Tertiary Domestic Wastewater Treatment Using Phytoremediation

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Erik Prasant Savariar
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My project is the application of phytoremediation in tertiary wastewater treatment. Phytoremediation is a natural biological process of plants to “remediate” or in other words to remove a particular contaminant from the groundwater or water bodies hence cleaning and purifying the water. There is a wide variety of plants that we can choose from for removing different types of contaminants from ground water or water bodies such as heavy metals and nutrients from the water to prevent eutrophication and destroying aquatic plants and marine life. Eutrophication means that there is extra nutrients in the water namely phosphorus, ammonia and nitrate, these nutrients takes up most of the oxygen from the water bodies and basically suffocating and killing other marine and aquatic plants from flourishing. This specific project is using two plants and algae to remove the nutrients from the tertiary wastewater treatment process, which is the final stage of the wastewater treatment before being discharged into the river. The aim is to determine the optimum hydraulic retention time, removal efficiency and for the algae the optimum concentration of algae to wastewater. This is done in two phases. Phase 1 where the optimum hydraulic retention time and algae concentration to wastewater, by using four beakers of different algae concentrations to wastewater and conducting experiments to test the removal efficiency of phosphorus, ammonia, nitrate and Chemical Oxygen Demand (COD) for a 6 hour time period taking the results of phosphorus, ammonia and nitrate every hour and COD for every 2 hours starting from the first hour. The second phase of the experiments is to determine the hydraulic retention time of 24 hours for the two plants and algae. The initial wastewater concentration sample is taken a day before the experiment and kept in the Environmental laboratory and allowed to react with the aquatic plants and algae in three separate tanks for 24 hours and the experiments of turbidity, colour, pH value, ammonia, nitrate, phosphorus and COD and the results were tested and recorded. The results that were obtain for the phase 1 experiments shows that the best results were obtained for the lowest algae concentration to wastewater and the maximum hydraulic retention time of 6 hours showing that a higher concentration of algae to wastewater does not mean higher removal of nutrients because it changes the effectiveness of algae at removing nutrients and thus the nutrient content was increased compared to the initial wastewater concentration but still reduces over time but still higher than the initial wastewater concentration. For phase 2 of the experiments, the 24 hour hydraulic retention time the experiment was conducted for the two aquatic plants and the algae, however the results of the algae fluctuates with some experiments producing better results compared to the plants. But the plants has a consistent decreasing trend compared to initial wastewater concentration.
FYP Sem 2 2019/2020