ABSTRACT
Currently, white fish or Kutum Rutilus frissi is considered to be a good candidate for commercial aquaculture. However, little information is available regarding the nutritional requirement of this fish fry. Experiments were conducted to examine the effects Daphnia magna as live food cultured on two freshwater green algae, Chlorella sp. and scenedesmus obliquus enriched with different B group vitamin dosages [0.00 as control, 0.50, 1.00 and 2.00 mL of enriching solution per liter of algae culture medium] on the growth and survival rates of Rutilus frisii kutum fry. Results demonstrated that increasing in B group vitamin dosages are caused an increasing in nutritional value [Kcal] of two freshwater green algae species Chlorella sp. and Scenedesmus obliquus significantly. Significant differences were observed in BWG [%] and SGR between different vitamins treatments both the fed Daphnia magnia cultured on Chlorella sp. and Scenedesmus obliquus enriched [P<0.05] but not in survival percentage [P>0.05]
ABSTRACT
The different methods are used for the removal of heavy metals as important contaminants in water and waste water. Biosorption is an alternative to traditional physicochemical in removing toxic metals from wastewaters and groundwater resources. In this study biosorption of lead and chromium ions from solution was studied using Bacillus circulans isolated from Anzali wetland in batch and biofilter modes and optimum conditions were determined. The experimental results showed 900-950 mg/L and 1050-1100 mg/L, for minimum bactericidal concentration and minimum inhibitory concenteration for lead and chromium, respectively. Results of metal concentration in solution containing 500 mg/L in batch culture showed a reduction about 65% and 48% in five and four days for lead and chromium, respectively. The highest value of lead and chromium uptake in solution with 500 mg/L was 78% and 40% in biofilter mode, respectively. The biosorption of lead and chromium were increased up to pH=5.5, 6, 5.5 and 7, respectively. In the other hand, maximum sorption occurred at neutral pH. There was a significant decreasing of biosorption levels by lowering pH fewer than 3. Accumulation of lead and chromium was determined by scanning electron microscopy analysis of the biofilm exposed to 500 mg/L metal concentration. Based on this analysis, the highest metal concentrations were observed in regions with including bacteria