Phytoplankton role in waste water treatment by stabilization ponds system

In developing countries, oxidation pond system is considered now as a valid means of wastewater treatment, and the effluent can be reused for fish aquaculture or on agricultural land for crop irrigation. Since oxidation ponds require large areas, land should be available at low cost. This could be applied successfully in aired areas affected by water shortage and protein deficiencies. Maturation pond showed their best performance during spring season and at lower detention times in summer and autumn. It was noticed that high temperature, high intensity of light and longer detention times decreased the efficiency of the pond instead of increasing it as a result of the formation of algal mats on the surface. Although algae produce an additional organic load during hot seasons, yet their merits are as follows: [1] They constitute valuable source of oxygen in facultative and maturation ponds, leading to an acceleration in the aerobic degradation of organic compounds. [2] They remove appreciable amounts of nitrogen and phosphorus from the final effluent. [3] They play an important role in raising the pH which acts as a bactericidal factor. [4] Finally, algae serve as food source for the fish Tilapia nilotica in the aquacultural pond. Phytoplankton diversity was found to maintain high values in the maturation ponds confirming successful performance of the system in wastewater treatment

Impact of pollution in Alexandria harbour

This research was conducted to evaluate the status of marine pollution in the harbor, its sources and impacts on the harbor authority. It also focuses on the possible remedies. The harbor survey revealed clearly the direct impacts of the different activities taking place there and the vivid pollution status of the harbor. The physical and chemical characterization of the eighteen selected stations are shown. Mean, standard deviation and range of reported values are based on six sets of data collected all over the year 1989. Starting from the inner harbor, the first zone is used by the Military Navy Academy where their ships dock. Sewage submerged outfalls are discharging domestic waste in this area without treatment from the buildings close to the shore line. Oil pollution is observed clearly due to the improper disposal of lubricating oils and petroleum oil from the ships while fueling. The oil and grease content in station no. 8 which was in a median position of this area showed a value of 29.7 mg/l and a range of 12-46.4 mg/l. Those values are within the highest value recorded in the harbor area. The biological oxygen demand value [BOD] which is a direct measure of the organic load present in this area showed a mean of 74 mg O2/L and a range of 56-112 mg O2.L. The volatile solid mean value was 7.3 x 103 with a range of 4.9 - 9.1 x 103 mg/L. This value indicated the presence of organic matter whether from sewage or from the biomass present in the water as a result of its content of nitrogen, phosphorus and organic matter as a carbon source for active biological growth and algae eutrophication. Bacterial total counts showed 40 to 300/ml, the coliform group counts ranged between zero and 23/100 ml. The E. coli counts recorded a value of 0-3.6 indicating the presence of human sources of pollution

Heavy metals accumulation in crops and soils irrigated with raw and treated wastewater

Application of wastewater effluents with its heavy metals content as originated from the vast array of industrial activity located in Alex. pose a threat on both irrigated land and raised crops with respect to heavy metal accumulation. 2 important crops were selected for this study, corn [Zea mays] as a summer crop and wheat [Triticum aestivum] as a winter crop were grown on lysimeters irrigated with raw, primary, settled, activated sludge, trickling filtered and chemically, aided primary sediment effluent followed by the above mentioned biological treatment were all used as irrigation effluents. Samples of both plants and the surface and subsurface layers of the three tested soils were analyzed for Cd, Cr, Fe, Mn, Ni and Zn contents. The application of different wastewater effluents to the three soils led to heavy metals accumulation in the leaves of both corn and wheat more than in their seeds. Since the green parts of these two crops are used as animal fodder, this will lead to heavy metal accumulation in the animal tissues which is further eaten by humans. The behavior of each metal is discussed with respect to each plant and the three tested soils. The soil surface layer seems to accumulate Cu, Fe, Mb, Pb, and Zn more than the other two soils. Sand soil having high permeability seems to wash down the absorbed heavy metals and lower their content ratios in the soil

Mutagenic effect of inorganic mercury in drosophila melanogaster

The mutagenic effects of mercury chloride and its effects on some fitness components have been investigated on a population of Drosophila melanogaster. The flies were reared on media containing mercury chloride with a concentration below the LC[50] level for six successive generations. The changes in percentage emergence, body size and the frequencies of the sex linked recessive lethals were detected. For the first three generations of the treatment there was a significant decline in the viability of the flies below the control level after which percentage emergence tended to increase towards that level. On the contrary, body size tended to decline with continuous application by the chemical. After six generations of the treatment, body size has been reduced by about 17%. Exposing larvae to mercury chloride led to a considerable increase in the frequency of the sex linked recessive lethals when compared with that in the untreated population