Document Type : Original Article
Authors
1
Botany and microbiology department, Faculty of science, Helwan university
2
Department of Agricultural microbiology, Faculty of Agriculture, Minia University, Minia, Egypt
3
Sanitary & Environmental Engineering, Department of Public Works, Faculty of Engineering, Ain Shams University, Cairo, Egypt.
4
Department of Agricultural Engineering, Faculty of Agriculture, Ain Shams University, Cairo, Egypt.
Abstract
This study was carried out to evaluate the efficiency of mixed algal cultures for wastewater treatment. Free and alginate-immobilized forms of mixed algal culture were used. The highest removal percentages of biological oxygen demand (BOD) were 86.4% and 71.2 % after 32hrs and 48 hrs. in case of free and immobilized cells, respectively. Moreover, the highest values of chemical oxygen demand (COD) removal were 83.74% and 59.71% after 32hrs and 48 hrs for free and immobilized cells, respectively. Treatment with free cells showed removal values for total dissolved salts (TDS), phosphorus and NH3-N were 20.5%, 34.6% and 43.8% respectively after 32 hours. While in case of immobilized cells the highest removal values 18.4%, 34% and 58.5%, for TDS, Phosphorus and NH3-N, respectively were recorded after 48 hrs. Generally, concentration of heavy metals decreased due to treatment with algal free and immobilized cells. As a result of treatment with algal free and immobilized cells, 100% and 95.9% of Cu wastewater content was removed after 8 hrs and 48 hrs, respectively. Moreover, 96.2% and 98.1% of Fe was removed after 32 and 48 hours due to application of free and immobilized cells, respectively. As a result of inoculation with the mixed algal cultures in free cells 99.4% of Mn and 84.2% of Zn content were removed after 32 hours. Whereas, 98.6% of Pb content was removed after only 8 hrs. In case of using the immobilized cells the highest removal percentages of the three heavy metals recorded after 48 hours as follow 97.8% of Mn, 89.0% of Pb and 97.37% of Zn. Accordingly, treatment of wastewater with mixed algal free or immobilized cells is a fruitful method to produce an effluent of high quality to be used for irrigation. Whereas, the algal free cells were found to be more efficient than the immobilized ones.
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