The impacts of different CO 2 concentrations on the growth, physiology and ultrastructure of noncalcifying microalga Chaetoceros gracilis F.Schu¨tt (Diatom) were studied. We incubated Ch. gracilis under different CO 2 concentrations, preindustrial and current ambient atmospheric concentrations (285 and 385 latm, respectively) or predicted year-2100 CO 2 levels (550, 750 and 1050 latm) in continuous culture conditions. The growth of Ch. gracilis measured as cell number was decreased by increasing the pCO 2 concentration from nowadays concentration (385 latm) to 1050 latm. The lowest percentage changes of oxidizable organic matter, nitrite, nitrate, phosphate and silicate were recorded at a higher pCO 2 (1050 latm), and this is in consistence with the lowest recorded cell number indicating unsuitable conditions for the growth of Ch. gracilis. The minimum cell numbers obtained at higher levels of CO 2 clearly demonstrate that, low improvement occurred when the carbon level was raised. This was confirmed by a highly negative correlation between cell number and carbon dioxide partial pressure (r = À0.742, p 6 0.05). On the other hand, highest growth rate at pCO 2 = 385 latm was also confirmed by the maximum uptake of nutrient salts (NO 3 = 68.96 lmol.l À1 , PO 4 = 29.75 lmol.l À1 , Si 2 O 3 = 36.99 lmol.l À1 ). Total protein, carbohydrate and lipid composition showed significant differences (p 6 0.05) at different carbon dioxide concentrations during the exponential growth phase (day 8). Transmission Electron Microscopy of Ch. gracilis showed enlargement of the cell, chloroplast damage, disorganization and disintegration of thylakoid membranes; cell lysis occurs at a higher CO 2 concentration (1050 latm). It is concluded from this regression equation and from the results that the growth of Ch. gracilis is expected to decrease by increasing pCO 2 and increasing ocean acidification.

The treatment of wastewater is a must due to the decrease of clean water and the increase in the consumption of fresh water for domestic uses. This study discusses the physical, chemical, and biological treatments of water from different types of Mariout Lake drains. It also aims at a designation of appropriate wastewater treatment process for sewage water (El-Qalah drain), agriculture water (El-Umoum drain), and raw drinking water before treatment (Nubareya canal) so as to adopt an appropriate procedure to be applied as the drains discharge their wastewaters in Mariout Lake affecting its water quality as well as its fish productivity. Obtaining secure effluents for discharge in natural water bodies (El-Mex bay), or using treated effluents in agriculture or industrial purposes, is a target too, open for estimation. Alum, aeration beside two natural medicinal plants, piper nigrum (Black Pepper) and dry ginger (Zingiber officinalis), and the eukaryotic microorganism yeast, were used for treatment, in addition to the freshwater submerged macrophyte Ceratophyllum demersum.The results of the physicochemical parameters revealed that the best material for treatment in El-Qalaa sewage drain was by Alum + Aeration + Ginger + Ceratophylum demersum.The most preferable material for both the raw drinking water of Nubareya canal and El-Umoum agricultural wastewater was Alum + Aeration + Yeast + Ceratophylum demersum.Regarding the four trace metals' (Zn, Pb, Fe, and Cu) concentration treatments, the best treatment in all cases was found to be Alum + Aeration + Yeast + Ceratophylum demersum, except for Zn in El-Qalaa sewage water which had to be treated by Alum + Aeration + Ginger + Ceratophylum demersum.

Background: Different bacterial isolates were obtained from a much-polluted lake (Lake Mariout) in Alexandria, Egypt. They were tested to bio-remove different heavy metal ions (Cu 2+ , Pb 2+ , Cd 2+ , Co 2+ , Ni 2+ , Zn 2+ , Mn 2+ , and Fe 3+ ). In addition, this study was aimed to create a fixed bed column to enhance the metal removal from some polluted wastewater samples. Results: The potent bacterium was selected and identified as Pseudomonas aeruginosa using the 16SrRNA gene sequence. The effect of some physicochemical parameters on the bio-removal process was studied in batch cultures; it was found the efficiency % of metal removal was increased on using pH 7.5 and bacterial biomass of 750 mg/l. Also, the use of the fixed bed column led to an increase in the removal efficiency % to 100% for the Cu 2+ , Zn 2+ , and Cd 2+ ions and decrease the consuming time from 48 to 24 h under using the optimum incubation conditions, while the removal of Fe 3+ and Pb 2+ showed 62% and 47%, respectively, with a 20% increase compared to the batch system. Conclusion:It was confirmed the use of fixed bed bioreactors was able to increase the efficiency towards the metal removal in polluted environmental samples while decreasing the exhaustion time. Also, Pseudomonas sp. showed great ability to get rid of many harmful health hazard substances.