- Thesis topic: Ammonia Recovery from Supernatant of Anaerobic Sludge Example of Dihua Wastewater Treatment Plant

- Doi: https://doi.org/10.6840/cycu202000563

- Abstract: 

       Dihua Wastewater Treatment Plant’s sludge has complex composition, but the sludge supernatant is rich in carbon, nitrogen, phosphorus and metal elements, which has recycling value. In this experiment, it use MAP method to recovery the ammonia nitrogen, and to achieve the goal of circular economy, and to supplement the nitrogen and phosphorus removal procedures of the Dihua Wastewater Treatment Plant, which improve processing efficiency. The experiment conducted three-part experiments on the sludge supernatant which after anaerobic digestion in Dihua Wastewater Treatment Plant, water quality analysis, simulation synthesis experiment and anaerobic digestion supernatant synthesis experiment. The results of water quality analysis showed that the average concentration of NH4-N was 1,147 mg/L. About the simulation synthesis experiment, using MgCl, Mg2+: NH4-N = 1:1, pH = 9, temperature = 20°C, reaction for 15 minutes and precipitation for 30 minutes and stirring speed of 250 rpm are the best parameters. As a result of anaerobic digestion supernatant synthesis experiment, the pH adjust to 10, and the temperature adjust to 25°C. After SEM-EDX and XRD, simulation synthesis experiment and anaerobic digestion supernatant synthesis experiment is Mg(NH4)PO4.

       About the costs and benefits, the construction of a plant is about 20 million, and the monthly dosing cost is about 73 million. The benefits Mg(NH4)PO4 is about 5.5 million, carbon supply Dihua Wastewater Treatment Plant which can province about 2.5 million, and save about 3.3 million in electricity bills. Although the current overall net benefit is negative, it can achieve great benefits in terms of environment and reduce the problem of eutrophication. About economy, it can achieve the value of circular economy, which is suitable for future governance directions.

Keywords: sludge supernatant, nitrogen recycle, MAP method, Mg(NH4)PO4.