil by Aspergillus niger and Monocillium sp. were compared using laboratory microcosms.The moulds were isolated from a site receiving effluent from a petroleum refinery. They were identified using their macroscopic and microscopic characteristics and subsequently screened for their ability to utilize hydrocarbons for their metabolic requirements. Following the biodegradation studies, Aspergillus niger and Monocillium sp. recorded an increase in hydrocarbon utilizing fungal counts of 8.5 x 107 spores/ml and 6.1 x 107 spores/ml and crude oil weight loss of 80 % and 70 %. Both fungi were tested singly and in a consortium for their ability to degrade crude oil, itwas observed that Monocillium sp. and A.niger performed better when tested individually (94.2 %; 92.8 %) than in consortium (76.3 %). This may suggest that their combined metabolism may have created some antagonistic effect on the degradation process as opposed to their enzymatic capabilities which appeared to be more favourable to the process. The biodegradation experiment analysis showed that contact time plays a  significant role in biodegradation of crude oil (p<0.05), and Monocillium sp. and Aspergillus niger are excellent crude oil degraders and can be usedin the bioremediation of petroleum-contaminated soil and water. Keywords: Biodegradation, Aspergillus niger, Monocillium sp., soil, Crude oil

Activated carbon was produced from rice husk via thermal pretreatment preceding chemical modification with phosphoric acid. In order to study the effect of phosphoric acid modification, the characteristics of the activated carbon produced were determined before and after acid modification and subsequently compared. These characteristics include surface morphology, surface functional groups, surface area, average pore diameter and pore volume. Characterization results showed that modification of the thermally treated rice husk with phosphoric acid enhanced the surface area of the activated carbon from 12.47 to 102.4m 2 /g. The average pore diameter was also enhanced from 2.4 to 1.82nm. It also shows improvement in micropore volume from 0.0052 to 0.034cm 3 /g. SEM analysis confirmed the improvement in surface area and pore development resulting from the phosphoric acid modification while FTIR analysis revealed the existence of phosphorous-oxy-containing functional groups on the surface of the phosphoric acid modified activated carbon.