Effect of glucose and lactose on uptake of phenol by lemna minor

Previous researches have demonstrated that presence of some carbohydrates in the culture medium will cause callus induction and frond regeneration in Lemna minor, and it is expected that presence of carbohydrates will affect the uptake of organics by this plant. However, limited studies have investigated the uptake of organics by this plant. The aim of this study was to clarify the effect of conventional carbohydrates such as glucose and lactose on uptake of phenol by Lemna- minor. Experiments were carried out in the presence and absence of glucose and lactose in the growth solution. The growth solution was fresh water collected from river and phenol was added to it. The initial concentrations of phenol were 20, 50 and 100 mg/L and density of Lemna minor [fresh weight] were 50, 100 and 150 g/m[2]. The plants were contacted with growth solutions for 4 weeks. Control bottles [without plants] were examined with the same manner. The bottles were placed under white cool light with 12h photo periods at room temperature. Every four days sample was taken and the concentration of phenol was determined by spectrophotometer. Uptake of phenol by lemna-minor increased with increasing the contact time and decreased by increasing phenol concentration. In the presence of glucose and lactose in the growth solutions, uptake of phenol was decreased. Phenol uptake was dependent to plant density and when Lemna minor completely covered the surface of the water, uptake decreased. In the presence of glucose and lactose, uptake of phenol by Lemna minor was decreased. Uptake of phenol by lemna minor was affected by density of plant

Study of Cadmium Removal from Environmental Water by Biofil Covered Granular Activated Carbon

The contamination of water by toxic heavy metals is a world-wide environmental problem. Discharges containing cadmium, in particular, are strictly controlled due to the highly toxic nature of this element and its tendency to accumulate in the tissues of living organisms. Low concentration [below 5 mg/L] of cadmium is difficult to treat economically using chemical precipitation methodologies. Ion exchange and reverse Osmosis which can guarantee the metal concentration limits required by regulatory st and ards, have high operation and maintenance costs. The goal of this research was to determination of efficacy of using GAC, Biofilm and BAC columns to treat low concentration cadmium bearing water streams and was to determination of the effects of temperature and pH on the adsorption isotherms. Studies were conducted to delineate the effect of pH, temperature, initial Cd and adsorbent concentration on adsorption of Cd2+ by GAC, BAC and Biofilm. Breakthrough curves for removal of 0.5 mg/L Cd2+ by GAC, Biofilm and BAC columns at two contact times were plotted. Batch adsorption and column data are compared, pH is shown to be the decisive parameter in Cd removal for GAC but not for BAC or biofilter. Lagergren plots confirm applicability of first-order rate expression for adsorption of Cd by GAC, BAC and Biofilm. The adsorption coefficient [Kad] for BAC was 2-3 times greater than those with plain GAC. Bed Volumes of water containing 0.5 mg/L Cd2+ treated at breakthrough for GAC, Biofilm and BAC columns were 45, 85 and 180 BV respectively. BAC is more efficient than GAC in the removing of Cd from water environment