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During the processing of sewage sludge, highly concentrated wastewater called reject water is generated, characterised by high nitrogen and phosphorus contents. Despite its small share in the inflow of wastewater treatment plants, it might lead to many operational problem in such facilities. Therefore, before it recirculation to main wastewater stream, it should be pre-treated. In this study, a novel strategy using hydrodynamic cavitation (HC) and subsequent absorption and ion exchange using natural zeolites was adopted. In HC experiments, three inlet pressures of 3, 5 and 7 bar and two type of inducer were evaluated. The effectives of HC was examined at 0, 5, 10, 20, 30, 45 and 60 min were evaluated. The absorption and ion exchange experiment was performed in batch mode using clinoptolite. In this case, two contact times were tasted: 0.5 and 24h. The following doses of zeolites will be applied: 50, 100, 200 g/L. The most favourable results in terms of improved biodegradability and removal of ammonium nitrogen and phosphates were obtained using HC orifice plate with 9 cylindrical holes with diameter of 1 mm, pressure of 3 bar and time of 30 min, contact time of 24h and zeolite dose of 200g/L.
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